bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fecal Contamination of Pastoral Wetlands
Authors: Collins Robert 
Published: June 2010

ABSTRACTNear‐channel hill‐country wetlands draining steep pastoral land in New Zealand exhibit high levels of fecal contamination at a range of flows. This contamination is attributed to both the transport of bacteria into a wetland from the surrounding catchment and the direct excretion of fecal material onto wetlands by grazing cattle. E. coli concentrations observed at low to moderate flow at 20 sites varied between 0.5 × 101 and 2 × 104 most probable number (MPN) 100 mL−1 High flow concentrations measured at two wetlands ranged up to 6 × 106 MPN 100 mL−1 and yielded storm period bacterial loads of between 1 × 106 and 3 × 1010 MPN per event. Given the disproportionately large fraction of surface and subsurface flow from the catchment that passes through the wetlands, these yields represent a large proportion of the total loss of bacteria from steep grazed hillsides, across a range of storm events. Cattle are attracted to the smaller, shallower wetlands for grazing in both summer and winter. Excluding stock from shallow wetlands may therefore yield improvements in bacterial water quality, although accurately quantifying this improvement is difficult without long‐term studies. Cattle are not attracted to larger, deeper wetlands, presumably for fear of entrapment, and fencing them is unlikely to realize significant improvements in bacterial water quality. A statistical model incorporating solar radiation and flow explains 87% of the variance in E. coli concentrations across five monitored rainfall events. A positive correlation was found between solar radiation and E. coli concentration. The study was conducted in winter when clear, sunny days are relatively cold. Solar radiation on these days appears to be too weak to promote die‐off but the colder temperatures aid survival.
Phosphorus Runoff from Agricultural Land and Direct Fertilizer Effects: A Review
Authors: Hart Murray R. , Quin Bert F. , Nguyen M. Long 
Published: June 2010

ABSTRACTPhosphorus (P) is one of the most important mineral nutrients in agricultural systems, and along with nitrogen (N), is generally the most limiting nutrient for plant production. Farming systems have intensified greatly over time, and in recent years it has become apparent that the concomitant increase in losses of N and P from agricultural land is having a serious detrimental effect on water quality and the environment. The last two decades have seen a marked increase in research into the issues surrounding diffuse losses of P to surface and ground water. This paper reviews this research, examining the issue of P forms in runoff, and highlighting the exceptions to some generally held assumptions about land use and P transport. In particular the review focuses on P losses associated with recent P fertilizer application, as opposed to organic manures, both on the amounts and the forms of P in runoff water. The effects of the physicochemical characteristics of different forms of P fertilizer are explored, particularly in relation to water solubility. Various means of mitigating the risk of loss of P are discussed. It is argued that the influence of recent fertilizer applications is an under‐researched area, yet may offer the most readily applicable opportunity to mitigate P losses by land users. This review highlights and discusses some options that have recently become available that may make a significant contribution to the task of sustainable management of nutrient losses from agriculture.
Septic Systems as Potential Pollution Sources in the Cannonsville Reservoir Watershed, New York
Authors: Day Laurence 
Published: June 2010

ABSTRACTOn‐site septic systems require appropriate soil characteristics to provide effective wastewater treatment. The objective of this study was to evaluate siting practices and treatment efficacy of on‐site septic systems within the Cannonsville Reservoir watershed (115900 ha) in the state of New York. Using digital soil survey data, a database of on‐site conditions was developed from more than 1100 existing septic system siting records. Soil map units were grouped into four classes based on their suitability to meet common septic system design criteria. A geographic information system was found to be a useful tool for assessment and visual display of septic system and landscape information. Geographic information system analysis indicated that while 80% of soils in the watershed were found to have characteristics that interfere with septic system function, 69% of septic systems installed were of designs suited for soils with no or few restrictive parameters. Since the designs of many septic systems have relied heavily on horizontal distance to streams (mean = 130 m) to provide adequate treatment, potential failures would lead to discharge of compounds of environmental concern, such as phosphorus, with public health implications. The results imply that many septic systems functioning in the watershed are in need of design improvements.
Effect of Surfactants on Solubilization and Degradation of Phenanthrene under Thermophilic Conditions
Authors: Wong Jonathan W. C. , Fang Min , Zhao Zhenyong , Xing Baoshan 
Published: June 2010

ABSTRACTThe bioavailability and biodegradation of polycyclic aromatic hydrocarbons (PAHs) can be increased through the addition of surfactants. Previous studies of this nature have been conducted under mesophilic conditions. Hence, the aim of the present study was to investigate the effects of synthetic surfactants and biosurfactants on solubilization and degradation of phenanthrene (PHE) in a series of batch solution experiments under thermophilic conditions. Tween 80, Triton X‐100, and biosurfactants produced from Pseudomonas aeruginosa strain P‐CG3 (P‐CG3) and Pseudomonas aeruginosa ATCC 9027 (P. 9027) were used in this study. Surfactants effectively enhanced the solubility of PHE at 50°C and the biosurfactant from P‐CG3 was most effective with a 28‐fold increase in apparent solubility of PHE at a concentration of 10 × critical micelle concentration (CMC) compared with the controls. However, addition of synthetic surfactants or biosurfactants inhibited the biodegradation of PHE in mineral salts medium by an isolate Bacillus sp. B‐UM. Degradation of PHE diminished with increasing surfactant concentrations, and PHE degradation was completely inhibited for all the surfactants tested when the concentrations were greater than their respective CMC. The growth test suggested that Tween 80 and biosurfactants were degradable, but preferential utilization of these surfactants as substrates was not the mechanism for explaining the inhibition of PHE biodegradation. Because of the hydrophobic property of B‐UM, degradation inhibition of PHE by surfactants was probably due to the reduction of direct contact between bacterial cells and PHE.
Variation in Root Density along Stream Banks
Authors: Wynn Theresa M. , Mostaghimi Saied , Burger James A. , Harpold Adrian A. , Henderson Marc B. , Henry Leigh‐Anne 
Published: June 2010

ABSTRACTWhile it is recognized that vegetation plays a significant role in stream bank stabilization, the effects are not fully quantified. The study goal was to determine the type and density of vegetation that provides the greatest protection against stream bank erosion by determining the density of roots in stream banks. To quantify the density of roots along alluvial stream banks, 25 field sites in the Appalachian Mountains were sampled. The riparian buffers varied from short turfgrass to mature riparian forests, representing a range of vegetation types. Root length density (RLD) with depth and aboveground vegetation density were measured. The sites were divided into forested and herbaceous groups and differences in root density were evaluated. At the herbaceous sites, very fine roots (diameter < 0.5 mm) were most common and more than 75% of all roots were concentrated in the upper 30 cm of the stream bank. Under forested vegetation, fine roots (0.5 mm < diameter < 2.0 mm) were more common throughout the bank profile, with 55% of all roots in the top 30 cm. In the top 30 cm of the bank, herbaceous sites had significantly greater overall RLD than forested sites (α = 0.01). While there were no significant differences in total RLD below 30 cm, forested sites had significantly greater concentrations of fine roots, as compared with herbaceous sites (α = 0.01). As research has shown that erosion resistance has a direct relationship with fine root density, forested vegetation may provide better protection against stream bank erosion.
The Reduction of Internal Phosphorus Loading Using Alum in Spring Lake, Michigan
Authors: Steinman Alan , Rediske Rick , Reddy K. Ramesh 
Published: June 2010

ABSTRACTThe release of P from lake sediments, which occurs as a part of internal loading, may contribute a significant portion of the total P load to a lake. Phosphorus release rates from sediments in Spring Lake, Michigan, and the degree to which alum reduces P release from these sediments, were investigated during the summer of 2003. Triplicate sediment cores were sampled from four sites in the lake, and exposed to one of four treatments in the laboratory: (i) aerobic water column/alum, (ii) aerobic water column/no alum, (iii) anaerobic water column/alum, or (iv) anaerobic water column/no alum. Total P (TP) release rates were virtually undetectable in the alum treatments (both aerobic and anaerobic). Low, but detectable, release rates were measured in the aerobic/no alum treatment. The highest release rates were measured in the anaerobic/no alum treatments, and ranged from 1.6 to 29.5 mg P m−2 d−1 depending on how the calculations were derived. These fluxes translated to mean internal loads that ranged between 2.7 (low range) and 6.4 (high range) Mg yr−1 when extrapolated to a whole‐lake basis. Internal P loads accounted for between 55 and 65% of the total P load to Spring Lake. Although alum is a potentially effective means of reducing the sediment source of P, there is considerable uncertainty in how long an alum treatment would remain effective in this system given the current rates of external loading and the lack of information on wind‐wave action and bioturbation in Spring Lake.
Temporal Changes in Soil Partitioning and Bioaccessibility of Arsenic, Chromium, and Lead
Authors: Fendorf Scott , La Force Matthew J. , Li Guangchao 
Published: June 2010

ABSTRACTThe hazard imposed by trace element contaminants within soils is dependent on their ability to migrate into water systems and their availability for biological uptake. The degree to which a contaminant may dissociate from soil solids and become available to a target organism (i.e., bioaccessibility) is therefore a determining risk factor. We used a physiologically based extraction test (PBET) to estimate the bioaccessible fraction of arsenic‐, chromium‐, and lead‐amended soil. We investigated soils from the A and B horizons of the Melton Valley series, obtained from Oak Ridge National Laboratory site, to address temporal changes in bioaccessibility. Additionally, common extractions that seek to define reactive pools of metals were employed and their correlation to PBET levels evaluated. With the exception of Pb amended to the A horizon, all other treatments exhibited an exponential decrease in bioaccessibility with incubation time. The bioaccessible fraction was less than 0.2 mg kg−1 within 30 d of incubation for As and Cr in the A horizon and for As and Pb within the B horizon; Cr in the B horizon declined to nearly 0.3 mg kg−1 within 100 d of aging. The exchangeable fraction declined with incubation period and, with the exception of Pb, was highly correlated with the decline in bioaccessibility. Our results demonstrate limited bioaccessibility in all but one case and the need to address both short‐term temporal changes and, most importantly, the soil physiochemical properties. They further reveal the importance of incubation time on the reactivity of such trace elements.
Effect of the Prestige Oil Spill on Salt Marsh Soils on the Coast of Galicia (Northwestern Spain)
Authors: Andrade M. L. , Covelo E. F. , Vega F. A. , Marcet P. 
Published: June 2010

ABSTRACTAt four estuarine sites on the coast of Galicia (northwestern Spain), all of which were affected by the Prestige oil spill, soil samples were taken from polluted and unpolluted areas and their petroleum hydrocarbon contents, heavy metal contents, and other chemical and physical characteristics were measured. Oil pollution altered both chemical and physical soil properties, aggregating soil particles in plaques, lowering porosity, and increasing resistance to penetration and hydrophobicity. The chromium, nickel, copper, iron, lead, and vanadium contents of polluted soils were between 2 and 2500 times higher than those of their unpolluted counterparts and the background concentrations in Galician coastal sediments. In the cases of Cr, Cu, Ni, Pb, and V, their origin in the polluting oil was corroborated by the high correlation (r ≥ 0.74) between the concentrations of these metals and the total petroleum hydrocarbon (TPH) content of the polluted soils. Soil redox potentials ranged from −19 to −114 mV in polluted soils and 112 to 164 mV in unpolluted soils, and were negatively correlated with TPH content (p < 0.01). The low values in the polluted soils explain why the soluble fractions of their total heavy metal contents were very small (generally less than 3%, and in many cases undetectable).
Distribution and Leaching of Methyl Iodide in Soil following Emulated Shank and Drip Application
Authors: Guo Mingxin , Zheng Wei , Papiernik Sharon K. , Yates Scott R. 
Published: June 2010

ABSTRACTMethyl iodide (MeI) is a promising alternative to methyl bromide in soil fumigation. The pest‐control efficacy and ground water contamination risks of MeI as a fumigant are highly related to its gas‐phase distribution and leaching after soil application. In this study, the distribution and leaching of MeI in soil following shank injection and subsurface drip application were investigated. Methyl iodide (200 kg ha−1) was directly injected or drip‐applied at a 20‐cm depth into Arlington sandy loam (coarse‐loamy, mixed, thermic Haplic Durixeralfs) columns (12‐cm i.d., 70‐cm height) tarped with virtually impermeable film. Concentration profiles of MeI in the soil air were monitored for 7 d. Methyl iodide diffused rapidly after soil application, and reached a 70‐cm depth within 2 h. Relative to shank injection, drip application inhibited diffusion, resulting in significantly lower concentration profiles in the soil air. Seven days after MeI application, fumigated soil was uncapped, aerated for 7 d, and leached with water. Leaching of MeI was significant from the soil columns under both application methods, with concentrations of >10 μg L−1 in the early leachate. The leaching was greater following shank injection than drip application, with an overall potential of 33 g ha−1 for shank injection and 19 g ha−1 for drip application. Persistent residues of MeI remaining in soils after leaching were 50 to 240 ng kg−1, and the contents were slightly higher following shank injection than drip application. The results suggest that fumigation with MeI may pose a risk of ground water contamination in vulnerable areas.
Remediating RDX‐Contaminated Ground Water with Permanganate
Authors: Adam M. L. , Comfort S. D. , Morley M. C. , Snow D. D. 
Published: June 2010

ABSTRACTGround water beneath the U.S. Department of Energy Pantex Plant is contaminated with the high explosive RDX (hexahydro‐1,3,5‐trinitro‐1,3,5 triazine). The USDOE Innovative Treatment and Remediation Demonstration (ITRD) program identified in situ oxidation by permanganate as a technology fit for further investigation. We evaluated the efficacy of KMnO4 to transform and mineralize RDX by determining degradation kinetics and carbon mass balances using 14C‐RDX. Aqueous RDX solutions (2–5 mg L−1) and RDX‐contaminated slurries (50% solids, w/v) were treated with KMnO4 at 1000, 2000, 4000, and 20000 mg L−1 Treating an aqueous RDX solution of 2.8 mg L−1 with 20000 mg KMnO4 L−1 decreased RDX to 0.1 mg L−1 within 11 d while cumulative mineralization proceeded for 14 d until 87% of the labeled carbon was trapped as 14CO2 Similar cumulative mineralization was obtained when Pantex aquifer material was included in the solution matrix. Other experiments using 4000 mg KMnO4 L−1 showed that initial RDX concentrations (1.3–10.4 mg L−1) or initial pH (4–11) had little effect on reaction rates. Attempts to identify RDX degradates and reaction products showed that N2O was a product of permanganate oxidation and constituted 20 to 30% of the N balance. Time‐course measurements of a 14C‐RDX solution treated with KMnO4 revealed few 14C‐labeled degradates but through liquid chromatography–mass spectrometry (LC–MS) analysis, we present evidence that 4‐nitro‐2,4‐diaza‐butanol is formed. Aquifer microcosm studies confirmed that the transformation products not mineralized by KMnO4 were much more biodegradable than parent RDX. These results indicate permanganate can effectively transform and mineralize RDX in the presence of aquifer material and support its use as an in situ chemical oxidation treatment for the Pantex perched aquifer.
Rainfall Timing and Poultry Litter Application Rate Effects on Phosphorus Loss in Surface Runoff
Authors: Schroeder P. D. , Radcliffe D. E. , Cabrera M. L. 
Published: June 2010

ABSTRACTPhosphorus (P) in runoff from pastures amended with poultry litter may be a significant contributor to eutrophication of lakes and streams in Georgia and other areas in the southeastern United States. The objectives of this research were to determine the effects of litter application rate and initial runoff timing on the long‐term loss of P in runoff from surface‐applied poultry litter and to develop equations that predict P loss in runoff under these conditions. Litter application rates of 2, 7, and 13 Mg ha−1, and three rainfall scenarios applied to 1‐ × 2‐m plots in a 3 × 3 randomized complete block design with three replications. The rainfall scenarios included (i) sufficient rainfall to produce runoff immediately after litter application; (ii) no rainfall for 30 d after litter application; and (iii) small rainfall events every 7 d (5 min at 75 mm h−1) for 30 d. Phosphorus loss was greatest from the high litter rate and immediate runoff treatments. Nonlinear regression equations based on the small plot study produced fairly accurate (r2 = 0.52–0.62) prediction of P concentrations in runoff water from larger (0.75 ha) fields over a 2‐yr period. Predicted P concentrations were closest to observed values for events that occurred shortly after litter application, and the relative error in predictions increased with time after litter application. In addition, previously developed equations relating soil test P levels to runoff P concentrations were ineffective in the presence of surface‐applied litter.
Pig Slurry Application and Irrigation Effects on Nitrate Leaching in Mediterranean Soil Lysimeters
Authors: Daudén A. , Quílez D. , Vera M. V. 
Published: June 2010

ABSTRACTLand application of animal manures, such as pig slurry (PS), is a common practice in intensive‐farming agriculture. However, this practice has a pitfall consisting of the loss of nutrients, in particular nitrate, toward water courses. The objective of this study was to evaluate nitrate leaching for three application rates of pig slurry (50, 100, and 200 Mg ha−1) and a control treatment of mineral fertilizer (275 kg N ha−1) applied to corn grown in 10 drainage lysimeters. The effects of two irrigation regimes (low vs. high irrigation efficiency) were also analyzed. In the first two irrigation events, drainage NO3–N concentrations as high as 145 and 69 mg L−1 were measured in the high and moderate PS rate treatments, respectively, in the low irrigation efficiency treatments. This indicates the fast transformation of the PS ammonium into nitrate and the subsequent leaching of the transformed nitrate. Drainage NO3–N concentration and load increased linearly by 0.69 mg NO3–N L−1 and 4.6 kg NO3–N ha−1, respectively, for each 10 kg N ha−1 applied over the minimum of 275 kg N ha−1 An increase in irrigation efficiency did not induce a significant increase of leachate concentration and the amount of nitrate leached decreased about 65%. Application of low PS doses before sowing complemented with sidedressing N application and a good irrigation management are the key factors to reduce nitrate contamination of water courses.
Phosphorus Dynamics in Soils Receiving Chemically Treated Dairy Manure
Authors: Kalbasi M. , Karthikeyan K. G. 
Published: June 2010

ABSTRACTChemical treatment of animal manure with Al, Fe, and Ca salts appears capable of concentrating P in a smaller volume, thereby providing increased manure management options. However, little information is available on the fate of nutrients in soils receiving chemically treated manure. An incubation study (1 d to 2 yr) was conducted with three soils (Soils I, II, and III with 12, 66, and 94 mg kg−1 Bray‐1 P, respectively) and four manure treatments (one untreated and three chemical including Al‐, Fe‐, and Ca‐treated) at two rates (12.5 and 25 mg P kg−1), and a control (no manure). Subsamples were analyzed for Bray‐1 P and water‐extractable phosphorus (WEP) after eight incubation time periods. Phosphorus distribution among different fractions (soluble and loosely bound; Al‐, Fe‐, and Ca‐bound; organic P; and residual) was also determined after 1 d and 1 yr. Water‐extractable P increased when soils received untreated or Ca‐treated manure in proportion to P application rate. Water‐extractable P, however, decreased (compared with control) for Soils II and III or slightly increased for Soil I with addition of Al‐ or Fe‐treated manure. Water‐extractable P decreased sharply between 1 d and 1 to 2 wk and then remained relatively constant or increased slightly up to 2 yr depending on treatment and soil type. Bray‐1 P increased for all treatment types and soils in the following order: Ca‐treated > Al‐treated ≥ untreated > Fe‐treated > control. Within each treatment, Bray‐1 P decreased between 1 d and 1 to 2 wk and then gradually increased for up to 3 mo (Soils II and III) or 6 mo (Soil I). Application of Al‐ or Fe‐treated manure decreased P solubility with the effect being more pronounced in soils with high background P. Since the application of Ca‐treated manure increased both WEP and Bray‐1 P, it should be recommended for soils where the objective is to increase P availability. Several years of P input through fertilizer and manure contributed mainly to aluminum‐bound phosphorus (Al‐P) and to a lesser degree to other fractions. Only soluble and loosely bound P (all soils) and Al‐P (Soil I) exhibited treatment‐type effects after receiving chemically treated manure. The study results will help bridge the gap between our knowledge of chemical treatment systems for animal manure and the ultimate fate of P when the treated manure is land‐applied.