bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Monitoring of Sewage Sludge in Pennsylvania: Variability and Application Uncertainty
Authors: Stehouwer Richard C. , Wolf Ann M. , Doty Willie T.
Published: July 2010

Application of sewage sludge to farmland in Pennsylvania (PA) is regulated by crop N needs and the cumulative loading of eight trace elements. A survey of 7746 sewage sludges produced at 177 publicly owned (wastewater) treatment works (POTWs) in PA from 1978 to 1997 was conducted to determine what changes have occurred in nutrient and trace element concentrations, how currently produced sewage sludges compare with regulatory trace element standards, inter‐ and intra‐POTW variability in sewage sludge constituents, and uncertainty estimates for application of nutrients and trace elements. Concentration medians and ranges of nutrients changed very little during the 20‐yr period, whereas there were large decreases in Cd, Cr, Cu, Pb, Hg, Ni, and Zn. Rates of decrease for concentrations of these elements and As, Se, and Mo were smaller or not different from zero in the last 5 yr of the survey. Assessment of sewage sludge constituents among a subset of 12 POTWs showed larger inter‐ than intra‐POTW variability. Sewage sludge N content uncertainty showed that the maximum error in determination of plant available N ranged from 0.39 to 1.09 of the intended amount. This uncertainty could be reduced by increased frequency of N analysis prior to sewage sludge application. Application uncertainty for trace elements was large relative to the amount of trace elements added to the soil in a single application, but very small relative to the cumulative loading limit (generally <0.01). Further decreases in trace element variability or increased frequency of analysis would not be expected to decrease error in trace element cumulative loading calculations.
Dissolved Organic Carbon and Methane Emissions from a Rice Paddy Fertilized with Ammonium and Nitrate
Authors: Lu Yahai , Wassmann Reiner , Neue Heinz‐Ulrich , Huang Changyong
Published: July 2010

The effect of nitrogen fertilizers on methane (CH4) production and emission in wetland rice (Oryza sativa L.) is not clearly understood. Greenhouse pot and laboratory incubation were conducted to determine whether the effect of N type (NH4‐N and NO3‐N) and rate (30 and 120 kg N ha−1) was related to the availability of carbon for CH4 production in flooded rice soils. In addition to CH4 emission rates, seasonal patterns of dissolved organic carbon (DOC) and dissolved CH4 were determined in soil solutions of the root zone (soil surrounding rice roots) and the non‐root zone (soil outside the root zone). Dissolved organic C in the root zone increased with plant growth and reached a maximum (16 to 21 mmol C L−1) at 1 wk after flowering, whereas DOC in the non‐root zone remained relatively low (1 to 5 mmol C L−1). The increase of dissolved CH4 concentrations was quicker and greater in the root zone (111 to 170 mol L−1) as compared with the non‐root zone (54 to 117 mol L−1). Methane emission increased from 0 to 1.0 mmol CH4 plant−1 d−1. From panicle initiation (PI) to maturation, the root zone DOC concentration was lower with NO3‐N application (8 to 13 mmol C L−1) than with NH4‐N (13 to 21 mmol CL−1). Similarly, NO3‐N application reduced dissolved CH4 concentration as well as CH4 emission. Anaerobic incubation showed that the inhibitory effect of NO3‐N addition on CH4 production lasted only 2 wk. Thus, the inhibitory effect of NO3‐N seemed not fully accountable for the prolonged reduction in CH4 production and emission in the fields. The root zone DOC that is enriched by plant‐borne C appears to be a main source for CH4 production and the lower DOC concentrations with NO3‐N application are accountable for the low CH4 emissions.
Mechanistic Modeling of Nitrite Accumulation and Nitrogen Oxide Gas Emissions during Nitrification
Authors: Venterea R. T. , Rolston D. E.
Published: July 2010

Nitrite (NO−2) accumulation in soil following nitrogen (N) fertilizer application has been observed under a variety of conditions. The presence of NO−2 together with soil acidity results in the formation of nitrous acid (HNO2), which decomposes abiotically to produce nitric oxide (NO) and nitrous oxide (N2O). These N oxide trace gases have potential effects on several atmospheric processes. Presented here is a model that describes some of the interactions between microbial, chemical, and physical processes that influence NO−2 accumulation and N oxide gas emissions following applications of NH+4‐based fertilizers. The model is applied to hypothetical and actual field scenarios. A two‐step, two‐population nitrification submodel is linked to gas production and transformation submodels. Transport of all chemical species occurs by diffusion. The model results suggest that some degree of transient nitrite accumulation following NH+4 application is a consequence of the nature of nitrification itself. Model simulations and sensitivity analysis indicate that (i) soils receiving similar fertilizer treatments but differing in their ability to buffer nitrification‐induced acidity may produce dramatically different N oxide gas emissions, (ii) subsurface fertilizer placement can significantly reduce net NO emissions, and (iii) the differential responses of Nitrosomonas and Nitrobacter populations to chemical toxicities associated with the form and/or rate of fertilizer application may significantly affect the extent of NO−2 accumulation and corresponding gas emissions. Overall, the results contribute to our basic understanding of how multiple microbial, chemical, and physical factors can interact to control the net soil‐to‐atmosphere emission of nitrification‐derived NO and N2O.
Native Plant Restoration of Copper Mine Tailings: II. Field Survival, Growth, and Nutrient Uptake
Authors: Kramer P. A. , Zabowski D. , Scherer G. , Everett R. L.
Published: July 2010

Copper mine tailings are difficult to revegetate due to nutrient deficiencies, high acidity, and metal toxicities. Despite these poor substrate properties, native species may be preferred for restoration for ecological and economic reasons, as they may require less long‐term maintenance. In this study, amended and unamended mine tailings are contrasted with a natural soil and gravel for factors potentially limiting to growth. Twelve individuals of five native species (big‐leaf maple, western yarrow, Sitka alder, pearly everlasting, and fireweed) were grown in five different field plots. Plots consisted of: (i) copper mine tailings, (ii) natural soil, (iii) 15 cm of gravel over tailings, (iv) biosolids plus wood chips with 15 cm gravel over tailings, and (v) gravel. Survival was highly variable by species and plot type, with highest survival among all species with pearly everlasting, and highest survival by treatment with the natural soil and biosolids plus wood chips with gravel over tailings. Treatments resulted in a significant difference (p = 0.05) in species biomass production, with the biosolids resulting in highest biomass in all species except big‐leaf maple. Plant nutrient content was also higher with the biosolids. The tailings were extremely acidic and had high exchangeable AI. Sitka alder was most tolerant of the tailings, despite high AI uptake, and was productive across all plot types, possibly due to its tolerance of metals and high nutrient use efficiency. Both Sitka alder and pearly everlasting show promise for revegetating copper mine tailings, although with a biosolids and gravel amendment other native species may do equally well.
Revisiting the Fresno DBCP Case Study Simulations: The Effect of Upscaling
Authors: Soutter Leigh A. , Loague Keith
Published: July 2010

The 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

There 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

The 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

Cattle (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

The 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

Phosphorus (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

An 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

Little 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

Soil 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

Loss 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

A 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

Past 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.
Laboratory System for Dust Generation from Soils
Authors: Domingo Rebecca A. , Southard Randal J. , Lee Kiyoung
Published: July 2010

Farm workers and residential communities adjacent to agricultural fields can be exposed to soil dust generated during field operations at levels that could result in respiratory problems. However, field sampling of agricultural dust faces logistical problems from spatial and temporal differences in soil properties, field operations, and meteorological conditions. To minimize these problems, we designed a dust generator that simulates dust generation during tilling of agricultural fields to provide samples of particulate matter derived from bulk soil and developed optimal operating conditions to assure reproducible results. The dust generator consisted of a rotating chamber, where soil samples were loaded and tumbled, and a settling chamber, where airborne soil dust samples were collected using particle size–selective samplers. The following operating conditions for dust generation were evaluated: initial soil mass, air intake, rotation speed, and sampling time to optimize dust sampling. We compared the laboratory‐generated dust from soil samples with field dust that we collected from the same plots during agricultural operations. We determined from X‐ray diffraction and energy‐dispersive X‐ray analyses that the mineralogy and chemical composition of field‐ and laboratory‐generated dust were similar, indicating that the apparatus reasonably simulated field mechanical processes that produce airborne particulate matter from soils. The results suggest that the laboratory dust generator provides reliable samples of soil‐derived dust and could be useful for future studies involving airborne particulate material from soils.
Transformation of Triclosan and Triclocarban in Soils and Biosolids‐applied Soils
Authors: Kwon Jeong‐Wook , Armbrust Kevin L. , Xia Kang
Published: July 2010

Triclosan (TCS) and triclocarban (TCC), widely used as antibacterial agents, have been frequently detected in biosolids. Biosolids land application may introduce pharmaceuticals and personal care products (PPCPs) such as TCS and TCC into the environment. Microcosm studies were conducted to investigate TCS and TCC transformation in Marietta fine loam and McLaurin coarse loam. Both compounds were spiked into the soils with and without biosolids amendment under non‐sterilized and sterilized conditions and incubated aerobically at 30°C for up to 100 d. In both soils, transformation of TCS followed second‐order reaction kinetics, with estimated reaction rate constants of (5.27 ± 0.920) × 10−1and (9.13 ± 1.58) × 10−2(mg kg−1)−1d−1for Marietta fine loam and McLaurin coarse loam, respectively. Transformation of TCC in both soils was slower than that for TCS. After 100 d, 53 ± 1% and 71 ± 2% of the initially added TCC and only 2.8 ± 0.35% and 6.2 ± 0.80% of initially added TCS remained in Marietta fine loam and McLaurin coarse loam, respectively. The transformation of both compounds were faster in the Marietta fine loam (pH 7.8; 1.8% organic matter) than in the McLaurin coarse loam (pH 4.7; 0.65% organic matter). Our result suggests that biotic processes are more of a controlling factor affecting TCS transformation, whereas abiotic processes may affect TCC transformation more significantly. Addition of biosolids to the two soils slowed the transformation of both compounds, indicating interactions between both compounds and biosolids may adversely affect their transformation in soils, an important factor that must be included in models predicting environmental fate of biosolids‐associated PPCPs.
Impact of Drought on Wastewater Contaminants in an Urban Water Supply
Authors: Benotti Mark J. , Stanford Benjamin D. , Snyder Shane A.
Published: July 2010

The concentrations of selected wastewater contaminants, including conductivity, nitrate, and pharmaceuticals and endocrine disrupting compounds (EDCs), were monitored from 2003 to 2007 in Lake Mead, the raw (untreated) drinking water for southern Nevada. Monitoring was also conducted in two inflows to Lake Mead: the Colorado River and the wastewater‐dominated Las Vegas Wash. There was a statistically significant increase in source water conductivity, nitrate, and pharmaceutical and EDC concentrations over this time period, concomitant with a statistically significant decline in the volume of Lake Mead. There was no statistically significant increase in conductivity and nitrate in the Colorado River or the Las Vegas Wash over this period, nor was there an increase in flow of the Las Vegas Wash or Colorado River. Thus, the deterioration of source drinking water quality is due to the decrease in the volume of Lake Mead which has been attributed to drought. This phenomenon may also be a harbinger of how water quality may be adversely affected by climate change as patterns of surface water flow shift and treated wastewater becomes a larger fraction of surface water flow in some areas.
Transport of Pharmaceuticals in Columns of a Wastewater‐Irrigated Mexican Clay Soil
Authors: Siemens Jan , Huschek Gerd , Walshe Gillian , Siebe Christina , Kasteel Roy , Wulf Sebastian , Clemens Joachim , Kaupenjohann Martin
Published: July 2010

The irrigation of agricultural land with wastewater is increasingly practiced in many parts of the world as a consequence of growing populations and urbanization. The risks emerging from pharmaceuticals that are contained in wastewater for soils and groundwater have hardly been investigated. We studied leaching and effects of naproxen, ibuprofen, bezafibrate, diclofenac, gemfibrocil, clarithromycin, trimethoprim, clindamycin, erythromycin, and metoprolol in a soil column experiment simulating an irrigation event with 8.6 cm of wastewater containing 20 μg L−1 or 2000 μg L−1 of each compound or of erythromycin alone. The leached fraction of applied pharmaceuticals ranged from 0.1 ± 0.1% (clarithromycin, 2000 μg L−1) to 130 ± 41% (naproxen, 20 μg L−1) and tended to increase with decreasing Kd or Koc Naproxen transport was similar to that of the tracer chloride. Ibuprofen was also hardly retarded (R = 1.20 ± 0.18), but showed a higher degradation rate of 0.02 ± 0.004 h−1 (2000 μg L−1) than naproxen. The transport of a pulse of 2000 μg L−1 of bezafibrate could be described with a retardation factor of 1.5 and a degradation rate of 0.033 h−1 The application of erythromycin alone or of a cocktail of all pharmaceuticals significantly increased soil CO2 emissions by 50% 1 d after the application. There is a considerable risk that pharmaceuticals are leached to groundwater during wastewater irrigation.
Transport of the Pathogenic Prion Protein through Soils
Authors: Jacobson Kurt H. , Lee Seunghak , Somerville Robert A. , McKenzie Debbie , Benson Craig H. , Pedersen Joel A.
Published: July 2010

Transmissible spongiform encephalopathies (TSEs) are progressive neurodegenerative diseases and include bovine spongiform encephalopathy of cattle, chronic wasting disease (CWD) of deer and elk, scrapie in sheep and goats, and Creutzfeldt‐Jakob disease in humans. An abnormally folded form of the prion protein (designated PrPTSE) is typically associated with TSE infectivity and may constitute the major, if not sole, component of the infectious agent. Transmission of CWD and scrapie is mediated in part by an environmental reservoir of infectivity. Soil appears to be a plausible candidate for this reservoir. The transport of TSE agent through soil is expected to influence the accessibility of the pathogen to animals after deposition and must be understood to assess the risks associated with burial of infected carcasses. We report the results of saturated column experiments designed to evaluate PrPTSE transport through five soils with relatively high sand or silt contents and low organic carbon content. Protease‐treated TSE‐infected brain homogenate was used as a model for PrPTSE present in decomposing infected tissue. Synthetic rainwater was used as the eluent. All five soils retained PrPTSE; no detectable PrPTSE was eluted over more than 40 pore volumes of flow. Lower bound apparent attachment coefficients were estimated for each soil. Our results suggest that TSE agent released from decomposing tissues to soils with low organic carbon content would remain near the site of initial deposition. In the case of infected carcasses deposited on the land surface, this may result in local sources of infectivity to other animals.
Influence of Biochars on Nitrous Oxide Emission and Nitrogen Leaching from Two Contrasting Soils
Authors: Singh Bhupinder Pal , Hatton Blake J. , Singh Balwant , Cowie Annette L. , Kathuria Amrit
Published: July 2010

The influence of biochar on nitrogen (N) transformation processes in soil is not fully understood. This study assessed the influence of four biochars (wood and poultry manure biochars synthesized at 400°C, nonactivated, and at 550°C, activated, abbreviated as: W400, PM400, W550, PM550, respectively) on nitrous oxide (N2O) emission and N leaching from an Alfisol and a Vertisol. Repacked soil columns were subjected to three wetting–drying (W–D) cycles to achieve a range of water‐filled pore space (WFPS) over a 5‐mo period. During the first two W–D cycles, W400 and W550 had inconsistent effects on N2O emissions and the soils amended with PM400 produced higher N2O emissions relative to the control. The initially greater N2O emission from the PM400 soils was ascribed to its higher labile intrinsic N content than the other biochars. During the third W–D cycle, all biochar treatments consistently decreased N2O emissions, cumulatively by 14 to 73% from the Alfisol and by 23 to 52% from the Vertisol, relative to their controls. In the first leaching event, higher nitrate leaching occurred from the PM400‐amended soils compared with the other treatments. In the second event, the leaching of ammonium was reduced by 55 to 93% from the W550‐ and PM550‐Alfisol and Vertisol, and by 87 to 94% from the W400‐ and PM400‐Vertisol only (cf. control). We propose that the increased effectiveness of biochars in reducing N2O emissions and ammonium leaching over time was due to increased sorption capacity of biochars through oxidative reactions on the biochar surfaces with ageing.
NASA‐Modified Precipitation Products to Improve USEPA Nonpoint Source Water Quality Modeling for the Chesapeake Bay
Authors: Joseph Nigro , David Toll , Ed Partington , Ni‐Meister Wenge , Shihyan Lee , Angelica Gutierrez‐Magness , Ted Engman , Kristi Arsenault
Published: July 2010

The USEPA has estimated that over 20,000 water bodies within the United States do not meet water quality standards. One of the regulations in the Clean Water Act of 1972 requires states to monitor the total maximum daily load, or the amount of pollution that can be carried by a water body before it is determined to be “polluted,” for any watershed in the United States (Copeland, 2005). In response to this mandate, the USEPA developed Better Assessment Science Integrating Nonpoint Sources (BASINS) as a decision support tool for assessing pollution and to guide the decision‐making process for improving water quality. One of the models in BASINS, the Hydrological Simulation Program–Fortran (HSPF), computes continuous streamflow rates and pollutant concentration at each basin outlet. By design, precipitation and other meteorological data from weather stations serve as standard model input. In practice, these stations may be unable to capture the spatial heterogeneity of precipitation events, especially if they are few and far between. An attempt was made to resolve this issue by substituting station data with NASA‐modified/NOAA precipitation data. Using these data within HSPF, streamflow was calculated for seven watersheds in the Chesapeake Bay Basin during low flow periods, convective storm periods, and annual flows. In almost every case, the modeling performance of HSPF increased when using the NASA‐modified precipitation data, resulting in better streamflow statistics and, potentially, in improved water quality assessment.
Pyrolysis–Gas Chromatography/Mass Spectrometry Identification of Distinctive Structures Providing Humic Character to Organic Materials
Authors: Fuentes Marta , Baigorri Roberto , González‐Vila Francisco J. , González‐Gaitano Gustavo , García‐Mina José M.
Published: July 2010

Flash pyrolysis–gas chromatography/mass spectrometry (Py‐GC/MS) was used to study the structural transformations of humic fractions formed as a result of composting processes of diverse organic materials (solid wastes of wineries, solid olive‐mill wastes, domestic wastes, ovine manures plus straw, and mixtures of animal manures). Sodium hydroxide–extracted total humic‐like extracts (THE; humic plus fulvic acids) from the composted and the initial noncomposted wastes and several reference humic and fulvic acids from soils were analyzed. These results were compared with results from previous studies using 13C‐cross polarization magic angle spinning–nuclear magnetic resonance (NMR), UV‐visible, and fluorescence emission spectroscopies. Alkylbenzenes and alkylphenols predominate in the pyrograms of the soil humic acids, whereas the fulvic acids showed higher contents of phenolic and polysaccharide‐derived compounds. The pyrolysates of THE from the composted samples showed an increase in aromatic and nitrogenated structures and a decrease in polysaccharide‐derived compounds. The aromatic contents as determined by Py‐GC/MS and 13C‐NMR were well correlated in the reference humic substances and THE from composted materials (r = 0.99 and 0.94, respectively; P < 0.01) but not in the case of THE from noncomposted materials, probably due to an aliphatic enhancement in the pyrolysates of these samples and other secondary reactions. The content in alkylbenzenes was consistent with the variations found previously for several UV‐visible and fluorescence indexes as a function of the degree of humification, suggesting their involvement in structures that are a characteristic feature of the formation and evolution of humic substances.
Occurrence of Herbicides and Pharmaceutical and Personal Care Products in Surface Water and Groundwater around Liberty Bay, Puget Sound, Washington
Authors: Dougherty Jennifer A. , Swarzenski Peter W. , Dinicola Richard S. , Reinhard Martin
Published: July 2010

Organic contaminants, such as pharmaceuticals and personal care products (PPCPs), pose a risk to water quality and the health of ecosystems. This study was designed to determine if a coastal community lacking point sources, such as waste water treatment plant effluent, could release PPCPs, herbicides, and plasticizers at detectable levels to their surface water and groundwater. Research was conducted in Liberty Bay, an embayment within Puget Sound, where 70% of the population (∼10,000) uses septic systems. Sampling included collection of groundwater and surface water with grab samples and the use of polar organic chemical integrative samplers (POCIS). We analyzed for a broad spectrum of 25 commonly used compounds, including PPCPs, herbicides, and a flame retardant. Twelve contaminants were detected at least once; only N,N‐diethyl‐meta‐toluamide, caffeine, and mecoprop, a herbicide not attributed to septic systems, were detected in more than one grab sample. The use of POCIS was essential because contaminants were present at very low levels (nanograms), which is common for PPCPs in general, but particularly so in such a small community. The use of POCIS allowed the detection of five compounds that were not present in grab samples. Data suggest that the community is contaminating local water with PPCPs; this effect is likely to increase as the population and product usage increase. The results presented here are a first step toward assessing the transport of herbicides and PPCPs into this coastal system.
Enhanced Degradation and Soil Depth Effects on the Fate of Atrazine and Major Metabolites in Colorado and Mississippi Soils
Authors: Krutz L. Jason , Shaner Dale L. , Zablotowicz Robert M.
Published: July 2010

The aim of this report is to inform modelers of the differences in atrazine fate betweens‐triazine–adapted and nonadapted soils as a function of depth in the profile and to recommend atrazine and metabolite input values for pesticide process submodules. The objectives of this study were to estimate the atrazine‐mineralizing bacterial population, cumulative atrazine mineralization, atrazine persistence, and metabolite (desethylatrazine [DEA], deisopropylatrazine [DIA], and hydroxyatrazine [HA]) formation and degradation in Colorado and Mississippis‐triazine–adapted and nonadapted soils at three depths (0–5, 5–15, and 15–30 cm). Regardless of depth, the AMBP and cumulative atrazine mineralization was at least 3.8‐fold higher ins‐triazine–adapted than in nonadapted soils. Atrazine half‐life (T1/2) values pooled over nonadapted soils and depths approximated historic estimates (T1/2= 60 d). Atrazine persistence in all depths ofs‐triazine–adapted soils was at least fourfold lower than that of the nonadapted soil. Atrazine metabolite concentrations were lower ins‐triazine–adapted than in nonadapted soil by 35 d after incubation regardless of depth. Results indicate that (i) reasonable fate and transport modeling of atrazine will require identifying if soils are adapted tos‐triazine herbicides. For example, our data confirm the 60‐d T1/2for atrazine in nonadapted soils, but a default input value of 6 d for atrazine is required fors‐triazine adapted soils. (ii) Literature estimates for DEA, DIA, and HA T1/2values in nonadapted soils are 52, 36, and 60 d, respectively, whereas our analysis indicates that reasonable T1/2values fors‐triazine–adapted soils are 10 d for DEA, 8 d for DIA, and 6 d for HA. (iii) An estimate for the relative distribution of DIA, DEA, and HA produced in nonadapted soils is 18, 72, and 10% of parent, respectively. Ins‐triazine–adapted soils, the values were 6, 23, and 71% for DIA, DEA, and HA, respectively. The effects of soil adaptation on metabolite distribution need to be confirmed in field experiments.
Release of Metals from Metal‐Amended Soil Treated with a Sulfosuccinamate Surfactant: Effects of Surfactant Concentration, Soil/Solution Ratio, and pH
Authors: Hernández‐Soriano Maria del Carmen , Peña Aránzazu , Mingorance Ma Dolores
Published: July 2010

Anionic surfactants, mainly sulfosuccinamates, can be found in soils as the result of sludge application, wastewater irrigation, and remediation processes. Relatively high concentrations of surfactants together with multimetals can represent an environmental risk. A study was performed to assess the potential of the anionic surfactant Aerosol 22 (A22) for release of Cd, Cu, Pb, and Zn from a metal‐amended soil representative of a Mediterranean area. Metal desorption was performed by batch experiments and release kinetics were assessed. Response surface methodology was applied to determine the influence of A22 concentration and the surfactant/soil ratio, as extraction key factors. An increase in solution/soil ratio to 100 (mL g−1) caused higher metal release. Leaching predictions found Pb to have the lowest and Cd the highest hazard. Metal release was highly dependent on pH. When extraction was made at pH less than 7, low or negligible amounts of metals were leached, whereas an increase to pH 7 caused desorption rates of 50 to 55% for Cd, Cu, and Zn but only 35% for Pb. Complexed metal‐carboxylic groups from A22 were mainly responsible for its higher extractive capacity, especially of Cd and Cu.