bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rice Pesticide Concentrations in the Colusa Basin Drain and the Sacramento River, California, 1990–1993
Authors: Crepeau Kathryn L. , Kuivila Kathryn M. 
Published: July 2010

AbstractThe pesticides molinate, thiobencarb, and carbofuran are applied to rice (Oryza sativa L.) fields in the Sacramento Valley, California, each year during April through June. These pesticides are of concern because of their adverse effects on water quality and their potential adverse effects on aquatic life. Therefore, the California Regional Water Quality Control Board (CRWQCB) mandated the holding of irrigation‐return water in rice fields to increase pesticide degradation and dissipation before the water is released to the Sacramento River. The CRWQCB also established performance goals to maintain drinking water quality for the city of Sacramento and to protect the habitat for aquatic life. The objectives of this study were to determine the effects of increased irrigation‐return water holding times on rice pesticide concentrations and loads in the Colusa Basin Drain and the Sacramento River. Dissolved pesticide concentrations were measured in water samples collected in May through July during 1990–1993 at the Colusa Basin Drain at Road 99E near Knights Landing (Colosa Basin Drain) and at the Sacramento River at Sacramento. Pesticide concentrations and loads at both sites showed a decrease from 1990–1992 and an increase in 1993. This trend cannot be explained by the yearly holding time regulations but can be explained by the amount of yearly emergency releases. The yearly changes in pesticide concentration detected demonstrate that continued monitoring and management of pesticides is necessary to maintain water quality.
Chemical Characterization of Ash from Gasification of Alfalfa Stems: Implications for Ash Management
Authors: Mozaffari M. , Rosen C. J. , Russelle M. P. , Nater E. A. 
Published: July 2010

AbstractElectricity generation from biomass is an attractive option from an environmental perspective. Pilot studies have indicated that alfalfa (Medicago sativa L.) stems are suitable feedstock for energy generation via gasification. Detailed information on chemical characteristics of the ash generated from gasification of alfalfa stem is required to develop environmentally and economically sound ash management strategies. Alfalfa fly and bottom ashes were characterized with respect to chemical properties that are important in developing ash management practices with emphasis on beneficial utilization as a soil amendment. Mean concentrations of total C, K, Ca, and Cl were 424, 120, 85, and 26 g kg−1, respectively, in fly ash. In bottom ash, the mean concentrations of C, K, and Ca, were 63, 61, and 193 g kg−1. Concentrations of total Pb, As, Cd, Co, and Se were below detection limits in both ash types. Naphthalene ranged from 6.2 to 74 mg kg−1, but concentrations of many other polyaromatic hydrocarbons were low or below mg kg−1 detection limits. Available K and P in fly ash were 90 to 120 and 8 to 10 g kg−1, respectively. Mean CaCO3 equivalent value of fly ash was 400 g kg−1, its electrical conductivity (EC) and pH were 127 dS m−1 and 11.5, respectively. These results suggest that when managed properly, gasified alfalfa ash could potentially be utilized as a beneficial soil amendment with few potential environmental concerns.
Organic Phosphorus Source Effects on Calcareous Soil Phosphorus and Organic Carbon
Authors: Robbins C. W. , Freeborn L. L. , Westermann D. T. 
Published: July 2010

AbstractThe loading, solubility, mobility, and plant availability of P is a growing environmental concern to regulators and planners of nutrient management plans, confined animal feeding operations, and wastewater land application permit sites. Insufficient information is available on how P reacts from different organic sources when applied to calcareous soils. A field study was conducted to determine the interactions among P application rate, source, extractability, and soil organic carbon (OC) concentration. A Portneuf silt loam (Coarse‐silty, mixed, superactive, mesic Durinodic Xeric Haplocalcids) topsoil and freshly exposed subsoil were fertilized with monocalcium phosphate (MCP), cheese whey, and dairy manure. Organic matter added with the whey did not influence soil OC concentrations whereas organic matter added with the manure doubled the subsoil OC and increased the topsoil OC concentrations. Bicarbonate and saturation paste extractable ortho‐ and organic‐P concentrations were linearly related to soil OC concentrations but were not related to the amount of ortho‐ or organic‐P added. All forms of P increased more per unit of added P in the order manure > whey > MCP and were correlated with the soil OC concentrations. These results suggest organic waste applications should be managed from soil P test data rather than on P application rates.
Removal of Perchlorate from Ground Water by Hydrogen‐Utilizing Bacteria
Authors: Giblin Tara L. , Herman David C. , Frankenberger W. T. 
Published: July 2010

AbstractAn autotrophic consortium of bacteria, utilizing hydrogen and bicarbonate as electron and carbon sources, respectively, for the reduction of perchlorate has been enriched. The efficiency of this consortium for perchlorate reduction in a packed‐bed bioreactor is described. The use of hydrogen as an electron source for microbial biodegradation of pollutants in a packed‐bed bioreactor is advantageous because hydrogen does not promote vigorous biomass growth, resulting in less clogging of the system, and hydrogen gas reduces the need for post‐reactor water cleanup. The consortium, comprised of four bacteria, was capable of removing nitrate and perchlorate simultaneously from mineral salts medium in a batch culture. A 120‐mL bioreactor was designed to test the capacity of the consortium to remove perchlorate in a flow‐through system. At a flow rate of 1 mL min−1, perchlorate levels naturally occurring in San Gabriel Valley ground water (0.740 mg L−1) were completely removed to less than 0.004 mg L−1, which is the detection limit. However, as the flow rate was increased, the removal efficiency decreased. Factors affecting the rate of perchlorate removal included nonuniform distribution of biomass in the column, unstable pH of the ground water, and limited delivery of hydrogen to the bacteria. This bioreactor also completely removes perchlorate from ground water at a flow rate of 1 mL min−1 without an added carbon source, presumably using the bicarbonate naturally present in the ground water.
Nitrogen Transformations and Losses in Forest Soil Subjected to Sprinkling Infiltration
Authors: Paavolainen Laura , Smolander Aino , Lindroos Antti‐Jussi , Derome John , Helmisaari Heljä‐Sisko 
Published: July 2010

AbstractArtificial ground water has been produced in Ahvenisto esker in southern Finland by sprinkling lake water directly onto the forest soil. The aim of this study was to investigate N transformations in the soil, especially nitrification, and N losses via leaching and gaseous emissions during the first three years of this sprinkling infiltration. During the first year, the pH of the humus layer increased from about 5 to 6.7 and net nitrification started. Intensive nitrification continued throughout the study period. Although infiltration increased N2O emissions from the soil, the emissions were very small compared with N losses via leaching. The esker retained organic N. The mean (NO2 + NO3)−N concentration in percolation water during infiltration was close to that of the infiltration water (about 0.2 mg L−1) but, during breaks in infiltration, the concentrations generally exceeded 10 mg L−1. The ground water (NO2 + NO3)−N concentration, however, remained very low (mean 0.2 mg L−1) due to dilution of the (NO2 + NO3)−N, produced in the soil, by the large volume of infiltration water. The results of this 3‐yr study show that the leaching of nitrate does not presently pose a threat to the quality of ground water as long as infiltration is continuous. As nitrate was still being produced 2 yr after cessation of infiltration, there is a risk of nitrate leaching into the ground water. The actual risk this poses to ground water quality depends on the size of the infiltration area in relation to the whole aquifer.
Nitrate Dynamics in Relation to Lithology and Hydrologic Flow Path in a River Riparian Zone
Authors: Devito Kevin J. , Fitzgerald Dan , Hill Alan R. , Aravena Ramon 
Published: July 2010

AbstractThe efficiency with which riparian zones remove nitrate (NO−3) from contaminated ground water can vary with landscape setting. This study was conducted to determine the influence of flood plain geometry, lithology, hydrologic flow path, and nitrate transport on mechanisms of nitrate depletion of contaminated ground water. Patterns of NO−3−N, chloride, and dissolved organic carbon (DOC) concentrations and δ15N‐NO−3 and δ18O‐NO−3 values in combination with detailed piezometric head measurements were investigated in a river floodplain connected to a large upland sand aquifer in an agricultural region near Alliston, Ontario, Canada. Ground water discharging to the forested floodplain from the sand aquifer exhibited large spatial variability in NO−3−N concentrations (10–50 mg/L). The transport and depletion of NO−3 was strongly influenced by floodplain geometry and lithology. Little ground water flow occurred through the low‐conductivity matrix of peat in the floodplain. Plumes of NO−3‐rich ground water passed beneath the riparian wetland peat and flowed laterally in a 2‐ to 4‐m‐thick zone of permeable sands across the floodplain to the river. Analyses of the distribution of the NO−3−N concentrations, isotopes, and DOC within the floodplain indicate that denitrification occurred within the sand aquifer near the river where nitrate‐rich ground water interacted with buried channel sediments and surface water recharged from peat to the deeper sands. This study shows that the depth of permeable riparian sediments, ground water flow path, and the location of organic‐rich subsurface deposits may be more important than the width of vegetated strips in influencing the ability of riparian zones to remove nitrate.
Crop Management and Corn Nitrogen Rate Effects on Nitrate Leaching
Authors: Andraski T. W. , Bundy L. G. , Brye K. R. 
Published: July 2010

AbstractExcess N use in crop production is often identified as a major contributor to NO3 enrichment of ground water. Little information is available to show the specific relationships between crop management systems and N fertilizer use on the amounts of NO3 lost by leaching. This study determined the effect of several cropping systems and N rates, providing a range of N availability to corn (Zea mays L.), on soil water NO3 concentrations and leaching below the root zone. Four cropping‐manure management systems were established in 1993 and 1994 (8‐site years) at Arlington, WI, on a Plano silt loam (fine‐silty, mixed, superactive, mesic Typic Argiudoll). Ammonium nitrate (0 to 204 kg N ha−1 in 34‐kg increments) was broadcast at the time of corn planting. Economic optimum N rates (EONR) for corn ranged from 0 to 150 kg ha−1 depending on site‐year. Soil water NO3 concentrations were determined for 18‐mo using porous‐cup samplers installed at a 120‐cm depth in the 0 and 204 kg N ha−1 treatments. Nitrate N concentrations in the samplers increased as the amount of N applied in excess of the observed EONR increased. Predicted soil water NO3−N concentration at EONR was 18 mg L−1. Average NO3−N concentrations were <10 mg L−1 where fertilizer N rates were >50 kg N ha−1 below the EONR and >20 mg L−1 where fertilizer N rates were >50 kg N ha−1 above the EONR. Total NO3−N leaching estimates based on water budget data and soil water NO3 concentrations for the 18‐mo study period ranged from 3 to 88 kg ha−1 depending on crop and manure management system, N fertilizer rate, amount of water drainage, and time of drainage event relative to treatment establishment. An end‐of‐season soil NO3 test appears to be capable of evaluating corn N management practices and indicating the amount of excess N fertilizer applied that may be leached from the root zone. These results illustrate the direct relationship between NO3 loss by leaching and N application rates that exceed crop needs.
Trace Metal Leachability of Land‐Disposed Dredged Sediments
Authors: Singh Satya P. , Ma Lena Q. , Tack Filip M. G. , Verloo Marc G. 
Published: July 2010

AbstractThe potential risk of surface and ground water contamination by trace metals leached from contaminated land‐disposed dredged sediment is a major environmental concern. The objective of this study was to evaluate trace metal leachability, leachate quality, and environmental effects of land‐disposed dredged sediments (LDDS). In addition to chemical characterization and determination of potential and actual leachability, dredged sediments were also subjected to solid phase fractionation using a sequential extraction procedure. Potential leachability, defined as the maximum metal pool that may become available for leaching at a constant pH 4, decreased in the following order: Zn ∼ Cd > Mn > Ni > Co > Cu ∼ As > Pb > Cr. Potential metal leachability was controlled mainly by solid phase distribution of metals in sediments. The acid‐extractable fraction of most metals correlated well with the potentially leachable metals extracted with a solution of pH 4 (r2 > 0.67), except for Pb. The kinetics of metal release were determined using the cascade leaching test (CLT) with water at pH 4. Except for Ni and Zn in the first fraction, metal concentrations in all consecutive leaching fractions remained below the maximum permissible level in water for human consumption. Actual metal leachability expressed as a percentage of potential leachability varied widely among trace metals and decreased in the order: As > Cu > Cr > Ni > Zn > Cd > Co > Pb. Our results indicate low risk of surface and ground water contamination resulting from land disposal of dredged sediments.
Bioaccumulation of Heavy Metals in Thionic Fluvisols by a Marine Polychaete: The Role of Metal Sulfides
Authors: Otero X. L. , Sánchez J. M. , Macías F. 
Published: July 2010

AbstractBioavailable heavy metals have been widely studied in recent years because of their toxicity to natural ecosystems. Despite the number of studies carried out, relatively little is known about the metal fraction that is biologically available. In this study, we analyzed seasonal concentrations of acid‐volatile sulfide (AVS) as well as heavy metals associated with the reactive (soluble in 1 M HCl) and pyrite (soluble in HNO3) fractions of the soils of three salt marshes in the ría of Ortigueira (NW Iberian Peninsula). Heavy metal concentrations in polychaete worms (Nereis diversicolor) collected from each salt marsh were also determined and compared with metal contents in the different fractions of the soil. We did not find a relationship between the concentration of total metal or metal incorporated into the reactive fraction in the soil and the tissue‐metal concentration in N. diversicolor. The results appear to indicate that this species preferentially accumulates metals associated with reduced forms of sulfur (pyrite and presumably AVS). Oxidation of these metal sulfides would lead to release of Cu and Ni into interstitial water and they would then be readily available to be taken up by these organisms, either by absorption through the body surface or across the digestive tract.
Nutrient Concentrations and Discharges in a Midwestern Agricultural Catchment
Authors: Castillo M. M. , Allan J. D. , Brunzell S. 
Published: July 2010

AbstractThe amounts of nitrogen and phosphorus in river water are significantly influenced by anthropogenic inputs associated with land cover, land use, and point sources. We quantified seasonal and spatial patterns in the concentrations of nitrate N and soluble reactive phosphorus (SRP) at 17 sites distributed among tributaries and along the mainstem of the River Raisin, Southeastern Michigan, and also determined land cover, surficial geology, and discharges from waste water treatment plants (WWTPs). Annual flow‐weighted mean concentrations (FWMCs) ranged from nondetectable levels to 18.1 mg L−1 for nitrate and to 184 µg L−1 for SRP. Nitrate concentrations increased from headwaters to river mouth, and were highest in spring and in association with high runoff episodes. Mean nitrate concentration correlated strongly with the ratio of agricultural to forested land upstream of the sampling location. Concentrations of SRP also increased markedly from headwaters downstream, and exhibited little seasonal variation other than a modest increase during the summer period of low flow. Geology and phosphorus loading from WWTPs best predicted SRP concentrations. The annual yield of nitrate was consistent with expectations based on land use. Point source loading contributed a negligible fraction of the river's discharge of nitrate and at most one‐fourth of its SRP discharge. Compared with findings from headwater sites and other, less altered rivers, nutrient concentrations in this catchment appear strongly influenced by human activity.
Soil Phosphorus Fertility Degradation: A Geographic Information System‐Based Assessment
Authors: Brown S. , Schreier H. , Shah P. B. 
Published: July 2010

AbstractSoil phosphorus is a critical macronutrient limiting agricultural productivity in many parts of Nepal. This study evaluates a geographic information system (GIS)‐based approach to assess soil P degradation risk as influenced by site factors and human land use impacts. The status of P fertility in a Nepalese watershed was evaluated by stratifying the soil analysis by soil type, elevation, aspect, and land use (irrigated or rainfed agriculture, rangeland, and forests). Human impacts were shown to be significant, and with GIS overlay techniques it was possible to produce a soil P status map based on land use and soil type. Some 27% of the area was found to be deficient in P. Soil nutrient budgets displaying annual surplus or deficit conditions for the common crops were combined with the soil fertility map to derive a soil P degradation risk map. Low P conditions with high annual deficits posed the greatest degradation risk, while adequate P status with high annual deficits were of more long‐term concern. Forty‐eight percent of the area was considered at low risk because of adequate conditions and minimal deficits for P. In contrast, some 36% of the study area had a high short‐term risk for degradation because of the low status and high annual deficit in P. Given the dynamics of soil fertility, the site factor approach used in combination with soil analysis, nutrient budget calculations based on farm interview data, and GIS overlay techniques provided a unique way of assessing long‐term soil P degradation risks.
Factors Affecting Phosphorus Export from a Pasture‐Based Grazing System
Authors: Nash David , Hannah Murray , Halliwell David , Murdoch Craig 
Published: July 2010

AbstractPasture‐based grazing systems contribute to the excessive nutrients found in some streams in southern Australia. This study investigated P exported from a 3.6 ha dairy pasture receiving high levels of P fertilizer with a view to identifying factors affecting P export. The runoff from 34 storms was monitored to examine factors thought to be associated with the variation in total phosphorus (TP). The relationships between TP and days since grazing (DG), days since fertilizing (DF), total storm flow (TF), and season (year and time of year) were examined. The variable DF was inversely related to the flow‐weighted mean TP concentration (P < 0.001) and accounted for 50.6% (adjusted R2) of the variance in ln (TP). However, DG was only weakly correlated to TP, suggesting that cattle did not mobilize large stores of available P relative to the fertilization at the study site. The initial half‐life of fertilizer effect (i.e. the period of time since fertilizing in which the TP concentration decreased by half) was estimated to be 4.3 d, with a 95% confidence interval of 3.1 to 8.0 d. However, unlike exponential decay where the half‐life is constant, the decay rate for these data declined over time. The data adjusted for the effects of DG and TF show little evidence of decline in TP after 20 d since fertilizing. Management of fertilizer application in relation to the timing of runoff events appears the main method by which P export can be decreased in the type of pasture‐based grazing system studied here.
Relating Soil Phosphorus Indices to Potential Phosphorus Release to Water
Authors: Hooda P. S. , Rendell A. R. , Edwards A. C. , Withers P. J. A. , Aitken M. N. , Truesdale V. W. 
Published: July 2010

AbstractRelationships between soil test phosphorus (STP) and release of P in surface and subsurface runoff are needed to help identify source areas for implementing management strategies to limit P loss to water. To determine whether soil P release could be predicted either by STP values, sorption‐desorption indices, or the degree of soil saturation with phosphorus (DSSP), 11 sites with contrasting chemical properties and management histories were sampled from long‐term field trials in the UK. Each site offered up to three treatments, resulting in a total of 29 soil samples. The results showed that the amount of P desorbed using a successive dilution procedure had no relationship with either total soil P content or P sorption capacity. The most significant property was the extent of P saturation. There was little desorption for DSSP values below 10%; above this point, the amount of P desorbed increased linearly with the DSSP. Five STP methods (Olsen, Mehlich‐3, acidified ammonium oxalate‐oxalic acid, Fe2O3‐coated paper strip, and distilled water) were compared to predict their effectiveness in predicting potential P release to water. While STP values obtained using acidified ammonium oxalate proved to be least effective, those extracted with water correlated best with the amount of P desorbed, accounting for 96% of the variability in differential P release from the soils.
Respective Horizon Contributions to Cesium‐137 Soil‐to‐Plant Transfer: A Pot Experiment Approach
Authors: Thiry Yves , Kruyts Nathalie , Delvaux Bruno 
Published: July 2010

AbstractThe OAh horizons in forest acid soils are reported to fix more radiocesium than the mineral horizons beneath and organic horizons above them. We determined the respective contributions of the Of, OAh, Ah, and Bw horizons in an acid brown soil to the total 137Cs soil‐to‐plant transfer by using young spruce plants [Picea abies (L.) H. Karst.l grown on reconstituted micro‐pedons in which these respective horizons were contaminated by carrier‐free 137Cs. The plants were grown in a greenhouse at 20°C during a period of 5 mo. The respective contributions to the 137Cs soil‐to‐plant transfer were 92.71% in Of, 0.18% in OAh, 3.28% in Ah, and 3.83% in Bw. The very high contribution of Of was due to its high organic matter (OM) content, while the very low contribution of OAh was related to Cs+ fixation by vermiculitic clay minerals. The higher 137Cs transfer from Ah and Bw vs. OAh was probably associated with Al interlayering of vermiculite. Our data suggest that plant roots and soil vermiculite acted as competitive sinks for 137Cs in the acid brown soil.