bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stabilization of Soil Nitrate by Reseeding with Perennial Ryegrass following Sudden Turf Death
Authors: Bushoven John T. , Jiang Zhongchun , Ford Heather J. , Sawyer Carl D. , Hull Richard J. , Amador José A. 
Published: July 2010

AbstractTurf death can result in the mineralization of organic nitrogen (N) within the turf‐soil ecosystem. If not reestablished within 12 mo, dead turf can leach 10% of its total soil N as nitrate into ground water. This study investigated how rapidly and completely soil N can be restabilized following reseeding of killed turf. Twelve‐year‐old field plots, comprising four cool‐season turfgrass species growing on an Enfield silt loam (coarse‐silty over sandy‐skeletal, mixed, active, mesic Typic Dystrudepts) at Kingston, RI, were used. In early September 1997, one‐half of the plots were killed by applying glyphosate and three‐fourths of the dead plots were reseeded with ‘Palmer III’ perennial ryegrass (Lolium perenne L.) in late March 1998. Soil moisture, temperature, pH, respiration, and extractable nitrate and ammonium were monitored every 6 to 8 wk. Nitrate levels in subsoil water were monitored at 2‐wk intervals and nitrate leaching estimated for each percolation event. Reseeding enhanced soil respiration, within 6 wk of seeding, to levels comparable with those of soil in healthy plots. Surface soil nitrate levels in killed and reseeded plots declined within 6 wk of reseeding. Nitrate levels in soil water beneath the root zone declined in reseeded plots relative to those of healthy plots (9 mg NO3‐N L−1) within 8 wk of reseeding. Nitrate leaching also declined 3 mo after seeding to rates less than half of those from turf that had been killed but not reseeded. Our results indicate that the potential for increased nitrate leaching following turf death can be eliminated within 2 mo if the site is promptly reseeded.
Treatment of Wastewater Phosphate by Reductive Dissolution of Iron
Authors: Robertson W. D. 
Published: July 2010

AbstractA new method for the treatment of wastewater phosphate is presented that relies on reductive iron dissolution (RID process). It is analogous to existing treatment methods that use iron salts (e.g., FeCl2) to precipitate P from wastewater, except that in this case ferrous iron is made available by the reductive dissolution of ferric iron solids that are contained in a reactive porous media. The ferric solids are minerals such as amorphous Fe(OH)3 that occur naturally in soils and sediments. A laboratory column study and a pilot scale field trial demonstrated that these solids are susceptible to reductive dissolution when mixed with sewage effluent, resulting in increased Fe(II) in solution. This promotes the precipitation of Fe(II)‐P solids and then Fe(III)‐P solids when the effluent is subsequently oxidized. Both experiments demonstrated the ability of the RID media to passively solubilize consistent, moderate concentrations of Fe (1–9 mg L−1) over extended periods (2–3 yr). In the column test, influent PO4 of 9.0 ± −3.7 mg P L−1 was lowered to 2.1 ± 1.1 mg P L−1. In the field trial, influent PO4 of 10.2 ± 6.0 mg P L−1 was lowered to <0.05 mg P L−1. This technique may be attractive for use with smaller wastewater treatment systems such as septic systems, because it can be maintenance‐free for long periods and it avoids excess sludge accumulation.
Denitrification in South Carolina (USA) Coastal Plain Aquatic Sediments
Authors: Aelion C. Marjorie , Shaw J. Nikki 
Published: July 2010

AbstractDenitrification rates in aquatic sediments from three sites upland of high salinity estuaries were measured to compare nitrate (NO−3) removal by sediment bacteria. The study sites included two blackwater creeks that drain to coastal inlets (one in an undeveloped coastal forest and the second in a suburban residential development) and drainage pond on a golf course. Two to 20 mmol NO−3 kg−1 soil was added to microcosms and the acetylene block technique was used to estimate denitrification. Nitrate, nitrous oxide (N2O) and ammonium (NH+4) concentrations were monitored over time. The rate and efficiency of denitrification was low at the 2 mmol NO−3 kg−1 addition and increased proportionally with NO−3 added. Across all treatments, the golf course sediment that received consistent N inputs in situ had the most rapid and greatest N2O production, while the salt marsh in the undeveloped area had the least. The NH+4 concentrations remained constant and low (2 mmol N kg−1) except at the undeveloped, forested Oyster Creek (8 mmol NH+4‐N kg−1). In most cases, the majority of NO−3 removal did not occur until 24 to 48 h of incubation, regardless of N2O production. During typical low‐ and no‐flow periods, this time frame may be adequate for slow diffusion of nutrients and removal of NO−3 prior to transport to coastal estuaries or ground water, particularly at the golf course site. However, this time frame may not be adequate during rapid water and nutrient transport due to severe storm events typical of this region.
Toward Site‐Specific Design Standards for Animal‐Waste Lagoons: Protecting Ground Water Quality
Authors: Ham J. M. , DeSutter T. M. 
Published: July 2010

abstractSeepage losses from animal‐waste lagoons can affect ground water quality, if facilities are not properly sited, designed, and constructed. Most states in the Great Plains stipulate that earthen lagoons cannot seep more than some specified rate (mm d−1). These criteria often apply to the entire state and all livestock species, although ground water vulnerability and waste characteristics are highly variable from site to site. Because of this variability, statewide “blanket” regulations may overregulate some producers and underregulate others. Furthermore, wide disparity exists in seepage allowances among neighboring states, and regulations often are influenced by public opinion rather than scientific findings. This paper argues that lagoon design should be site specific and presents a logical framework to determine the maximum allowable seepage rate for a given location and type of operation (e.g., dairy, swine, cattle feedlot). Site‐specific factors, such as soil properties, depth to water table, and chemistry of the waste, are used to arrive at lagoon performance standards that minimize long‐term risk. The decision process within the framework is presented as a conceptual model for lagoon permitting and may need to be customized to meet the requirements of each state. Nevertheless, use of site‐specific design criteria will ensure that manure storages are adequate (e.g., plastic‐lined lagoons) in regions with vulnerable ground water, while providing reduced lagoon construction costs (lower cost of soil‐lined lagoons) for producers who site their operations in areas of low risk. To complement the site‐specific approach, the whole‐lagoon seepage rate should be measured after construction to verify that the prescribed performance criteria have been met.
Water Quality Changes from Riparian Buffer Restoration in Connecticut
Authors: Clausen J. C. , Guillard K. , Sigmund C. M. , Dors K. Martin 
Published: July 2010

AbstractOne‐half of a 35‐ by 250‐m riparian buffer cropped in corn (Zea mays L.) was seeded with fine leaf fescue (Festuca spp.) and allowed to remain idle to determine water quality changes resulting from riparian buffer restoration. A corn control was also used in this paired watershed design located in Connecticut. Water, N, and P fluxes were determined for precipitation, overland flow, and ground water. Also, an N mass balance was calculated. Total Kjeldahl nitrogen (TKN) and total phosphorus (TP) concentrations significantly (P < 0.05) increased as ground water flowed through the restored buffer. Nitrate N (NO3‐N) concentrations declined significantly but most (52%) of the decrease occurred within a 2.5‐m wetland adjacent to the stream. An N mass balance for the 2.5‐m strip indicated that denitrification only accounted for 1% of the N losses and plant uptake was from 7 to 13% of the N losses annually. Ground water was the dominant source of N to the buffer and also the dominant loss. Restoration of the riparian buffer decreased (p < 0.05) overland flow concentrations of TKN by 70%, NO3‐N by 83%, TP by 73%, and total suspended solids (TSS) by 92% as compared with the control. Restoration reduced (p < 0.05) NO3‐N concentrations in ground water by 35% as compared with the control. Underestimated denitrification and dilution by upwelling ground water in the wetland area adjacent to the stream were believed to be primarily responsible for the decreasing NO3‐N concentrations observed.
Effect of pH on Sorption and Transport of Fluorobenzoic Acid Ground Water Tracers
Authors: McCarthy John F. , Howard Kevin M. , McKay Larry D. 
Published: July 2010

AbstractSorption and transport behavior of fluorobenzoic acid (FBA) tracers were evaluated as ground water tracers in a highly weathered and fractured clay‐rich saprolite under both acidic and neutral conditions in laboratory batch tests and column transport studies. The FBAs are a group of 14 organic acids with pKa from 2.71 to 3.83, and may thus be potentially retarded in weathered, acidic soils. The degree of sorption was directly related to the pKa of the isomer and the pH of the solution. A technique for determining the intrinsic partitioning coefficient (Kd) of an non‐ionized species was derived to predict the equilibrium sorption of a family of compounds over a range of pH and pKa. For the diflourobenzoic acids used in this study, Kd was 2.50 L/kg. The intact column transport experiments confirmed that at neutral pH, none of the FBA isomers were retarded relative to a nonreactive tracer (Br−). Under acidic conditions (pH = 5.2), significant retardation was observed for isomers with higher pKa. Because the use of FBA tracers could be limited by regulatory concerns about potential toxic effects in surface water receiving discharge from ground water containing FBA, aquatic toxicity was assessed using a Ceriodaphnia 96‐h acute toxicity test. The LD50 (the concentration resulting in mortality of ≥50% of the test organisms) for the four FBA isomers tested was above 100 mg/L. The results of these equilibrium isotherm and column transport experiments demonstrate that FBAs can be very useful as nonreactive ground water tracers in these materials as long as the pH is approximately 2 pH units above the pKa (i.e., >99% ionized).
Nitrate Leaching and Nitrogen Budget as Affected by Maize Nitrogen Rate and Soil Type
Authors: Sogbedji Jean M. , van Es Harold M. , Yang Charissa L. , Geohring Larry D. , Magdoff Fred R. 
Published: July 2010

AbstractLeaching loss as nitrate (NO3) is a growing concern because of its potential effect on water resources. Leaching of NO3 with drainage water from subsurface‐drained field plots seeded to maize (Zea mays L.) in 1992, 1993, and 1994 was measured on two soil types (a clay loam and a loamy sand) and for three N fertilization rates (22, 100, and 134 kg N ha−1). The 100 kg ha−1 rate was based on the results of a presidedress nitrate test (PSNT). Nitrate nitrogen (NO3‐N) leaching was similar between fertilizer N treatments at both sites in 1992, the first year after sod plowdown, but concentrations were greater than 10 mg L−1. For the subsequent two years, losses were similar for the 22 kg N ha−1 and the PSNT‐based treatments, but significantly higher for the 134 kg N ha−1 treatment on the clay loam. On the loamy sand, losses increased from the lowest to the highest N rate. Nitrate leaching losses were consistently higher on the loamy sand than on the clay loam. The N budget results showed that the 134 kg N ha−1 rate had the highest residual soil NO3‐N in the three years at both sites. On the clay loam, significant N losses occurred from denitrification following alfalfa plowdown and the subsequent fall and spring. Results indicate that N use efficiency rapidly decreases with overfertilization, even with N fertilization rates that only slightly exceed (134%) crop requirements. The PSNT‐based rate reduced N leaching losses while maintaining maize yields.
Molybdenum Content of Water Treatment Residuals
Authors: Elliott H. A. , Taylor M. 
Published: July 2010

AbstractMolybdenum (Mo) content of water treatment residuals (WTRs) was determined by inductively coupled plasma atomic emission spectroscopy (ICP‐AES) to evaluate suitability for land application under state regulatory policies that limit Mo to 18 mg kg−1. Samples of WTR were collected from 32 Pennsylvania facilities that employ aluminum salts, ferric chloride, and/or polymers for coagulation. The mean Mo content of all samples was 3.1 mg kg−1, with 78% having Mo levels <5 mg kg−1. The WTRs from plants using ferric chloride as a coagulant averaged 5.6 mg Mo kg−1, significantly higher (p = 0.02) than the 1.6 mg Mo kg−1 for utilities using alum. Differences were related to coagulant purity: Mo content in liquid ferric chloride was 10.0 mg L−1 but below detection by ICP‐AES for alum. The initial sample from one facility, collected from the filter backwash basin, contained 26.4 mg Mo kg−1. Elevated Mo in backwash solids was attributed to filtration capture of extremely fine, Mo‐enriched AI hydrous oxide particles and erosion of anthracite filter media during backwashing. Combined backwash and coagulation solids from this facility's storage lagoon averaged 6.3 mg Mo kg−1, underscoring the need for consistent sampling procedures. The mean Cu to Mo ratio in these WTRs was >100, well above the minimum dietary ratio (2:1) considered protective of grazing animals.
Stability and Mobility of Napropamide Complexed with Dissolved Organic Matter in Soil Columns
Authors: Nelson S. D. , Farmer W. J. , Letey J. , Williams C. F. 
Published: July 2010

AbstractThe herbicide napropamide [N,N‐diethyl‐2‐(1‐naphthyloxy)propanamide] has been shown to complex with various sources of dissolved organic matter (DOM), potentially increasing the risk of ground water contamination by facilitating napropamide transport through soil. Two factors that may reduce the threat of facilitated transport of chemicals through soils are soil profile depth and soil horizon variability. Movement through the soil profile may cause herbicide complexed with DOM to break apart and readsorb to the soil. Differences in soil horizon organic matter content throughout the soil profile may also alter the potential for facilitated transport of herbicides. Napropamide was used in column studies to determine if organic matter differences in horizons and soil profile depth would reduce the risk of facilitated transport. A silt loam soil was used with and without sewage sludge amendment (SS and NoSS) to represent differences in organic matter content. Results showed that <6% of the applied mass of napropamide moved as DOM complexes through soil. The majority of complexed napropamide was very stable and relatively nonadsorbing in solution such that doubling of soil depth only reduced facilitated transport by 20% or less. We present evidence to show that napropamide‐DOM complexes are relatively nonadsorbing in solution and exhibit transport characteristics similar to those of a inert compounds in soil solution.
Predicting Solute Transport Using Mapping‐Unit Data: Model Simulations versus Observed Data at Four Field Sites
Authors: Macur Richard E. , Gaber Hesham M. , Wraith Jon M. , Inskeep William P. 
Published: July 2010

AbstractSolute transport models may be used in conjunction with soils and climatic databases to predict the sensitivity of soil mapping units to leaching of agrichemicals. The primary objective of this study was to compare predicted solute transport obtained from several modeling approaches to observed data collected at four irrigated field sites throughout Montana. Observed solute distribution data as a function of soil depth was collected using Br− and a moderately sorbing herbicide, bromacil (5‐bromo‐3‐sec‐butyl‐6‐methyluracil), for three sampling dates over a period of 1 yr and used for evaluating different approaches for generating model predictions. The observed data were compared to predictions generated by two process‐based solute transport models, Chemical Movement in Layered Soils (CMLS) and Leaching Estimation and Chemistry Models (LEACHM), which differ in level of sophistication. Model predictions were obtained using inputs based on either detailed site characteristics (i.e., soil profile characterization) or the 1:24 000 scale USDA‐NRCS Soil Survey (SSURGO) database coupled with parameter estimation routines. Comparisons of observed and simulated transport showed that although LEACHM and CMLS frequently underestimated solute transport, both models performed similarly using either site‐specific inputs or SSURGO derived inputs. Model simulations using SSURGO soils data and 23 yr of historical climate data resulted in only slight variations in predictions of solute transport, suggesting that SSURGO inputs coupled with historic climate data provide a fairly robust approach for evaluating the sensitivity of mapping units to pesticide leaching out of the root zone.
Biodegradation Assessment of Woolscour Sludge and Fellmongery Sludge
Authors: Williamson W. M. , Greenfield L. G. , Beare M. H. 
Published: July 2010

AbstractSustainable land application of agricultural and industrial wastes requires an understanding of factors likely to limit waste decomposition and the release of plant‐available nitrogen. This paper describes the biodegradation of a woolscour sludge and a fellmongery sludge and suggests a biodegradation assessment strategy suitable for agricultural and industrial wastes. After 50 d of decomposition in microcosms, the woolscour sludge mineralized 18% of initial C and 9% of initial N, while the fellmongery sludge mineralized 37% of initial C and 53% of initial N. Net N mineralization from woolscour sludge was principally constrained by the recalcitrant behaviour of the wool fiber component, whereas elevated temperature (43°C) or anaerobic conditions constrained fellmongery sludge decomposition. Two negative consequences of soil amendment were identified. First, soil amended with fellmongery sludge leached up to 39% of applied sludge N as mineral N during 100 d of decomposition. Second, both sludges caused a reduction in microbial blomass (MB) after 1 yr of soil amendment. Our data indicated that the woolscour sludge was a substrate of low quality for soil microbial metabolism and that chemical parameters are a poor predictor of biodegradation. On the other hand, the fellmongery sludge was a substrate of moderately high quality for which chemical characteristics permitted relatively consistent prediction of N mineralization.
Denitrification Rates Predicted by Nitrogen‐15 Labeled Nitrate Microcosm Studies, In Situ Measurements, and Modeling
Authors: Hoffmann Carl Christian , Rysgaard Søren , Berg Peter 
Published: July 2010

AbstractDenitrification rates in the range of 359 to 599 niniol N m−2 d−1 were found in the waterlogged soil of a minerotrophic fen. Three different methods were used to estimate denitrification rates. The fen revealed a zone of enhanced denitrification and within this zone the spatial variation of denitrification rates was elucidated using two different approaches: microcosms and field observations. The denitrification rates in the microcosms were measured, either by use of 15N‐N2 production rates (Method 1) or by setting up a mass balance for nitrate (Method 2). Denitrification rates in the peat horizon at depths of 0 to 69 cm were in the range 182 to 243 mmol N m−2 d−1 (Method 1) and 213 to 217 mmol N m−2 d−1 (Method 2). Denitrification rates measured in the deeper sandy soil horizons at depths of 69 to 156 cm were 46 to 103 mmol N m−2 d−1 (Method 1) and 33 to 137 mmol N m−2 d−1 (Method 2). Thus, both experiments revealed a strong and comparable decrease in denitrification rate with depth, which also corresponded well to soil carbon content. Denitrification rates were calcultaed from field data using Daicy's law and the conservation equation for one‐dimensional, steady state, advective transport of nitrate in an incompressible porous medium. The same significant decrease in denitrification rates with depth was observed as in the microcosm setup. The calculated denitrification rates were: 330 mmol N m−2 d−1 at depths of 0 to 75 cm (peat), 20 mmol N m−2 d−1 at depths of 75 to 115 cm (sandy soil), and 9 mmol N m−2 d−1 in the sandy soil horizon at depths of 155 to 205 cm. This study shows that detailed spatial information about pedological and hydrological parameters in combination with detailed spatial mapping and measurement of denitrification rates is fundamental for properly understanding nitrogen removal in waterlogged soils with ground water through‐flow. Further, the results confirm that provided this information is present, it is possible to compare detailed laboratory experiments with field studies of denitrification.
Intervention Effects in the Case of Heterogeneity between Three Subgroups
Authors: Bender R. , Skipka G. 
Published: July 2010

Summary
Background: Usually, statistical tests for interactions are applied to investigate potential effect modifiers. If an effect modifier, consisting of three categories, is found to be statistically significant, the application of pairwise interaction tests is indicated. In this case, the problem of non-transitive relations may occur if the significance level is fixed at 0.05 for all tests.
Objective: To develop an algorithm for which non-transitive relations do not occur.
Methods: A hierarchical testing procedure is applied, based on the heterogeneity statistic Q. In a first step the interaction will be tested for the three trial subgroups altogether, applying the significance level α = 0.05 (global test). If a significant interaction is proven in the first step, pairwise tests for interaction will be applied in a second step. Theoretical data scenarios will be considered and p-values will be calculated for the pairwise tests. Based on these results the significance level for pairwise testing will be determined.
Results: Fixing the significance level at 0.05 for all tests, the problem of non-transitive relations is mostly relevant, if the difference in the effects between the three trial subgroups is approximately 3.5 standard errors and the effect of the ‘middle’ trial subgroup is not close to one of the other two effects. This problem vanishes when the significance level is set to α = 0.22. We propose to select α = 0.20 to get a more ’even’ and simple value.
Conclusions: By increasing the significance level for the pairwise tests to 0.20, non-transitive relations are virtually avoidable. The proposed hierarchical testing procedure represents a clear practical guidance to perform subgroup analyses in the framework of systematic reviews.
Concurrent and prospective associations between facial affect recognition accuracy and childhood antisocial behavior
Authors: Bowen Erica , Dixon Louise 
Published: July 2010

AbstractThis study examined the concurrent and prospective associations between children's ability to accurately recognize facial affect at age 8.5 and antisocial behavior at age 8.5 and 10.5 years in a sub sample of the Avon Longitudinal Study of Parents and Children cohort (5,396 children; 2,644, 49% males). All observed effects were small. It was found that at age 8.5 years, in contrast to nonantisocial children; antisocial children were less accurate at decoding happy and sad expressions when presented at low intensity. In addition, concurrent antisocial behavior was associated with misidentifying expressions of fear as expressions of sadness. In longitudinal analyses, children who misidentified fear as anger exhibited a decreased risk of antisocial behavior 2 years later. The study suggests that concurrent rather than future antisocial behavior is associated with facial affect recognition accuracy. Aggr. Behav. 36:305–314, 2010. © 2010 Wiley‐Liss, Inc.