Biogeochemical Cycling of Phosphorus in Constructed Flow-through Wetlands Receiving Agricultural Runoff in the San Joaquin Valley, California PDF Download
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Author: Jonathan Maynard
Publisher:
ISBN:
Category :
Languages : en
Pages : 150
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Book Description
Author: Jonathan Maynard
Publisher:
ISBN:
Category :
Languages : en
Pages : 150
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Book Description
Author: Jonathan Maynard
Publisher:
ISBN: 9781124025568
Category :
Languages : en
Pages :
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Book Description
The biogeochemical cycles of carbon (C) and phosphorus (P) are intricately linked in aquatic systems, as P is often the limiting nutrient for primary productivity. The conversion of flood plain agroecosystems to flow-through wetlands is becoming a popular land-use practice for treating agricultural runoff nation wide, yet little information exists to document how these systems function in California where constructed wetlands dry out in late winter and spring. I examined the biogeochemical cycling of carbon and phosphorus in a small flow-through constructed wetland that receives agricultural runoff from approximately 2,300 ha of irrigated farmland. The first study (Chapter 2) examined the potential for wetland C sequestration via exogenous and endogenous C sources over a 13-year period. Results from this study showed that although surface sediments were enriched with endogenous sources of C (24 g kg−1), the long-term storage of C (~14 g kg−1) was maintained at the same level as inflowing sediment (14 g kg−1) due to fluctuating cycles of flooding and drying. Thus additional C sequestration from endogenous sources may be limited in seasonally-saturated wetlands due to enhanced oxidation during drying cycles. The second study (Chapter 3) quantified wetland metabolism across a range of spatial scales (meters to 100s of meters) to better understand the linkages between ecosystem metabolism and biotic and abiotic factors. Results from this study showed that despite high rates of primary productivity, high respiration rates limited net C production in this wetland, resulting in heterotrophic conditions during most of the season. However, the addition of high C loads in inflowing water and moderate retention efficiencies resulted in a positive C mass balance during most sampling dates. The third study (Chapter 4) quantified the role of sulfides in inducing mobilization of P in constructed wetland soils. This study shows that sulfide induced P flux can play an important role in the retention and cycling of P in wetland soils. However, soils enriched in iron oxides can effectively buffer sulfide concentration in pore water. These studies illustrate the potential role small flow-though wetlands can play in sequestering carbon and improving water quality in agriculturally intensive watersheds.
Author:
Publisher:
ISBN: 9789175191072
Category :
Languages : en
Pages : 49
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Author: William Carl Vicars
Publisher:
ISBN:
Category : Atmospheric chemistry
Languages : en
Pages : 246
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Author: Beth Kondro
Publisher:
ISBN:
Category : Agricultural pollution
Languages : en
Pages : 0
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Book Description
Excess nutrient loading to the Great Lakes Basin from agricultural runoff has negatively impacted water quality, resulting in harmful algal blooms. Best management practices, including constructed wetlands and sedimentation basins, can be used to reduce phosphorus losses from agricultural fields. Constructed wetlands are efficient in the removal of particulate phosphorus; however, removal of dissolved phosphorus is limited and requires further treatment to improve surface water quality. Several types of filter media (composed of Ca, Fe, and/or Al) can be used to further reduce the amount of dissolved phosphorus that enters surface water, and a media consisting of low-cost waste residual would be beneficial to adoption. Drinking water treatment residuals (DWTR) that often contain Al could be reused as an adsorbent for dissolved phosphorus. We evaluated the use of modified drinking water treatment residuals for removing dissolved phosphorus from wastewater. DWTR were mixed with binders, made into pellets to create an insoluble media with mechanical strength, and pyrolyzed to create a reactive media pellet. Pellets were evaluated using flow through columns and included experiments to determine the impact of pH (i.e. 6, 8, and 10), retention time (i.e. 1, 5, and 10 min), and field-collected agricultural runoff on dissolved P removal. Cement was found to be the best binding material to create an insoluble pellet with mechanical strength. The P removal capacity of the pellet consisting of the cement binder (1,397 mg P/kg) was within the range of previously evaluated steel slag (120-10,210 mg P/kg), a common reactive media for P removal. The addition of drinking water treatment residual and metals decreased the P removal capacity of the cement binder at pH 6-1 min retention at exhaustion. Increasing retention time increased the P removal capacity of the filter media tested. Wastewater pH has a minimal impact on the P removal capacity of all media except the pyrolyzed DWTR + cement binder media. Evaluated media was negatively impacted by real agricultural runoff with a measured decrease in P removal capacity (43-146 mg/kg decrease) compared to P-spiked distilled water at the same retention time. The pyrolyzed cement pellet was the most cost-effective reactive media, due to an increased P removal capacity. Pyrolyzed DWTR + cement binder would be more costly than the pyrolyzed cement binder alone but could provide a solution for the disposal of DWTR.
Author: Duane Gorman
Publisher:
ISBN:
Category : Constructed wetlands
Languages : en
Pages : 510
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Author: Barbara J. Cade-Menun
Publisher: Frontiers Media SA
ISBN: 2889458296
Category :
Languages : en
Pages : 165
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Book Description
Phosphorus (P) is an essential element for all organisms. However, there is a P paradox, whereby P concentrations considered deficient in some environments such as in agricultural soils are considered excessive in water, where they trigger eutrophication. Ensuring adequate P for crop production while minimizing water quality degradation requires consideration of the P continuum from soils to freshwater and oceans. It also requires an international, interdisciplinary approach to monitoring and scientific research. This eBook brings together P studies in soil science, lakes, rivers, estuaries and oceans, with 74 authors from 12 countries in Asia, Europe and North America. The papers assembled here provide important new information to address knowledge gaps, cover P forms and cycling in soil and water, and identify key priorities for future research. Thus, the papers assembled here provide current and interdisciplinary information about P forms and their cycling along the soil-freshwater-ocean continuum, which is essential for environmentally sustainable P use.
Author: Steven P. Simmons
Publisher:
ISBN:
Category : Periphyton
Languages : en
Pages : 78
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Author: Donald B. Porcella
Publisher:
ISBN:
Category : Eutrophication
Languages : en
Pages : 436
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Author: Shannon C. Curtis
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Inorganic fractionation of soils indicated that surficial soils contained larger pools of inorganic P and a significant portion of the inorganic P exists in the Ca-bound pool. Although STA 1 West Cell 5b often reduces TP concentrations below 50 ug L−1, the DOP and PP concentrations must be reduced more efficiently to meet the new standard of 10 ug L−1.
