bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutrient Attenuation by a Riparian Wetland during Natural and Artificial Runoff Events
Authors: Casey Ryan E. , Klaine Stephen J. 
Published: June 2010

ABSTRACTDue to chronic nutrient enrichment of surface water, wetlands adjacent to land managed with fertilizer have been studied to determine their role in nutrient dynamics. We sampled golf course runoff and determined the loads of NO−3 and PO3−4 transported during storms and the attenuation of those loads when runoff passed through a riparian wetland. All sampled storm events contained NO−3 (2 to 1470 g NO3–N per event) and PO3−4 (1 to 4156 g PO4–P per event). Extensive nutrient attenuation occurred when water passed through the riparian wetland. In 11 events, NO−3 and PO3−4 attenuation averaged 80 and 74%, respectively. In subsequent experiments, we created a stream of water flowing into the wetland and amended it with NO−3, PO3−4 and Br−, creating an artificial runoff event. The experiments were conducted using conditions similar to those of natural runoff events. We observed rapid and complete attenuation of PO3−4 immediately after runoff water infiltrated into the wetland subsurface. No PO3−4 was observed in discharge from the wetland. Nitrate attenuation occurred following a lag phase of several hours that was probably due to reactivation of denitrifying enzymes. Nitrate attenuation was initially less than 60% but increased to 100% in all experiments. We observed extensive dilution of runoff water in the wetland subsurface indicating mixing with pre‐event ground water in the wetland. The results indicated that intermittent inputs of NO−3 and PO3−4 could be successfully attenuated in the wetland on the time scale of natural storm events.
Phosphorus Loading in the Frome Catchment, UK: Seasonal Refinement of the Coefficient Modeling Approach
Authors: Hanrahan Grady , Gledhill Martha , House William A. , Worsfold Paul J. 
Published: June 2010

ABSTRACTThis paper describes the results of an export coefficient modeling approach to predict total phosphorus (TP) loading in the Frome catchment, Dorset, UK from point and diffuse sources on a seasonal (monthly) basis in 1998 and on an annual basis for 1990–1998. The model predicted an annual TP load of 25605 kg yr−1, compared with an observed (measured) value of 23400 kg yr−1 Monthly loads calculated using the export coefficient model agreed well with monthly observed values except in months of variable discharge, when observed values were low, probably due to infrequent, and therefore unrepresentative, sampling. Comparison between filterable reactive phosphorus (FRP) and TP concentrations observed in the period 1990–1997 showed that trends in FRP could be estimated from trends in TP. A sensitivity analysis (varying individual export coefficients by ±10%) showed that sewage treatment works (STWs) (3.5%), tilled land (2.7%), meadow–verge–seminatural (1.0%), and mown and grazed turf (0.6%) had the most significant effect (percent difference from base contribution) on model prediction. The model was also used to estimate the effect of phosphorus stripping at STWs in order to comply with a pending change in the European Union wastewater directive. Theoretical reduction of TP from the largest STW in the catchment gave a predicted reduction in TP loading of 2174 kg yr−1 This illustrates the value of this seasonal export coefficient model as a practical management tool.
Chloride Persistence in a Deiced Access Road Drainage System
Authors: Ostendorf David W. , Peeling David C. , Mitchell Travis J. , Pollock Samuel J. 
Published: June 2010

ABSTRACTThree years of field data, classical linear reservoir theory, and a new dissolution model confirm the hypothesis that residual chloride from highway deicing applications dissolves into precipitation throughout the year. The measured input includes 52 storm hyetographs and logs of salt and premix applications on an access road with a closed drainage system subject to runoff, interflow, and baseflow. The output data feature discharge and conductivity in an outlet weir measured continuously from February 1998 to May 2000. Individual storm hydrographs and pollutographs yield calibrated first flush dissolved chloride concentrations and residual solid chloride loads that persist at appreciable levels over the entire period of record. The storm calibrations imply a source strength ω of 2.01 × 10−6 s−1 that accurately models chloride dissolution kinetics through three salt seasons on the access road. This ω rests on physically plausible values for the depression storage depth ζ (3 mm) and porosity n (0.40) that store the residual chloride.
Using Phosphorus Concentration in the Soil Solution to Predict Phosphorus Desorption to Water
Authors: Torrent José , Delgado Antonio 
Published: June 2010

ABSTRACTThe growing concerns about water eutrophication have made it urgent to restrict losses of phosphorus (P) from agricultural soils and to develop methods for predicting such losses. In this work, we used the paradigm of P sorption–desorption curves to confirm the hypothesis that the amount of dissolved reactive phosphorus (DRP) released to a dilute electrolyte tends to be proportional to the concentration of DRP in the soil solution raised to a power that decreases with increasing solution to soil ratio (W). The hypothesis was tested for a group of 12 widely ranging European agricultural soils fertilized with P in excess of crop needs. Phosphorus desorption was studied under near‐static and turbulent conditions in laboratory experiments. The concentration of DRP in the 1:1 soil to water extract (P1:1) was used as a proxy for the DRP concentration in the soil solution. The amount of desorbed P was found to be correlated with P1:1 raised to a power that decreased from 0.7 to 0.9 at W = 100 to 0.2 to 0.4 at W = 10000. Correlation was not improved by introducing additional variables related to P sorption–desorption properties. Olsen P was found to be of lower predictive value than P1:1 Also, the index of degree of soil saturation with phosphorus (DSSP) based on oxalate extraction failed to predict P desorption. The fact that P1:1 seemingly predicts P desorption accurately for a wide range of soils makes it potentially useful in areas of high soil diversity.
Atmospheric Methyl Tertiary Butyl Ether (MTBE) at a Rural Mountain Site in California
Authors: Schade Gunnar W. , Dreyfus Gabrielle B. , Goldstein Allen H. 
Published: June 2010

ABSTRACTMethyl tertiary butyl ether (MTBE) was measured in air samples collected at hourly intervals near Blodgett Forest Research Station on the western slope of the Sierra Nevada, California, in July 1997, October 1998, and June through September 1999. Mixing ratios ranged from below the detection limit (< approximately 0.01 ppbv) to 0.5 ppbv, but were generally less than 0.3 ppbv. At these mixing ratios partitioning of MTBE into surface waters would lead to MTBE concentrations of less than 0.2 μg L−1 As expected, MTBE mixing ratios were highly correlated with other anthropogenically emitted hydrocarbons. Based on the observed diurnal cycle of MTBE and its ratio to 2‐methyl‐butane (isopentane), we estimated the average regional daytime oxidant concentration to be (9 to 13) × 106 OH radicals per cubic centimeter, consistent with our earlier estimates for this region. Furthermore, MTBE ratios to toluene, another ubiquitous anthropogenic hydrocarbon, were generally consistent with regional transport and dilution, as well as atmospheric oxidation. Exceptions, pertaining to MTBE mixing ratios below or close to the detection limit, were associated with the influence of marine air masses that did not experience anthropogenic hydrocarbon input from California. With all these constraints in place, evidence for an additional atmospheric loss process, such as nonreversible deposition of MTBE, could not be established, and we conclude that any deposition is slow compared with removal from the atmosphere by the OH radical.
Influence of Flow Rate on Transport of Bacteriophage in Shale Saprolite
Authors: McKay L.D. , Harton A.D. , Wilson G.V. 
Published: June 2010

ABSTRACTThe objective of this study was to investigate the influence of flow rate on transport and retention of bacteriophage tracers in a fractured shale saprolite, which is a highly weathered, fine‐grained subsoil that retains much of the fabric of the parent bedrock. Synthetic ground water containing PRD‐1, MS‐2, and bromide was passed through a saturated column of undisturbed shale saprolite at rates ranging from 0.0075 to 0.96 m d−1 First arrival of the bacteriophage tracers in effluent samples in each of the experiments occurred within 0.01 to 0.04 pore volumes (PV) of the start of injection, indicating that bacteriophage were advectively transported mainly through fractures or macropores. Bacteriophage transport velocities, based on first arrival in the effluent, were very similar to fracture flow velocities calculated using the cubic law for flow in a fractured material. For MS‐2, maximum concentration and mass of tracer recovered both increased steadily as flow rate increased. For PRD‐1, these values initially increased, but were nearly constant at flow rates above 0.039 m d−1, indicating that approximately 50% of the observed losses were independent of flow rate. Evaluation of the data indicates that physical straining and electrostatic or hydrophobic attachment to fracture or macropore walls were the dominant retention processes. Inactivation and gravitational settling playing secondary roles, except at the slowest flow rates. The study suggests that microbial contamination from sources such as septic fields and sewage ponds may pose a threat to the quality of ground water and surface water in areas with saprolitic subsoils.
Influence of Manure Application on Surface Energy and Snow Cover
Authors: Kongoli C. E. , Bland W. L. 
Published: June 2010

ABSTRACTApplication of manure to frozen and/or snow‐covered soils of high‐latitude, continental climate regions is associated with enhanced P losses to surface water bodies, but the practice is an essential part of most animal farming systems in these regions. Field experiments of the fates of winter‐applied manure P are so difficult as to make them essentially impractical, so a mechanistic, modeling approach is required. Central to a mechanistic understanding of manure P snowmelt runoff is knowledge of snowpack disappearance (ablation) as affected by manure application. The objective of this study was to learn how solid manure applied to snow‐covered fields modulates the surface energy balance and thereby snow cover ablation. Manure landspreading experiments were conducted in Arlington, WI during the winters of 1998 and 1999. Solid dairy manure was applied on top of snow at a rate of 70 Mg ha−1 in 1998, and at 45 and 100 Mg ha−1 in 1999. Results showed that the manure retarded melt, in proportion to the rate applied. The low‐albedo manure increased absorption of shortwave radiation compared with snow, but this extra energy was lost in longwave radiation and turbulent flux of sensible and latent heat. These losses result in significant attenuation of melt peaks, retarding snowmelt. Lower snowmelt rates beneath manure may allow more infiltration of meltwater compared with bare snow. This infiltration and attenuated snowmelt runoff may partially mitigate the enhanced likelihood of P runoff from unincorporated winter‐spread manure.
Modeling Atmospheric Nitrogen Deposition and Transport in the Chesapeake Bay Watershed
Authors: Sheeder Scott A. , Lynch James A. , Grimm Jeffrey 
Published: June 2010

ABSTRACTAtmospheric deposition of nitrate nitrogen and ammonium nitrogen has been identified as a major factor in the decline of water quality in the Chesapeake Bay. Reports have indicated that atmospheric deposition may account for 25 to 80% of the total nitrogen load entering the bay. However, uncertainties exist regarding the accuracy of the atmospheric deposition inputs, nitrogen retention coefficients, and in‐stream nutrient uptake rates used in these studies. This project was designed to reassess the potential inputs of atmospheric nitrogen deposition to the bay through the use of a high‐resolution wet deposition model, improved wet and dry deposition and nutrient retention estimates, existing soils and land use data, and geographic information systems software. Model results indicate that the methods used in previous studies may overestimate the contribution of atmospheric nitrate and ammonium deposition to the Chesapeake Bay watershed (CBW). Wet and dry atmospheric nitrate and ammonium nitrogen deposition estimates to the CBW ranged from 52.7 to 141.9 and 41.9 to 60.1 million kg/yr, respectively, between 1984 and 1996. Dry and total atmospheric deposition loads to the watershed are substantially less than previous estimates. Estimates of the percent contribution of atmospherically deposited nitrogen to the Chesapeake Bay represent between 20 and 32% of the total nitrate and ammonium nitrogen load to the watershed from all nitrogen sources. While these estimates are lower than many other published estimates, regression analysis of model parameters, nitrogen retention coefficients, output, and measured in‐stream nitrogen loads indicate that the calculated nitrogen loads may still be too high.
Agroforestry Practices, Runoff, and Nutrient Loss
Authors: Udawatta Ranjith P. , Krstansky J. John , Henderson Gray S. , Garrett Harold E. 
Published: June 2010

ABSTRACTA paired watershed study consisting of agroforestry (trees plus grass buffer strips), contour strips (grass buffer strips), and control treatments with a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation was used to examine treatment effects on runoff, sediment, and nutrient losses. During the (1991–1997) calibration and subsequent three‐year treatment periods, runoff was measured in 0.91‐ and 1.37‐m H‐flumes with bubbler flow meters. Composite samples were analyzed for sediment, total phosphorus (TP), total nitrogen (TN), nitrate, and ammonium. Calibration equations developed to predict runoff, sediment, and nutrients losses explained 66 to 97% of the variability between treatment watersheds. The contour strip and agroforestry treatments reduced runoff by 10 and 1% during the treatment period. In both treatments, most runoff reductions occurred in the second and third years after treatment establishment. The contour strip treatment reduced erosion by 19% in 1999, while erosion in the agroforestry treatment exceeded the predicted loss. Treatments reduced TP loss by 8 and 17% on contour strip and agroforestry watersheds. Treatments did not result in reductions in TN during the first two years of the treatment period. The contour strip and agroforestry treatments reduced TN loss by 21 and 20%, respectively, during a large precipitation event in the third year. During the third year of treatments, nitrate N loss was reduced 24 and 37% by contour strip and agroforestry treatments. Contour strip and agroforestry management practices effectively reduced nonpoint‐source pollution in runoff from a corn–soybean rotation in the clay pan soils of northeastern Missouri.
An Assessment of Stream Water Quality of the Rio San Juan, Nuevo Leon, Mexico, 1995–1996
Authors: Laureano José Santos Flores , Návar José 
Published: June 2010

ABSTRACTGood water quality of the Rio San Juan is critical for economic development of northeastern Mexico. However, water quality of the river has rapidly degraded during the last few decades. Societal concerns include indications of contamination problems and increased water diversions for agriculture, residential, and industrial water supplies. Eight sampling sites were selected along the river where water samples were collected monthly for 10 mo (October 1995–July 1996). The concentration of heavy metals and chemical constituents and measurements of bacteriological and physical parameters were determined on water samples. In addition, river discharge was recorded. Constituent concentrations in 18.7% of all samples exceeded at least one water quality standard. In particular, concentrations of fecal and total coliform bacteria, sulfate, detergent, dissolved solids, Al, Ba, Cr, Fe, and Cd, exceeded several water quality standards. Pollution showed spatial and temporal variations and trends. These variations were statistically explained by spatial and temporal changes of constituent inputs and discharge. Samples collected from the site upstream of El Cuchillo reservoir had large constituent concentrations when discharge was small; this reservoir supplies domestic and industrial water to the city of Monterrey.
Long‐Term Studies on the Effects of Nonvolatile Organic Compounds on Porous Media Surface Areas
Authors: Khachikian Crist S. , Harmon Thomas C. 
Published: June 2010

ABSTRACTThis paper investigates the long‐term behavior of porous media contaminated by nonvolatile organic compounds (NVOC) in terms of specific interfacial surface area. Specifically, a natural sand, Moffett sand (MS), was contaminated with naphthalene and the surface area was measured repeatedly over time using nitrogen adsorption–desorption techniques. A field‐contaminated sand affected by lampblack material (LB) from former manufactured gas plant operations was also studied. Lampblack is a carbonaceous skeleton containing polycyclic aromatic hydrocarbons (PAHs) and other hydrocarbons. It is hypothesized that soils contaminated by these types of chemicals will exhibit significantly less surface area than their clean counterparts. The surface areas for the contaminated MS samples increased toward their clean‐MS values during the 700‐h aging period, but achieved the clean values only after pentane extraction or heating at 60°C. Heating at 50°C failed to achieve a similar recovery of the clean‐MS surface area value. Nonspecific mass loss tracked the increase in surface area as indirect evidence that naphthalene loss was the cause of the surface area increase. For the LB samples, aging at 100°C produced a slight decrease in surface area and mass while aging at 250°C caused the surface area to increase roughly threefold while the mass decreased by approximately 1%. These results suggest that, under moderate heating and over the time scale of this investigation, there is a redistribution of the complex contaminant mixture on the solid matrix. Greater temperatures remove mass more efficiently and therefore exhibited the surface area increase expected in this experiment.
Influence of Water Treatment Residuals on Phosphorus Solubility and Leaching
Authors: Elliott H.A. , O'Connor G.A. , Lu P. , Brinton S. 
Published: June 2010

ABSTRACTLaboratory and greenhouse studies compared the ability of water treatment residuals (WTRs) to alter P solubility and leaching in Immokalee sandy soil (sandy, siliceous, hyperthermic Arenic Alaquod) amended with biosolids and triple superphosphate (TSP). Aluminum sulfate (Al‐WTR) and ferric sulfate (Fe‐WTR) coagulation residuals, a lime softening residual (Ca‐WTR) produced during hardness removal, and pure hematite were examined. In equilibration studies, the ability to reduce soluble P followed the order: Al‐WTR > Ca‐WTR ≈ Fe‐WTR >> hematite. Differences in the P‐fixing capacity of the sesquioxide‐dominated materials (Al‐WTR, Fe‐WTR, hematite) were attributed to their varying reactive Fe‐ and Al‐hydrous oxide contents as measured by oxalate extraction. Leachate P was monitored from greenhouse columns where bahiagrass (Paspalum notatum Flugge) was grown on Immokalee soil amended with biosolids or TSP at an equivalent rate of 224 kg P ha−1 and WTRs at 2.5% (56 Mg ha−1). In the absence of WTRs, 21% of TSP and 11% of Largo cake biosolids total phosphorus (PT) leached over 4 mo. With co‐applied WTRs, losses from TSP columns were reduced to 3.5% (Fe‐WTR), 2.5% (Ca‐WTR), and <1% (Al‐WTR) of applied P. For the Largo biosolids treatments all WTRs retarded downward P flux such that leachate P was not statistically different than for control (soil only) columns. The phosphorus saturation index (PSI = [Pox]/[Alox + Feox], where Pox, Alox, and Feox are oxalate‐extractable P, Al, and Fe, respectively) based on a simple oxalate extraction of the WTR and biosolids is potentially useful for determining WTR application rates for controlled reduction of P in drainage when biosolids are applied to low P‐sorbing soils.
Particulate and Dissolved Phosphorus Chemical Separation and Phosphorus Release from Treated Dairy Manure
Authors: Dao Thanh H. , Daniel Tommy C. 
Published: June 2010

ABSTRACTIn confined animal feeding operations, liquid manure systems present special handling and storage challenges because of the large volume of diluted wastes. Water treatment polymers and mineral phosphorus (P) immobilizing chemicals [Al2(SO4)3·18H2O, FeCl3·6H2O, and Class C fly ash] were used to determine particulate and dissolved reactive phosphorus (DRP) reduction mechanisms in high total suspended solid (TSS) dairy manure and the P release from treated manure and amended soils. Co‐application exceeded the aggregation level achieved with individual manure amendments and resulted in 80 and 90% reduction in metal salt and polymer rates, respectively. At marginally effective polymer rates between 0.01 and 0.25 g L−1, maximal aggregation was attained in combination with 1 and 10 g L−1 of aluminum sulfate (3 and 30 mmol Al3+ L−1) and iron chloride (3.7 and 37 mmol Fe3+ L−1) in 30 g L−1 (TSS30) and 100 g L−1 TSS (TSS100) suspensions, respectively. Fly ash induced particulate destabilization at rates ≥50 g L−1 and reduced solution‐phase DRP at all rates ≥1 g L−1 by 52 and 71% in TSS30 and TSS100 suspensions, respectively. Aluminum and Fe salts also lowered DRP at rates ≤10 g L−1 and higher concentrations redispersed particulates and increased DRP due to increased suspension acidity and electrical conductivity. The DRP release from treated manure solids and a Typic Paleudult amended with treated manure was reduced, although the amendments increased Mehlich 3–extractable P. Therefore, the synergism of flocculant types allowed input reduction in aggregation aid chemicals, enhancing particulate and dissolved P separation and immobilization in high TSS liquid manure.
Accelerated Deployment of an Agricultural Nutrient Management Tool
Authors: Coale Frank J. , Sims J. Thomas , Leytem April B. 
Published: June 2010

ABSTRACTIn 1998, the Maryland legislature mandated nitrogen (N) and phosphorus (P) nutrient management planning for nearly all of Maryland's commercial agricultural operations. State regulations required that a phosphorus indexing tool (P Index) be used for determining the potential for P losses from agricultural land, even though a reliable P Index did not exist. The development and assessment of the P Index as a dependable tool for the evaluation of the potential for P losses was constrained by a very aggressive implementation schedule imposed by state regulations. The Maryland Phosphorus Site Index (PSI) was evaluated on 646 state‐representative field sites beginning in the spring of 1999 and continuing through the spring of 2000. Of the representative fields, 69% were determined to have a “low” P loss rating, 19% were in the “medium” P loss rating category, 8% were determined to be a “high” risk for P loss, and 4% rated as “very high” P loss potential. Fifty‐five percent of the fields evaluated had soil test phosphorus (STP) levels less than the 75 mg kg−1 Mehlich‐1 P environmental threshold established by state regulations. The frequency distribution of PSI performance was evaluated for several subcategories of the statewide data set. The Maryland PSI will be deployed for use in constructing farm nutrient management plans well before its predictive capabilities can be objectively and rigorously validated. Field validation is essential. In the meantime, the Maryland PSI should function adequately as a tool to assist in the prioritization of field P loss risk potential.