Dissertations / Theses on the topic 'Water Victoria Phosphorus content'
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1
Abou, Nahra Joumana. "Modeling phosphorus transport in soil and water." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102946.
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The main objective of this project was to investigate and model phosphorus (P) transport in soil column studies. A model named HYDRUS-NICA was developed, by coupling a hydrological and transport model (HYDRUS-1D model) with an aqueous chemical model (non-ideal competitive adsorption - NICA), to improve the predictions of P transport in soil and water. The HYDRUS-NICA model was developed by replacing the non-linear empirical (Freundlich and Langmuir) equations of the HYDRUS-1D model with the NICA model equations. The numerical accuracy of the HYDRUS-NICA model was then evaluated by comparing the relative errors produced by the HYDRUS-NICA and HYDRUS-1D models. The results showed that the numerical schemes of the HYDRUS-NICA code are stable.The ability of the NICA model to describe phosphate (PO4) adsorption to soil particles was tested using soils collected from agricultural fields in southern Quebec. The surface charge and PO4 adsorption capacity of these soils were measured. Results were used to estimate the NICA model parameters using a non-linear fitting function. The NICA model accurately described the surface charge of these soils and the PO4 adsorption processes.
The HYDRUS-1D model was applied to simulate water flow and PO4 transport in re-constructed soil column experiments. The HYDRUS-1D model was calibrated based on physical and chemical parameters that were estimated from different experiments. Overall, the HYDRUS-1D model successfully simulated the water flow in the columns; however, it overestimated the final adsorbed PO4 concentrations in the soil. The discrepancies in the results suggested that the HYDRUS-1D model could not account for the differences in the soil structure found in the columns, or that the Freundlich isotherm could not adequately describe PO4 adsorption.
The HYDRUS-NICA model was calibrated and validated with results from re-packed column experiments. The simulated results were then compared with results obtained by the HYDRUS-1D model. The overall goodness-of-fit for the HYDRUS-1D model simulations was classified as poor. The HYDRUS-NICA model improved significantly the prediction of PO4 transport, with the coefficient of modeling efficiency values being close to unity, and the coefficient of residual mass values being close to zero. The HYDRUS-NICA model can be used as a tool to improve the prediction of PO4 transport at the field scale.
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Simm, Robert. "Enhanced biological phosphorus removal using a sequencing batch RBC." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28517.
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The objective of the research program was to demonstrate the technical feasibility of removing phosphorus, by the enhanced biological phosphorus removal mechanism, from domestic wastewater using a laboratory scale Sequencing Batch Rotating Biological Contactor (SBRBC). The rotating discs of the RBC were subjected to alternating anaerobic/aerobic conditions by varying the water level in the reaction vessel. At the start of the treatment cycle, the RBC reactor would be filled submerging the rotating discs and ensuring anaerobic conditions in the RBC biofilm. Acetate would be added to the reaction vessel at this time. Following the batch anaerobic react period part of the reactor contents were decanted to either the sewage feed tank or a separate holding vessel to later become part of the influent for the next treatment cycle. With the rotating: discs of the-RBC partially submerged oxygen was available to the bacteria, in the RBC biofilm.
Three operating schedules were tried with the above process. Each operating schedule
differed in the way the decanted wastewater from the anaerobic phase was handled.
Batch tests were conducted weekly to determine the nature of the biological reactions
taking place in each of the batch anaerobic and aerobic phases.
The SBRBC process showed promise for enhanced biological phosphorus removal from domestic wastewater. Carbon removal and nitrification of the wastewater were secondary benefits to this process. The success of the process was found to be dependent on the attainment of proper anaerobic conditions at the start of each treatment cycle.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
3
Coolidge, Kyle Marvin. "Phosphorus Cycling in Maine Lakes: A Sedimentary Analysis." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/CoolidgeKM2004.pdf.
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D'Angelo, Donna Jean. "Mechanisms governing phosphorus retention in streams." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39241.
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A, Heskett Richard. "Determining soil phosphorus concentrations using cattail indicators." Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1048396.
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Excess phosphorus is often identified as a major factor in the eutrophication of wetlands and lakes. Often attributed to agricultural practices, the specific source of a large part of this excess has been difficult to determine. The term "nonpoint" source is often used to broadly describe the inflow along waterways of significant amounts of this essential plant nutrient and other pollution. This research was intended to determine the effectiveness of using cattails (Typha), a common plant along waterways, as indicators of plant available phosphorus in the soil along these waterways. Two sites in the southern part of Michigan's lower peninsula (45°N,84°W) where cattails grew were systematically examined for phosphorus and certain cattail characteristics. Plant and soil data were gathered in a grid-like pattern to determine both the relationship of paired data and their spatial distribution across each site. One set of data was shown to be significant. At one site, the density of cattails is weakly correlated with Phosphorus concentrations. Of particular importance, the spatial distribution of both variables is also noticeably similar at the site. No significant correlation between other data was shown. There is also no apparent similarity in spatial distribution. Though weakly correlated, we were able to support a hypothesis that a reasonable correlation exists between cattail density and plant available phosphorus at one site. The spatial distribution of these traits are also similar suggesting that cattails may, in some cases, be useful as indicators of excess phosphorus, perhaps better defining its source than “nonprint”.Department of Biology
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Yurk, Jeffrey J. "Assessment of total phosphorus concentration as a predictor and determinant of fishery productivity in southern Appalachian reservoirs: application to Smith Mountain Lake, Virginia." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/50103.
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Phosphorus is often the limiting nutrient of primary productivity in southern Appalachian reservoirs, but its impact on higher trophic levels has not been assessed. Regression analysis was used to examine the relationship between total phosphorus concentrations and estimates of fish standing stock in Smith Mountain Lake (SML) over time and for 22 southern Appalachian reservoirs (SAR) at the same time. ln SML, which had responded to a nutrient reduction program, total phosphorus concentration and fish biomass concurrently declined over an 12-year period; phosphorus concentration accounted for one-third (cove-specific) and two-thirds (whole-Iake) of the annual variation in fish standing stock. Total phosphorus concentration was also the best predictor of fish abundance in SARs, accounting for 84% of the variation in standing stock despite great diversity in reservoir physical, chemical, and biological characteristics. Predictive power was generally higher at lower levels of the food chain (i.e. planktivores, younger fish) than for piscivores. Planktivore response to phosphorus was found to be immediate. Piscivore biomass did not vary significantly with phosphorus, owing in part to poor energy transfer up the food chain and variable management practices. Phosphorus concentration and total fish standing stock appear to have stabilized in SML since 1980. Losses in fish standing stock due to deceased fertility in SML have been partly offset by an increase in coolwater habitat. Aesthetic versus fishery benefits and the complexity of dealing with a longitudinal trophic gradient need to be considered for future management of SML.Master of Science
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Stämpfli, Nicolas. "The effect of water table management on the migration of phosphorus and on grain corn yields." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19763.
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Due to recent research suggesting that water table management (WTM) can significantly reduce nitrate (NO3") loads in agricultural drainage, a study was carried out in 2001 and 2002 in Coteau-du-Lac, 60 km west of Montreal, to investigate the effect of water table management on the migration of phosphorus (P) via tile drainage and surface runoff. The second main objective was to study the influence of WTM on grain corn yields. Two drainage treatments were compared: conventional free drainage and WTM (combined controlled drainage and subirrigation) with a design water table depth at 0.6 m below the ground surface. Tile drainage and surface runoff were monitored and sampled automatically. Increased outflow volumes and concentrations - and therefore increased P loads - were measured in drainage water from plots under WTM. Plots under WTM also generally exhibited higher P loads in surface runoff. Higher P concentrations in surface runoff from plots under WTM were observed in surface runoff, especially during winter. Phosphorus loads from combined tile drainage and surface runoff were low compared with literature data (<0.4 kg/ha/year). However, the mean P concentrations in tile drainage were above Quebec's surface water quality standard of 0.03 mg total P/L during both growing seasons in plots under WTM, but not in plots with conventional free drainage. Mean P concentrations in surface runoff water routinely exceeded the criteria, except in plots with conventional free drainage in winter 2002. Therefore, P from tile drainage and surface runoff could contribute to the eutrophication of surface water. Based on these results, WTM increases P loads from the field, both in tile drainage and surface runoff. However, the well water used for subirrigation was found to contain P concentrations above Quebec's surface water quality standard, and this could partly explain the higher P concentrations found in water from plots under WTM. Water table management increased grain corn yields by 35% in both years. The growing seasons of 2001 and 2002 were among the driest ever recorded in Canada.
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Shetterly, Benjamin James. "Soil Phosphorus Characterization and Vulnerability to Release in Urban Stormwater Bioretention Facilities." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4354.
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Modern urban stormwater infrastructure includes vegetated bioretention facilities (BRFs) that are designed to detain water and pollutants. Phosphorus (P) is a pollutant in stormwater which can be retained in BRF soils in mineral, plant, and microbial pools. We explored soil properties and phosphorus forms in the soils of 16 operational BRFs in Portland, OR. Since soil hydrology can significantly impact P retention, we selected BRFs along an infiltration rate (IR) gradient. We conducted sequential fractionation and tests of P pools and measured P release in a subset of soils after drying and flooding samples for ten days. We hypothesized that mineral or organic soil P forms would be correlated with IR, and that vulnerability to P release would depend on the interaction of drying and flooding treatments with P forms and pools. IR did not significantly explain differences in P forms. Soil TP was elevated across all sites, compared with TP in agriculturally-impacted wetlands and was substantially composed of soil organic matter (OM)-associated P. Phosphorus sorbed to mineral Fe and Al oxides- was variable but positively correlated with water-extractable P. The concentration gradient of water-extractable P was primarily controlled by overall P pools. Experimentally induced P releases were seen in 5 of 6 soils exposed to drying conditions, presumably released through microbial mineralization of OM. Only one site showed significant P release following the flooding treatment. Our measurements supported the idea that Fe and Al oxides provide P sorption capacity in these BRF soils. Variable inputs of P to BRFs through stormwater and litterfall may contribute to variability in P profiles and P release vulnerability across sites. Design specifications and management decisions relating to bioretention soils (e.g. establishment of acceptable soil test P levels, focusing on P forms known to influence vulnerability of P release) may benefit from detailed biogeochemical investigations.
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Jamieson, Andrew 1976. "Evaluating phosphorus losses in surface and subsurface runoff from two agricultural fields in Quebec." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33784.
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Phosphorous concentrations exceed water quality guidelines in most of the major rivers in southern Quebec. The problem is particularly acute in the Pike River, which drains into the Missisquoi Bay of Lake Champlain, in southeastern Quebec. Elevated phosphorus concentrations can lead to a reduction in the palatability of drinking water, a decrease in diversity of aquatic life and loss of recreational opportunities. All of these problems have been observed in the Bay.Two agricultural fields (the Marchand and Gagnon sites) located on the Pike River watershed, in southeastern Quebec were selected and equipped with instrumentation to measure and evaluate the partitioning of phosphorus between surface runoff and subsurface drainage, on a year round basis. The snowmelt event was the dominant surface and subsurface event for the 2000/2001 hydrological year. On the Marchand site surface flow data was incomplete as a result of a failure of the surface runoff flume. On both sites the IF 200 subsurface flow meters failed, which resulted in missing subsurface flow data during certain runoff events. Therefore, the majority of the comparisons made relate to the Gagnon site.
The 2000/2001 hydrological year was unusually dry, which resulted in a limited number of surface and subsurface runoff events. The annual depth of surface runoff for the Gagnon site was 87.5 mm/ha, of which only 0.2mm occurred outside the snowmelt event. The estimated depth of subsurface runoff of the snowmelt event at the Gagnon site based upon a water balance equation was 93.7 mm/ha, or 51.7% of the total volume that occurred on the Gagnon field during the snowmelt event.
The total phosphorus load in surface runoff for the spring snowmelt at the Gagnon site was 166.4 g/ha, whereas the estimated total phosphorus load in subsurface drainage was 98.2 g/ha, or 37.1% of the total load. Subsurface drains can therefore be a significant pathway for phosphorus losses.
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Rooney, Neil. "Scale of analysis and the influence of submerged macrophytes on lake processes." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37665.
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The goal of this thesis was to examine submerged macrophoe biomass, distribution, and ecosystem effects at scales large enough to incorporate the littoral zone into models of whole lake structure and function. Submerged macrophyte biomass and distribution was shown to be highly variable between growing seasons and primarily dependant upon air temperature and the timing of the onset of the growing season. Within a growing season, a mass balance study showed an undisturbed macrophyte bed to markedly lower phytoplankton biomass: total phosphorus ratios, although the net effect of the bed on the growing season phosphorus budget was minimal. The weedbed preferentially retained phytoplankton biomass while being a source of bacterial production to the open water. These findings were mirrored at the among lake scale, as planktonic respiration and bacterial production were higher in macrophyte dominated lakes than would be expected based on phytoplankton biomass alone. Further, phytoplankton biomass was lower than would be expected based on epilimnetic phosphorus levels, showing that the classical view of pelagic interactions that proposes phosphorus determines phytoplankton abundance, which in turn determines bacterial abundance through the production of organic carbon, becomes less relevant as macrophyte cover increases. Long term phosphorus accumulation in the littoral zone was shown to be linked to macrophyte biomass, and on average almost an order of magnitude higher than calculated from the growing season (June--October) phosphorus budget, suggesting that the bulk of phosphorus accumulation in weedbeds occurs outside of the growing season. Finally, sediment core data showed that while submerged weedbeds accumulate up to four times as much bulk sediment compared to the profundal zone, phosphorus accumulation in weedbeds is much less than observed in the profundal zone. These results strongly indicating that submerged macrophyte beds play a central role in trapping ep
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Stewart, Scott R. "Phosphorus loading in Baker Creek, Oregon." Thesis, 1992. http://hdl.handle.net/1957/36578.
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Mayakaduwage, Sonia Samanthi. "Influence of pH, phosphorus addition and soil water content on phosphorus pools in acid sulfate soils." Thesis, 2020. http://hdl.handle.net/2440/128818.
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Acid sulfate soils (ASS) are common in wetlands and important for crop production. However, little is known about P availability in ASS which is constrained due to high Fe content and changing redox potential. This thesis aimed to investigate the effect of P addition, pH and soil water content on P pools in ASS. A sandy sulfuric ASS (pH 3.2) was used in the experiments. In the first experiment, the ASS was amended with NaOH or Ca(OH)2) to achieve soil pH 4 or 5.5, without or with addition of inorganic P equivalent to 20 kg ha−1. Soils were incubated in either submerged or moist conditions (100% of maximum water holding capacity). After two weeks, P pools and Fe /Al oxides were determined. P pools were higher with P addition than without. The increase in pH enhanced Fe oxides but had little effect on labile P. Added soluble P was available after two weeks of addition under submerged conditions. In Experiment 2, the ASS (pH adjusted to 5.5) was amended with phosphate at 0, 96, 385, 578 and 770 mg P kg−1 and incubated under submerged conditions. P pools were measured after two and four weeks. Sorption and release of P were determined in incubated soils and jarosite, separately. The maximum sorption capacity of the soil was 350 mg P kg-1. Jarosite had a high capacity to bind P and contributed about 50% to P binding in this soil. Labile P represented more than 50% of added P at P rates above 350 mg P kg-1. The third chapter included two experiments. In the first experiment, the ASS (pH adjusted to 5.5) was amended with 400 mg P kg-1 as inorganic P, manure or combinations of inorganic P/manure and was incubated submerged. After two and four weeks, labile P was measured. Labile P in treatments with 50% of P added as manure was about half of that in treatments with a greater proportion of inorganic P. In the second experiment, treatments (inorganic P alone: 100F, manure alone: 100M, combination of manure and inorganic P: 50M/50F and unamended control) were kept submerged, then moist, followed by resubmergence. At the end of first submergence, labile P was two-fold higher in 100F than in manure treatments. But in the moist period and after resubmergence, labile P did not differ between 100F and 100M. Oxalate extractable Fe was higher in 100M than 100F and remained unchanged until the end of the experiment. In experiment 4, the ASS (without or with pH increase to 5.5) was amended with mangrove roots to achieve an organic carbon (OC) addition of 50% or 150% of native soil OC and incubated under submerged, moist and then resubmerged conditions. At the end of each four-week period, P pools, amorphous Fe/Al and potential P sorption were measured. Mangrove roots addition decreased the redox potential and increased labile P under submerged conditions, but only at pH 5.5. P binding was enhanced by root addition during the first 8 weeks, but not after re-submergence.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2020
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Norris, Matthew. "Phosphorus sorption behaviour of some South African water treatment residues." Thesis, 2009. http://hdl.handle.net/10413/673.
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Blair, Michael Stuart. "Oregon coastal lake study : phosphorus loading and water quality implications." Thesis, 1993. http://hdl.handle.net/1957/36085.
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A study of phosphorus loading and water quality implications was conducted for
the Oregon coastal lakes. The study was based on existing data for lake total phosphorus
concentrations and for watershed land uses. A phosphorus mass-balance model was
developed to predict lake total phosphorus concentrations from estimated phosphorus
loading from land uses within the lake's watershed. Uncertainty in total phosphorus
concentration estimates are included in the model, and model predictions are considered
to be moderately to highly reliable.
The Oregon coastal lake phosphorus mass-balance model was calibrated from data
for 12 Oregon coastal lakes. Land use phosphorus loading coefficients for forestry, the
coastal dunal aquifer, and precipitation were derived from data specific to the Oregon
coastal region, while other phosphorus loading coefficients were estimated based on
correlations between literature values and Oregon coastal conditions.
The model may be used as an aid for land use management decisions by
estimating water quality effects of projected land use changes. A case study of Mercer
Lake was used to illustrate the model application.Graduation date: 1994
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Erinle, Kehinde Olajide. "Effect of crop residue quality on phosphorus pools in the detritusphere and P uptake by wheat." Thesis, 2019. http://hdl.handle.net/2440/123091.
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Little is known about the effect of the influence of water availability, crop residue quality and plant growth on phosphorus (P) pools in the detritusphere, the soil adjacent to plant residues. The detritusphere soil was generated in microcosms as described in Ha et al. (2007). The soil at 0-2 mm distance from the surface of soil incubated in PVC caps was collected as the detritusphere soil and used for further experiments. Bioavailable P pools (readily available P pools: CaCl2 and anion exchange P; P bound to soil particles: citrate and HCl P; acid phosphatase and microbial P), available N and microbial N were measured in the detritusphere. The experiment described in Chapter 2 investigated the influence of drying and rewetting on soil P pools in the detritusphere of two crop residues, young faba bean residue (C/P 38) and mature barley straw (C/P 255). The detritusphere and unamended control soils were dried to approximately 5% water holding capacity (WHC) and kept dry for two weeks followed by rapid rewetting to 50% WHC, or maintained at 50% of WHC. Rewetting of dry soils induced a respiration flush and the flush was greater with faba bean than barley. P pools were higher with faba bean than with barley, due to lower C/P ratio of the former. In general, drying and rewetting had little effect on P pools. In Chapter 3, an experiment is described that assessed the influence of soil water availability on P pools in the detritusphere of crop residues. Detritusphere was generated with barley straw (C/P 255) or barley straw mixed with faba bean residue at a 75:25 ratio (C/P 200) in soil at 50% WHC. Water availability in the detritusphere soils was reduced to -0.320 and -1.700 MPa (30% and 10% WHC), or maintained at -0.078 MPa (50% WHC). In the detritusphere of the residue mix, soil respiration, P pools and available N were lower at -1.700 MPa than at -0.078 MPa. However, water availability had little effect in barley detritusphere. The aim of the experiment described in Chapter 4 was to elucidate the effect of soil amendment with inorganic N and P on P pools in the detritusphere of mature barley straw (C/N 95; C/P 255). Addition of inorganic N to soil increased P pools likely due to enhanced mineralisation of native soil organic matter. Barley straw decomposition reduced available P pools in the detritusphere, particularly in soil to which inorganic P was added. In Chapter 5, an experiment was described to determine the influence of a change of residue types on P pools in the detritusphere of crop residues with differing C/P ratios. In the first experiment, after two weeks of incubation at 50% WHC, with young faba bean residue (L) or mature barley straw (H), the residues were replaced with either a H or L, resulting in four residue treatments: high-high (HH), high-low (HL), low-low (LL) or low-high (LH), which were incubated for another 14 days. On day 14, P pools and available N were higher, but MBP and MBN were lower in L than in H. On day 28, P pools and available N followed the order LL>HL>LH>HH, whereas MBN and MBP were highest in HL. The experiment described in Chapter 6 aimed to determine the influence of residue C/P ratio on changes in P pools and N availability in wheat rhizosphere. Pre-germinated wheat seeds were sown in unamended soil or soil amended with two crop residues (young faba bean residue, C/P 38; mature barley straw, C/P 255). After 28 days with faba bean, P uptake in wheat was higher than with barley straw and control. P pools were lower in the interface of wheat rhizosphere and faba bean detritusphere than in detritusphere alone, due to plant uptake. With barley straw, presence of wheat roots had no effect on P pools.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food & Wine, 2019
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Nowlin, Weston Hugh. "Phosphorus dynamics in coastal and inland lakes and reservoirs in British Columbia with special reference to water level fluctuation and climate variability." 2003. http://hdl.handle.net/1828/346.
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Peterson, Heidi Marliese. "Hybrid cattail (Typha x glauca) growth and nutrient content along a water depth gradient in two prairie marshes." 2015. http://hdl.handle.net/1993/30838.
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Emergent macrophytes are an integral part of prairie marshes and involved in many of the services that make these ecosystems valuable. Water depth and hydroperiod are two environmental variables that can influence the growth and nutrient content of emergent macrophytes. This study looked at the growth and nutrient content response of hybrid cattail (Typha x glauca) to water depth and hydroperiod in two prairie marshes in southern Manitoba, Canada. Above- and belowground samples of hybrid cattails were collected along a water depth gradient at Oak Hammock Marsh, Canada, and analyzed for biomass, total phosphorus, total nitrogen, total Kjeldahl nitrogen content, shoot height, and density. A second dataset was obtained from the Marsh Ecology Research Program (MERP) experiment, and used to determine the biomass and nutrient content response of the hybrid cattail following one or two years of drawdown.October 2015
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Johnstone, Joseph A. "Nitrogen, Phosphorus and Carbon Dynamics during Storms in a Glaciated Third-Order Watershed in the US Midwest." Thesis, 2013. http://hdl.handle.net/1805/3460.
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Indiana University-Purdue University Indianapolis (IUPUI)The characterization of the nutrients nitrogen, phosphorus and carbon (NPC) export to streams during storms is an integral part of understanding processes affecting water quality. Despite the fact that excessive levels of these nutrients in the Mississippi River basin adversely affects water quality in the Gulf of Mexico, little research has been conducted on NPC dynamics during storms on larger (>20 km2) agriculturally dominated Midwestern watersheds. This project examined the storm export of nitrate, ammonium, total phosphorus, and dissolved organic carbon (DOC) in the upper Eagle Creek Watershed (UECW) (274 km2) in Central Indiana, USA. Water samples were collected during five winter and spring storms in 2007 and 2008 on the rising and falling limb of the hydrograph, in order to characterize NPC dynamics during storm events. Stream discharge and precipitation was monitored continuously, and major cations were used to examine changes in source water over the duration of the storm and assist in the determination of potential flowpaths. DOC, total P, and TKN (Total Kjeldahl Nitrogen) tended to peak with discharge, while nitrate usually exhibited a slight lag and peaked on the receding limb. Total phosphorus, NH3-, TKN, and DOC appear to be delivered to the stream primarily by overland flow. NO3--N appear to be delivered by a combination of tile drain and macropore flow. Overall UECW displayed smoother nutrient export patterns than smaller previously studied watersheds in the area suggesting that scale may influence nutrient export dynamics. Further research is underway on a 3000 km2 watershed in the area to further examine the role scale may play in nutrient export patterns.
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Adams, Geoffrey. "Development of a simple hydrological modelling methodology for estimating phosphorus generation from rural land." Phd thesis, 2010. http://hdl.handle.net/1885/150832.
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Gopinath, Raju. "Modeling the impact of buffer strips on phosphorus concentration in Buck Creek Watershed, Indiana : a GIS approach." 2010. http://liblink.bsu.edu/uhtbin/catkey/1629786.
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This study has attempted to model and quantify the impacts of Beneficial Management Practices (BMP) like buffer strips on the phosphorus concentration and loading in the Buck Creek Watershed of Central Indiana. The GIS based modeling was done using the Soil and Water Assessment Tool (SWAT) developed by the U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). The results from the EPA funded two year (2002-2004) Upper White River Watershed Project (UWRWP) for the Buck Creek Watershed were used as the measured base data for the modeling evaluation. These measured data were compared against the data generated out of the model simulation based on two different scenarios which took into consideration the combinations of land use, agricultural management practices, point source pollutions and BMPs. Scenario-1 simulated all the aspects of land use intensity, moderate agricultural management practices and moderate point source pollutions taking place in the Buck Creek watershed. While running the model in scenario-1, there was a noticeable increase in the phosphorus loading to the sub-watersheds ranging from 10% in the lowland sub-watershed of BC-4 to 39% in the highland sub-watershed of BC-7. In scenario-2, BMPs were implemented in the model which added 100 acres of vegetated buffer strips uniformly in all sub-watersheds and 3 acres of grassed buffers along the streams except BC-3. On re-running the model in scenario-2, there was a drastic decline in the phosphorus loading to the stream. It has been noted that there was at least 15% reduction in the loading of phosphorus to the stream where buffer strips were implemented. The present GIS modeling study helped to quantify the changes in the loading of sediments and nutrients which are induced by any parametric changes in the watershed including soil, slope, land use, agricultural management practices and BMPs.Department of Geography
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Liu, Qianhe. "Rhizosphere processes influencing soil and fertilizer phosphorus availability to Pinus radiata : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North, New Zealand." 2005. http://hdl.handle.net/10179/1669.
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Production of Pinus radiata is a major contributor to New Zealand's economy and new plantings are a valuable carbon sink. Phosphorus (P) deficiency and high P fixing capacity of some volcanic ash soils (e.g. Allophanic Soil) may constrain radiata productivity. This thesis investigates the role of ectomycorrhizal (ECM) root processes in the acquisition of P by P. radiata fiom native soil and soil fertilised with two reactive phosphate rock (RPR) fertilisers. The application of finely-divided RPRs to a P deficient Allophanic Soil significantly increased P. radiata seedling growth and P uptake in 10 month pot trials. RPR dissolution was high in this soil, and it was further enhanced by the radiata rhizosphere processes. The development and formation of ECM in radiata seedlings was stimulated by low rates of RPR application but was hindered in unfertilised soils and high rates of RPR application. The P. radiata ECM roots induced acidification and increased oxalate concentration and phosphatase activities in the rhizosphere soil. These changes in rhizosphere biochemical properties were associated with enhanced solubilisation of fertiliser and soil inorganic P and increased mineralisation of organic P, leading to increased P bioavailability in the rhizosphere. ECM inoculation of P. radiata roots with Rhizopogen rubescens and Suillus luteus stimulated production of phosphatase enzymes and oxalate and induced acidification in the rhizosphere. The extent of root-induced changes in the rhizosphere soils was associated with ECM hyphae length density. A technique using pulse labelling of radiata shoots with 14CO2 showed promise in estimating the active ECM hyphae density. The 14C activity was highly correlated with ECM hyphae density measured by an agar film technique. Overall, observations made in this thesis indicate that sparingly soluble forms of organic and inorganic P in soils low in plant-available P are readily solubilised and utilised for P. radiata growth through ECM rhizosphere processes.
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Liu, Xiaoqiang. "Coupled biogeochemical cycles in riparian zones with contrasting hydrogeomorphic characteristics in the US Midwest." Thesis, 2013. http://hdl.handle.net/1805/3756.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)Numerous studies have investigated the fate of pollutants in riparian buffers, but few studies have focused on the control of multiple contaminants simultaneously in riparian zones. To better understand what drives the biogeochemical cycles of multiple contaminants in riparian zones, a 19-month study was conducted in riparian buffers across a range of hydrogeomorphic (HGM) settings in the White River watershed in Indiana. Three research sites [Leary Webber Ditch (LWD), Scott Starling (SS) and White River (WR)] with contrasting hydro-geomorphology were selected. We monitored groundwater table depth, oxidation reduction potential (ORP), dissolved oxygen (DO), dissolved organic carbon (DOC), NO3-, NH4+, soluble reactive phosphorus (SRP), SO42- , total Hg and methylmercury (MeHg). Our results revealed that differences in HGM conditions translated into distinctive site hydrology, but significant differences in site hydrology did not lead to different biogeochemical conditions. Nitrate reduction and sulfate re-oxidation were likely associated with major hydrological events, while sulfate reduction, ammonia and methylmercury production were likely associated with seasonal changes in biogeochemical conditions. Results also suggest that the LWD site was a small sink for nitrate but a source for sulfate and MeHg, the SS site was a small sink for MeHg but had little effect on NO3-, SO42- and SRP, and the WR was an intermediate to a large sink for nitrate, an intermediate sink for SRP, and a small source for MeHg. Land use and point source appears to have played an important role in regulating solute concentrations (NO3-, SRP and THg). Thermodynamic theories probably oversimplify the complex patterns of solute dynamics which, at the sites monitored in the present study, were more strongly impacted by HGM settings, land use, and proximity to a point source.