bluuebunny/crossref_metadata_2025_split huggingface dataset:
Revisiting the Fresno DBCP Case Study Simulations: The Effect of Upscaling
Authors: Soutter Leigh A. , Loague Keith 
Published: July 2010

AbstractThe Fresno case study (see Loagne et al., 1998b) was a regional‐scale assessment of nonpoint‐source DBCP (1‐2‐dibromo‐3‐chloropropane) leaching that employed upscaled near‐surface information. The effort reported here focuses on the effect that upscaling spatially variable soil and crop cover information had on the Fresno case study simulations. The DBCP water‐table loading concentrations estimated by Loague et al. were evaluated by statistical comparison with three new water‐table loading scenarios that were developed in this study from simulations that did not employ the same upscaling techniques as previously used. Four model performance statistics were used to assess the upscaling effects revealed by the comparison. The relative statistical results indicate that: (i) the area most sensitive to the upscaling was small relative to the total study area, (ii) the new concentration estimates were within the range of the DBCP concentrations reported by Loague et al., and (iii) the effects from the upscaling of soil‐order information far exceeded the effects from the upscaling of the crop covers. The results of the upscaling analysis suggest that the intensely variable concentrations observed for the Fresno study area would probably not have been predicted from new near‐surface simulations involving smaller elements (and less upscaling) than the 1‐km2 elements used by Loague et al. Inasmuch as this study demonstrates that a somewhat coarse grid may be suitable for certain locations, thoughtful planning for variations in the grid size, using the methods reported here, should help to target where upscaling is a potential problem for future regional‐scale nonpoint‐source simulation efforts.
Rainfastening of Bifenthrin to Cotton Leaves with Selected Adjuvants
Authors: Mulrooney J. E. , Elmore C. D. 
Published: July 2010

AbstractThere are thousands of adjuvants on the market, yet little is known about their effects on the activity of insecticides on plant surfaces. The effects of 11 selected adjuvants on the rainfastness and retention of bifenthrin ([1α,3α‐(Z)‐(±)‐(2 methyl[1,1′‐biphenyl]‐3‐yl) methyl 3‐(2‐chloro‐3,3,3‐trifluoro‐1‐propenyl)‐2,2‐dimethylcyclopropanecarboxylate) on cotton (Gossypium hirsutum L.) leaves were investigated. In addition, the effect of the adjuvant Bond on the efficacy of bifenthrin and a Bacillus thuringiensis (Berliner) formulation was determined. Bifenthrin mixed with each adjuvant was applied to greenhouse grown cotton plants using a spray chamber. Simulated rainfall of 13 mm was then applied to treated cotton plants at 0.25, 1, and 4 h after treatment. Bond and Agrimax‐3 were the only adjuvants to significantly increase the rainfastness of bifenthrin on cotton leaves. Agri‐Dex, Soy‐Dex, and Dyne‐Amic significantly decreased the rainfastness of bifenthrin. In tests conducted with an immersion cell apparatus, Orchex 796 resulted in twice the retention of Agri‐Dex, the next highest retained adjuvant. Both petroleum and vegetable oils enhanced retention of bifenthrin on the leaf surface. Bond mixed with bifenthrin and a B. thuringiensis formulation did not reduce the activity of these insecticides against tobacco budworm (Heliothis virescens) and soybean looper (Pseudoplusia includens) larvae. Retention on the leaf may be related to spread and to the degree of binding of the insecticide to the surface by properties of the adjuvant. Yet, the properties of Agri‐Dex that enhanced the retention of bifenthrin to the cotton leaf decreased its rainfastness.
Long‐Term Effects of Land Use and Fertilizer Treatments on Sulfur Cycling
Authors: Knights J. S. , Zhao F. J. , Spiro B. , McGrath S. P. 
Published: July 2010

AbstractThe unique archived samples from the Rothamsted Broadbalk Experiment, England, were used to evaluate long‐term effects of changing S inputs from atmospheric deposition and fertilization on soil S pools and soil S isotope ratio since 1843. The effects of changing land uses were also investigated. Large S inputs from atmospheric deposition and from sulfate fertilizers did not result in any significant accumulation of soil organic or inorganic S in the arable plots where organic C remained stable. Inputs of sulfate in excess of crop uptake were lost mainly through leaching. Organic S accumulated markedly in the arable plot receiving farmyard manure (FYM) or where arable land was allowed to revert to woodland or grassland. In the latter two systems soil organic C accumulated faster than organic S. In all soils investigated the S isotope ratio (δ34S) decreased substantially during the last 150 yr. The decrease in δ34S was greater in the woodland, grassland, and the arable FYM plot than in other arable plots receiving either inorganic fertilizers only or no fertilizers. The results indicate that atmospheric S was more depleted in 34S than the soil native S at the experimental site, and that atmospheric S was incorporated into the organic pool to varying degrees depending on the C pool. In conclusion, land use had a large effect on the S cycling in soils, which is driven mainly by soil organic C cycling. Without accumulating soil organic C, there appears to be little scope for S retention in temperate soils with neutral pH.
Nonpoint‐Source Pollutant Load Reductions Associated with Livestock Exclusion
Authors: Line D. E. , Harman W. A. , Jennings G. D. , Thompson E. J. , Osmond D. L. 
Published: July 2010

AbstractCattle (Bos taurus) grazing on unimproved pastures can be a significant, yet often overlooked, source of pollutants to surface waters, especially when the cattle have unlimited access to streams in the pastures. Livestock exclusion from streams has been demonstrated to reduce sediment and possibly nutrient yield from streams draining pastures. The purpose of this study was to evaluate the effects of excluding dairy cows from, and planting trees in, a 335‐m‐long and 10‐ to 16‐m‐ wide riparian corridor along a small North Carolina stream. Analysis of 81 wk of pre‐exclusion and 137 wk of post‐exclusion fencing data documented 33, 78, 76, and 82% reductions in weekly nitrate + nitrite, total Kjeldahl nitrogen (TKN), total phosphorus (TP), and sediment loads, respectively, from the 14.9‐ha pasture area adjacent to the fenced section of stream. Statistical analyses by t‐tests and analysis of variance suggested that the reductions in mean weekly loads post‐fencing were significant (P < 0.05) for all pollutants except nitrate + nitrite. Thus, the results indicated that livestock exclusion and subsequent riparian vegetation establishment was effective at reducing pollutant export from an intensively grazed pasture.
Phosphorus Availability in Soils Amended with Dewatered Water Treatment Residual and Metal Concentrations with Time in Residual
Authors: Hyde J. E. , Morris T. F. 
Published: July 2010

AbstractThe objective of this laboratory study was to measure the effect of dewatered water treatment residual (WTR) on extractable P and Al in soils with above‐optimum P concentrations. A secondary objective was to document the variability of the metal content of WTR during 1 yr. Two soils, a Paxton fine sandy loam (coarse‐loamy, mixed, active, mesic Oxyaquic Dystrudept) and an Enfield silt loam (coarse‐silty over sandy or sandy‐skeletal, mixed, active, mesic Typic Dystrudept) with above‐optimum Mehlich 3 P concentrations (833 mg kg−1 and 630 mg kg−1, respectively) were amended with four dewatered WTRs. The WTRs were dewatered using three treatments: (i) WTR dewatered at 40°C in a forced‐air oven (DRY), (ii) WTR dewatered by freezing at −4°C and then dried at 40°C in a forced‐air oven (FROZEN), and (iii) WTR dewatered to 4.5% solids at 40°C in a forced‐air oven (RAW). The WTRs were added to the soils at rates of 20 or 60 g kg−1 and incubated for 21 d. The WTRs in the RAW treatment significantly reduced Mehlich 3 P concentrations compared with the DRY and FROZEN treatments. The RAW treatment reduced soil P concentrations an average of 64% compared with a reduction of 28% for the DRY treatment and 23% for the FROZEN treatment. The results suggest that the method used to dewater WTR will alter its ability to decrease Mehlich 3 P soil concentrations. The secondary objective involved collection of two of the WTRs every 3 wk for 1 yr and subsequent analysis for metal concentrations. The metal concentrations changed little during the year and only Cu, due to its use as an algicide, was elevated.
Aluminum‐Containing Residuals Influence High‐Phosphorus Soils and Runoff Water Quality
Authors: Haustein G. K. , Daniel T. C. , Miller D. M. , Moore P. A. , McNew R. W. 
Published: July 2010

AbstractPhosphorus (P) loading in surface water can degrade water quality. Previous research has shown that soil test P levels are directly correlated to runoff P levels and that aluminum (Al) will bind P in the soil. Both water treatment residuals (WTR) and HiClay Alumina (HCA) are readily available waste materials high in Al. Water treatment residuals and HCA are by‐products of the potable water treatment and commercial alum production process, respectively. Our objective was to determine if runoff P from fields excessively high in soil test P could be decreased by land applying these materials. Water treatment residuals and HCA were surface applied at rates of 0, 2.2, 9.0, and 18 Mg ha−1 to plots high in P. We used rainfall simulation to produce runoff 1 d, 1 mo, and 4 mo following application. The P adsorption capacity for the WTR was 20 times higher than HCA because it was predominantly clay (95%) and contained three times as much Al. High rates of WTR increased the total recoverable Al concentrations in the soil, whereas HCA had no effect. High rates of both materials decreased Mehlich III soil test P levels due to the increased levels of soil Al. The two highest rates of WTR decreased runoff P levels significantly below those of the control plots for all dates, whereas the two highest rates of HCA decreased P levels for only the first two dates. Relative to the control, runoff concentrations of either total or dissolved Al were not significantly increased by WTR.
The Suitability of an Iron Oxide‐Rich Gypsum By‐Product as a Soil Amendment
Authors: Peacock Simon , Rimmer David L. 
Published: July 2010

AbstractAn industrial titanium dioxide process produces a gypsum by‐product rich in iron oxides (red gypsum). Dissolution of red gypsum when applied to soil may be affected by the presence of the oxides due to adsorption of sulfate. This may affect red gypsum's suitability as a sulfur source for crops compared with other forms of gypsum. In addition, the oxides could act as a sink for metal cations, again by adsorption. Adsorption behavior depends on the properties of the material. Characterization showed that the gypsum and iron oxide were present as discrete particles, and that these components had very large surface areas. The iron oxides were a mixture of crystalline and amorphous hydrated forms. They had a point of zero net charge (PZNC) of 6.5. The affinity of anions for adsorption on the iron oxide material was in the order: phosphate > sulfate > nitrate > chloride. Metal cation adsorption revealed an affinity order of Pb > Cu > Ni > Zn > Cd for the iron oxide material and Pb > Zn > Cd > Cu > Ni for red gypsum. In a soil column dissolution experiment, retention of SO2−4 by adsorption on the soil was not evident. Only a pelleted form of the red gypsum appeared to be effective at providing sulfate at a controlled rate. In contrast to sulfate, phosphate was strongly retained in the amended soil columns, while there was little retention of nitrate. Metal cation adsorption on the red gypsum suggested that it could be beneficial as an amendment in soils that have potentially toxic metals present.
Multiple Applications of Paper Mill Sludge in an Agricultural System: Soil Effects
Authors: Zibilske L. M. , Clapham W. M. , Rourke R. V. 
Published: July 2010

AbstractLittle information exists regarding the effects of field‐scale application of paper mill sludge on soil properties. A 5‐yr field study determined the long‐term effects of land application of paper mill sludge on an agricultural soil. The goal of this study was to determine the responses of soil chemical and physical properties to multiple applications of sludge. Five rates of sludge application were tested, ranging from 0 to 225 Mg ha−1 in multiple applications under three management protocols: applied once, applied in alternate years, or applied annually. Results indicate strong relationships between added sludge C and several soil physical properties. Increases or maintenance of soil C were observed when sludge was applied annually or biennially, but little residual effect of the single application was seen after 5 yr. Significant increases were observed in soil aggregation and moisture holding properties at higher rates of sludge application and when cumulative C additions reached 225 Mg ha−1 in other sludge application rates. It was concluded that long‐term paper mill sludge application can be managed to effect positive changes in soil physical properties that are correlated to soil quality.
Methane Oxidation at Low Temperatures in Soil Exposed to Landfill Gas
Authors: Christophersen Mette , Linderød Lisbet , Jensen Pernille Erland , Kjeldsen Peter 
Published: July 2010

AbstractSoil exposed to elevated methane concentrations can develop a high capacity for methane oxidation. Methane oxidation at high and low methane concentrations is performed by different types of methanotrops and therefore oxidation rates found at low temperatures at the atmospheric methane content cannot be extrapolated to soils exposed to high methane concentrations. Four sandy soils with different organic matter content (1–9% w/w) from two landfills in Denmark were investigated in batch experiments in the laboratory to determine the response of methane oxidation at low temperatures and different soil moisture regimes. At 2°C the methane oxidation rates were 0.005 to 0.17 µmol g−1 h−1, and calculations showed that it was possible to oxidize all the produced methane at older landfills, even during the winter. Therefore, methane oxidation in top covers of landfills is an alternative to gas recovery at smaller and older landfills in northern Europe. Equations have been developed that describe the dependency of temperature and soil moisture content for each soil. The oxidation rates depended significantly on the soils (and thereby organic matter content), temperature, and soil moisture content. Soil moisture was the most important factor. However, high Q10 values indicate that temperature also was important. The four soils tested had optimum soil moisture content between 11 and 32%. At increasing organic matter content, both the optimal soil moisture content and the maximum oxidation rate increased.
The Impact of Hydraulic Load and Aggregation on Sedimentation of Soil Particles in Small Constructed Wetlands
Authors: Braskerud B. C. , Lundekvam H. , Krogstad T. 
Published: July 2010

AbstractLoss of soil particles from arable land to streams and lakes negatively affects water quality. When initiatives to mitigate soil erosion are insufficient or fail, constructed wetlands (CWs) could be a last buffer to mitigate pollution. The objectives in this study were to (i) determine the influence of aggregation on clay sedimentation in CWs and (ii) evaluate the prediction performance of two commonly used retention models, based on hydraulic load and particle sedimentation velocity. Retention was measured three ways, with (i) water flow proportional sampling systems in the inlet and in the outlet, (ii) sedimentation traps, and (iii) sedimentation plates. Surface area of the CWs was 0.03 to 0.07% of the watershed, which consisted of silty clay loam (18–33% clay). Some runoff episodes, usually at high runoff rates, accounted for a relatively high proportion of total sedimentation. Thus 80% of the particles were retained from less than 44% of the total runoff. Constructed wetland performance increased with increased hydraulic load or decreased detention time. The clay content in the CW sediment reflected the clay content in the arable soil. Actual CW sediment exceeded model estimates 2.5 to 8.2 times, depending on CW size and runoff. The probable reason for the prediction error is clay particles entering the CWs as aggregates. Constructed wetlands should be located in small streams to avoid break up of aggregates and a reduction in retention efficiency.
Subsurface Flow Constructed Wetland Performance at a Pennsylvania Campground and Conference Center
Authors: Shannon Robert D. , Flite Oscar P. , Hunter Michael S. 
Published: July 2010

AbstractA constructed wetland treatment system consisting of subsurface flow (SSF) wetland cells, sand filters, and final effluent wetlands was found to be effective in removing carbonaceous biochemical oxygen demand (CBOD) and total suspended solids (TSS) to below 30 and 10 mg L−1, respectively. Removal efficiency of total nitrogen (TN) loads improved from 60.1 to 88.5% over the 2‐yr study, primarily due to increased vegetation densities in the SSF wetland cells. In both years, parallel wetland treatment cells had significantly different (p < 0.001) plant densities of broadleaf cattail (Typha latifolia L.) and softstem bulrush [Schoenoplectus tabernaemontani (K.C. Gmel.) Palla], with significantly more TN removed from the more densely vegetated cell. Overall, the assimilation of N by plants removed less than 25% of the TN load, regardless of plant density, indicating that the primary role of deeply rooted macrophytes is supporting sequential nitrification‐denitrification within the anaerobic wetland substrate. More than 99% of the dissolved phosphate (PO3−4‐P) was removed within the entire system in both years, but removal efficiencies within the wetland cells decreased from 91.2% the first year to 66.1% the second year, indicating that adsorption sites for PO3−4‐P may be saturated despite increased plant assimilation. Experimental manipulation of waste applied to the sand filters demonstrated that a header‐type distribution system promoting horizontal flow was more effective at nitrifying ammonium (NH+4‐N) discharged to the sand filters than the surface application of waste promoting vertical flow.
Effect of Extraction Pretreatment on Radial Variation of Nitrogen Concentration in Tree Rings
Authors: Sheppard Paul R. , Thompson Thomas L. 
Published: July 2010

AbstractPast research in the paleoenvironmental subdiscipline of dendrochemistry has concluded that N concentration variation in tree rings cannot provide information on past conditions of environmental availability of N. The objective of this study was to test wood extraction pretreatments to remove wood extractives and sap, both of which may obscure the environmental signal of N availability in tree rings. Three increment cores were collected from each of six trees (three ponderosa pines and three Douglas‐firs). Within each tree, the first core was left untreated (referred to as CONTROL), the second core was extracted for several hours in organic solvents and distilled water (referred to as EXTRACT), and the third core also was extracted but for a total time of 3 d (referred to as 3‐DAY), A semimicro Kjeldahl method was used to determine total N on decadal groups of rings. Average N concentration of EXTRACT cores was significantly less than that of CONTROL, and the coefficient of variation of EXTRACT cores also was significantly less than that of CONTROL. Most CONTROL cores showed substantial temporal variation in N concentration related to heartwood and sapwood and/or recently formed rings. In contrast, most EXTRACT cores showed no substantial change in N concentration related to heartwood and sapwood and/or recently formed rings. The 3‐DAY cores confirmed, but did not improve upon, results obtained with extraction using the shorter time duration. Thus, pretreating wood by extraction appears to substantially reduce the variation in N concentration of tree rings, which is a necessary first step toward interpreting ring N as an indicator of past environmental N availability.
Assessment of rigid overlying strata failure in face mining
Authors: Jiránková Eva 
Published: July 2010

AbstractThe method of overlying strata failure assessment of extracted seams is based upon the simultaneous assessment of surface subsidence and seismic activity, considering the spatiatemporal progress of mining, depending on the character of the rock mass. The rigid overlying strata failure assessment results in finding whether a failure of the firm overlying rocks occurred or whether a strutting arch was formed over the mined-out area. The practical importance of the overlying strata failure assessment consists in determining the size of the mined-out area at which the com-plete failure of the rigid overlying strata occurred and in the assessment of the current stress condition of the overlying strata failure. The assessment method is applicable in deep mine workings where thick coal seams are being mined by means of the method of longwall mining with controlled caving. The results of this method are used to amend contemporary known methods of rock-burst protection, namely (regarding the use of surface measurements for the evaluation) in overlying strata areas.
Geographic variation in primary sex allocation per flower within and among 12 species of Pedicularis (Orobanchaceae): Proportional male investment increases with elevation
Authors: Guo Hui , Mazer Susan J. , Du Guozhen 
Published: July 2010

• Premise of the study: The study of geographic variation in ecologically important traits within and among taxa is a first step toward understanding the environmental factors that contribute to population differentiation and species divergence. This study examines variation in mean sex allocation per flower (androecium mass/gynoecium mass) among 49 wild populations representing 12 Pedicularis species across an elevation gradient on the eastern Tibetan Plateau.• Methods: We used population means to evaluate sources of variation in per‐flower sex allocation within and across species. In particular, we evaluate the relative influence of intrinsic (i.e., plant size, estimated as aboveground stem biomass) vs. extrinsic factors affecting mean sex allocation among populations.• Key results: Mean sex allocation per flower (the relative investment in male floral organs) is negatively correlated with mean plant size; populations of large plants produce relatively female‐biased flowers. This relationship between mean plant size and mean sex allocation is not statistically significant, however, when the effect of elevation is controlled statistically. Among populations within and across species, mean sex allocation increases with elevation. This relationship persists even when the effect of mean plant size is controlled statistically. Factors associated with increasing elevation appear to favor genotypes and/or taxa with male‐biased flowers.• Conclusion: Extrinsic environmental conditions may be more important than intrinsic resource status in determining patterns of geographic variation in mean sex allocation among populations or species of Pedicularis. We cannot conclude whether the effect of elevation on mean sex allocation is the result of environmentally induced plasticity, genetically based adaptation, or species sorting, but it is only partly mediated by mean plant size.