Dissertations / Theses on the topic 'Water and nutrient use'
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1
Wang, Xin. "Linking Hydroperiod with Water Use and Nutrient Accumulation in Wetland Tree Islands." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/531.
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Many large terrestrial ecosystems have patterned landscapes as a result of a positive feedback system between vegetation communities and environmental factors. One example is tree island habitats in the Florida Everglades. Although they only occupy a small portion of the Everglades landscape, tree islands are important features as the focus of nutrient accumulation and wildlife biodiversity in the Everglades ecosystem. The hardwood hammock community on the elevated head of tree island habitats can accumulate high phosphorus concentration in the otherwise P-limited Everglades ecosystem. In this dissertation, I examined two hypotheses derived from the chemohydrodynamic nutrient accumulation model, which suggests that high transpiration of tree island hammock plants is the driving force for nutrient accumulation in tree island soil. According to this model, I hypothesized that tree islands with lower dry season transpiration should have less phosphorus accumulated than the tree islands with higher dry season transpiration. By examining the water use and nutrient status from 18 tree islands in both slough (perennially wet) and prairie (seasonally wet) locations, I was able to compare water availability and nutrient accumulation in slough and prairie tree islands with different marsh hydroperiods. Chapter 1 uses elemental and stable isotope analysis to look at water stress and nutrient concentration in tree island plants. I showed that the prairie tree island plants suffer from drought stress during the dry season, when the marshes in the prairies dry out. Prairie tree islands also have lower soil and plant P concentration than the slough tree islands. Moreover, I showed that foliar N isotope ratio serves as a stable proxy for community level P availability for tree island plants, and prairie tree island plants have less P available than slough tree island plants. In Chapter 2, I showed that the satellite imagery derived normalized difference water index (NDWI) provides a robust indicator of community level canopy water content of these tree islands. NDWI, used as a proxy for water status, was positively related to foliar N isotope ratio, which suggests that water availability is linked to nutrient availability in the tree island hardwood hammock plant communities. These findings are consistent to the chemohydrodynamic nutrient accumulation model. In Chapter 3, I used sap flow sensors on individual trees to provide a real-time measurement of plant transpiration. I showed that tree island plant transpiration is affected by multiple factors including weather fluctuations, marsh water depth regulated by local water management, and canopy structure of different tree islands. Overall, my dissertation establishes a link between tree island plant water use and nutrient accumulation. It could be potentially important for future restoration plan of tree islands and Everglades hydrological management.
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Kempen, Estelle. "Nutrient and water use of tomato (Solanum Lycopersicum) in soilless production systems." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97988.
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Thesis (PhD)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Soilless production of crops relies on the addition of high concentrations of nutrients with the irrigation water. The drained nutrient solution should be re-used to reduce the risk of pollution and to increase the water- and nutrient use efficiency of the system. Besides the risk of pathogen build-up, one of the main impediments of a wider application of this method is the frequent analysis required to maintain optimum nutrient concentrations and ratios in the rootzone. Yield reductions may be caused by an unbalanced nutrient solution. Alternatively the addition level of nutrients can be calculated through the use of nutrient uptake models that simulate the change in the re-circulated nutrient solution. To simulate crop water and nutrient demand necessary for model based regulation it was necessary to quantify the key factors affecting nutrient uptake by plants. The nutrient solution concentration and ratios between the macro-nutrients affected the uptake of water and nutrients. The total nutrient uptake per root dry weight increased and more specifically the nitrate (NO3 -), phosphate (H2PO4 -), potassium (K+) and sulphate (SO4 2-) uptake increased with an increase in nutrient solution electrical conductivity (EC) from 0.8 to 4.0 mS cm-1 while water uptake decreased. Except for Ca2+ uptake there was no correlation between nutrient and water uptake. Nutrient uptake can thus not be calculated based on water uptake. Instead a mechanistic high-affinity Michaelis-Menten based model can be used to estimate macro-nutrient uptake (Un, mg m-2 hr-1). Water and nutrient uptake was also affected by the solar radiation levels. Since nutrient uptake is related to the growth rate, solar radiation levels can be expected to influence nutrient uptake. The uptake of all ions increased with an increase in the solar radiation levels and for NO3 -, K+ and H2PO4 - the uptake rate was higher at higher nutrient solution concentrations. The Michaelis-Menten based model was adjusted to incorporate the effect of solar radiation levels on nutrient uptake. Water uptake (Wu, L m-2 day-1) was simulated as a function of crop transpiration and crop leaf area using a linear regression model, but since leaf area development was affected by solar radiation levels this was additionally incorporated into the estimation of the leaf area index (LAI). The composition of the nutrient solution also affected the biomass allocation of the crop which can again affect nutrient use as well as the fruit yield. There was also a direct effect of nutrient solution composition on fruit yield and quality with higher EC’s resulting in smaller fruit but an increase in fruit dry matter %, total soluble solids (TSS), titratable acidity (TA) and lycopene content. The results in this thesis make a valuable contribution to our understanding of the effect of nutrient availability (concentration and ratios) and nutrient requirement for growth (solar radiation levels) on nutrient uptake. Incorporating these into nutrient uptake models resulted in the development of a handy tool to simulate changes in composition of re-circulating nutrient solutions ultimately resulting in an improvement of the water and nutrient use efficiency of soilless systems.
AFRIKAANSE OPSOMMING: Die grondlose verbouing van gewasse is afhanklik van toediening van voedingselemente teen hoë peile in die besproeiingswater. Die voedingsoplossing wat dreineer moet hergebruik word om die risiko van besoedeling te verminder en ook om die water en nutriënt verbruik doeltreffendheid van die sisteem te verbeter. ʼn Ongebalanseerde voedingsoplossing kan ʼn verlaging in opbrengste veroorsaak. Benewens die risiko van patogene wat opbou, is die gereelde analises nodig word vir die handhawing van optimale nutriënt konsentrasies en verhouding tussen elemente in die wortelsone een van die hoof faktore wat ʼn meer algemene gebruik van die metode verhoed. Alternatiewelik kan die nutriënt toedieningspeile bereken word deur voedingstof opname modelle en simulasie van die verandering in water en nutriente wat dreineer. Om ʼn model gebaseerde reguleringsmetode daar te stel was dit nodig om die belangrikste faktore wat nutriënt opname beïnvloed te kwantifiseer. Beide die konsentrasie van die voedingsoplossing en die verhouding tussen elemente het ‘n effek gehad op die opname van water en nutriënte. Die totale nutriënt opname per wortel droë massa het toegeneem. Terwyl water opname afgeneem het met ‘n toename in die elektriese geleding (EG) van die voedingsoplossing vanaf 0.8 tot 4.0 mS cm-1 het die nitraat (NO3 -), fosfaat (H2PO4 -), kalium (K+) en sulfaat (SO4 2-) opname verhoog. Behalwe vir Ca2+ opname was daar geen korrelasie tussen water en nutriënt opname nie. Nutriënt opname kan dus nie bepaal word gebaseer op wateropname nie. Alternatiewelik is die gebruik van ʼn meganistiese hoë-affiniteit Michaelis-Menten-gebaseerde model voorgestel om die opname van makro-nutriente (Un, mg m-2 hr-1) te bepaal. Water- en voedingstofopname is beinvloed deur die ligintensiteit vlakke. Voedingsopname word bepaal deur die groei van die plant, daarom is dit verwag dat ligintensiteit vlakke die opname van voedingstowwe sal beïnvloed. Die opname van al die ione het toegeneem met 'n toename in die ligintensiteit vlakke en die tempo van NO3 -, K+ en H2PO4 - opname was hoër by 'n hoër voedingsoplossing konsentrasie. Die Michaelis-Menten gebaseerde model is aangepas om die effek van ligintensiteit vlakke op nutriënt opname te inkorporeer. Opname van water (Wu, L m-2 dag-1) is gesimuleer as 'n funksie van transpirasie en blaaroppervlakte met behulp van 'n lineêre regressiemodel en aangesien die blaaroppervlak ontwikkeling ook deur ligintensiteit vlakke beïnvloed word, is dit opgeneem in die skatting van die blaaroppervlakte-indeks (LAI). Die samestelling van die voedingsoplossing het die biomassa verspreiding beïnvloed. Dit kan nutriënt gebruik en vrug opbrengs beïnvloed. Die voedingsoplossing samestelling het vrug opbrengs en - kwaliteit beinvloed met kleiner vrugte, maar 'n toename in droëmateriaal %, totale oplosbare vastestowwe (TOVS), titreerbare suur (TA) en likopeen inhoud by ʼn hoër EG. Die resultate in hierdie tesis lewer 'n waardevolle bydrae tot ons begrip van die effek van nutriënt beskikbaarheid (konsentrasie en verhoudings) en voedingstof behoefte vir groei (ligintensiteit vlakke) op voedingsopname. Deur die inligting te inkorporeer in voedingsopname modelle het gelei tot die ontwikkeling van 'n handige instrument om die veranderinge in die samestelling van hersirkulerende voedingsoplossings te simuleer. Dit lei gevolglik tot die verbetering van die water en voedingstof gebruik doeltreffendheid van grondlose stelsels.
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Kerr, Barry Douglas. "Multiple Regression Equations to Estimate Mean Nutrient Concentrations in Streams of North Central Texas from Landsat Derived Land Use." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc278778/.
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Nutrients are of critical concern in water quality assessment. The development of empirical models to estimate mean nutrient concentrations, based on satellite derived land use, could aid water resource managers. Models using land use acreages outperformed those using percentages, and discrete urban land uses were superior to lumped urban. Regressions of the combinations of two, three and four of the eight possible land use variables were investigated. Sensitivity analyses, with one stream deleted each series, identified robust combinations of variables at each level. Although uncertainty exists regarding the final regression coefficients, five of the six actual measured nitrate and total phosphorus mean concentrations were within the 95 percent confidence limits.
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Mir, Rigau Xavier. "Land Use Impact Assessment on the Nutrient Transport in the lake Mälaren." Thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170450.
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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.
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Becnel, Audrey R. "Land Use and Water Quality Correlations in Miami-Dade, Florida." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1549.
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South Florida continues to become increasingly developed and urbanized. My exploratory study examines connections between land use and water quality. The main objectives of the project were to develop an understanding of how land use has affected water quality in Miami-Dade canals, and an economic optimization model to estimate the costs of best management practices necessary to improve water quality. Results indicate Miami-Dade County land use and water quality are correlated. Through statistical factor and cluster analysis, it is apparent that agricultural areas are associated with higher concentrations of nitrogen, while urban areas commonly have higher levels of phosphorous than agricultural areas.
The economic optimization model shows that urban areas can improve water quality by lowering fertilizer inputs. Agricultural areas can also implement methods to improve water quality although it may be more expensive than urban areas. It is important to keep solutions in mind when looking towards future water quality improvements in South Florida.
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Edwards, Richard Reginald. "The potential for the use of willow (Salix spp.) in buffer zones for reducing nitrate and atrazine pollution." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322361.
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Taylor, Richard Peter. "The use of treated brewery effluent as a water and nutrient source in crop irrigation." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/d1021265.
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Brewery effluent (BE) needs to be treated before it can be released into the environment, reused or used in down-stream activities. Current technologies used to address this concern at the experimental wastewater treatment plant at Ibahyi Brewery (SAB Ltd) include anaerobic digestion (AD), primary facultative ponds (PFP), high rate algal ponds (HRAP) and constructed wetlands (CW). The aim of this work was to determine if BE treated in these systems might be suitable for crop irrigation. A test crop, cabbage (Brassica oleracea cv. Star 3301), grew best on post-AD and post-PFP BE compared to those irrigated with post-HRAP or post-CW effluent. However, the yield was 13% lower than cabbage plants irrigated with a commercial nutrient solution and fresh water. The relatively high conductivity (3019.05 ± 48.72 μs/cm2) of BE may be the main factor reducing the cabbage yields. Post-HRAP and post-CW BE were the least suitable for irrigated crop production due to the higher conductivity and lower nutrient content of these treated effluents. After three months, soils irrigated with post-AD and post-PFP BE had a significantly higher sodium content and sodium adsorption ratio (3919 ± 94.77 mg/kg & 8.18 ± 0.17) than soil irrigated with a commercial nutrient solution (920.58 ± 27.46 mg/kg & 2.20 ± 0.05; p<0.05). However, this was not accompanied by a deterioration in the soil’s hydro-physical properties, nor a change in the metabolic community structure of the soil (p>0.05). After prolonged irrigation with treated BE, sodium is likely to build up in the soil and this can be expected to be accompanied by a deterioration in the soil physical structure. However, crops species such as millet (Echinochloa esculenta), lucerne (Medicago sativa) and saltbush (Atriplex nummularia) reduced the build-up of sodium in the soil. The results suggest that sodium was mainly removed from the soil through plant-assisted leaching. Of the crops grown, lucerne showed the most promise because it improved the soil physical properties, is able to grow well in alkaline environments, is a popular fodder crop and can be harvested multiple times from a single stand. Brewery effluent is more suitable for soil production systems than hydroponic production systems because the soil was able to act as a buffer against the high pH of post-AD BE, whereas in a hydroponics systems the high pH reduced the availability of key minerals to plants. In conclusion brewery effluent contains sufficient plants nutrients to support the growth of cabbages, saltbush, lucerne and millet. However the sodium content of BE is a concern as it accumulates in the soil, and in the long-term it may lead to soil degradation. It is suggested that the brewery change the pH neutralising treatment of BE from sodium hydroxide to potassium hydroxide, or dolomitic lime (calcium and magnesium carbonate) because this would reduce the introduction of sodium into the system, and would increase the suitability of BE for crop production, given potassium and calcium are plant nutrients. The benefits of developing this nutrient and water resource could contribute to cost-reductions at the brewery, more efficient water, nutrient and energy management, create job opportunities with the potential of improving food security in the local community.
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Hoskins, Tyler Courtney. "Water and nutrient transport dynamics during the irrigation of containerized nursery crops." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/48165.
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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
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Mack, Rachel E. "Best Management Practice Use and Efficacy for the Virginia Nursery and Greenhouse Industry." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/84159.
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Best management practices (BMPs) are used in the nursery and greenhouse industry to increase production efficiency, and also serve to help meet clean water limitations on contaminants entering waters such as the Chesapeake Bay Watershed. Research is lacking on which BMPs are most widely used or most efficacious for Virginia nursery and greenhouse growers. Objectives of this work were to determine BMP use, barriers to adoption, and scientific efficacy.
We conducted a survey of Virginia growers to find the 1) most widely used BMPs, 2) reasons behind BMP use, and 3) any barriers to BMP adoption. Sixty growers (17%) responded to the survey. The most widely used BMPs included irrigation scheduling, integrated pest management, optimized irrigation efficiency, plant need based watering, grouping plants by water needs, on-site water capture and collection, and use of controlled-release fertilizers (CRFs). Cost was a barrier to BMP adoption, and environmental concern was a commonly reported reason for BMP use. We documented the science supporting selected water-related BMPs (grass buffer strips, CRFs, and irrigation optimization BMPs). Providing the science supporting BMP use gives growers confidence in implementing BMPs to limit water contamination, and prevent waste.Master of Science
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Spooner, Daniel Ron, and n/a. "Nutrient, organic carbon and suspended solid loadings in two ICOLLs, NSW Australia : biogeochemical responses." University of Canberra. Resource, Environmental & Heritage Sciences, 2005. http://erl.canberra.edu.au./public/adt-AUC20070129.130745.
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Intermittently Closed and Open Lake Lagoons (ICOLLs) are very common along the
southern NSW coastline. Expanding urban populations are expanding and these systems are
under increasing pressure from anthropogenic activities that change landscape processes and
significantly alter the amounts of organic and inorganic constituents entering their waters.
Once efficient cycling of nutrients in ICOLLs is overcome, the symptoms of eutrophication
establish and the entire ecosystem suffers. These systems have great ecological, social, and
economic values that require insightful, well balanced, and educated management to
promote sustainable use of these often-sensitive areas.
Corunna and Nangudga Lake are ICOLLs in the Eurobodalla Shire on the south
coast of NSW. These two ICOLLs receive discharges from catchments covered by native
vegetation and grassland. The primary objective of this research component was to quantify
catchment exports of total nitrogen (TN), total phosphorus (TP), suspended solids (SS),
particulate organic matter (POM) and dissolved organic carbon (DOC) from three small
coastal sub catchments that deliver constituents into Corunna and Nangudga Lakes. As part
of this investigation the fates of catchment loads in the ICOLLs were established focusing
on the lakes water column response to catchment loads and the biogeochemical cycling of
nitrogen and phosphorus in sediments.
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Carey, Richard O. "Evaluating temporal and spatial land use influences affecting nutrient water quality in the Biscayne Bay Watershed, Florida." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0025165.
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Crane, Kristy Susanne. "Pressurized Hot Water: An Alternative Method of Nutrient Extraction and Subsequent Analysis for Use in Small-Scale Agriculture." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd495.pdf.
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Cowan, Watts Cara Ailene. "Critical review of us environmental protection agency numerical nutrient criteria with respect to culturally significant waters as a designated use." Thesis, Oklahoma State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10163015.
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The Cherokee Nation, a Federally-recognized Tribal government in Northeastern Oklahoma lacks Tribal water quality standards for numerical nutrient standards based on baseline conditions in the Cherokee Nation. Lotic waters are of special significance in Cherokee Nation culture and ceremonies. Three water quality standard priorities within the Tribe include defining Culturally Significant Waters as a designated use, identifying Culturally Significant Waterbodies and determining applicable numerical nutrient standards. Culturally Significant Water as a designated use was defined based on community surveys. Twelve rivers and streams were identified as a portion of the Culturally Significant Waters of the Cherokee Nation based on a tribal community survey using a Use Attainability Analysis. To address excess nutrients in the Cherokee Nation, a total phosphorus numerical nutrient criterion was determined using data for Culturally Significant Water bodies, literature guidance and the US Environmental Protection Agency recommended nutrient criteria process for the respective Aggregate Nutrient Ecoregion. The Oklahoma Scenic Rivers criterion of 0.037 mg/L total phosphorus for a 90-day geometric mean was evaluated and determined not to be protective of Cherokee Nation’s Culturally Significant Waters. A total phosphorus criterion of 0.016 mg/L was recommended to protect Cherokee Nation Culturally Significant Waters from benthic algae greater than 100 mg/m2 Chlorophyll a.
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Nishigaki, Tomohiro. "Improvement of Water- and Nutrient-Use Efficiency with Optimum Agricultural Management Practices in Upland Cropping Systems in Morogoro, Tanzania." Kyoto University, 2017. http://hdl.handle.net/2433/228243.
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Culumber, Catherine Mae. "Soil Nutrient Cycling and Water Use in Response to Orchard Floor Management in Stone-Fruit Orchards in the Intermountain West." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5030.
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Fruit growers in Utah and other areas across the Intermountain West are faced with growing production challenges stemming from declining soil quality and water resources. Population growth presents challenges in terms of the cost and availability of land, but also presents opportunities in the form of new marketing options such as organic fruit. Few certified organic fruit orchards are operating in Utah currently, which is attributed to a lack of locally tested and adapted organic management practices. An organic peach orchard trial evaluated the effectiveness of different organic management approaches to enhance soil quality and conserve water without compromise to fruit tree growth and fertility. Two tree-row treatments: ‘straw mulch' (Triticum aestivum L.) and ‘living mulch’ (Lobularia maritima (L.) Desv.) were tested in combination with two alleyway groundcovers: ‘grass’ (Festuca rubra L. with Lolium perenne L.) and a legume, ‘Birdsfoot trefoil’ (Lotus corniculatus L.). The novel systems were compared with industry standards, tillage and weed fabric tree-rows with grass alleyways. Trefoil alleyway biomass deposited into tree-rows contributed an estimated 6.24 kg biomass and 0.21 kg total N/tree annually. Trefoil treatments had higher levels of organic carbon (C) and nitrogen (N), inorganic N, microbial biomass and enzyme activities, suggesting trefoil alleyways enhanced soil nutrient cycling, as well as C and N reserves in comparison to grass and tillage treatments. A functional gene array analysis was conducted to describe the mechanisms, microbial functional composition and diversity underlying the observed soil processes, however few differences were detected in soil community structure between soils under different orchard floor management.
Significantly lower leaf δ15N in trees grown with trefoil compared to grass, and an association between root biomass, diameter and trunk cross-sectional area (TCSA) suggests nitrogen sources derived from the trefoil groundcover contributed to improved fruit tree vigor. Few differences resulted among orchard treatments for water use (mm/week). Trends indicated slightly higher water use in trefoil over grass, but not enough to offset observed soil quality and tree growth benefits. These findings suggest, trefoil alleyways may provide ecological benefits such as improved soil quality and efficient nutrient cycling, without substantial increases in water use.
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Jacobs, Suzanne Robin [Verfasser]. "Assessing the impact of land use on water and nutrient fluxes in the South-West Mau, Kenya / Suzanne Robin Jacobs." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1160874921/34.
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Jacobs, Suzanne [Verfasser]. "Assessing the impact of land use on water and nutrient fluxes in the South-West Mau, Kenya / Suzanne Robin Jacobs." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1160874921/34.
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Akshaya, Devendra Kumar. "IMPACTS OF LAND USE/LAND COVER AND SOIL ON WATER QUALITY IN THE UPPER LITTLE MIAMI RIVER SUB-BASIN THE UPPER LITTLE MIAMI RIVER SUB-BASIN." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1334693369.
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Madriñan, Max Jacobo Moreno. "Eutrophication Trend of Lakes in the Tampa Bay Watershed and the Role of Submerged Aquatic Vegetation in Buffering Lake Water Phosphorus Concentration." Scholar Commons, 2008. https://scholarcommons.usf.edu/etd/373.
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Twentieth century human settlement within the Tampa Bay watershed was linked to a dramatic mid-century decline in bay water quality and loss of seagrass acreage. Decades of direct and indirect nutrient discharges to the bay from phosphorus mining, fertilizer manufacturing, and wastewater treatment, as examples, impaired the estuary. In the past twenty years, regional stakeholders have worked to improve the bay water quality by reducing point and non-point source nutrient loading to the bay.
Lakes within the Tampa Bay watershed may play an important role in attenuating the flow of nutrients into the bay. This study hypothesized that between 1990 and 2007 lake water concentrations of total phosphorus (TP) and chlorophyll-a, as well as the ratio of total nitrogen to total phosphorus (TN:TP), have changed for selected lakes in the Tampa Bay watershed. During this period, the watershed underwent a rapid shift in land use as groves and farms became shopping malls and new homes. A two-way analysis of variance (ANOVA) revealed that for 10 lakes clustered in the northern portion of the Tampa Bay watershed and classified as oligotrophic or mesotrophic, observed increases in water concentrations of TP and chlorophyll-a were statistically significant. For 6 lakes classified as hypereutrophic and scattered across the watershed, observed decreases in water TP concentrations were statistically significant, while chlorophyll-a concentrations did not change. For both groups of lakes, the TN:TP ratio declined significantly; however, oligotrophic and mesotrophic lakes were phosphorus-limited but hypereutrophic lakes were nitrogen-limited, based on this ratio.
A second hypothesis of this study was that lake water concentrations of TP, total nitrogen (TN) and chlorophyll-a were lower in lakes that had more coverage of submerged aquatic vegetation, as vegetation suppresses re-suspension of sediments and is a reservoir for nitrogen and phosphorus and a surface for biofilms. The results of a one-way ANOVA showed that for 34 lakes within the Tampa Bay watershed, lakes with a greater than 20 percent volume infested by macrophytes (PVI), water concentrations of TP and chlorophyll-a but not TN were statistically lower than for lakes with a less than 20 PVI.
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Kabore, Bertin. "Investigations into soil nutrient and change in soil physical characteristics under complementary forage rotation in comparison to pasture systems for dairy cows." University of Sydney, 2009. http://hdl.handle.net/2123/5355.
Full textAbstract:
Master of Science in Veterinary ScienceA investigation into soil nutrient and the change soil physical properties was carried out for three pasture systems for dairy cows; the complementary forage rotation (CFR) which comprised of brassica (Brassica napus )/clover (Trifolium resupinatum ) and maize (Zea mays) capable of achieving more than 40 t/ha, the typical intensive pasture (PI) with kikuyu grass (Penisetum clandestinum) over-sown with ryegrass ( Lolium multiflorum ) and the extensive system (PE); on two soil types (brown chromosol and black vertisol) . The study demonstrated that the CFR system was capable of doubling its yield by using similar fertilizers (N, P and K) and water inputs compared to these of the PI system resulting of greater nutrients (N and K) and water use efficiencies. Overall, the nutrient lost through runoff water was very limited for two intensive systems and nearly nil for PE system. Also similar trends were observed for soil physical properties in the intensive systems except for the topsoil (0-10 cm) where light acidification (P= 0.04) was recorded in the CFR probably due to the soil works before the maize sowing.
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Kabore, Bertin. "Investigations into soil nutrient and change in soil physical characteristics under complementary forage rotation in comparison to pasture systems for dairy cows." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/5355.
Full textAbstract:
A investigation into soil nutrient and the change soil physical properties was carried out for three pasture systems for dairy cows; the complementary forage rotation (CFR) which comprised of brassica (Brassica napus )/clover (Trifolium resupinatum ) and maize (Zea mays) capable of achieving more than 40 t/ha, the typical intensive pasture (PI) with kikuyu grass (Penisetum clandestinum) over-sown with ryegrass ( Lolium multiflorum ) and the extensive system (PE); on two soil types (brown chromosol and black vertisol) . The study demonstrated that the CFR system was capable of doubling its yield by using similar fertilizers (N, P and K) and water inputs compared to these of the PI system resulting of greater nutrients (N and K) and water use efficiencies. Overall, the nutrient lost through runoff water was very limited for two intensive systems and nearly nil for PE system. Also similar trends were observed for soil physical properties in the intensive systems except for the topsoil (0-10 cm) where light acidification (P= 0.04) was recorded in the CFR probably due to the soil works before the maize sowing.
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Cornelisen, Christopher David. "Nutrient Uptake by Seagrass Communities and Associated Organisms: Impact of Hydrodynamic Regime Quantified through Field Measurements and use of an Isotope Label." [Tampa, Fla. : s.n.], 2003. http://purl.fcla.edu/fcla/etd/SFE0000079.
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Sutter, Lori A. "Effects of Saltwater Intrusion on Vegetation Dynamics and Nutrient Pools in Low-Salinity Tidal Marshes, Pamunkey River (Virginia, USA)." W&M ScholarWorks, 2014. https://scholarworks.wm.edu/etd/1539616868.
Full textAbstract:
This study investigated vegetation changes in a former tidal freshwater marsh (TFM) to determine the role that salinity intrusion plays in vegetation dynamics. Field observations along a narrow salinity gradient in the Pamunkey River revealed that vegetation is shifting to fewer dominants with increasing salinity. Two remaining dominants, Peltandra virginica and Zizania aquatica (hereafter Peltandra and Zizania, respectively), had variable net CO2 assimilation throughout the growing season. Peltandra net CO2 assimilation declined both over the growing season and in marshes with higher salinity; whereas, Zizania generally increased over the growing season peaking in late summer. The same species' tissue nutrients tracked similarly when compared across marshes of different salinity throughout the season, suggesting that the plants have adapted to their environment. Soils, however, contained higher carbon (C) and nitrogen (N) in a TFM relative to higher salinity marshes across years and within a single season. The soil N: phosphorus (P) ratio is relatively stable and well above 16:1 in the TFM, suggesting P-limitation. The other marshes appeared to be in transition with high fluctuations throughout the season and variability within the marsh. Soils responded to changes in salinity faster than vegetation by adsorbing or releasing nutrients. A mesocosm testing plant traits subjected to four low salinity levels found Spartina alterniflora (hereafter Spartina) unresponsive to salinity ranging from 0 to 6, although CO2 assimilation decreased between treatments fresh and 6. Two TFM species, Peltandra and Leersia oryzoides (hereafter Leersia ), responded to salinity over 2 with decreases in aboveground and belowground biomass. The same two species exhibited an improvement in biomass quality (measured by C:N and C:P) over the salinity gradient, and both held greater N and P in the vegetation pool relative to Spartina. The pool of nutrients held in vegetation may shift with salinity intrusion, and the enhanced biomass quality may lead to greater herbivory due to improved palatability. A second mesocosm study paired Spartina, a facultative halophyte, with each of three TFM species: Peltandra, Leersia, and Phragmites australis (hereafter Phragmites). Spartina outperformed Peltandra in all aspects measured -- both aboveground and belowground. In the presence of Leersia, Spartina offered mixed responses, but Phragmites changed Spartina responses considerably. The results of this experiment suggest that Spartina can succeed in less benign environments in the presence of at least some species. A field manipulation excluding insect herbivory within treatments in three marshes along a salinity gradient found that overall biomass did not respond to the removal of insect herbivory, except for Peltandra in Cumberland Marsh (TFM). Peltandra biomass in TFM exclosures was approximately double that of controls, but this result was not significant in other marshes. Zizania N-content was higher in exclosures, suggesting a loss of this nutrient with herbivory, perhaps from rebuilding scarred tissue and/or loss through guttation. Given Peltandra's salt intolerance and Spartina's ability to outperform common species, it is possible that Sweet Hall Marsh, a previous TFM transitioning to an oligohaline marsh, will become a Spartina-Phragmites marsh in the future driven by bottom-up controls.
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Rivera, Anamarie Elizabeth. "A Review of Reclaimed Water for Irrigation Use in an Urban Watershed." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6576.
Full textAbstract:
It is well established that converting wastewater, a point-source of pollution, into reclaimed water makes management of nutrients more difficult. Not all service lines measure the volume of reclaimed water used by a customer, and frequently there are no restrictions on the amount of reclaimed water that is used. Nutrients applied in excess have the potential to runoff or leach through soils and contaminate surface and groundwater resources. This research attempted to determine if corresponding surface water quality monitoring sites in reclaimed service areas reflect elevated total nitrogen (TN) and total phosphorous (TP) concentrations.
The Joe’s Creek Watershed in Pinellas County, FL is a highly urbanized watershed with one wastewater plant providing tertiary treatment for reclaimed water (Pinellas County Utilities Dept.) and another wastewater plant providing secondary treatment (City of St. Petersburg Water Resources Dept.). This research reviewed concentrations of TN and TP in the reclaimed water effluent for each wastewater treatment plant and at four tributary sites in the Joe’s Creek Watershed. One tributary site, Bonn Creek, is in the tertiary treated service area, another tributary site, Miles Creek, is in the secondary treated service area, and a third tributary, Joe’s Creek, provides two control sites which are both outside of reclaimed service areas.
Based on the results of comparisons and statistical analyses of the 6-year period, the TN and TP concentrations of reclaimed water from the City of St. Pete Wastewater Treatment Plant (WWTP) far exceed those of the Pinellas County WWTP. The TN concentration in the reclaimed effluent from St. Pete was nine times higher than that of Pinellas County. The TP concentration was almost five times higher at St. Pete than Pinellas County. The sites within reclaimed service areas had higher concentrations of TN and TP when compared to the control sites for the same period. Miles Creek recorded the highest mean concentrations of TN and TP of the four monitoring sites. Bonn Creek recorded the second highest mean concentrations of TN and TP. Rainfall data were reviewed and results show that several monitoring dates for Miles Creek and Bonn Creek had elevated TN and TP concentrations which coincided with periods of rainfall deficit. These and other results of this research indicate a need to reconsider minimum wastewater treatment levels in urban environments in an effort to reduce nutrient pollution, as well as a need to expand watering restrictions and enforcement, and expand education of consumers about reclaimed water.
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Uhlenbrock, Kristan M. "Nutrient Distribution Effects from Freshwater Discharge at Franklin Lock and Dam (S-79) in 2005 and 2006 on the Caloosahatchee Estuary and San Carlos Bay, Fort Myers, Florida." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002877.
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Morris, Kay. "Salinity and nutrients : growth and water use of aquatic macrophytes under controlled and natural conditions /." Title page, contents and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phm876.pdf.
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Beale, C. V. "Analysis of the radiation-, nutrient- and water-use efficiencies of the potential energy crops Miscanthus x giganteous and Spartina cynosuroides, grown under field conditions in S.E.England." Thesis, University of Essex, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361035.
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Vaughan, Matthew CH. "Shining light on the storm: Using high-frequency optical water quality sensors to characterize and interpret storm nutrient and carbon dynamics among contrasting land uses." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1002.
Full textAbstract:
Elevated nutrient concentrations present significant challenges to surface water quality management globally, and dissolved organic matter mediates several key biogeochemical processes. Storm events often dominate riverine loads of nitrate, phosphorus, and dissolved organic matter, and are expected to increase in frequency and intensity in many regions due to climate change. The recent development of in situ optical sensors has revolutionized water quality monitoring and has highlighted the important role storms play in water quality. This dissertation focuses on improving the application of in situ optical water quality sensors and interpreting the high-frequency data they produce to better understand biogeochemical and watershed processes that are critical for resource management.
We deployed in situ sensors to monitor water quality in three watersheds with contrasting land use / land cover, including agricultural, urban, and forested landscapes. The sensors measured absorbance of ultraviolet-visible light through the water column at 2.5 nanometer wavelength increments at 15-minute intervals for three years. These deployments provided a testbed to evaluate the sensors and improve models to predict concentrations of nitrate, three phosphorus fractions, and dissolved organic carbon using absorbance spectra and laboratory analyses through multivariate statistical techniques. In addition, an improved hysteresis calculation method was used to determine short-timescale storm dynamics for several parameters during 220 storm events.
Goals of each dissertation chapter were to: (1) examine the influences of seasonality, storm size, and dominant land use / land cover on storm dissolved organic carbon and nitrate hysteresis and loads; (2) evaluate the utility of the sensors to determine total, dissolved, and soluble reactive phosphorus concentrations in streams draining different land use / land covers, and perform the first statistically robust validation technique applied to optical water quality sensor calibration models; and (3) analyze storm event dissolved organic matter quantity and character dynamics by calculating hysteresis indices for DOC concentration and spectral slope ratio, and develop a novel analytical framework that leverages these high frequency measurements to infer biogeochemical and watershed processes. Each chapter includes key lessons and future recommendations for using in situ optical sensors to monitor water quality.
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Kostrzewski, Jennifer Marie, and Jennifer Marie Kostrzewski. "Quantifying seasonal variations in water source and nutrient concentrations: a catchment comparison in Valles Caldera National Preserve, NM, USA." Thesis, The University of Arizona, 2006. http://hdl.handle.net/10150/626915.
Full textAbstract:
The purpose of this study is to examine the interactions between physical and
biological processes, and their influence on nutrient cycling and export in two semiarid,
montane, headwater catchments. We measured stream chemistry in two neighboring
catchments within the Valles Caldera National Preserve, New Mexico from February
through August 2005 to identify (1) how variable water sources and flowpaths affect
carbon and nutrient concentrations, and (2) how these solutes were modified as they were
transported out of the catchments. Both catchments were characterized by a large
snowmelt flush of carbon and nutrients in spring and a smaller flush of carbon and
nutrients during the monsoon season. Although similar in elevation, soil, vegetation, and
climate, the catchments exhibited significantly differences in stream water C, N, and P
concentrations during the spring flush. End member mixing using conservative solutes
identified the cause of this variability was due primarily to differences in hydro logic
residence time and streamflow generation between catchments. These mixing models for
each catchment indicated that variability in carbon and nutrients was explained by
physical transport during the spring snowmelt and the first flushing events of the
monsoon season. In contrast, conservative mixing did a poor job of predicting carbon
and nutrient chemistry during other season suggesting biological modification during
transport was a major control on streamwater chemistry. After correcting for variability
in water sources, both catchments exhibited higher than expected N concentrations during
winter and snowmelt, switching to higher than expected P concentrations during the
summer monsoon season suggesting a seasonal switch in limiting nutrients. These data demonstrate how simple, quantitative evaluation of hydrologic flowpaths and residence
time can be used to separate physical and biological controls on catchment-scale stream
water chemistry.
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Hasnat, Abul, University of Western Sydney, of Science Technology and Environment College, and School of Environment and Agriculture. "Soil-water use and irrigation scheduling under fruit tree-turf alley cropping system in Hawkesbury Area." THESIS_CSTE_EAG_Hasnat_A.xml, 2003. http://handle.uws.edu.au:8081/1959.7/614.
Full textAbstract:
Efficient use of irrigation and nutrients are becoming increasingly important in commercial orchards in the Hawkesbury area. Proper irrigation scheduling practices can help in the better use of irrigation water and reduce environmental impacts. Field experiments were conducted during February 1999 to June 2000 to understand soil-water use, and to evaluate farmer’s irrigation practice under an alley cropping system consisting of turf and stone fruits. The study was carried out at Atlas Farm, 3.5 km from the University of Western Sydney, Hawkesbury campus. The experimental site is a floodplain of the Hawkesbury River. The river flows within 1 km of the farm boundaries. The study was conducted under the farmer’s existing irrigation water and nutrient management practices. The main aims of the thesis were to study the movement and redistribution of soil-water and soil-moisture dynamics in the turf and stone fruit alley cropping system and to understand deep percolation losses and nitrogen leaching using the water balance approach. The study indicated that drainage occurred mainly after heavy rainfall and when there was rainfall for a few consecutive days. Thus irrigation application should be delayed if there is a likelihood of rain in a few consecutive days to prevent loss of water due to deep drainage. Furthermore, the study showed irrigation scheduling was essential to reduce nitrate leaching in the field; that irrigation depths should be varied according to the stage of crop growth, and the proper timing of irrigation application could help reduce deep percolation and runoff losses.Master of Science (Hons) (Agriculture)
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Bergsten, Steven J. "Certain Agave Species Exhibit the Capability to be Moderately Productive Under Conditions of High Salt and Drought Stress." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3818.
Full textAbstract:
Water availability and arable lands are increasingly limiting resources in many parts of the U.S., particularly in semi-arid and arid regions. As a means of addressing food and fuel demands associated with burgeoning population growth, highly productive and water-use efficient crops need to be identified. One potential crop, Agave, merits consideration and evaluation due to its putative capability to provide sustenance and energy despite growing in water-limited regions and on marginal soils. However, little is known regarding the productivity these succulent plants will have under growing conditions of the Southwest, where high concentrated saline soils are abundant, and water is often limited. The objectives of these studies were to determine the effects of high levels of salinity and different volumetric water content levels (VWC) on plant growth, biomass accumulation, and nutrient uptake. I used a hydroponic study to compare the effects of four salinity treatments (0.5, 3, 6, and 9 dS m-1) on productivity of four Agave species (Agave parryi, Agave utahensis ssp. kaibabensis, Agave utahensis ssp. utahensis, and Agave weberi). In a second study, an automated irrigation system was established to examine four pre-determined VWC threshold set-points and simulated a gradient of well-watered to drought conditions, to evaluate how A. weberi would respond to varying levels of water availability. Salinity concentrations did not significantly affect root and plant dry weight accumulation in A. weberi, but all other agave plants experienced less biomass accumulation under high saline conditions (>6 dS m-1). Seedlings of A. utahensis were two times more likely to die in the two highest saline treatments (6 and 9 dS m-1) than the two lower treatments (0.5 dS m-1 and 3 dS m-1). Calcium, Mg, S, Mn levels decreased in both A. parryi and A. weberi at higher salinity levels. Agave weberi was able to tolerate salinity, but it also experienced lower biomass production ≤3 dS m-1. In the water-stress study, Agave weberi plants experienced a decrease of 2.11 g as compared to plants in the highest treatment. Plants in the intermediate VWC treatments had similar dry mass values as those in the highest treatment, which suggests that this species could have moderately high yields under limited water conditions, and consequently should be evaluated as a potential bioenergy crop for semi-arid regions, such as the U.S. Southwest. Agave shows considerable potential to be grown in arid and semi-arid regions that are moderately high in salinity and have limited water availability. Indeed, the cultivation of Agave as a crop appears to be a viable option for many areas of the Southwest. While some of the Agave species evaluated were quite productive under moderate salt and water stress, it is uncertain if growth will be significantly reduced if under these stress conditions for periods longer than 3 months.
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Ross, James Donald. "Influence of climate and land use on nutrient and bacterial dynamics in surface waters of the Lower Fraser Valley, British Columbia." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/31057.
Full textAbstract:
It is understood that intensive agricultural activities can adversely impact surface-water quality
resulting in risks to ecosystem and human health. What is less clear are the links between agricultural
land use (type and intensity), environmental conditions and surface-water quality at varying spatial and
temporal scales. There are also challenges with detecting agricultural influence on surface waters in a
timely and accurate manner. This is of concern in the Lower Fraser Valley as this region has experienced
significant agricultural intensification and population growth in recent years. This study examined
influences of agricultural land use, climate and hydrology on water quality in three watersheds to identify
land-use practices and environmental conditions producing the greatest risk of contamination. This was
accomplished through an intensive surface-water sampling program to assess nutrient and bacterial
dynamics in the Hatzic, Elk Creek and Salmon watersheds, combined with hydrometric and
meteorological monitoring from 2002-2005. Spectroscopic techniques (absorption and fluorescence) were
also evaluated as tools to detect and quantify agricultural influence.
Consistent correlations between agricultural land use and contamination (nutrient and bacterial
concentrations) were observed across all watersheds. Seasonal trends were consistent, with nutrient
concentrations peaking during winter months (illustrating strong hydrological control over mobilisation and
transport) and bacterial concentrations peaking during summer months (illustrating the supply-constrained
nature of bacterial stores). Contaminant concentrations correlated with measures of
agricultural intensity. Livestock operations represented the highest-risk land use for contamination, with
even small operations producing observable impacts on water quality. Temporally, the greatest risk of
bacterial contamination was associated with storm events preceded by periods of dry weather during
summer months.
Absorption and fluorescence were effective measures of agricultural influence as they quantify
and characterize agriculturally-derived dissolved organic matter. Advantages of these techniques include
rapid sample processing, minimal requirements for sample treatment and volume. Further, they provide
qualitative information regarding water quality, water source and land use that is not available from
nutrient or bacterial analyses alone. These techniques do not accurately detect contaminants in areas
with minimal agricultural influence and therefore are limited as direct indicators of bacterial or nutrient
concentrations.Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate
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Goward, Kelly J. "Relationship of nutrients and pesticides to landuse characteristics in three subwatersheds of the upper White River, IN." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1286601.
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Stream samples were tested at 18 sites in three subwatersheds of the Upper White River for ammonia, nitrate, orthophosphate, atrazine, and diazinon. Nutrient results were tested with a general linear model and in linear regressions with selected landuse characteristics. A critical areas index for surface runoff of pollutants was created using a geographic information system. Comparisons were made between results obtained by Ball State University and by the Muncie Bureau of Water Quality and other outside laboratories. Most mean concentrations of nutrients were likely related to combinations of agricultural and residential landuse factors. Only concentrations of ammonia and orthophosphate were significantly related (a = 0.05) to any landuse characteristics. Atrazine levels were high in the spring, but decreased in the fall. Results suggest that improved or increased best management practices should be implemented in these subwatersheds to control non-point source pollution of the streams.Department of Natural Resources and Environmental Management
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Neves, AntÃnia Leila Rocha. "Irrigation of cowpea with saline water at different growth stages and their effects on the plant and soil." Universidade Federal do CearÃ, 2008. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5227.
Full textAbstract:
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoA sensibilidade à salinidade varia com o estÃdio de desenvolvimento da cultura. O feijÃo-de-corda [Vigna unguiculata (L.) Walp.] constitui uma das principais culturas, em diversas regiÃes semi-Ãridas do mundo. Avaliou-se o efeito da irrigaÃÃo com Ãgua salina, aplicada em diferentes estÃdios de desenvolvimento de plantas de feijÃo-de-corda. O experimento foi conduzido no campo, e obedeceu ao delineamento em blocos ao acaso, com cinco tratamentos (T1, T2, T3, T4 e T5) e cinco repetiÃÃes. O feijÃo-de-corda foi cultivado no espaÃamento de 0,8 m entre linhas e 0,3 m entre plantas, com duas plantas por cova. Os tratamentos utilizados foram: T1 - plantas irrigadas com Ãgua do poÃo (CEa de 0,8 dS m-1) durante todo o ciclo; T2 - Ãgua salina com CEa de 5,0 dS m-1, com aplicaÃÃo iniciada apÃs a germinaÃÃo e permanecendo atà o final do ciclo; T3 - Ãgua salina com CEa de 5,0 dS m-1, da semeadura atà 22 dias apÃs o plantio (DAP), correspondendo Ãs fases de germinaÃÃo e crescimento inicial, e Ãgua do poÃo no restante do ciclo; T4 - Ãgua salina com CEa de 5,0 dS m-1, aplicada de 23 a 42 DAP (fase de intenso crescimento vegetativo atà a prÃ-floraÃÃo), e Ãgua do poÃo nas demais fases do ciclo; T5 - Ãgua do poÃo da semeadura atà 42 DAP e Ãgua salina (CEa de 5,0 dS m- 1) aplicada a partir dos 43 DAP (floraÃÃo e frutificaÃÃo). Foram avaliadas a cobertura vegetal do solo, crescimento vegetativo, fotossÃntese, transpiraÃÃo, condutÃncia estomÃtica, produtividade, partiÃÃo de matÃria seca, os teores, os totais extraÃdos e a distribuiÃÃo dos nutrientes na planta, a eficiÃncia nutricional, eficiÃncia no uso da Ãgua e o acÃmulo de sais no solo. A irrigaÃÃo com a combinaÃÃo de Ãgua do poÃo com Ãgua salina reduziu o acÃmulo de sais no solo, em relaÃÃo ao T2. O T2 reduziu as taxas de fotossÃntese e transpiraÃÃo, em relaÃÃo ao T1. O T3 provocou reduÃÃo das trocas gasosas somente na primeira mediÃÃo, enquanto, que similar aplicaÃÃo nos outros estÃdios (T4 e T5) nÃo provocou reduÃÃes significativas nas trocas gasosas das plantas. O T2 inibiu o crescimento vegetativo da planta, enquanto o T3 provocou retardo no desenvolvimento da planta. Os tratamentos T2 e T3 provocaram reduÃÃes significativas no nÃmero de vagens e na produÃÃo de sementes por planta, em relaÃÃo aos demais tratamentos. Por outro lado, os tratamentos T4 e T5 nÃo afetaram o crescimento e a produtividade da cultura, sendo que o T4 causou aceleraÃÃo no ciclo reprodutivo da cultura. Os minerais foram extraÃdos pelo feijÃo-de-corda na seguinte ordem decrescente: N > K > Cl > Ca > Na > P > Fe > Zn > Mn > Cu, no entanto, o T2 reduziu a extraÃÃo da maioria dos elementos analisados, com exceÃÃo do Na e Cl. Os minerais Na, Cl, K, Ca, Fe e Mn permaneceram preferencialmente nas partes vegetativas enquanto N e P foram exportados em maiores proporÃÃes pelos frutos. O T3 reduziu a eficiÃncia de utilizaÃÃo da maioria dos nutrientes. O T2 reduziu a eficiÃncia agronÃmica de utilizaÃÃo de N, P e K, entretanto nÃo afetou a eficiÃncia de utilizaÃÃo dos nutrientes extraÃdos pelas plantas.
The sensitivity of crops to salinity often changes from one growth stage to another. Cowpea [Vigna unguiculata (L.) Walp.] is an important crop specie cultivated in different semi-arid regions of the world. The objective of this work was to evaluate the effect of the irrigation with saline water, applied at different growth development stages of cowpea. The experiment was set up in the field, during the dry season. A completely randomized block design, with five treatments (T1, T2, T3, T4 and T5) and five repetitions, was adopted. The distance between lines and plants were 0.8 m and 0.3 m, respectively, with two plants per hole. The treatments studied were: T1 - Groundwater with electrical conductivity (ECw) of 0.8 dS m-1 during the whole crop cycle; T2 - Saline water (ECw = 5.0 dS m-1) during the whole crop cycle, starting after germination; T3 - Saline water (ECw = 5.0 dS m-1) from sowing until the 22th day after sowing (germination and initial growth) and groundwater in remaining stages of the crop cycle; T4 - Saline water (ECw = 5.0 dS m-1) from the 23th to the 42nd day after germination (intense growth and pre-flowering), and groundwater irrigation for the remaining growth stages. T5 - Groundwater from sowing to the 42nd day after sowing and saline water (ECw = 5.0 dS m-1) during flowering and pod-filling stages. Soil coverage, gas exchange, vegetative growth and crop yield were measured. The mineral concentration and quantity of nutrient removed from the soil, as well as the nutrient use efficiency and salt accumulation in soil were also determined. The irrigation with combination of groundwater and saline water reduced the salt accumulation in soil, in relation to continuous use of saline water. The continuous application of water with ECw of 5.0 dS m-1 (T2) reduced the rates of photosynthesis and transpiration, in relation to the well water (T1). Plants of the treatment 3 showed reduction in gas exchanges only in the first measurement, while the saline water application in other growth stages (T 4 and T5) did not provoke significant reductions in leaf in the gas exchanges of the plants. It was found that the continuous use of saline water inhibits plant growth, while the irrigation with saline water during germination and initial growth causes retardation in plant development. For treatments 2 and 3, reduction in the number of pods and in seed production was verified. Irrigation with saline water from the 23rd to the 42nd day (T4) and from the 43rd to the 63rd (T5) day after sowing did not affect reproductive and vegetative growth, but the saline water application in the pre-flowering (T4) caused anticipation of reproductive cycle. Cowpea plants removed the minerals analyzed in the following decreasing sequence: N > K > Cl > Ca > Na > P > Fe > Zn > Mn > Cu, but the continuous use of saline water (T2) reduced the total extracted for the most nutrients, except for Na e Cl. The minerals Na, Cl, K, Ca, Fe and Mn were distributed preferentially to vegetative plant parts, while the most of N and P were exported in the pods. The irrigation with saline water during germination and initial growth stage (T3) reduced the mineral use efficiency of most of analyzed nutrients. The continuous application of saline water (T2) reduced the agronomic efficiency of the fertilizer application (N, P and K), but it did not affect the nutrient use efficiency by the plants.
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Johnson, David Richard. "Use of In-Stream Water Quality Measurements and Geospatial Parameters to Predict Consumer Surfactant Toxic Units in the Upper Trinity River Watershed, Texas." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc6091/.
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Surfactants are used in a wide assortment of "down-the-drain" consumer products, yet they are often discharged in wastewater treatment plant effluent into receiving water, potentially causing environmental harm. The objective of this project was to predict surfactant toxic units and in-stream nutrients in the upper Trinity River watershed. Surface and pore water samples were collected in late summer 2005. General chemistries and surfactant toxic units were calculated. GIS models of anthropogenic and natural factors were collected and analyzed according to subwatersheds. Multiple regression analyses using the Maximum R2 improvement method were performed to predict surfactant toxic units and in-stream nutrients using GIS and in-stream values. Both geospatial and in-stream parameters generated multiple regression models for surfactant surface and pore water toxic units, as well as in-stream nutrients, with high R2 values. Thus, GIS and in-stream parameter modeling have the potential to be reliable and inexpensive method of predicting surfactant toxic units and nutrient loading in the upper Trinity River watershed.
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Schroder, Jonathan H. "Soil moisture-based drip irrigation for efficient use of water and nutrients and sustainability of vegetables cropped on coarse soils." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0014283.
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Schaible, Candace J. "Assessing Homeowners' Lawn Management Practices and Preferred Sources of Educational Information." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7041.
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Prior to the development of programing and outreach materials it is important for Extension outreach and education professionals to assess the educational needs and preference of the communities they serve. Survey data was gathered from residents of Cedar City, UT, in an effort to gain an understanding of current lawn management practices and the resources homeowners utilize when making management decisions. In addition, soil samples were collected from a subset of participants to compare nutrient levels to management practices.
Survey results found that homeowners accessed multiple sources, with preferences leaning towards the use of friends and family members, the internet, and the point of purchase. Few homeowners are aware of and utilize educational resources and services provided by Extension. This is especially true for those under the age of 50, which poses a challenge to Extension professionals to find effective ways to reach younger generations.
It was difficult to form associations between nutrient levels and management practices Although, there was a strong association between those with excessive phosphorus concentration and the application of biosolids. More research needs to be done to examine the distribution and end use of biosolids.
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Köhler, Iris [Verfasser], Johannes [Akademischer Betreuer] Schnyder, Margaret [Akademischer Betreuer] Barbour, and Rainer [Akademischer Betreuer] Matyssek. "The interactive effects of rising atmospheric CO2 and nutrient supply on carbon and water relations in grassland ecosystems : an analysis of stable carbon isotopes and water-use efficiency in vegetation samples from the Park Grass Experiment / Iris Köhler. Gutachter: Margaret Barbour ; Rainer Matyssek ; Johannes Schnyder. Betreuer: Johannes Schnyder." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1033403032/34.
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Doley, Todd Michael. "Maintaining a Nitrogen Cap for Virginia's Potomac River: The Contribution of Alternative Development Patterns." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/31142.
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The Chesapeake Bay, once one of the worlds most productive estuaries, has been severely impacted by human activity in the water and on the lands around it. Viewed as an ecosystem, the Bay is no longer able to support the variety and abundance of biota that it was historically able to. Several decades of research on the Chesapeake have pointed to human activities as being the principle reason for this decline. Of these detrimental activities, elevated inputs of Nitrogen and Phosphorus to the Bay were singled out as being the greatest cause of water quality deterioration.
The state of Virginia is trying to reduce its annual load of Nitrogen, to the Potomac River, to 60% of what the load was estimated to be in 1985. Virginia would like to accomplish this goal at the lowest cost to its citizens. Therefore the state needs to determine the combination of nitrogen control efforts which will achieve the goal at the lowest cost. The state would also like to be able to maintain nitrogen loads at or below this cap level, indefinitely into the future.
This study was undertaken with three primary objectives. The first was to project the level of annual nitrogen inputs to the Potomac River, from the state of Virginia, over the next 15 years. The second was to estimate the minimum annual costs necessary to achieve and maintain a 40% reduction in total nitrogen inputs, using the Virginiaâ s estimated 1985 inputs as a baseline. The final objective was to assess the potential cost savings that may result from using one of two alternative development patterns within the rapidly urbanizing Northern Virginia portion of the Potomac Watershed. The first alternative is prohibiting low-density development within the Northern Virginia region, and the second is to restrict all new development to be within 5 miles of an existing urban area.
Study results suggest that there has been no significant progress toward meeting the nitrogen reduction goal, due to the increase in population within the watershed, over the past 13 years. To attain the goal in 1998, a minimum of $27 million, above what is currently being spent annually, would be required. Under the current land use trend within Virginiaâ s Potomac Basin, the annual cost for maintaining the goal is estimated to rise to $38 million annually, in 1998 dollars, by the year 2013. This is a 40% increase in cost.
If the first alternative development pattern is adhered to over this 15-year period, then the annual cost will be $33 million, for an annual cost saving of approximately $5 million in 2013. The second alternative could achieve similar results if implemented, costing roughly $5 million less in 2013 than the annual cost per year under the current trend. These findings suggest that the use of alternative development patterns can help slow but not prevent the annual cost, of maintaining the cap, from rising.
The study indicates that the reason for the continuous rise in annual cost, over this fifteen-year period, is due primarily to an increase in nitrogen loading to the Potomac that will result from the wastewater disposal needs of the growing population within the Basin. Furthermore, the state will eventually exhaust its lower cost options for reducing Nitrogen loadings, and at that point the annual cost for maintaining the Nitrogen Cap will begin to rise exponentially. Under current land use trends this rapid rise in cost is unlikely to occur within the next 15 years, and is more apt to occur sometime within the next 20 to 40 years. Once annual expenditures begin to rise exponentially it is unlikely that the state of Virginia would be able to maintain its 40% reduction goal.Master of Science
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Voß, Anja. "Untersuchung und Modellierung der Stickstoff- und Phosphorumsatz- und Transportprozesse in mesoskaligen Einzugsgebieten des Tieflandes am Beispiel von Nuthe, Hammerfließ und Stepenitz." Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2007/1548/.
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Ziel dieser Arbeit war es, die Stickstoff- und Phosphorprozesse im nordostdeutschen Tiefland detailliert zu untersuchen und Handlungsoptionen hinsichtlich der Landnutzung zur nachhaltigen Steuerung der Stickstoff- und Phosphoreinträge in die Fließgewässer aufzuzeigen.
Als Grundvoraussetzung für die Modellierung des Nährstoffhaushaltes mussten zunächst die hydrologischen Prozesse und die Abflüsse für die Einzugsgebiete validiert werden. Dafür wurde in dieser Arbeit das ökohydrologische Modell SWIM verwendet. Die Abflussmodellierung umfasste den Zeitraum 1991 - 2000. Die Ergebnisse dazu zeigen, dass SWIM in der Lage war, die hydrologischen Prozesse in den Untersuchungsgebieten adäquat wiederzugeben.
Auf der Grundlage der Modellierung des Wasserhaushaltes wurden mit SWIM die Stoffumsatzprozesse für den Zeitraum 1996 - 2000 simuliert. Um dabei besonders das Prozessgeschehen im Tiefland zu berücksichtigen, war die Erweiterung von SWIM um einen Ammonium-Pool mit dessen Umsatzprozessen erforderlich. Außerdem wurde der Prozess der Nährstoffversickerung so ergänzt, dass neben Nitrat auch Ammonium und Phosphat durch das gesamte Bodenprofil verlagert und über die Abflusskomponenten zum Gebietsauslass transportiert werden können. Mit diesen Modellerweiterungen konnten die Stickstoff und Phosphorprozesse in den Untersuchungsgebieten gut abgebildet werden.
Mit dem so validierten Modell wurden weitere Anwendungen ermöglicht. Nährstoffsimulationen für den Zeitraum 1981 bis 2000 dienten der Untersuchung des abnehmenden Trends in den Nährstoffkonzentrationen der Nuthe. Die Untersuchungsergebnisse lassen deutlich erkennen, dass sich die Konzentrationen nach 1990 hauptsächlich auf Grund der Reduzierung der Einträge aus punktförmigen Quellen und Rieselfeldern verringert haben.
Weitere Modellrechnungen zur Herkunft der Nährstoffe haben ergeben, dass Nitrat überwiegend aus diffusen Quellen, Ammonium und Phosphat dagegen aus punktförmigen Quellen stammen. Als besonders sensitiv auf die Modellergebnisse haben sich die Parameter zu Landnutzung und -management und die Durchwurzelungstiefe der Pflanzen herausgestellt.
Abschließend wurden verschiedene Landnutzungsszenarien angewendet. Die Ergebnisse zu den Szenariorechnungen zeigen, dass fast alle vorgegebenen Landnutzungsszenarien zu einer Verringerung der Stickstoff- bzw. Phosphoremissionen führten. Die Anwendung von Szenarien, die alle relevanten Zielvorgaben und Empfehlungen zum Ressourcenschutz berücksichtigen, zeigen die größten Veränderungen.The main objective of this study was to investigate the nitrogen and phosphorus processes in the north-eastern German lowlands and to suggest sustainable management options concerning land use that could lead to a reduction in nitrogen and phosphorous emissions into the river network. In order to fulfil the basic requirements of water quality modelling on river basin scale, the hydrological processes had to be validated first. For this purpose the ecohydrological model SWIM was used. The simulations were carried out on a daily time step within the period 1991 - 2000. The results have shown that SWIM was able to reproduce adequately the hydrological processes within all investigation areas. Based on these hydrological simulations the nutrient processes were modelled with SWIM for the time period 1996 - 2000. It became obvious that the modelling approaches within SWIM, especially concerning the nutrient cycling processes in lowland watersheds, had to be modified. Thus, an ammonium pool including its transformations processes was added. In addition, leaching not only of nitrate but also of ammonium and phosphate throughout the whole soil profile is now possible. Thus all nutrients can be transported to the outlet of the watersheds by the flow components. It could be shown that with these modifications the model was able to reproduce well the nitrogen and phosphorus processes in the research areas. With the validated model further applications were enabled. In order to investigate the reason for the decreasing trend in the nutrient concentrations in the Nuthe River, nutrient simulations were performed for the period 1981 - 2000. The results show that the concentrations after 1990 have decreased mainly because of the reduction of emissions from point sources and sewage fields. Further simulations in order to gain more information about the different nutrient sources showed that nitrate basically originates from diffuse sources and ammonium as well as phosphorus from point sources. Especially parameters related to land use and management as well as the root depth of plants turned out to be very sensitive to model results. Concluding, different land use change scenarios were adapted. The calculation results demonstrate that almost all provided scenarios lead to a reduction in the emission rates. Applying those scenarios which consider all relevant aims and recommendations concerning the protection of resources the highest changing rates could be achieved.
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Voß, Anja. "Untersuchung und Modellierung der Stickstoff- und Phosphorumsatz- und Transportprozesse in mesoskaligen Einzugsgebieten des Tieflandes am Beispiel von Nuthe, Hammerfließ und Stepenitz." Potsdam Universitätsverlag Potsdam, 2008. http://deposit.d-nb.de/cgi-bin/dokserv?id=3071462&prov=M&dokv̲ar=1&doke̲xt=htm.
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Labadz, Martin. "A catchment modelling approach integrating surface and groundwater processes, land use and distribution of nutrients : Elimbah Creek, southeast Queensland." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/60017/1/Martin_Labadz_Thesis.pdf.
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As the world’s population is growing, so is the demand for agricultural products. However, natural nitrogen (N) fixation and phosphorus (P) availability cannot sustain the rising agricultural production, thus, the application of N and P fertilisers as additional nutrient sources is common. It is those anthropogenic activities that can contribute high amounts of organic and inorganic nutrients to both surface and groundwaters resulting in degradation of water quality and a possible reduction of aquatic life. In addition, runoff and sewage from urban and residential areas can contain high amounts of inorganic and organic nutrients which may also affect water quality. For example, blooms of the cyanobacterium Lyngbya majuscula along the coastline of southeast Queensland are an indicator of at least short term decreases of water quality. Although Australian catchments, including those with intensive forms of land use, show in general a low export of nutrients compared to North American and European catchments, certain land use practices may still have a detrimental effect on the coastal environment.
Numerous studies are reported on nutrient cycling and associated processes on a catchment scale in the Northern Hemisphere. Comparable studies in Australia, in particular in subtropical regions are, however, limited and there is a paucity in the data, in particular for inorganic and organic forms of nitrogen and phosphorus; these nutrients are important limiting factors in surface waters to promote algal blooms. Therefore, the monitoring of N and P and understanding the sources and pathways of these nutrients within a catchment is important in coastal zone management. Although Australia is the driest continent, in subtropical regions such as southeast Queensland, rainfall patterns have a significant effect on runoff and thus the nutrient cycle at a catchment scale. Increasingly, these rainfall patterns are becoming variable. The monitoring of these climatic conditions and the hydrological response of agricultural catchments is therefore also important to reduce the anthropogenic effects on surface and groundwater quality.
This study consists of an integrated hydrological–hydrochemical approach that assesses N and P in an environment with multiple land uses. The main aim is to determine the nutrient cycle within a representative coastal catchment in southeast Queensland, the Elimbah Creek catchment. In particular, the investigation confirms the influence associated with forestry and agriculture on N and P forms, sources, distribution and fate in the surface and groundwaters of this subtropical setting. In addition, the study determines whether N and P are subject to transport into the adjacent estuary and thus into the marine environment; also considered is the effect of local topography, soils and geology on N and P sources and distribution. The thesis is structured on four components individually reported.
The first paper determines the controls of catchment settings and processes on stream water, riverbank sediment, and shallow groundwater N and P concentrations, in particular during the extended dry conditions that were encountered during the study. Temporal and spatial factors such as seasonal changes, soil character, land use and catchment morphology are considered as well as their effect on controls over distributions of N and P in surface waters and associated groundwater. A total number of 30 surface and 13 shallow groundwater sampling sites were established throughout the catchment to represent dominant soil types and the land use upstream of each sampling location. Sampling comprises five rounds and was conducted over one year between October 2008 and November 2009. Surface water and groundwater samples were analysed for all major dissolved inorganic forms of N and for total N. Phosphorus was determined in the form of dissolved reactive P (predominantly orthophosphate) and total P. In addition, extracts of stream bank sediments and soil grab samples were analysed for these N and P species. Findings show that major storm events, in particular after long periods of drought conditions, are the driving force of N cycling. This is expressed by higher inorganic N concentrations in the agricultural subcatchment compared to the forested subcatchment. Nitrate N is the dominant inorganic form of N in both the surface and groundwaters and values are significantly higher in the groundwaters. Concentrations in the surface water range from 0.03 to 0.34 mg N L..1; organic N concentrations are considerably higher (average range: 0.33 to 0.85 mg N L..1), in particular in the forested subcatchment. Average NO3-N in the groundwater has a range of 0.39 to 2.08 mg N L..1, and organic N averages between 0.07 and 0.3 mg N L..1. The stream bank sediments are dominated by organic N (range: 0.53 to 0.65 mg N L..1), and the dominant inorganic form of N is NH4-N with values ranging between 0.38 and 0.41 mg N L..1. Topography and soils, however, were not to have a significant effect on N and P concentrations in waters. Detectable phosphorus in the surface and groundwaters of the catchment is limited to several locations typically in the proximity of areas with intensive animal use; in soil and sediments, P is negligible.
In the second paper, the stable isotopes of N (14N/15N) and H2O (16O/18O and 2H/H) in surface and groundwaters are used to identify sources of dissolved inorganic and organic N in these waters, and to determine their pathways within the catchment; specific emphasis is placed on the relation of forestry and agriculture. Forestry is predominantly concentrated in the northern subcatchment (Beerburrum Creek) while agriculture is mainly found in the southern subcatchment (Six Mile Creek). Results show that agriculture (horticulture, crops, grazing) is the main source of inorganic N in the surface waters of the agricultural subcatchment, and their isotopic signature shows a close link to evaporation processes that may occur during water storage in farm dams that are used for irrigation. Groundwaters are subject to denitrification processes that may result in reduced dissolved inorganic N concentrations. Soil organic matter delivers most of the inorganic N to the surface water in the forested subcatchment. Here, precipitation and subsequently runoff is the main source of the surface waters. Groundwater in this area is affected by agricultural processes. The findings also show that the catchment can attenuate the effects of anthropogenic land use on surface water quality. Riparian strips of natural remnant vegetation, commonly 50 to 100 m in width, act as buffer zones along the drainage lines in the catchment and remove inorganic N from the soil water before it enters the creek. These riparian buffer zones are common in most agricultural catchments of southeast Queensland and are indicated to reduce the impact of agriculture on stream water quality and subsequently on the estuary and marine environments. This reduction is expressed by a significant decrease in DIN concentrations from 1.6 mg N L..1 to 0.09 mg N L..1, and a decrease in the �15N signatures from upstream surface water locations downstream to the outlet of the agricultural subcatchment. Further testing is, however, necessary to confirm these processes. Most importantly, the amount of N that is transported to the adjacent estuary is shown to be negligible.
The third and fourth components of the thesis use a hydrological catchment model approach to determine the water balance of the Elimbah Creek catchment. The model is then used to simulate the effects of land use on the water balance and nutrient loads of the study area. The tool that is used is the internationally widely applied Soil and Water Assessment Tool (SWAT). Knowledge about the water cycle of a catchment is imperative in nutrient studies as processes such as rainfall, surface runoff, soil infiltration and routing of water through the drainage system are the driving forces of the catchment nutrient cycle. Long-term information about discharge volumes of the creeks and rivers do, however, not exist for a number of agricultural catchments in southeast Queensland, and such information is necessary to calibrate and validate numerical models. Therefore, a two-step modelling approach was used to calibrate and validate parameters values from a near-by gauged reference catchment as starting values for the ungauged Elimbah Creek catchment. Transposing monthly calibrated and validated parameter values from the reference catchment to the ungauged catchment significantly improved model performance showing that the hydrological model of the catchment of interest is a strong predictor of the water water balance. The model efficiency coefficient EF shows that 94% of the simulated discharge matches the observed flow whereas only 54% of the observed streamflow was simulated by the SWAT model prior to using the validated values from the reference catchment. In addition, the hydrological model confirmed that total surface runoff contributes the majority of flow to the surface water in the catchment (65%). Only a small proportion of the water in the creek is contributed by total base-flow (35%). This finding supports the results of the stable isotopes 16O/18O and 2H/H, which show the main source of water in the creeks is either from local precipitation or irrigation waters delivered by surface runoff; a contribution from the groundwater (baseflow) to the creeks could not be identified using 16O/18O and 2H/H. In addition, the SWAT model calculated that around 68% of the rainfall occurring in the catchment is lost through evapotranspiration reflecting the prevailing long-term drought conditions that were observed prior and during the study. Stream discharge from the forested subcatchment was an order of magnitude lower than discharge from the agricultural Six Mile Creek subcatchment. A change in land use from forestry to agriculture did not significantly change the catchment water balance, however, nutrient loads increased considerably. Conversely, a simulated change from agriculture to forestry resulted in a significant decrease of nitrogen loads.
The findings of the thesis and the approach used are shown to be of value to catchment water quality monitoring on a wider scale, in particular the implications of mixed land use on nutrient forms, distributions and concentrations. The study confirms that in the tropics and subtropics the water balance is affected by extended dry periods and seasonal rainfall with intensive storm events. In particular, the comprehensive data set of inorganic and organic N and P forms in the surface and groundwaters of this subtropical setting acquired during the one year sampling program may be used in similar catchment hydrological studies where these detailed information is missing. Also, the study concludes that riparian buffer zones along the catchment drainage system attenuate the transport of nitrogen from agricultural sources in the surface water. Concentrations of N decreased from upstream to downstream locations and were negligible at the outlet of the catchment.
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Lindner, Björn. "The black water loop : water efficiency and nutrient recovery combined /." Hamburg : GFEU, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016561528&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Stone, Harry James. "THE POLITICAL ECONOMY OF ECOLOGICAL RESEARCH: ANALYZING THE “TOTAL MAXIMUM DAILY LOAD” PROCESS IN THE UPPER MILL CREEK (CINCINNATI)." Oxford, Ohio : Miami University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1082567599.
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Kwan, Cheuk Hung. "Biosensors for biological nutrient monitoring /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?AMCE%202004%20KWAN.
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Darrow, Brian P. "Effects of nutrients from the water column on the growth of benthic microalgae in permeable sediments." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002431.
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Du, Plessis D. "Impacts of cage aquaculture on the farm dam ecosystem and its use as a multipurpose resource : implications for irrigation." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2206.
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Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2007.Small farm dams (< 20 ha) in the Western Cape Province provide adequate water conditions for intensive cage production of rainbow trout (Oncorhynchus mykiss). A major environmental concern of cage aquaculture, however, is the high inputs of nutrients via commercial diets and the subsequent eutrophication of the water source. Eutrophication can result in the degradation of the general water quality (increasing pH levels, oxygen depletion, increased hydrogen sulphide and free ammonia) and shifts in the phytoplankton structure (increased biomass, single species dominance). Deterioration of water quality will affect the success of the fish farming enterprise as well as the performance of irrigation equipment by increasing the risk of clogging and corrosion. Water quality, phytoplankton and zooplankton compositions were monitored at four sites from June 2005 to November 2006 to determine the effects of cage culture on the farm dam environment, its associated biota as well as irrigation water quality. The distribution of nutrients, nitrogen and phosphorus, was mainly influenced by the stratification and mixing regime of the water bodies. Nutrient concentrations increased during the winter mixing period while in the summer months, they seem to settle to the lower part of the water column. Nutrient concentrations of production sites and reference sites were comparable except for the ammonia levels that were significantly higher at the production sites. Phytoplankton corresponded with nutrient availability resulting in high biomass during winter. In terms of biomass, phytoplankton was approximately two times more abundant in production sites compared to reference sites. Assemblage dominance by cyanophytes (Anabaena circinalis, Microcystis spp.) was found more often in production sites, while reference sites were dominated by dinophytes (Ceratium hirundinella, Peridinium spp.). Zooplankton biomass concurred with high phytoplankton biomass in winter. Zooplankton assemblages in production sites sustained much higher biomass. Effects of cage culture on irrigation water quality are evident from increased algal biomass and shifts in species composition. These results indicated that at its present production level, cage culture had impacts on the farm dam environment and irrigation water quality. The most significant evidence was given by increased plankton biomass and single species dominance in production sites. However, these findings can not solely be ascribed to the introduction of aquaculture as various other factors may also contribute to the water quality of these ecosystems.
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Miguntanna, Nandika Prasadani. "Nutrients build-up and wash-off processes in urban land uses." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/31236/1/Nandika_Miguntanna_Thesis.pdf.
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This thesis describes outcomes of a research study conducted to investigate the nutrient build-up and wash-off processes on urban impervious surfaces. The data needed for the study was generated through a series of field investigations and laboratory test procedures. The study sites were selected in urbanised catchments to represent typical characteristics of residential, industrial and commercial land uses. The build-up and wash-off samples were collected from road surfaces in the selected study sites. A specially designed vacuum collection system and a rainfall simulator were used for sample collection. According to the data analysis, the solids build-up on road surfaces was significantly finer with more than 80% of the particles below 150 ìm for all the land uses. Nutrients were mostly associated with the particle size range below 150 ìm in both build-up and wash-off samples irrespective of type of land use. Therefore, the finer fraction of solids was the most important for the nutrient build-up and particulate nutrient wash-off processes. Consequently, the design of stormwater quality mitigation measures should target particles less than 150 ìm for the removal of nutrients irrespective of type of land use. Total kjeldahl nitrogen (TKN) was the most dominant form of nitrogen species in build-up on road surfaces. Phosphorus build-up on road surfaces was mainly in inorganic form and phosphate (PO4 3-) was the most dominant form. The nutrient wash-off process was found to be dependent on rainfall intensity and duration. Concentration of both total nitrogen and phosphorus was higher at the beginning of the rain event and decreased with the increase in rainfall duration. Consequently, in the design of stormwater quality mitigation strategies for nutrients removal, it is important to target the initial period of rain events. The variability of wash-off of nitrogen with rainfall intensity was significantly different to phosphorus wash-off. The concentration of nitrogen was higher in the wash-off for low intensity rain events compared to the wash-off for high intensity rain events. On the other hand, the concentration of phosphorus in the wash-off was high for high intensity rain events compared to low intensity rain events. Consequently, the nitrogen washoff can be defined as a source limiting process and phosphorus wash-off as a transport limiting process. This highlights the importance of taking into consideration the wash-off of low intensity rain events in the design of stormwater quality mitigation strategies targeting the nitrogen removal. All the nitrogen species in wash-off are primarily in dissolved form whereas phosphorus is in particulate form. The differences in the nitrogen and phosphorus wash-off processes is principally due to the degree of solubility, attachment to particulates, composition of total nitrogen and total phosphorus and the degree of adherence of the solids particles to the surface to which nutrients are attached. The particulate nitrogen available for wash-off is removed readily as these are mobilised as free solids particles on the surface. Phosphorus is washed-off mostly with the solids particles which are strongly adhered to the surface or as the fixed solids load. Investigation of the nitrogen wash-off process using bulk wash-off samples was in close agreement with the investigation of dissolved fraction of wash-off solids. This was primarily due to the predominant nature of dissolved nitrogen. However, the investigation of the processes which underpin phosphorus wash-off using bulk washoff samples could lead to loss of information. This is due to the composition of total phosphorus in wash-off solids and the inherent variability of the wash-off process for the different particle size ranges. This variability should preferably be taken into consideration as phosphorus wash-off is predominantly in particulate form. Therefore, care needs to be taken in the investigation of the phosphorus wash-off process using bulk wash-off samples to ensure that there is no loss of information and hence result in misleading outcomes. The investigation of different particle size ranges of wash-off solids is preferable in the interest of designing effective stormwater quality management strategies targeting phosphorus removal.
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Júnior, Cícero Renê Almeida Barboza. "Desenvolvimento de mudas de pinhão manso (Jatropha curcas L.) em tubetes e submetidas a diferentes níveis de déficit hídrico." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11143/tde-23032012-102119/.
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Com a crescente procura por alternativas para suprir energeticamente o mundo, cada vez mais, fontes mais limpas e renováveis estão sendo utilizadas. No Brasil, a produção de óleos vegetais visando a geração de energia (biodiesel) ainda é incipiente. Dentre as diferentes espécies de oleaginosas, o pinhão manso (Jatropha curcas L.) vem se destacando como uma ótima alternativa no fornecimento de matéria prima para a produção de biodiesel. Informações sobre essa cultura ainda são escassas, principalmente no Brasil, onde há pouco tempo foram iniciadas as pesquisas. A necessidade de informações locais também ressalta a importância da pesquisa com o Pinhão Manso. Com base nessas necessidades, o objetivo desse experimento foi analisar a viabilidade técnica da produção de mudas irrigadas de pinhão manso por sistema de subirrigação e desenvolver um sistema automatizado de manejo. O controle da irrigação foi realizado a partir da variação de peso dos tubetes com as mudas, devido a perda de água por evapotranspiração. No processo de controle dos pesos foram utilizadas células de carga, que monitoraram a variação de peso de um conjunto de tubetes denominado conjunto controle. O delineamento experimental foi em delineamento inteiramente aleatorizado, com quatro repetições. Os tratamentos avaliados foram quatro níveis de depleção da máxima capacidade de retenção de água (MCRA) apresentada pelo substrato (T1=20%, T2=40%, T3=60% e T4=80% da MCRA). Para se quantificar os efeitos dos tratamentos foram avaliadas semanalmente as seguintes características das mudas: altura e diâmetro do caule, número de folhas e área foliar, bem como a produção de matéria fresca e seca da parte aérea e do sistema radicular. Os resultados mostram que o tratamento 2 foi o que se destacou dentre os demais, produzindo mudas de melhor qualidade, com maior acúmulo de matéria seca e maior consumo hídrico.With the growing demand for alternative energy to meet the world, increasingly more clean and renewable sources are being used. In Brazil, the production of vegetable oils aimed at producing energy (biodiesel) is still incipient. Among the different species of oleaginous plants, jatropha (Jatropha curcas L.) has emerged as a great alternative in providing raw material for biodiesel production. Information on this crop are still scarce, especially in Brazil where they recently started research. The need for local information also emphasizes the importance of research with Jatropha. Based on these needs, the aim of this experiment was to analyze the technical viability production of jatropha seedlings irrigated by subirrigation system and develop an automated system management. The irrigation control was carried out from the weight variation of the vials with the seedlings because of water loss through evapotranspiration. In the process of weight control were used load cells, which monitored the weight variation of a set of vials called the control group. The experimental design was the completely randomized with four replications. The treatments were four levels of depletion of the maximum water holding capacity (MCRA) presented by the substrate (T1=20%, T2=40%, T3=60% e T4=80% da MCRA). To quantify the effects of the treatments were evaluated weekly the following characteristics of seedlings: height and diameter of the stem, leaf number and leaf area, and the production of fresh and dry shoot and root. The results show that treatment 2 was what stood out among the others, producing higher quality seedlings with greater dry matter accumulation and increased water consumption.
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Murasko, Susan Mary. "Particulate carbon, nitrogen and phosphorus stoichiometry of south west Florida waters." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003036.
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