Author: Zhenpeng ChenPublisher:
ISBN:
Category :
Languages : en
Pages : 768
Book Description
Transformations and Transport of Fixed Nitrogen from Septic Tanks in Soil Absorption Systems and Underlying Aquifers
Author: Zhenpeng ChenAustralian Journal of Soil Research
Author: Report to the Legislature
Author: Wisconsin Groundwater Coordinating CouncilPublisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 106
Book Description
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 898
Book Description
A Systems Study of the Transport and Transformations of Soil Nitrogen
Author: Fred J. EndelmanPublisher:
ISBN:
Category : Soil science
Languages : en
Pages : 384
Book Description
Managing Soils in an Urban Environment
Author: Randall Barber BrownPublisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 326
Book Description
Soil science, with its roots in both the plant sciences and geology, first carne into being as a recognizable discipline in response to questions conceming plant growth. The chemical and physical characteristics of the soil as well as landscape processes that controlled those characteristics were of great interest to agronomists, horticulturists, geographers, geomorphologists, and geologists, some of whom drifted into one another's orbit and - over the late nineteenth and early twentieth centuries-brought their experiences and talents together to form the nucleus of soil science. In those early years, a perception developed that soil science was simply an agricultural and edaphological science, which indeed it was in large measure. However pervasive and stubbom that perception was, there has been from the beginning a segment of the community of soil scientists that has maintained an interest in soil science "writ large." These soil scientists, while continuing to interact with agronomists, horticulturists, and foresters, have maintained communications, collaborations, and linkages with such disciplines as geology, geomorphology, geography, land use planning, and engineering. In the second half of the twentieth century, soil science has expanded its contacts with these nonagricultural disciplines, and now finds itself addressing a much wider range of problems, questions, and issues than it did in the first half of the century. In response to a growing demand for information, nonagriculturalland uses increasingly have been the focus of soil studies and of the development of soil interpretations and other decision tools for land users.
Nitrogen Cycling and Transport Under Agricultural Managed Aquifer Recharge
Author: Hannah WaterhousePublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
In semi-arid regions, including much of California, there is great interest amongst water management and conservation districts to implement agricultural managed aquifer recharge (AgMAR). AgMAR is a concept in which farmlands are leveraged to capture and recharge legally and hydrologically available flood waters to increase regional capacity for recharge to replenish the underlying aquifers and combat overdraft. The potential benefits of AgMAR, in addition to a more reliable future basin-wide water supply, include decreasing downstream flood risks by removing excess water from near flood stage rivers, reducing groundwater pumping costs by increasing groundwater levels, flushing salts from the rooting zone, increasing water storage in the root zone, improving ecosystem health of groundwater dependent ecosystems, and mitigating land subsidence. When flooding farmland for groundwater recharge, of particular concern is the potential for AgMAR to exacerbate nitrate (NO3−) contamination of already at-risk aquifers. Nitrate, when ingested, has been linked to methaemoglobinaemia, or "blue baby syndrome", miscarriages, and non-Hodgkin's lymphoma. Thus, it is necessary to determine if implementing AgMAR increases the risk of transporting residual NO3− below the root zone, as well as legacy NO3− accumulated in the vadose zone, into aquifers used for drinking water. This dissertation focuses on understanding how to mitigate NO3− contamination to groundwater under AgMAR implementation. First, I identified the crops and soils with the lowest potential risk of NO3− loading to groundwater when considering AgMAR. Cores down to 9 m were taken on both permeable and less permeable soils within almond, grape, and tomato cropping systems and stored-NO3− -N within each system were determined. Considerations for historical and current nutrient and water management under AgMAR are discussed as well and discussion is targeted toward stakeholders, including growers, water managers, and policy makers considering AgMAR. Next, I explored the mineralization potential, denitrification capacity, and denitrification potential for subsurface soils and sediments. Denitrification represents a permanent sink to the underlying aquifer and would be a positive outcome of AgMAR implementation. Using the acetylene incubation method, denitrification potential (glucose and NO3− addition) and denitrification capacity (no glucose or NO3− addition) were determined for vadose zone sediment samples to a depth of 9 m. The denitrification potential assays (addition of glucose and NO3−) resulted, on average, in over 108% to 175% of NO3− being reduced to N2O across all layers. Denitrification capacity, the ability of the sediment to denitrify without the addition of glucose or NO3− , resulted in 19-133% of NO3− being reduced to N2O. Across all depths, net immobilization was found on incubations of post-AgMAR soil samples, which represents a delay in NO3− arrival to the underlying aquifer. Finally, chapter 4 examines the transport and transformation of NO3− under varying management of AgMAR and across differing vadose zone heterogeneities using a reactive transport model, TOUGHREACT. Results show that silt loams are important features in the deep subsurface for creating reducing zones where denitrification can occur via both heterotrophic and chemolithoautotrophic pathways. Furthermore, applying floodwaters all at once increased denitrification compared to applying floodwaters incrementally, however, higher concentrations of NO3− moved faster and to further depths when water was applied all at once. Additionally, wetter antecedent moisture conditions while promoting denitrification more readily, increased the depths to which NO3− leached compared to drier antecedent moisture conditions. Thus the geologic heterogeneity, depth to the water table, and antecedent moisture conditions should be considered when applying floodflows for AgMAR. Further work is needed on how varying management practices, such as cover cropping, could retain residual soil NO3− and increase leached dissolved organic carbon to the subsurface to promote denitrification.
Nitrogen in the Subsurface Environment
Author: M. L. RowePublisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 52
Book Description
Chemical Abstracts
Author: Field and Numberical Evaluation of Nitrogen Transport from Septic Systems in Surfical Aquifer Systems to Charlotte Harbor, Florida
Author: Tanten T. BuszkaPublisher:
ISBN:
Category : Charlotte Harbor (Fla.)
Languages : en
Pages : 40
Book Description
Shallow water tables in coastal surficial aquifers limit effective treatment of septic effluent which can result in excess nutrient loading into nearby surface water bodies. Approximately 45,000 septic systems in Charlotte County, Florida transmit effluent into an under studied surficial aquifer and contribute to harmful algal blooms and outbreaks of E. coli. An undeveloped field site was characterized using standard hydrogeologic methods, including a one-year duration natural gradient tracer test, to obtain representative lithology of the sandy surficial aquifer and estimates of groundwater velocity, flow directions, effective porosity and dispersion. These data were used to support the development of a groundwater flow and nitrogen transport model of a nearby coastal subdivision connected to 2000 septic systems with high septic and canal density. Model results were used to assess the impacts of coastal ground water discharge in regions with high septic density near the coastline, and ground water – canal interaction and potential for rapid transport into Charlotte Harbor. Timescales associated with nitrogen removal by natural groundwater flow in the surficial aquifer following instantaneous septic to sewer conversion were on the order of 2-3 years for 50% reduction and 8-10 years for 90% reduction. Canals were found to significantly influence groundwater flow and rapidly convey nitrogen to Charlotte Harbor. Pre and post sewer conversion data on nitrate and total nitrogen in shallow groundwater from a nearby field site was obtained post-model development and supports the timescales predicted by the numerical model.