Dissertations / Theses on the topic 'Transport of nutrients'

The overall goal of this research was to improve simulation of soil phosphorus (P) transport and transformations in GLEAMS 3.0, a non-point source model that simulates edge-of-field and bottom-of-root-zone loadings of nutrients from climate-soil-management interactions to assess management alternatives. The objectives of this research were to identify the state of the science for P transport and transformations, determine appropriate relationships for inclusion in GLEAMS, and determine if modifications to GLEAMS improved predictions of P loss in runoff, sediment, and leachate.

The state of the science review revealed numerous equations available to predict dissolved P loss in runoff and leachate from a soilâ s nutrient status. These equations use a single variable to predict P loss and were developed for site-specific conditions based on empirical data. Use of these equations in GLEAMS is not reasonable as transport factors must also be considered when predicting P loss.

Results from the sensitivity analysis showed that GLEAMS prediction of leached P were extremely sensitive to changes in the P partitioning coefficient (CPKD). Runoff PO4-P output was slightly to moderately sensitive, sediment PO4-P was moderately sensitive to sensitive, and sediment organic P was moderately sensitive to changes in CPKD whereas plant uptake of P was insensitive to slightly sensitive. The weakness of GLEAMS to estimate CPKD has been documented. Upon further investigation, it was determined that CPKD was highly over-estimated in GLEAMS as compared to measured values found during the literature review. Furthermore, this over-estimation caused under-estimation of the P extraction coefficient (BETA P); the value of BETA P remained constant at 0.10 and did not vary over the simulation period.

Expressions for CPKD and BETA P were modified in GLEAMS. Data from three published studies (Belle Mina, Gilbert Farm, and Watkinsville) were used in the analyses of three modifications to GLEAMS: GLEAMS BETA P, GLEAMS CPKD, and GLEAMS BETA P+CPKD. GLEAMS BETA P investigated the change in BETA P as a function of soil clay content, GLEAMS CPKD attempted to improve GLEAMSâ estimation of CPKD, and GLEAMS BETA P+CPKD assessed the combined effects of changes to BETA P and CPKD.

Over the respective study periods, GLEAMS over predicted runoff PO4-P for Belle Mina by 193 to 238% while under-predicting runoff PO4-P at Gilbert Farm by 41% and Watkinsville by 81%. Sediment P was over-predicted by GLEAMS for Belle Mina by 225 to 233% and Gilbert Farm by 560%, while sediment P was under-predicted by 62% at Watkinsville. Leached PO4-P was both over- and under-predicted by GLEAMS; Belle Mina was the only data set with observed leached P values.

Simulation results from the model changes were inconclusive. There was no clear evidence supporting use of one model over another. Modifications increased predicted dissolved P in runoff and leachate, while decreasing predicted sediment-bound P in runoff. The original GLEAMS model best predicted runoff and leached PO4-P at the Belle Mina sites. GLEAMS CPKD was the best predictor of runoff PO4-P and sediment P at Gilbert Farm. GLEAMS BETA P+CPKD best predicted runoff PO4-P at Watkinsville. Overall, the proposed improvements to GLEAMS did not improve GLEAMS predictions.

In conclusion, GLEAMS should not be used for quantitative estimates of hydrology, sediment, and nutrient loss for specific management practices. As recommended by the GLEAMS model developers, GLEAMS should only be used to predict relative differences in alternative management systems. It is recommended that future research focus on developing a better correlation between CPKD, clay mineralogy and content, and organic matter content, as CPKD has been identified as a vital component of the GLEAMS P sub-model that requires further examination.

Master of Science

The presence of large-scale Ekman pumping associated with the climatological wind-stress curl is the textbook explanation for low biological activity in the subtropical gyres. Using an idealised model it is shown that Eulerian-mean Ekman pumping may be opposed by an eddy-driven circulation, analogous to the way in which the atmospheric Ferrel cell and the Southern Ocean Deacon cell are opposed by eddy-driven circulations. Potential vorticity fluxes, Lagrangian particle tracking, and depth-density streamfunctions are used to show that, in the model, the rectified effect of eddies acts to largely cancel the Eulerian-mean Ekman downwelling. To distinguish this effect from eddy compensation, it is proposed that the suppression of Eulerian-mean downwelling by eddies be called "eddy cancellation." Eddy cancellation highlights that the thermocline forms a barrier between the surface waters and the abyssal ocean. The presence of this barrier suggests that the nutrient budget of the subtropical mode water and euphotic zone should be considered together. An idealised two-layer axisymmetric model of nutrient concentration in subtropical gyres is developed. This model is used to explore the concept of a unified nutrient budget for the euphotic zone and mode water of subtropical gyres. The steady-state nutrient distribution and fluxes from the idealised model are compared with observations and previous studies. These comparisons show that the solutions of the idealised model are reasonable. Following this validation the sensitivity of the model to changes in parameter values is explored. The model predicts a non-monotonic response to changes in the residual Ekman pumping velocity, with a productivity minimum at 30 m year ^-1. The model also predicts a positive relationship between primary productivity and mode water thickness. The predicted relationship between primary productivity and mode water thickness is tested using observational datasets, which provide some evidence to support the conclusion that thicker mode waters lead to higher productivity in the oligotrophic gyres.

The placenta is thought to play a vital role in the transfer of essential fatty (EFA) and their long-chain polyunsaturated derivatives (LCPUFA) from mother to the fetus. There is a preferential accumulation of these fatty acids from maternal to fetal tissues. However, little was known about the manner in which these nutrients preferentially traversed the placenta. This study investigated part of this placental transport mechanism. The results from these investigations demonstrated that the preferential transport of LCPUFA to the fetal circulation may at least be partially mediated by a preferential uptake system in the placenta involving a 40 kDa, placental membrane fatty acid binding protein (p-FABP_pm). This protein was found exclusively in the maternal facing microvillous membranes. It was characterised as different from previously identified ubiquitous FABP_pm by virtue of having a different pl value, different amino acid composition, no aspartate aminotransferase activity and a higher binding affinity for LCPUFA over non-essential fatty acids. The human choriocarcinoma cell line (BeWo) expressed a protein immunoreactive to anti-p-FABP_pm anti-serum. This anti-serum inhibited the binding of LCPUFA to placental membranes and the uptake of LCPUFA by BeWo cells, to a greater degree than it inhibited the uptake and binding of non essential fatty acids. In addition to p-FABP_pm the existence of multiple types of both cytosolic (L-FABP and H-FABP) and membrane (FAT and FATP) fatty acid-binding proteins was demonstrated in placental cells. These proteins could play important roles in both the uptake of fatty acids by the placenta and in controlling the fate of fatty acids inside placental cells.

Dingle Marsh is a wetland complex separating the Bear River from Bear Lake. Flow direction through the marsh is controlled at four major inflow and outflow sites. These sites were chosen as monitoring sites to assess the suspended solid and nutrient transport through the marsh. High frequency turbidity measurements were collected at each site and used as a surrogate for total phosphorus (TP) and total suspended solid (TSS) concentrations. Loads of TP and TSS were calculated using flow data from the 2008 water year. Load calculations for TP and TSS were compiled at 30-minute intervals and annual mass balances were calculated for Dingle Marsh and Bear Lake. These calculations were used to identify the seasonal loading patterns within this system. This study found the majority of TSS and TP loading entered the marsh from the Bear River. As flows moved across the marsh, the loading of TSS and TP was greatly reduced. Seasonal flow patterns were analyzed to determine the loading patterns to Dingle Marsh, Bear Lake, and the Bear River. This study also identified water management strategies aimed at setting a target endpoint for TSS and TP loads.

Transport of fecal bacteria and nutrients from point and nonpoint sources to surface water bodies is of significant concern in Virginia and the United States. In Virginia, 4,320 river miles are impaired for one or more beneficial use and 72% of the streams are impaired due to pathogen indicators (VDEQ, 2002). Land applications of manure from confined animal systems and by direct deposit by grazing animals are both major sources of fecal bacteria and nutrients in runoff. Therefore, an understanding of the overland transport mechanisms for fecal bacteria and nutrients is very important for the development of best management practices to reduce loading of pathogens and nutrients to surface water bodies. The objectives of this study were to quantify the release and transport potential of three fecal bacterial indicators: E. coli, Enterococcus, and fecal coliforms; and nitrogen and phosphorus from land applied manure during runoff events. Another objective was to identify the Enterococcus species present in dairy manure and determine which species have the highest potential to be transported by runoff.

Release plots were established to study the in-field bacteria and nutrient release. The bacteria and nutrients released from the plots are available to be transported to the edge of the field in runoff. Four manure treatments (turkey litter, liquid dairy manure, cowpies, and none or control) and three land type treatments: pasture with a history of poultry litter application (Turkey Farm), pasture with a history of liquid dairy manure application (Dairy Farm), and pasture with no prior manure application (Tech Research Farm) were studied. During a short but intense rainfall event, the highest bacterial release was measured under the cowpie treatment (E. coli concentrations ranging from 37,000 to >300,000 and FC concentrations ranging from 65,000 to >300,000). Pasturelands with a history of previous manure applications did not release higher bacteria concentrations compared with pasturelands which had never received manure applications. Pasturelands with a history of land application of liquid dairy manure and turkey litter had 143% and 94% higher TSS concentrations available to be transported off the field during overland flow events because of the build up of organic material on the soil surface. TP concentrations released from the cowpie, liquid dairy, and turkey litter treatments were 3.12 mg/L, 3.00 mg/L, and 1.76 mg/L, respectively.

Transport plots were developed to measure the concentrations of fecal bacteria and nutrients present in overland flow at the edge of the field. The bacteria flow-weighted concentrations were highest in runoff samples from the plots treated with cowpies (200,000 CFU/100 mL of E. coli and 234,000 CFU/100 mL of FC). The turkey litter had the highest concentration of dissolved phosphorus in runoff from pasturelands (1.22 mg/L), but the cowpie treatment had the highest concentrations of sediment bound phosphorus in runoff (0.73 mg/L). All three treatments investigated in this study contributed to phosphorus loading in surface waters and could potentially increase the risk of eutrophication. Total nitrogen concentrations from the transport plots exceeded the threshold for likely eutrophication problems for all treatments and the total nitrogen concentrations from plots treated with cowpies exceeded the threshold for severe eutrophication problems.

The Biolog System, a method of bacterial source tracking, was used to identify the different species of Enterococcus present both in the cowpie source manure and in the runoff collected from the transport plots treated with cowpies. The source manure is dominated by the Enterococcus mundtii (55%), Enterococcus gallinarum (20%), Enterococcus faecium (10%), and Enterococcus faecalis (10%). Enterococcus faecalis had the highest percentage of isolates present in runoff with a total of 37%, followed by Enterococcus mundtii which was present in 21% of the runoff events and Enterococcus gallinarum and Enterococcus faecium (11%).

Improvements in understanding the bacterial release and overland processes will enhance modeling of bacteria and nutrient transport, and provide a basis for a more realistic evaluation of the impacts of management practices implementation. The data from this study will serve as a baseline to model the release and transport of fecal bacteria and nutrients from agricultural watersheds to surface waters.

Master of Science

The U.S. EPA has identified pathogen indicators as a leading cause of impairments in rivers and streams in the U.S. Elevated levels of bacteria in streams draining the agricultural watersheds cause concern because they indicate the potential presence of pathogenic organisms. Limited understanding of how bacteria survive in the environment and are released from fecal matter and transported along overland flow pathways results in high uncertainty in the design and selection of appropriate best management practices (BMPs) and in the bacterial fate and transport models used to identify sources of pathogens. The overall goal of this study was to improve understanding of the fate and transport mechanisms of two pathogen indicators, E. coli and enterococci, from grazed pasturelands. This goal was addressed by monitoring pathogen indicator concentrations in fresh fecal deposits for an extended period of time. Transport mechanisms of pathogen indicators were examined by developing a method to partition between the attached and unattached phases and then applying this method to analyze runoff samples collected from small box plots and large transport plots. The box plot experiments examined the partitioning of pathogen indicators in runoff from three different soil types while the transport plot experiments examined partitioning at the edge-of-the-field from well-managed and poorly-managed pasturelands. A variety of techniques have been previously used to assess bacterial attachment to particulates including filtration, fractional filtration and centrifugation. In addition, a variety of chemical and physical dispersion techniques are employed to release attached and bioflocculated cells from particulates. This research developed and validated an easy-to-replicate laboratory procedure for separation of unattached from attached E. coli with the ability to identify particle sizes to which indicators preferentially attach. Testing of physical and chemical dispersion techniques identified a hand shaker treatment for 10 minutes followed by dilutions in 1,000 mg L-1 of Tween-85 as increasing total E. coli concentrations by 31% (P value = 0.0028) and enterococci concentrations by 17% (P value = 0.3425) when compared to a control. Separation of the unattached and attached fractions was achieved by fractional filtration followed by centrifugation. Samples receiving the filtration and centrifugation treatments did not produce statistically different E. coli (P value = 0.97) or enterococci (P value = 0.83) concentrations when compared to a control, indicating that damage was not inflicted upon the cells during the separation procedure. In-field monitoring of E. coli and enterococci re-growth and decay patterns in cowpats applied to pasturelands was conducted during the spring, summer, fall and winter seasons. First order approximations were used to determine die-off rate coefficients and decimal reduction times (D-values). Higher order approximations and weather parameters were evaluated by multiple regression analysis to identify environmental parameters impacting in-field E. coli and enterococci decay. First order kinetics approximated E. coli and enterococci decay rates with regression coefficients ranging from 0.70 to 0.90. Die-off rate constants were greatest in cowpats applied to pasture during late winter and monitored into summer months for E. coli (k = 0.0995 d-1) and applied to the field during the summer and monitored until December for enterococci (k = 0.0978 d-1). Decay rates were lowest in cowpats applied to the pasture during the fall and monitored over the winter (k = 0.0581 d-1 for E. coli and k = 0.0557 d-1 for enterococci). Higher order approximations and the addition of weather variables improved regression coefficients (R2) to values ranging from 0.81 to 0.97. Statistically significant variables used in the models for predicting bacterial decay included temperature, solar radiation, rainfall and relative humidity. Attachment of E. coli and enterococci to particulates present in runoff from highly erodible soils was evaluated through the application of rainfall to small box plots containing different soil types. Partitioning varied by indicator and by soil type. In general, enterococci had a higher percent attached to the silty loam (49%) and silty clay loam (43%) soils while E. coli had a higher percent attached to the loamy fine sand soils (43%). At least 50% of all attached E. coli and enterococci were associated with sediment and organic particles ranging from 8 â 62 μm in diameter. Much lower attachment rates were observed from runoff samples collected at the edge-of-the-field, regardless of pastureland management strategy. On average, 4.8% of E. coli and 13% of enterococci were attached to particulates in runoff from well-managed pasturelands. A second transport plot study found that on average only 0.06% of E. coli PC and 0.98% of enterococci were attached to particulates in runoff from well-managed pasturelands, but percent attachment increased slightly in runoff from poorly-managed pasture with 2.8% of E. coli and 1.23% of enterococci attached to particulates. Equations to predict E. coli and enterococci loading rates in the attached and unattached forms as a function of total suspended solids (TSS), phosphorous and organic carbon loading rates appeared to be a promising tool for improving prediction of bacterial loading rates from grazed pasturelands (R2 values ranged from 0.61 to 0.99). This study provides field-based seasonal die-off rate coefficients and higher order approximations to improve predictions of indicator re-growth and decay patterns. The transport studies provide partitioning coefficients that can be implemented into NPS models to improve predictions of bacterial concentrations in surface waters and regression equations to predict bacterial partitioning and loading based on TSS and nutrient data. Best management practices to reduce bacterial loadings to the edge-of-the-field from pasturelands (regardless of management strategy) should focus on retention of pathogen indicators moving through overland flow pathways in the unattached state. Settling of particulates prior to release of runoff to surface waters might be an appropriate method of reducing bacterial loadings by as much as 50% from highly erodible soils.
Ph. D.

The increase of animal agriculture coupled with excess manure production, and the reduced availability of land has led to the over application of animal manure on agricultural fields. The excessive application of manure is responsible for nutrient and bacterial pollution of downstream waterbodies. Manure application based on the crop phosphorus (P) requirements has been recommended as a viable method to reduce nutrient pollution. A plot scale study was conducted to measure the loss of nutrients and bacterial transport in runoff from cropland treated with poultry litter, dairy manure and inorganic fertilizer according to the P requirements of the crop. Three simulated rainfall events were conducted 1, 2 and 35 days after planting of corn. Highest P and N concentrations were observed in the runoff from plots treated with poultry litter, followed by dairy manure and inorganic fertilizer. The poultry litter treated plots exhibited highest concentrations of bioavailable P in the runoff, compared to all other treatments. The P from poultry litter treated plots was also mostly in the soluble form, which underscores the need to control the runoff from cropland in order to decrease the P losses from the poultry litter treated fields. The edge of the field nutrient concentrations observed in this study were high enough to cause severe to moderate eutrophication problems in downstream waterbodies unless they are diluted. In general, nutrient concentrations were lower during the second simulated event, compared with those from the first event. A significant reduction in the nutrient concentrations of runoff was observed from the second to the third simulated event for all the treatments. This reduction was attributed to the loss of nutrients by natural rainfall-runoff events during the time period between the second and the third simulated rainfall event, plant uptake of nutrients, sorption and leaching processes. The indicator bacteria analyzed in the present study were fecal Coliform (FC), Escherichia Coli (E.Coli) and Enterococcus (ENT). The bacterial concentrations reported in the runoff for the first and second simulated events were 104 to 105 times higher than the federal and state limits for primary contact recreation waters. No significant effect of treatments was observed on the bacterial concentrations in runoff. The highest concentrations were observed for FC, followed by ENT and EC in the runoff. The ratio of bacteria removed in runoff to the bacteria applied also followed the above trend. The concentrations of bacteria generally increased from the first to second simulated event; unlike the nutrients. However, the bacterial concentrations dropped significantly from second to the third simulated rainfall event to the levels lower than those designated for primary contact recreation water limits. This reduction was attributed to the washing away of bacteria by the heavy rainfall-runoff events in the period between second and third simulated rainfall events and the die-off of bacteria. The results reported from this study suggest that the manure application based on crop P requirements can also be a significant source of nutrient pollution and should be coupled with other best management practices (BMPs) also to reduce nutrient pollution. The results also suggest that the manure treated cropland can be a source for significant indicator bacterial pollution and appropriate BMPs are required to mitigate their effect.
Master of Science

Abstract Peatland drainage changes catchment conditions and increases the transport of suspended solids (SS) and nutrients. New knowledge and management methods are needed to reduce SS loading from these areas. This thesis examines sediment delivery and erosion processes in a number of peatland drainage areas and catchments in order to determine the effects of drainage on sediment and erosion dynamics and mechanics. Results from studies performed in peat mining, peatland forestry and disturbed headwater catchments in Finland are presented and potential sediment load management methods are discussed for drainage areas and headwater brooks. Particular attention is devoted to erosion of organic peat, sediment transport and methods to reduce the impacts of peatland drainage in boreal headwaters. This thesis consists of six articles. The first and second papers focus on the erosion and sediment transport processes at peat harvesting and peatland forestry drainage networks. The results indicate that in-channel processes are important in drained peatland, since the drainage network often constitutes temporary inter-storm storage for eroding and transporting material. Sediment properties determine the bed sediment erosion sensitivity, as fluffy organic peat sediment consolidates over time. As flashiness and peak runoff control sediment entrainment and transport from drained peatland areas, water quality management should include peak runoff management. The third, fourth and fifth papers studies use and application of peak runoff control (PRC) method to the peat harvesting and peatland forestry conditions for water protection. Results indicate that effective water quality management in drained peatland areas can be achieved using this method. Installation of the PRC structures is a useful and cost-effective way of storing storm runoff waters temporarily in the ditch system and providing a retention time for eroded sediment to settle to the ditch bed and drainage network. The main effect of the PRC is on SS and SS-bound nutrients. The sixth paper is concentrated to test new restoration structure to be used in degraded headwater brooks. The results show that addition of woody restoration structures to the channel is effective and simple sediment management methods in headwater areas. New information provided in this thesis on sediment erosion and transport processes in drained peatland areas can help to improve water quality control in these areas. In-channel processes are important for both peatland uses, since the drainage network often constitutes temporary inter-storm storage for eroding and transporting material. Therefore, controlling these processes is a key to effective water quality management, which can be achieved using the PRC method in drainage areas or by utilisation of natural fluvial processes in natural channels downstream.

La symbiose mycorhizienne entre les champignons du sol et les racines de la plupart des plantes constitue une relation à bénéfice réciproque et joue un rôle majeur dans la productivité des écosystèmes. Les récentes avancées dans le domaine ont abouties à l'identification et à la caractérisation fonctionnelle de nombreux systèmes de transport du partenaire fongique. Le travail présenté s'inscrit dans le cadre de développement d'outils permettant la localisation de gènes d'intérêts du champignon ectomycorhizien Hebeloma cylindrosporum et de leur caractérisation fonctionnelle. Les systèmes de transport candidats ont été identifiés au sein d'une banque EST du champignon et semblent impliqués dans les échanges de phosphate (Pi) et de potassium (K+) entre Hebeloma et la plante hôte Pinus pinaster. Une stratégie de fusion transcriptionnelle utilisant l'EGFP comme gène rapporteur a été développée pour permettre la localisation de deux transporteurs de phosphate, HcPT1 et HcPT2, d'un transporteur de potassium, HcTrk1, et d'un canal potassique de type Shaker, HcSKC1, dans les hyphes en culture pure et au sein de l'ectomycorhize. Les Agrotransformations de la souche h7 d'Hebeloma avec des vecteurs de fusion transcriptionnelle ont montré une expression mycélienne de l'EGFP sous contrôle des promoteurs de nos gènes d'intérêts. Sous contrôle des différents promoteurs, l'expression de l'EGFP apparait comme étant site-spécifique dans les hyphes différenciés des ectomycorhizes. Le promoteur du transporteur de Pi HcPT1 induit l'expression du gène rapporteur au niveau des hyphes extramatriciels et du manteau mycélien entourant la racine. De plus, son expression est stimulée en cas de carence en Pi, indiquant ainsi l'implication de ce transporteur dans la récupération du Pi du sol lorsque celui-ci devient limitant. Pour ce qui est du promoteur de HcTrk1, il permet l'expression de l'EGFP dans les hyphes extraracinaires et dans le manteau, tandis que celui de HcSKC1 permet son expression au niveau du réseau de Hartig et du manteau. Ceci indique, qu'ils semblent respectivement participer à la récupération du K+ du sol et à son excrétion vers la plante. Pour poursuivre la caractérisation fonctionnelle de nos systèmes de transport candidats, un second canal potassique, HcSKC2, a été isolé à partir de la souche h1 et exprimé dans des ovocytes de xénope. Tout comme HcSKC1, HcSKC2 n'a pas été actif en système d'expression hétérologue. Cependant, des fusions traductionnelles avec l'EGFP ont montré que la protéine HcSKC2 est bien dirigée à la membrane. En perspective, la caractérisation fonctionnelle de ce canal issue de la souche h7 récemment séquencée sera tentée
The mycorrhizal symbiosis made it possible the first plants to conquest emerged lands and is a major biological phenomenon of terrestrial ecosystems. The fungal partner efficiently takes up nutritive ions from the soil solution and transfers them to the host plants in exchange for photosynthetates. However, despite the importance of this symbiosis on ecosystem productivity, our knowledge about molecular processes controlling this symbiotic interaction and solute transports at the membrane level is very scarce. The objective of the project aims at dissecting part of the molecular mechanisms required for a functional ectomycorrhizal symbiosis associated with most of the woody species from boreal and temperate forests, by focusing on K+ exchanges occurring through the continuum soil-hyphae-plant. The general aim of the project is to gain new insights into the molecular mechanisms responsible for the polarization and differentiation of the plasma membrane between the site of nutrient uptake and the site of efflux into the apoplastic space in the ectomycorrhizal root. The team "Canaux Ioniques – Ion channels" has obtained an EST library of the fungus Hebeloma cylindrosporum (1) and has identified and characterized a potassium transporter of the Trk family (2). Also a Shaker-type potassium cannel was identified within the EST library but it is not yet functionally characterized. A second transcript was found from this channel with a longer N-terminus compared to the first transcript isolated in the beginning. Also, a sugar transporter was identified among the ESTs that could participate in the absorption of sugars, coming from the host plant, by the fungus. The objective of the PhD thesis is the functional characterization of these fungal transport systems as well as their localization. The functional characterization of these candidate genes will be accomplished using heterologous expression systems (Xenopus oocytes, COS cells, complementation of yeast mutants) and by the means of electrophysiology. Localization of genes within the fungus being in symbiotic interaction with the host plant, the tree Pinus pinaster, will help to better understand the role of the transport systems. The differentiation of the fungus, when establishing symbiosis, into the specialized interfaces soil-fungus and fungal cell- host plant cell within the ectomycorrhiza (Hartig net) is probably accompanied by a specific expression of transport proteins and ion channels

No intuito de identificar as relações entre as variações espaciais e temporais da biomassa e produção primária fitoplanctônica frente às variáveis físicas e químicas da coluna de água, foram realizadas coletas mensais de parâmetros físicos, químicos (nutrientes inorgânicos), séston e biomassa fitoplanctônica em 4 estações oceanográficas localizadas na baía e 3 no canal de Santos no período entre novembro de 2004 a dezembro de 2005. O transporte de propriedades entre os canais estuarinos e a baía foi estimado através de medidas realizadas em estações fixas, nas entradas dos canais de Santos e São Vicente, durante um ciclo completo de maré (13h). Os principais fatores limitantes ao desenvolvimento da biomassa fitoplanctônica e da produtividade primária foram: a disponibilidade de luz, a estratificação da coluna de água e a temperatura. Os canais de Santos e São Vicente atuaram como importadores de sal, nutrientes e biomassa fitoplanctônica na maioria das ocasiões estudadas. Os elevados teores de nutrientes inorgânicos dissolvidos, associados à ausência de correlação entre nutrientes e biomassa, indicam que não há limitação nutricional, apesar das condições distróficas observadas. Os altos teores de Cl-a (média de 10,1 mg m-3) indicam que o ambiente continua apresentando características eutróficas, já reportadas em trabalhos realizados na área há mais de 30 anos.
The relationship between time-space variations of phytoplankton biomass and primary productivity and the variability in physical and chemical characteristics of the water column was investigated by monthly samplings of temperature, salinity, inorganic nutrients, seston and phytoplankton biomass in 4 oceanographic stations in Santos Bay and 3 stations in Santos Channel, during the period from November 2004 to December 2005. The transport of properties between estuarine channels and the bay was estimated by measurements conducted in fixed stations located at Santos and São Vicente Channels inlets throughout a complete tidal cycle (13h). The main limiting factors to phytoplankton biomass development were: light availability, water column stratification and temperature. Santos and São Vicente channels imported salt, nutrients and phytoplankton biomass in the majority of the studied cases. High levels of dissolved inorganic nutrients and biomass indicate no nutritional limitation, despite the dystrophic conditions observed. High chlorophyll-a concentrations (mean value 9.82 mg m-3) indicate the environment still displays the eutrophic characteristics already reported in former studies conducted in this area by more than 30 years ago.

Les rivières sont une source importante de constituants biogéochimiques pour les océans. Jusqu’à présent, les modèles océaniques globaux représentaient de manière inadéquate ou ignoraient simplement les apports continentaux de nutriments, de carbone, d’alcalinité provenant des rivières. En particulier, les perturbations anthropiques des apports fluviaux au cours du 20 ème siècle et leurs conséquences sur l’état physique et biogéochimique des océans - notamment la zone côtière - n’ont pas encore été analysées à l’aide d’un modèle global prenant en compte la circulation tridimensionnelle de l’océan. L’objectif principal de cette thèse était donc d’intégrer les apports biogéochimiques provenant des rivières dans un modèle océanique global afin d’améliorer la compréhension du cycle du carbone de l’océan côtier et son évolution au cours du 20 ème siècle. Dans un premier temps, mon travail a visé à l’amélioration des connaissances concernant le rôle des apports biogéochimiques fluviaux sur le cycle du carbone océanique à long-terme, en se focalisant sur la période préindustrielle. Pour cela, j’ai estimé les apports des rivières en utilisant des modèles permettant d’estimer l’érosion chimique et le transfert de matière organique desécosystèmes terrestres à l’océan. Ces apports fluviaux ont ensuite été ajoutés dans le modèle biogéochimique océanique HAMOCC et leurs impacts sur la production primaire océanique et les flux de CO2 entre l’atmosphère et l’océan ont été analysés. Les résultats nous ont permis de quantifier un dégazage de CO 2 préindustriel de 0.23 Pg C yr -1 pour l’océan global, principalement localisé à proximité de l’embouchure des rivières. Le modèle a également démontré l’existence d’un transfert inter-hémisphèrique de carbone, avec un plus grand apport des rivières à l’océan dans l’hémisphère nord, et un transfert de l’hémisphère nord à l’hémisphère sud où un dégazage net se produit. Une augmentation considérable de la production primaire océanique induite par les apports des rivières a également été prédite.La modélisation biogéochimique de l’océan côtier a ensuite été améliorée, en augmentant la vitesse de minéralisation de la matière organique dans les sédiments côtiers et en incluant la dégradation de la matière organique dissoute d’origine terrestre (tDOM) dans l’océan. Par ailleurs, notre analyse suggère un temps de résidence des eaux dans la zone côtière significativement plus courte (14-16 mois en moyenne) que celui estimé jusqu’à présent (>4 ans). Ce temps de courte résidence implique un transfert efficace de matière organiquede l’océan côtier à l’océan ouvert, un état autotrophe net de l’océan côtier, ainsi qu’un puit de CO 2 (0.06-0.08 Pg C yr -1) pour la période préindustrielle, contrairement aux hypothèses précédemment proposées dans la littérature.Dans le dernier chapitre, les perturbations océaniques induites par les changements de la concentration en CO 2 dans l’atmosphère, de la physique de l’océan et des apports biogéochimiques fluviaux au cours du 20 ème siècle ont été analysées. Les résultats indiquent que la réduction de production primaire nette (NPP) observée dans les océans tropicaux et subtropicaux, pourrait être entièrement compensée par une augmentation de la NPP dans l’océan austral et dans les systèmes côtiers de type «EBUS». Les simulations montrent aussi que l’augmentation des apports fluviaux provoque une augmentation de NPP océanique à l’échelle de l’océan côtier (+15 %) et à l’échelle globale (+ 4 %). En conclusion, cette thèse a permis de démontrer l’importance d’inclure la variabilité spatio-temporelle des apports fluviaux et des processus biogéochimiques de l’océan côtier dans la description du cycle du carbone océanique global. Les améliorations apportées au modèle océanique global HAMOCC permettront d’affiner les prédictions du rôle de l’océan dans le cycle du carbone au cours du 21 ème siècle.
River deliver vast amounts of terrestrially derived compounds to the ocean. These fluxes are of particular importance for the coastal ocean, which is recognized as a region of disproportionate contribution to global oceanic biological fluxes. Until now, the riverine carbon, nutrient and alkalinity inputs have been poorly represented or omitted in global ocean biogeochemistry models. In particular, there has yet to be a model that considers the pre-industrial riverine loads of biogeochemical compounds to the ocean, and terrestrial inputs of organic matter are greatly simplified in their composition and reactivities in the ocean. Furthermore, the coastal ocean and its contribution to the globalcarbon cycle have remained enigmatic, with little attention being paid to this area of high biological productivity in global model analysis of carbon fluxes. Lastly, 20 th century perturbations in riverine fluxes as well as of the physical and biogeochemical states of the coastal ocean have remained unexplored in a 3-dimensional model. Thus, the main goals of this thesis are to integrate an improved representation of riverine supplies in a global ocean model, as well as to improve the representation of the coastal ocean in the model, in order to solve open questions with respect its global contributions to carbon cycling.In this thesis, I first aimed to close gaps of knowledge in the long-term implications of pre-industrial riverine loads for the oceanic cycling of carbon in a novel framework. I estimated pre-industrial biogeochemical riverine loads and their spatial distributions derived from Earth System Model variables while using a hierarchy of state-of-the-art weathering and organic matter land-ocean export models. I incorporated these loads into the global ocean biogeochemical model HAMOCC and investigated the induced changes in oceanic biological production and in the air-sea carbon flux, both at the global scale and in a regional shelf analysis. Finally, I summarized the results by assessing the net land sink of atmospheric carbon prescribed by the terrestrial models, and comparing it to the long-term carbon outgassing determined in the ocean model. The study reveals a pre-industrial oceanic outgassing flux of 231 Tg C yr -1 ,which is found to a large degree in proximity to the river mouths. The model also indicates an interhemispheric transfer of carbon from dominant northern hemisphere riverine inputs to outgassing in the southern hemisphere. Furthermore, I observe substantial riverine-induced increases in biological productivity in the tropical West Atlantic (+166 %), the Bay of Bengal (+377 %) and in the East China Sea (+71 %), in comparison to a model simulation which does not consider the riverine inputs.In addition to considering supplies provided by riverine fluxes, the biogeochemical representation of the coastal ocean is improved in HAMOCC, by firstly increasing organic matter remineralization rates in the coastal sediment and by secondly explicitly representing the breakdown process of terrestrial dissolved organic matter (tDOM) in the ocean. In an analysis of the coastal fluxes, the model shows a much shorter residence time of coastal waters (14-16 months) than previously assumed, which leads to an efficient cross-shelf transport of organic matter and a net autotrophic state for both the pre-industrial timeframe and the present day. The coastal ocean is also revealed as a CO2 sink for the pre-industrial time period (0.06-0.08 Pg C yr -1 ) in contrary to to the suggested source in published literature. The sink is however not only caused by the autotrophic state of the coastal ocean, but it is likely also strongly influenced by the effects of biological alkalinity production, as well as both physical and biogeochemical characteristics of open ocean inflows.In the final chapter, 20 th century oceanic perturbations due to changes in atmospheric CO 2 concentrations and in the physical climate, and to increases in riverine nutrient supplies were investigated by using sequential model simulations. The model results show that the decrease in the net primary production (NPP) in the tropical and subtropical oceans due to temperature-induced stratification may be completely compensated by increases in the Southern Ocean and in Eastern Boundary Upwelling Systems (EBUS). The model also reveals that including increases in riverine supplies causes a global ocean NPP increase of +4 %, with the coastal ocean being a particularlystrongly affected region (+15 %).This thesis shows a strong necessity to represent spatio-temporal changes in riverine supplies and of the coastal ocean state in spatially explicit global models in order to assess changes of the global cycling of carbon in the ocean in the past and potentially in the future.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Oceanografia Física, Química e Geológica, Instituto de Oceanografia, 2007.
Submitted by Cristiane Silva (cristiane_gomides@hotmail.com) on 2013-02-18T17:26:18Z No. of bitstreams: 1 2007_karina_attisano.pdf: 8850374 bytes, checksum: 292caec84f69bf4efc38580f79e98729 (MD5)
Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2013-06-13T18:40:54Z (GMT) No. of bitstreams: 1 2007_karina_attisano.pdf: 8850374 bytes, checksum: 292caec84f69bf4efc38580f79e98729 (MD5)
Made available in DSpace on 2013-06-13T18:40:54Z (GMT). No. of bitstreams: 1 2007_karina_attisano.pdf: 8850374 bytes, checksum: 292caec84f69bf4efc38580f79e98729 (MD5) Previous issue date: 2007
A costa sul do Brasil, constituída pelas áreas costeiras e oceânicas do Rio Grande do Sul e Santa Catarina, é conhecida como uma das regiões de maior potencial pesqueiro de todo o litoral brasileiro. Isto se deve, sobretudo, a presença de várias massas de água que interagem formando um sistema complexo, dinâmico e altamente produtivo. Além dos intensos processos de mistura, essas regiões apresentam frentes termohalinas e ação de ventos. O presente trabalho apresenta um diagnóstico comparativo, de enfoque químico, entre a plataforma das regiões de Santa Marta (SC) e Albardão (RS). Para tanto, são utilizados parâmetros hidroquímicos, amostrados em 33 estações oceanográficas importantes para a avaliação da produção biológica, e também a interpretação dos processos oceanográficos. Ao efetuar a comparação entre as referidas regiões de plataforma, durante o inverno de 2005, observou-se claramente maiores concentrações de nutrientes dissolvidos na região do Albardão, devido a menor influência da Água Tropical, apresentando-se submetida a processos oceanográficos mais intensos resultantes da proximidade à Convergência Subtropical, da intrusão da Água Subtropical de Plataforma (através do paleocanal), da formação da Frente Subtropical de Plataforma, frentes frias e do volume de descarga continental substancial proveniente do Rio do Prata, Lagoa dos Patos e do transporte subterrâneo que potencializam a dinâmica entre as massas de água, elevando a produtividade da região.
The southern Brazilian Coast comprises of the coastal and oceanic areas of Rio Grande do Sul and Santa Catarina and is a region with the highest fishing potential along the Brazilian coast. This is due to the presence of several water masses that interact form a complex, dynamic and highly productive system. Mixing is also provided by thermohaline fronts, upwelling and wind. The present work presents a diagnosis, using hydrochemical data, between Santa Marta Shelf (SC) and Albardão (RS) (33 oceanographic stations) to determine biological production and other oceanographical processes. During the 2005 winter there were higher nutrients concentrations in Albardão zone, due to less influence of Tropical Water. There is high productivity in the region due to mixing of water masses by proximity to Subtropical Convergence, intrusion of the Subtropical Water on to the Shelf (through the paleochannel), formation of Subtropical Shelf Front, groundwater transport, cold fronts discharge from Prata River, Patos Lagoon.

River-floodplain connectivity is defined as the water mediated transfer of materials and energy between a river or stream and its adjacent floodplain. It is generally accepted that restoring and/or enhancing river-floodplain connectivity can reduce the downstream flux of reactive solutes such as nitrogen (N) and phosphorus (P) and thus improve downstream water quality. However, there is little scientific literature to guide ecological engineering efforts which optimize river-floodplain connectivity for solute retention. Therefore, the aim of my dissertation research was to examine feedbacks between inundation hydrology and floodplain biogeochemistry, with an emphasis on analyzing variation experienced along the river continuum and the cumulative effects of river-floodplain connectivity at the basin scale. This was completed through four independent investigations. Field sites ranged from the Atchafalaya River Basin, the largest river-floodplain system in the continental US, to the floodplain of a recently restored headwater stream in Appalachia. We also developed a method to examine river-floodplain connectivity across large- river networks and applied that methodology to US stream network. Largely, our results highlight the role floodwater residence time distributions play in floodplain biogeochemistry. In headwater streams, residence times restrict redox dependent processes (e.g. denitrification) and downstream flushing of reactive solutes is the dominant process. However, in large-river floodplains, redox dependent processes can become solute limited because of prolonged residence times and hydrologic isolation. In these floodplains, the dominant process is often autochthonous solute accumulation. Further, results from our modeling study suggest large-river floodplains have a greater impact on downstream water quality than floodplains associated with smaller streams, even when considering cumulative effects across the entire river network.
Ph. D.

[Truncated abstract] Most of Australia, and large areas of many other continents, is drained by intermittent rivers and streams, however comparatively few biogeochemical studies have been completed for these systems. Intermittent, dryland streams are highly dynamic environments subject to unpredictable and sporadic flow. Natural disturbance from lengthy drought periods and sudden floods are typical for these systems. Without adequate baselines for natural disturbances, it is difficult to quantify other effects from anthropogenic disturbance such as dewatering, land clearing, and urbanisation, or climate change. This thesis presents work from a four-year study examining the biogeochemistry of nitrogen (N), phosphorus (P) and carbon (C) in soils and sediments of two intermittent streams (Barnett Creek and Pirraburdoo Creek) in the Pilbara region of north-west Australia. The Pilbara is an area of ancient geology and highly weathered environments that is undergoing rapid development yet is poorly understood from an ecological perspective. The principal objectives of this thesis were to determine: i) how flooding affects the spatiotemporal patterns of nutrients in intermittent stream landscapes; ii) the role of flooding in N and C mineralisation and microbial dynamics; and iii) the connections between benthic algae, microbes and nutrient availability in channel sediments. To address these objectives, three field studies and two incubation experiments were conducted. Field studies at Barnett Creek indicated that flooding reduced the spatial heterogeneity of available soil nutrients and microbes in the stream landscape, and that topography (relative elevation) in the stream landscape was of less importance in influencing nutrient and microbial patterns than flooding or landscape position. ... Field studies at Pirraburdoo Creek indicated that microbial biomass and activity increased in benthic algal mats during mat senescent stages, and decreased after flooding when mat biomass peaked. Benthic algae grew rapidly in gravel run environments after flooding, while declining in pools, and demonstrated moderate N limitation and strong P limitation. Pools had two to eight times greater NO3-N, three to five times more total N, and two to three times more labile P, OC and total C than either pools after flooding, or runs before or after flooding. Hence, the pools at Pirraburdoo Creek represented a local, interflood store of nutrients in otherwise nutrient-poor landscape, when connectivity to upstream reaches or upland environments was weak or non-existent. This thesis provides the first detailed analysis of soil and sediment biogeochemical responses to flooding for intermittent streams in the Pilbara region and for semi-arid Australia. Further pressing questions raised by this work include: What is the key pulse size and frequency for maintaining Pilbara riparian communities as well as soil microbial function? How do the spatio-temporal nutrient and microbial patterns observed persist over (i) multi-decadal scales, (ii) mega-spatial (larger landscape to regional) scales, (iii) different flood frequency-magnitude regimes, and (iv) different stream sizes? Stream biogeochemistry is a burgeoning field, and it is therefore reasonable to expect such existing gaps in knowledge may be addressed in the near future.

Ectomycorrhizal (ECM) fungi form mutualistic symbioses with trees in boreal and north temperate forests and have key roles in regulating biogeochemical cycles. The extensive mycelium produced by many ECM fungi enables resources to be transported over large distances. Some ECM fungi are considered to be specialists and have a restricted range of host plant species whilst others are considered generalists and can form mycorrhizas with a number of species. Little is currently known about the reasons why specialist and generalist mutualists have evolved and so this project aims to investigate the basis for these different strategies. The resource stoichiometry between plant and fungal partners was predicted to be a key factor: specialist fungi may be more efficient in obtaining nutrients from litter and transporting these rapidly to host plants and in return may receive larger amounts of plant photosynthate. Here, stable and radioisotopes were used to trace and quantify transfer of carbon and phosphorus, and fine-scale spatial-temporal analysis of amino acid transportation between host plants and fungi. The photon-counting scintillation imaging (PCSI) was used to show the amino acid was transported long-distance by ECM fungi intact and that the transportation was highly directional but the speed of transfer varies between species of ECM. The transportation of amino acid and phosphorus from generalist fungus to the host plant was rapid compared to the specialist fungus.

Purified brush border membrane vesicles (BBMV) were isolated to characterize primary cellular transport mechanisms for white shrimp. The ultimate goal is to determine the effective components of a shrimp’s diet, thereby enhancing growth, as well as nutrient content. Juvenile shrimp are dependent on plant material as a food source. Potassium is a key component of plants, thus it may play a role in nutrient transport. In addition, divalent metals have been shown to act as co-transporters in several other organisms, thus they may serve as a transport mechanism for shrimp. Fresh, live, white or brown shrimp were obtained, and from them 15-30 hepatopancreases were dissected to prepare the BBMV. Methods for preparing BBMV were based on the Mg2+ precipitation technique developed by Kessler et al., (1978) and Biber et al. (1981) for mammalian eipithelia and applied to crustaceans. The results suggest that there is a sodium/potassium-dependent glucose transport system that resembles the SGLT1 system of vertebrates, except the shrimp transporter can accept both sodium and potassium as cofactors, while the vertebrate system is restricted to sodium stimulation. Potassium showed strong stimulation of L-histidine uptake by shrimp BBMV, suggesting that a crustacean isoform of the insect potassium-dependent carrier protein (KAAT1) might be present in shrimp, and contribute to amino acid uptake. Amino acids also appear to form bis-complexes with divalent metals, that are transported by an analog of the dipeptide transporter (PEPT1). The metals appear to be accommodated, with varying affinities. PEPT1 has been described as a very non-specific carrier process because it transports such a wide range of di- and tripeptide combinations.

Lake restoration and management strategies focus on reducing the negative impacts of enriched or polluted inflows. These strategies become of paramount importance when lakes are used for recreational and/or drinking water purposes. Long term control of eutrophication and turbidity problems associated with large inflow loads is usually oriented to catchment management. Although it has been suggested that this is the correct long term approach, public concerns usually require a short term solution. In addition, due to political and economic costs related to changes in catchment management, in-lake restoration technologies have been emerging as a viable pretreatment option, complementary to water treatment plants, both reducing the operational costs of the water treatment plant and ameliorating the water residing in the lakes. This research investigates the effects of two in-lake technologies on the dynamics of inflowing rivers, where basin shape plays a significant role. The three lakes in this study suffer from eutrophication combined with a distinctive water quality problem: from turbidity in Silvan Reservoir (Australia), to heavy metal loads in Coeur d'Alene Lake (USA) and industrial wastes in Lake Como (Italy). Firstly, the influence of basin morphology, wind speed, and wind direction on the fate and transport of two rivers flowing into the L-shaped Coeur d'Alene Lake was examined, and it was shown that transport and mixing patterns in a lake can be greatly influenced by the shape of the lake, leading to important consequences for the plankton ecology in the lake. Secondly, in Silvan Reservoir we investigated the potential to modify the basin shape using vertical barriers, increasing the retention time and hence the barrier capacity to microbial pollution. A final in-lake technology was tested for Lake Como, using a downward pointing impeller to remove polluted water from the coastal margin. Lessons from these three examples indicate that there is significant potential for in-lake remediation at relatively low cost, over relatively short timescales.

Övergödning utgör ett av de allvarligaste hoten mot Östersjöns miljö. Storleken av näringsbelastningen till havet behöver därför bestämmas med hjälp av tillgängliga matematiska modeller. Modellen ”Generalised Watershed Loading Functions” (GWLF), en ickedistribuerad parametermodell som uppskattar hydrologi och månatlig näringsbelastning, tillämpades på avrinningsområdet till Daugava som mynnar i Östersjön. Syftet med studien var att genom modellering av historisk transport av näringsämnen till Östersjön ta fram parametrar och indata som sedan kan användas vid applicering av GWLF på omkringliggande avrinningsområden. Data från 1990-talet användes för kalibrering av modellen och data från 1980-talet för validering. Årlig kvävebelastning modellerades med R2värdet 0,78 för kalibreringsperioden. Modellerad årlig kvävebelastning för valideringsperioden underskattades med ungefär 30 % vilket troligen beror på att kvävekoncentrationer i grundvatten och ytavrinning minskade mellan 1980- och 1990-talen.

Fosforbelastningen underskattades jämfört med rapporterade värden vilket troligen beror på att enskilda avlopp inte inkluderades och att rapporterade punktutsläpp är för låga.

Modifikationer av modellen föreslås för prediktion av näringsbelastningar under lång tid och behovet av harmoniserad, uppdaterad och lättillgänglig data för näringstransportsmodellering diskuteras.

Eutrophication is one of the most serious threats to the Baltic Sea environment. Nutrient loading into the sea therefore needs to be quantified by available mathematical models. The Generalised Watershed Loading Functions (GWLF), a lumpedparameter model that predicts hydrology and monthly nutrient loads, was applied to the Daugava River Basin, discharging into the Baltic Sea. The aim of the study was to model historic transport of nutrients into the Baltic Sea and thereby produce estimates of parameters and input data needed for a spatial extension of the GWLF to surrounding river basins.

Calibration data were taken from the 1990’s and validation data from the 1980’s. Yearly nitrogen loads were modelled with an R2 value of 0.78 for the calibration period. Predicted yearly nitrogen loads for the validation period were about 30 % lower than reported values, probably depending on decreasing groundwater and runoff concentrations between the 1980’s and 1990’s. Phosphorus loads were underestimated compared to reported values, the main reason probably being the exclusion of septic systems and too low reported point sources.

Modifications of the model are suggested for longterm predictions of nutrient loads and the need for harmonised, uptodate and generally accessible data for nutrient transport modelling discussed.

In the Missisquoi Bay of Lake Champlain situated in the South of Quebec, phosphorus originating from agricultural sources has been found to be a major contributor to the deterioration of water quality. This study sought to evaluate the nutrient loads, most particularly phosphorus, exported through surface runoff and tile drainage from two agricultural fields of the Missisquoi Bay watershed. As part of the study, a phosphorus simulation model was tested on one agricultural field. The evaluation of FHANTM 2.0 assessed the model's capacity to simulate the transport of phosphorus on agricultural fields.
From the two experimental fields studied, the results showed that the mean phosphorus load exported was larger in surface runoff than in tile drainage. The mean phosphorus load exported was 1.21 kg ha-1yr -1 in surface runoff, and 0.61 kg ha-1yr-1 in tile drainage. In contrast, nitrate loads exiting the fields were larger in tile drainage than in surface runoff. Over the two year study, the mean nitrate load was 5.64 kg ha-1yr-1 in surface runoff, and 91.43 kg ha-1yr-1 in tile drainage.
FHANTM's simulation of hydrology for one field gave slightly negative coefficients of performance (CP), representing a poor capacity to simulate surface and subsurface runoff depths. The simulation of phosphorus concentrations in surface runoff showed a small range of values compared to field measurements, while simulations of phosphorus concentration in tile drainage were considered acceptable. Therefore, the overall evaluation of the FHANTM 2.0 model indicated that it had difficulty in simulating the transport of phosphorus from an agricultural field in Quebec.

Thesis (M.S.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Dept. of Natural Resource Sciences and Landscape Architecture. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Motivated by applications in tissue engineering, this thesis is concerned with the flow through and around a free-moving porous tissue construct (TC) within a high-aspect-ratio vessel (HARV) bioreactor. We formalise and extend various results for flow within a Hele-Shaw cell containing a porous obstacle. We also consider the impact of the flow on related nutrient transport problems. The HARV bioreactor is a cylinder with circular cross-section which rotates about its axis at a constant rate, and is filled with a nutrient-rich culture medium. The porous TC is modelled as a rigid porous cylinder with circular cross-section and is fully saturated with the fluid. We formulate the flow problem for a porous TC (governed by Darcy's equations) within a HARV bioreactor (governed by the Navier-Stokes equations). We couple the two regions via appropriate interfacial conditions which are derived by consideration of the intricate boundary-layer structure close to the TC surface. By exploiting various small parameters, we simplify the system of equations by performing an asymptotic analysis, and investigate the resulting system for the flow due to a prescribed TC motion. The motion of the TC is determined by analysis of the force and torque acting upon it, and the resulting equations of motion (which are coupled to the flow) are investigated. The short-time TC behaviour is periodic, but we are able to study the long-time drift from this periodic solution by considering the effect of inertia using a multiple-scale analysis. We find that, contrary to received wisdom, inertia affects TC drift on a similar timescale to tissue growth. Finally, we consider the advection of nutrient through the bioreactor and TC, and investigate the problem of nutrient advection-diffusion for a simplified model involving nutrient uptake.

Land use changes such as lowering of lakes, draining of wetlands and channelizing of streams have affected the hydrological environment in many catchment areas. Numerous studies report that these changes affect the nutrient retention. The river Svärtaå catchment, near Nyköping is identified as one of the areas in Sweden that transport most phosphorus and nitrogen to the Baltic Sea per unit area. The aim of this study was therefore to analyse to which extent land use changes such as lowering of lakes, draining of wetlands and channelizing of streams have affected the nutrient transport to the Baltic Sea. Land use changes were to a large extent performed between the years 1880 and 1930 inSweden, historical maps from the late 19th century have therefore been studied. An application based on the concept of a Geographical Information System (GIS) has been used in order to compare the district map from late 19th century and the terrain map from today. To address the nutrient transport retention coefficients have been found in the literature and implemented on the changes in water area.  Changes in the hydrological environment reached totally1068 ha,964 hawere decreasing water areas and104 haincreasing water areas. Wet areas totally decreased with 28 % when the historical setting was compared with the contemporary environment. The loss in wet area represents860 ha. Watercourses with riparian zones have decreased with 54 %, bogs with 53 %, wetlands with 43 % and lakes with 13 %. The loss in retained mass regarding phosphorus was, based on calculations involving retention coefficients, 7,18 – 146 tonnes, and regarding nitrogen 37,9 – 941 tonnes. The changes in the catchment are probably connected to measures like lowering of lakes, draining of wetlands and channelizing of streams. The assumed lost retained masses shows to be high compared to the measured output from the catchment. This leads to questioning of the retention coefficients and the vast range between them, as well as questioning of other assumptions in the method. The consequences of the hydrological changes are therefore difficult to evaluate.

Previous work at IGER has revealed that soil structural differentiation under white clover is phenomenally rapid and enhanced when compared with ryegrass. White clover is one of the most nutritious and widely distributed forage legumes. Its use is advocated in sustainable systems of livestock production because of its ability to acquire atmospheric N through biological fixation in the root nodules. It thus provides an economically viable alternative to the N-demanding conventional system, and a possible solution to reduce the environmental impacts of nitrate leaching from agricultural land. There are, however, potentially negative impacts associated with improving soil aggregation through the use of clover that need further investigation. It appears that legume-based systems are not environmentally benign: similar amounts of N and P are leached from beneath grass-clover swards as those leached from beneath fertilised grass operating at the same level of production. In some circumstances, clover rich swards can give rise to very high levels of nitrate leaching. Thus, this observation of clover induced soil aggregation has important implications for the pollutant transport qualities of soils and for the organic/conventional agriculture debate. Re-packed soil columns of four soil series and 0.5 m intact monoliths of the Crediton series were planted with white clover, perennial ryegrass and a mixture of the two species, and managed according to an organic and conventional farming regime. Visual observations revealed a rapid enhancement in soil structure beneath white clover compared to ryegrass and unplanted soil. A novel technique to determine oxygen diffusion as an indicator of soil porosity, gave a diffusion rate that was nearly nine times greater than that of the grass treatments and fifteen times greater than the unplanted control soil, with intermediate values for the mixed treatment Thus enhanced structural differentiation beneath white clover was supported by greater permeability to air and freer drainage to water. Structural stability tests suggested that white clover improved the ability of the soil to maintain its structure under the action of water, and was estimated to be three times more stable than ryegrass. There was also evidence which implied improved shear strength and resistance to mechanical forces. Differences in soil structure were verified with water retention measurements, which showed a greater proportion of macropores. The void structure was simulated with the 30 Pore-Cor network model, which also suggested a number of larger pores and a saturated hydraulic conductivity which was four times greater than ryegrass. This also highlighted inadequacies in the current standard ISO protocol for water retention. The solute transport studies showed elevated levels of nitrate and phosphate leaching. Concomitant transport of bromide inferred structural differentiation and changes in leaching dynamics. In addition, white clover allowed the passage of greater volumes of water. Most importantly, this was manifested at the soil profile scale and therefore likely to be of consequence in the field. The implications of the research are that enhanced soil structure beneath white clover alters the transport of gases, water, nutrients and other dissolved substances. Further understanding of these soil processes are needed before advocating the use of forage rich legumes in sustainable systems, and for the development of management strategies.

Stockholm and its surroundings are facing strong urban changes and it is forecasted that the increase of population will be the principal driver for the urban regions surrounding the lake Mälaren in the next decades. A thorough regional and urban planning is needed in order to build a sustainable society and protect the environment. In this sense Coupled Human and Natural Systems (CHANS) are useful tools for the creation of future scenarios of how urbanization and landuse changes will impact the ecosystems and the water resources. This master thesis is focused on how population growth and landuse changes impact both the surface water discharges and the nutrient transport in the Norrström Drainage Basin. In this regard the different comprehensive plans of 26 municipalities in the Stockholm-Mälardalen region were studied in order to create a landuse evolution model until 2040. The impacts of the changes of urbanization on the surface waters and the nutrient transport were obtained using the PCRaster environmental modelling tool following the guidelines of the PolFlow model. The results show an increase of the built-up urban areas of a 25% by 2040. Regarding the increase of flow in the surface waters, the results show a very small increase in the flow, due to the large scale of the study area. Finally the results for the nutrient transport show an increase of the nutrient loads at the outlet of the lake Mälaren of 20% in the case of nitrogen and 15% for phosphorus.
Stockholm regionen står inför kraftiga urbana förändringar och det förutses att befolkningsökningen kommer att bli den främsta drivkraften för storstadsregionerna kring Mälaren under de kommande årtiondena. En grundlig regional- och stadsplanering behövs för att bygga ett hållbart samhälle och skydda miljön. I detta sammanhang är Coupled Human and Natural Systems (CHANS) användbara verktyg för att skapa framtidsscenarier för hur urbanisering och markanvändningar kommer att påverka ekosystem och vattenresurser. CHANS verktyg möjliggör analys av komplexa mönster och processer som inte framgår tydligt vid separata sociala och naturvetenskapliga studier. Inom CHANS ramverk fokuserar detta examensarbete på hur befolkningstillväxt och markanvändning och de ändringear de medför påverkar ytvattenutsläpp samt näringstransport i Norrström avrinningsområden. I detta avseende studerades olika översiktsplaner av 26 kommuner i Stockholm-Mälardalen regionen för att bygga en markanvändning evolutionmodell fram till 2040. Det studerade scenariot utvärderade konsekvenser av förändringarna i urbaniseringen som beskrivs i de omfattande översiktplanerna på ytvatten och näringsämne transport. Verktyget som användes för att utföra detta examensarbete var PCRaster. Det är ett miljömodelleringsverktyg som tillåter behandling av stora distribuerade data och kan skapa spatiotemporala miljömodeller. I detta avseende fördelades modellen i tre delar. Först erhölls den temporala markanvändningsevolutionen efter uppgifter från kommunala översiktplaner. Därefter beräknades ytvattenutsläppen med CN-metoden. Slutligen byggdes den näringstransportmodellen med hjälp av riktlinjerna från PolFlow modellen och näringsbelastningen från HELCOM och TRK-projektet. Resultaten visar en ökning av de bebyggda stadsområdena från 3,3 % bebyggda under år 2005 till 4,2 % år 2040 för hela Norrström avrinningsområde, som innebär en ökning med 25 % av de bebyggda områdena. Beträffande flödet i ytvattnet visar resultaten en jätteliten ökning av flödet på grund av att det studerade området har en stor skala. Slutligen visar resultaten för näringsämnenstransport en ökning av näringsbelastningen vid utloppet av sjön Mälaren med 20 % kväve och 15 % fosfor.

Tissue engineering aims to regenerate, repair or replace organs or tissues which have become defective due to trauma, disease or age related degeneration. This engineering may take place within the patient's body or tissue can be regenerated in a bioreactor for later implantation into the patient. Regeneration of soft tissue is one of the most demanding applications of tissue engineering. Producing proper nutrient supply, uniform cell distribution and high cell density are the important challenges. Many experimental models exist for tissue growth in a bioreactor. It is important to put experiments into a theoretical framework. Mathematical modelling in terms of physical and biochemical mechanisms is the best tool to understand experimental results. In this work a mathematical model of convective and diffusive transport of nutrients and cell growth in a perfusion bioreactor is developed. A cell-seeded porous scaffold is placed in a perfusion bioreactor and fluid delivers the nutrients to the cells for their growth. The model describes the key features of the tissue engineering processes which includes the interaction between the cell growth,variation of material porosity, flow of fluid through the material and delivery of nutrients to the cells. The fluid flow through the porous scaffold is modelled by Darcy's law, and the delivery of nutrients to the cells is modelled by the advection-diffusion equation. A non-linear reaction diffusion system is used to model the cell growth. The cell diffusion depends on the cell density and growth of cells is modelled by logistic growth. The effect of shear stress on nutrient consumption and cell growth is also included in the model. COMSOL (a commercial finite element solver) is used to numerically solve the model. The results show that the distribution of cells and total cell number in the scaffold depends on the initial cell density and porosity. We suggest various seeding strategies and scaffold designs to improve the cell growth rate and total cell yield.

Thesis submitted in fulfilment of the requirements for the degree Doctor technologiae (engineering: chemical) In the faculty of engineering at the cape peninsula university of technology
Since the first uses of hollow-fiber membrane bioreactors (MBR’s) to immobilize whole cells were reported in the early 1970’s, this technology has been used in as wide ranging applications as enzyme production to bone tissue engineering. The potential of these devices in industrial applications is often diminished by the large diffusional resistances of the membranes. Currently, there are no analytical studies on the performance of the MBR which account for both convective and diffusive transport. The purpose of this study was to quantify the efficiency of a biocatalytic membrane reactor used for the production of enzymes. This was done by developing exact solutions of the concentration and velocity profiles in the different regions of the membrane bioreactor (MBR). The emphasis of this study was on the influence of radial convective flows, which have generally been neglected in previous analytical studies. The efficiency of the MBR was measured by means of the effectiveness factor. An analytical model for substrate concentration profiles in the lumen of the MBR was developed. The model was based on the solution of the Navier-Stokes equations and Darcy’s law for velocity profiles, and the convective-diffusion equation for the solute concentration profiles. The model allowed for the evaluation of the influence of both hydrodynamic and mass transfer operating parameters on the performance of the MBR. These parameters include the fraction retentate, the transmembrane pressure, the membrane hydraulic permeability, the Reynolds number, the axial and radial Peclet numbers, and the dimensions of the MBR. The significant findings on the hydrodynamic studies were on the influence of the fraction retentate. In the dead-end mode it was found that there was increased radial convective flow, and hence more solute contact with the enzymes/biofilm immobilised on the surface of the membrane. The improved solute-biofilm contact however was only limited to the entrance half of the MBR. In the closed shell mode there was uniform distribution of solute, however, radial convective flows were significantly reduced. The developed model therefore allowed for the evaluation of an optimum fraction retentate value, where both the distribution of solutes and radial convective flows could be maximised.

Increased water- and fertilizer-use-efficiency in containerized crop production, via reduced water loss, enhances crop-available nutrients while reducing non-point source agrichemical contributions in accordance with regulatory standards. Previous studies detailed nutrient leaching patterns throughout crop production seasons, leaving little known about water and dissolved nutrient (solute) movement through soilless substrates during irrigation. The following experiments evaluated fundamental water and solute transport principles through pine-bark based substrates. 1) Ilex crenata Thunb. 'Bennett's Compactum' were grown in 2.7 L containers. Tensiometers detected wetting front (WF) movement throughout the substrate during irrigation. 2) Tracer solution (containing NO3-, PO43- and K+) and deionized water (DI) were applied to substrate-filled columns to characterize tracer breakthrough under saturated and unsaturated conditions. 3) Controlled-release fertilizer (CRF) was topdressed (surface-applied), incorporated (throughout substrate), dibbled (center of substrate) or not applied to fallow substrate, irrigated with DI and leachate analyzed to determine nutrient concentrations throughout irrigation. Tensiometers revealed that seasonal root growth affected substrate pre-irrigation moisture distribution. Wetting fronts channeled through the substrate before becoming thoroughly wetted. Tracer breakthrough occurred with less effluent volume under unsaturated conditions. Breakthrough of NO3- and PO43- was relatively conservative, though 37% of K+ was retained by the substrate. Leachate concentrations for topdressed and incorporated CRF peaked early (first 50mL effluent) before diminishing with continued leaching. Leachate concentrations for dibbled CRF initially increased (first 150mL leachate), plateaued and then diminished. These results show the relative rapidity which water and solutes move through pine-bark during irrigation and demonstrate methods for future research on within-irrigation solute transport.
Master of Science

Overapplication of manure in sensitive watersheds is an issue of increasing environmental concern due to increased nutrient loading and antibiotic release into aquatic environments. Manure is typically surface applied, leaving nutrients and antibiotics vulnerable to loss at the soil surface. Elevated nutrient and antibiotic loading into water bodies can increase the rate of eutrophication and occurrence of antibiotic resistance genes in areas of high animal agriculture production, such as the Chesapeake Bay watershed. Manure injection is a new technology that incorporates manure into the soil with minimal disturbance, and management strategies that reduce manure loss from agricultural fields could prevent the transport of nutrients and antibiotics to sensitive waterways. However, little is known about the efficacy of dry litter injection to decrease nitrogen (N) loss when compared to surface application. Also, there are no studies that determine the effects of injection on antibiotic transport and transformation after manure application. Therefore, this project focused on changes in N cycling, orchardgrass hay yield and quality, and transport and transformation of pirlimycin and cephapirin, two common antibiotics in dairy production, when manure is injected. Subsurface injection eliminated ammonia volatilization and N loss in runoff and increased soil inorganic N when compared to surface application after volatilization, incubation, and rainfall simulation studies. Although these benefits did not translate to higher yields in orchardgrass hay, protein increased when poultry litter was injected, indicating greater N uptake. Injection of dairy manure decreased losses of pirlimycin to levels of the control when compared to surface application. Although, pirlimycin had a slower degradation rate within the injection slit compared to surface application, potentially increasing the amount of time soil microbes are exposed to antibiotics. In an incubation study, pirlimycin concentrations decreased after 7 days, but concentrations increased sharply after 14 days. This indicates that conjugates formed in the liver or digestive tract of dairy cows may revert back to the parent compound after manure application. With increased retention of nutrients and antibiotics, injection could be a best management practice used to reduce the loss of these compounds to the environment while increasing the quality of crops produced.
Ph. D.

Made available in DSpace on 2014-12-17T14:33:04Z (GMT). No. of bitstreams: 1 FranciscoRV_DISSERT.pdf: 943640 bytes, checksum: d6134d4d93c5e755e9cda7290579f131 (MD5) Previous issue date: 2010-07-02
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The omnivorous filter-feeding fish, Nile tilapia (Oreochromis niloticus), can have negative effects on water quality enhancing the eutrophication process. These effects depend on the nutrient enrichment level in the water. We carried out a mesocosm experiment for five weeks in a tropical man-made lake in Brazil to test ifthe effects of tilapias depend on of the level of nutrient enrichment. The experiment lasted for 5 weeks and a factorial 2x5 experimental design was used where the presence and absence of tilapias were manipulated in combination to 5 different levels of nutrient load in a total of 10 treatments. A two way repeated measure ANOVA was performed to evaluate the effects of time (t), tilapia (F), nutrients (NP) and the interactions among these factors on: chlorophyll a, water transparency, total phosphorous, total nitrogen, N:P ratio, zooplankton biomass and phytoplankton biovolume. The tilapia effect was evident, but nutrient enrichment didn t have any effect on the variables analyzed. Tilapia decreased the water transparency, total zooplankton biomass, calanoid copepod biomass, nauplii copepod biomass and cladocerans biomass. On the other hand, tilapia had no effect on phytoplankton biovolume. This lack of effect on phytoplankton is probably due to tilapia grazing that may counteract the positive effect of tilapia on phytoplankton via trophic cascades and nutrient recycling. Hence, a reduction in tilapia stock would not be an effective way to reduce phytoplankton biomass and improve water quality
A til?pia do Nilo (Oreochromis niloticus) ? um peixe on?voro filtrador que pode ter efeitos negativos sobre a qualidade da ?gua favorecendo o processo de eutrofiz??o. Esses efeitos negativos dos peixes on?voros filtradores devem ser dependentes do n?vel de enriquecimento da ?gua por nutrientes. N?s realizamos um experimento em mesocosmos por cinco semanas em um lago artificial tropical para testar se os efeitos das til?pias s?o dependentes do n?vel de enriquecimento por nutrientes. O experimento teve dura??o de 5 semanas e consistiu num delineamento fatorial 2x5 onde 2 n?veis de til?pia (presen?a e aus?ncia) foram manipulados em combina??o com 5 diferentes niveis (aportes) de nutrientes num total de 10 tratamentos.. Uma ANOVA bifatorial com medidas repetidas no tempo foi realizada para testar os efeitos do tempo (t), da til?pia (F) e do nutriente (NP) e os efeitos de suas intera??es sobre a clorofila a, transpar?ncia do disco de Secchi, concentra??o de f?sforo e nitrog?nio total e a raz?o entre eles (N:P), al?m do efeito sobre a biomassa da comunidade zooplanct?nica e o biovolume de fitopl?ncton. O efeito da til?pia foi evidente, enquanto o enriquecimento por nutrientes n?o mostrou efeito algum. Quando presente, a til?pia diminuiu a transpar?ncia do disco de Secchi e a biomassa total do zoopl?ncton, de cop?podos calan?ides, na?plios de cop?podos e de clad?ceros. Por?m, nenhum efeito foi detectado da til?pia sobre o biovolume do fitopl?ncton. Essa aus?ncia de efeito pode ser devido a herbivoria da til?pia que contrabalan?a os seus efeitos positivos via cascata tr?fica e ciclagem de nutrientes. Desta forma, uma redu??o do estoque pesqueiro de til?pias para promover uma melhoria na qualidade da ?gua n?o afetaria a biomassa fitoplanct?nica e consequentemente n?o atingiria o seu objetivo

The purpose of this project is to gain an improved understanding of the transformations that occur in the subsurface downstream of on-site wastewater disposal systems and septic systems. These systems are used widely throughout the United States to treat and discharge wastewater effluent. The approach involved the collection of samples from a septic research center in Cape Cod, MA, and analysis of these samples for nitrogen, phosphorus, dissolved oxygen, pH, alkalinity, suspended solids, metals, and other water quality parameters. Inverse modeling was used to compare samples collected upstream and downstream of subsurface “leaching” fields consisting of sand beds. This approach provided a basis to identify key reactions occurring in the subsurface downstream of the discharge. In addition, a reactive transport software package, based on the PHREEQC and Hydrus-1d models, was used to model the transport in these sand beds and identify possible reactions and changes in contaminant concentrations with depth. To understand the implications of the discharges, an additional field study was completed in an area where septic systems have impacts on surface waters. Samples collected from a stream provided an indication of the loads entering the stream as a result of septic system discharges. Combining the results from the modeling with the results of this field investigation provided an approach to estimate the transport of nutrients and other contaminants entering the surface waters from septic system discharges. The results provide a basis for understanding the impacts of septic systems on surface waters, and develop better approaches for reducing the impacts of these discharges.

Nutrient transport models are being used increasingly as a tool for the research and management of nutrient enrichment (eutrophication) of freshwaters. Phosphorus is seen as the main cause of freshwater eutrophication. A nutrient transport model was acquired that could simulate the movement of phosphorus through a catchment. The SWAT model from the US Department of Agriculture, Agricultural Research Service appeared to suit the requirements of a catchment-scale, continual time model that was distributed in nature. It is based on physical processes in order that predictions could be made for land management practices or environmental conditions that had been absent in calibration processes.;Remote sensing technology has the potential to improve on estimates of distributed variables based on spot measurements and interpolative techniques. The initial intention of this project was to estimate several parameters from remote sensing images and use them as input to the chosen nutrient transport model. The SWAT model is only able to utilise mapped data for soil types and land cover. Whilst the latter can be extracted from various remote-sensing devices the former cannot. Synthetic aperture radar (SAR) has the potential to estimate several of the parameters considered influential to the movement of nutrients in a catchment. This study utilised five SAR images to investigate the potential of extracting: (i) land cover data, (ii) soil moisture, (iii) soil surface roughness, (iv) soil organic matter content (v) oilseed rape leaf area index and (vi) oilseed rape biomass. No significant relationships were found between any of the soil parameters and radar backscatter using linear regression. It is thought that this may be due to the excessive moisture levels at the time of sampling, but sampling intensity could also have been better. Likewise no significant relationships were found between the botanical parameters and radar backscatter. Wheat and oilseed rape characteristics were also collected and applied to the MIMICS model to assess the technology of radiative transfer models in the UK. There was a significant correlation between the backscatter values obtained through the MIMICS model and the backscatter from mature wheat to the SAR images to but not to green wheat or oilseed rape.;A land cover map was generated using a multi date composite of three of the SAR images. The images were acquired in May, July and August of 1999. Land-classes were assigned using supervised maximum likelihood estimation (MLE) and unsupervised training. Out of 11 classes of land cover found on the Stonton Brook, 11 were identified using the supervised training and MLE and only seven using the unsupervised training. The former method acquired a total accuracy of 46 % against the latter's 53%. On applying the classification schemes to a field boundary map the total accuracies improved to 58 % and 54 % respectively. Both maps were regarded as moderately accurate and both were used in the SWAT model.

Submitted by Inácio de Oliveira Lima Neto (inacio.neto@inpa.gov.br) on 2016-08-29T15:29:46Z No. of bitstreams: 1 Joana D'Arc de Paula.pdf: 2958755 bytes, checksum: 8a5b9ee4dc39e0c4602a466f580f63b3 (MD5)
Made available in DSpace on 2016-08-29T15:29:46Z (GMT). No. of bitstreams: 1 Joana D'Arc de Paula.pdf: 2958755 bytes, checksum: 8a5b9ee4dc39e0c4602a466f580f63b3 (MD5) Previous issue date: 2013-05-24
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The allochthnous organic matter (OM) is the main energy source in aquatic forested ecosystems. When entering streams it can be retained and be kept stored. And it is in its retention and afterwards decomposition that it will occur the chain between primary consumers and its food source. The geological structure of the Amazon Basin results in a mosaic of distinct geochemical formations, which determines differences that allows the occurrence of soil fertility gradients and rainfall at the forest. But, these gradients will be also reflected into the contribution, transport and decomposition of the organic matter in headwater streams of Amazon Basin? Based on this it was formulated the following hypothesis: is the dynamics of organic matter in headwater streams of the Amazon Basin influenced by the soil fertility gradients and rainfall. To test the hypothesis there were collected samples from OM lateral contribution, experiments of leaf transportation and leaf decomposition and it was performed samples of storage organic matter and Dissolved organic carbon (DOC) in transport, simultaneously there were collected soil and water samples to characterize the streams and their soil fertility. Experiments and samples were collected along 90 days, in 16 headwater streams distributed in a soil fertility gradient and rainfall. The thesis was formatted in 4 chapters. In each one, the following hypothesis were tested: chapter 1) Differences into the soil characteristics and rainfall reflect into differences in quantity and quality of the input litter the low order streams of Amazon Basin; chapter 2) Headwater streams of Amazon Basin present high retentiveness influenced by local factors as well as local rainfall and soil fertility; 3) The concentration of dissolved nutrients into the headwater streams water throughout Amazon Basin is distinct reflecting into the soil fertility gradients and rainfall, resulting in different decomposition times; and chapter 4) The fertility of the soil and rainfall of Amazon Basin promote distinction of the fractions distribution of organic matter coarse particulate, fine particulate and dissolved (DOC). The quality and quantity of litter that enter laterally into the low order streams of Amazon Basin showed been influenced by soil fertility, soil texture and rainfall. The streams presented high retentiveness that was explained by the channel characteristics as obstacles frequency and free water column, factors influenced by rainfall patterns. The decomposition time between the studied species was distinct, and it was due to the characteristics of the species and location; differences between locations were due to the soil fertility patterns and rainfall. It was observed a high stock of OM on the streambed and also that less than 50% of carbon has been really computed when considered only the fraction of fine particulate organic and DOC, and that studies that include the coarse particulate carbon storage into the streambed of the streams allow more accurate estimates of the carbon concentration in aquatic ecosystems, enabling the extrapolation of results obtained in terms of the global carbon balance. Therefore the rainfall and soil fertility gradients explain not only the dynamic diversity of arboreal species but also the dynamic of the dead organic matter in headwater streams at the Basin. However, it is important to highlight that these results are stillxiii preliminary, and more studies that provide even better verification of seasonality are needed in the region. Still, in view of the extensive drainage network and high input values of organic matter in headwaters streams, the high retention capacity of these streams, as well as the different stages of decomposition, promoting high concentrations of carbon stored in fractions streambed, we can say that the maintenance of the integrity of the water bodies of low-order has fundamental source importance to these ecosystems, allowing the maintenance of long food webs present in them.
A matéria orgânica (MO) alóctone é a principal fonte de energia em ecossistemas aquáticos florestados. Ao entrar em riachos ela pode ser retida e se manter estocada. E é na retenção desta e subsequente decomposição que ocorrerá o elo entre consumidores primários e sua fonte de alimento. A estrutura geológica da Bacia Amazônica resulta em um mosaico de distintas formações geoquímicas, determinando diferenças que permitem a ocorrência de gradientes de fertilidade do solo e pluviosidade, na floresta. Mas esses gradientes serão também refletidos no aporte, transporte e decomposição de matéria orgânica nos riachos de cabeceira da Bacia Amazônica? Baseado nisso formulamos a seguinte hipótese: a dinâmica da matéria orgânica em riachos de cabeceira da Bacia Amazônica é influenciada pelos gradientes de fertilidade do solo e pluviosidade. Para que a hipótese fosse testada foram realizadas coletas de aporte lateral de MO, experimentos de transporte foliar e decomposição foliar e realizadas coletas de matéria orgânica estocada e carbono orgânico dissolvido (COD) em transporte, concomitantemente foram coletadas amostras de solo e água para caracterização dos riachos e da fertilidade do solo. Experimentos e coletas foram realizados ao longo de 90 dias, em 16 riachos de cabeceira, distribuídos em um gradiente de fertilidade do solo e pluviosidade. A tese foi formatada em 4 capítulos. Em cada um testamos as seguintes hipóteses: capítulo 1) Diferenças nas características do solo e pluviosidade se refletem em diferenças na quantidade e qualidade da liteira que entra em riachos de baixa ordem da Bacia Amazônica; capítulo 2) Riachos de cabeceira da Bacia Amazônica apresentam alta retentividade influenciada por fatores locais assim como pela pluviosidade local e fertilidade do solo; 3) A concentração dos nutrientes dissolvidos na água dos riachos de cabeceira, ao longo da Bacia Amazônica, é distinta, refletindo os gradientes de fertilidade do solo e pluviosidade, resultando em diferentes tempos de decomposição; e capítulo 4) A fertilidade do solo e pluviosidade da Bacia Amazônica promovem distinções da distribuição das frações de matéria orgânica particulada grossa, particulada fina e COD. A qualidade e quantidade da liteira que entra lateralmente nos riachos de baixa ordem da Bacia Amazônica se mostrou influenciada pela fertilidade do solo, textura do solo e pluviosidade. Os riachos apresentaram alta retentividade que foi explicada pelas características do canal, como frequência de obstáculos e coluna de água livre, fatores influenciados pelos padrões de pluviosidade e fertilidade do solo. O tempo de decomposição entre as espécies estudadas foi distinto, o que se deveu às caracteríticas das espécies e das localidades; diferenças entre localidades foram decorrentes dos padrões de fertilidade do solo e pluviosidade. Foi observado um alto estoque de MO no leito e observado que menos de 50% do carbono tem sido realmente computado quando levados em consideração apenas as frações de carbono orgânico particulado fino e COD, e que trabalhos que incluam o carbono orgânico particulado grosso estocado no leito de riachos permitem estimativas mais precisas das concentrações de carbono em ecossistemas aquáticos, viabilizando a extrapolação dos resultados obtidos em termos do balanço global de carbono. Assim os gradientes de pluviosidade e fertilidade do solo explicam não só a dinâmica e diversidade de espécies arbóreas como também podem explicar a dinâmica da matéria orgânica morta em riachos de cabeceira na Bacia. Mas, é importante salientar que estes resultados são ainda preliminares, e que mais estudos que possibilitem inclusive umaxi melhor verificação da sazonalidade são necessários na região. Ainda assim, tendo em vista a extensa rede de drenagem e os altos valores de entrada de matéria orgânica nos riachos de cabeceira, a alta capacidade de retenção desses riachos, bem como os diferentes tempos de decomposição, promovendo altas concentrações de frações de carbono estocadas no leito, podemos dizer que a manutenção da integridade dos corpos de água de baixa ordem é de fundamental importância energética para esses ecossistemas, permitindo a manutenção das longas teias alimentares neles presentes.

Background: It is well established throughout the literature that regularly engaging in physical activity throughout pregnancy is associated with optimized health outcomes for both the mother and the fetus. The mediators and mechanistic pathways through which these observed exercise-induced outcomes are achieved are largely unknown. This thesis attempts to address this gap in knowledge. Methods: The objective of the first study was to develop an exercise protocol based on the recommendations from the ‘2019 Canadian guideline for physical activity throughout pregnancy’ and to subsequently evaluate the myokine response post-exercise. Pregnant (n=13) and non-pregnant (n=17) women performed a moderate-intensity bout of treadmill walking following which pre- and post-exercise serum for a panel of ten well-characterized myokines was analyzed. The objective of the second study was to evaluate whether acute and/or chronic exercise elicited changes in metrics of placental growth and development – thereby proposing possible mechanisms through which physical activity may be conferring health benefits to the fetus. Serum (pre- and post-exercise) collected from the first study was used to treat placental cell lines to assess the effect of acute exercise on cellular proliferation as well as nutrient transporter (GLUT1, SNAT1, FATP4) expression and localization. Term placental tissue collected from active (n=10) and non-active (n=10) participants in the PLACENTA study were used to evaluate the role of chronic exercise on changes in nutrient transporter (GLUT1, SNAT1, FATP4) expression and localization. Results: Pregnant women from the first study exhibited higher levels of four myokines post- versus pre-exercise: FGF21, EPO, BDNF and IL-15. As for the second study, BeWo cell lines treated with serum collected from pregnant women yielded higher GLUT1 expression compared to non-pregnant serum, independently of exercise. Lastly, FATP4 expression was found to be higher in term placentas of active compared to non-active pregnant women. Conclusion: This thesis identified four myokines that are elevated in the serum of pregnant women following a bout of acute exercise. The role of these myokines in pregnancy remains to be elucidated. Further, chronic and acute exercise are shown to alter expression of key placental macronutrient transporters.

Depression occurs in 15% of pregnant women and 1/3 are taking selective serotonin reuptake inhibitors (SSRIs) as antidepressants. The neurotransmitter, serotonin, plays a critical role in modulating stress responses and early brain development. Serotonin transporter (SLC6A4) regulates extracellular serotonin levels, and an insertion/deletion variant in the promoter (5HTTLPR) is associated with depression. Maternal mood and SSRIs may program newborns’ behaviour later in life. The underlying molecular mechanism for developmental programming may involve DNA methylation, which requires methyl nutrients as enzymatic cofactors. While low methyl nutrient status (folate and vitamin B₁₂) and a genetic variant in methylenetetrahydrofolate reductase (MTHFR C677T) have been associated with depression in adults, the role of methyl nutrient metabolism in depression during pregnancy remains unclear. Furthermore, little is known about the combined roles of methyl nutrient status and depression in the epigenetic regulation of SLC6A4. The experiments in this thesis explored whether disturbances in methyl nutrient metabolism and depressed mood during the 3rd trimester of pregnancy affect SLC6A4 methylation and expression in mothers and their newborns. Maternal folate status was positively associated with maternal SLC6A4 methylation at CpGs 1, 4, and 8 (P<0.05). Maternal 3rd trimester mood was inversely associated with SLC6A4 CpG 10 methylation in both mothers and newborns (P<0.05). Methylation at SLC6A4 CpG 8 was lower in newborns with mothers with the MTHFR 677TT genotype, and methylation at CpGs 6 and 10 were lower in newborns with the MTHFR 677TT genotype (P<0.05). Maternal SLC6A4 mRNA level was positively associated with mean maternal methylation and methylation at CpGs 5, 7, 8, and 10 (P<0.05). Yet, newborn SLC6A4 mRNA level was negatively associated with newborn methylation at CpGs 4 and 7 (P<0.05). Homozygosity for the minor allele for MTHFR C677T and 5-HTTLPR insertion/deletion variants in mothers were not associated with maternal mood (P>0.05). These results provide evidence to suggest that maternal mood during pregnancy and methyl nutrient metabolism may program SLC6A4 gene expression through DNA methylation in both mothers and their newborns. Mood during pregnancy and disturbances in methyl nutrient metabolism could set up life-long health consequences in the development of the offspring.

Mudanças sazonais nas condições ambientais alteram o ritmo sazonal endógeno com efeitos sobre a fisiologia e o comportamento de diversas espécies animais. Caranguejos estuarinos da espécie Neohelice granulata (Crustácea, Decapoda, Brachyura) são anualmente expostos a múltiplas condições estressantes a exemplo das variações de salinidade da água, pressão parcial de oxigênio, temperatura, pH, fotoperíodo, disponibilidade de alimentos, entre outras. Em crustáceos a insulina de mamífero estimula a atividade tirosina quinase do receptor insulin/ IGF I- like, a fosforilaçao de proteínas citoplasmáticas como o substrato-1 do receptor de insulina (IRS-1), o transporte de glicose, a glicogênese e a síntese lipídica, além disso, Kucharski e cols (2002) mostraram uma variação sazonal na ação do hormônio. Essas evidências motivam a investigação do sistema de sinalização insulin/ IGF I- like e suas relações com as mudanças sazonais do meio ambiente em invertebrados aquáticos. Assim, o objetivo desse trabalho foi avaliar o efeito da sazonalidade sobre a expressão, as características de ligação e a transdução do sinal insulínico, bem como, a captação de glicose e aminoácidos neutros em brânquias posteriores (BP), anteriores (BA) e músculo mandibular (MM) de N.granulata em seu ambiente natural. No presente trabalho mostrou-se, pela primeira vez, a expressão do gene CGIRLTK (Chasmagnathus granulata Insulin Receptor Like Tirosine Kinase) e sua variação sazonal em tecidos com diferentes características morfológicas e funcionais. Nas BP os mecanismos de modulação da via insulin/ IGF I-like no verão mostraramse diferentes, quando comparados àqueles verificados no inverno. No inverno o aumento da afinidade e da atividade tirosina quinase do receptor foi acompanhado de significativa elevação na expressão do gene CGIRLTK. Contudo, no verão o aumento na concentração de receptores e na fosforilação do substrato exógeno ocorreu paralelamente ao aumento da expressão do gene CGIRLTK. Já nas BA a sazonalidade não afetou a concentração de mRNA do CGIRLTK e as características de ligação (Kd e Bmax) e fosforilação do receptor tirosina quinase mostraram eventos similares àqueles verificados nas BP no inverno e verão, entretanto, na primavera, verificou-se uma resistência à insulina nesses órgãos. Quanto ao MM constatou-se elevada sensibilidade à insulina na primavera. Nessa estação a elevação da concentração de mRNA do CGIRLTK foi acompanhada do aumento da concentração de receptores, da afinidade do receptor ao hormônio e da atividade tirosina quinase do receptor. No presente trabalho a captação de 1-[14C] 2-deoxi-D-glicose (DG) foi marcadamente superior aquela de 3-O-[14C] metil-D-glicose (MG) nas BP e BA de N. granulata em todas as estações. A maior captação de DG e de MG nas BP e BA ocorre na primavera e no verão, sugerindo, que o transporte de glicose, possivelmente, ocorra via GLUT nas brânquias. Em contraste ao observado nas brânquias, não se constatou diferenças marcantes entre a captação de DG e de MG no músculo nos meses de inverno, primavera e verão. É possível que no tecido muscular existam dois sistemas de transporte de glicose com diferentes propriedades cinéticas e moduladoras: via GLUT e via co-transporte de sódio. Concluindo, a sazonalidade dos fatores ambientais altera a expressão do gene GCIRLTK, as características de ligação e de transdução do sinal insulínico, o transporte de nutrientes e de osmólitos em brânquias anteriores e posteriores e em músculo de N. granulata.

Eutrophication impacts the quality of many surface waters worldwide. Algal blooms threaten lake water quality and in order to control their growth, understanding of nutrient transport at the field-scale is essential. In order to accomplish this, a combination of field monitoring and computer modeling with the SWAT model was undertaken.
Four sites located in the Pike River watershed of southern Quebec were instrumented to monitor nutrient losses from both clay loam and sandy loam soils under both subsurface and naturally drained conditions. Results illustrate how the presence of subsurface drainage influences phosphorus loss depending on soil texture and structure. Total phosphorus loss from the clay loam subsurface drained site was 4.0 kg ha-1, 55% greater than the naturally drained clay loam site. Total phosphorus loss from the sandy loam subsurface drained site was 1.2 kg ha-1, 14% less than the naturally drained sandy loam site. Total phosphorus losses from the subsurface drainage systems in the clay loam field and the sandy loam field were 2.3 and 0.4 kg ha-1, respectively. Particulate phosphorus was the dominant (78%) form of phosphorus loss from the subsurface drainage system at the clay loam site. This indicates that bypass flow through the soil profile in the clay loam field led to excessive total phosphorus loss.
SWAT, a watershed-scale model was calibrated with over 6 site years of data, in an attempt to simulate hydrology and pollutant transport at the field-scale. After calibration, the monthly Nash-Sutcliffe Efficiency varied from 0.09 to 0.74 for total drainage; 0.04 to 0.71 for sediment loading; 0.29 to 0.48 for nitrate loads and 0.28 to 0.64 for total phosphorus loads. Overall, SWAT has shown that it has the ability to simulate long-term sediment and nutrient transport at the field-scale. This makes SWAT a valuable tool for the development and evaluation of various beneficial management practices which control sediment and nutrient loss from agricultural fields.