bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing Bioavailability of Phosphorus from Fly Ash through Vermicomposting
Authors: Bhattacharya S. S. , Chattopadhyay G. N.
Published: June 2010

Due to the environmental problems created by large‐scale fly ash generation throughout the world, efforts are being made to recycle these materials. An important component of the recycling effort is using fly ash to improve low‐fertility soils. Because availability of many nutrients is very low in fly ash, available ranges of such nutrients must be improved to increase the effectiveness of fly ash as a soil amendment. In the present study, we assessed the possibility of increasing P bioavailability in fly ash through vermicomposting in a yard experiment. Fly ash was mixed with organic matter in the form of cow (Bos taurus) dung at 1:3, 1:1, and 3:1 ratios and incubated with and without epigeic earthworm (Eisenia fetida) for 50 d. The concentration of phosphate‐solubilizing bacteria (PSB) was found to increase many fold in the earthworm‐treated series of fly ash and organic matter combinations compared with the series without earthworm. This helped to transform considerable amounts of insoluble P from fly ash into more soluble forms and thus resulted in increased bioavailability of the nutrients in the vermicomposted series. Among different combinations of fly ash and organic matter, P availability in fly ash due to vermicomposting was significantly higher in the 1:1 fly ash to cow dung treatment compared with the other treatments.
Testing Soils and Cornstalks to Evaluate Nitrogen Management on the Watershed Scale
Authors: Balkcom Kipling S. , Blackmer Alfred M. , Hansen David J. , Morris Thomas F. , Mallarino Antonio P.
Published: June 2010

High nitrate (NO3–N) concentrations in Iowa rivers have been linked to areas of intensive row crop production, but they have not been experimentally linked to specific management practices used during row crop production. This study demonstrates how the late‐spring test for soil NO3–N and the end‐of‐season test for cornstalk NO3–N can be used to measure N sufficiency levels across many fields and how the results can be used to evaluate management practices within a watershed. More than 3200 soil and cornstalk samples were collected over a 12‐yr period from fields planted to corn (Zea maysL.) and already fertilized by farmers using their normal practices. Results showed that early‐season rainfall and associated N losses were major factors affecting N concentrations in soils and cornstalks. Evidence for NO3–N movement from fields to rivers was provided by an inverse relationship between annual means for NO3–N concentrations in soils and rivers. Because these losses can be avoided by delaying N applications, the practice of applying N several weeks or months before plants grow was linked to inefficient use of fertilizer and manure N by crops. Results of the study demonstrate how aggregate analyses of soil and cornstalk samples collected across many farms and years make it possible to identify the major factors affecting N management outcomes and, therefore, N management practices that are likely to produce the best outcomes within a watershed or region. This approach seems to have unique potential to interrelate the management practices of farmers, the efficiency of N fertilization, and NO3–N concentrations in rivers.
Herbicides and Herbicide Degradation Products in Upper Midwest Agricultural Streams during August Base‐Flow Conditions
Authors: Kalkhoff Stephen J. , Lee Kathy E. , Porter Stephen D. , Terrio Paul J. , Thurman E. Michael
Published: June 2010

Herbicide concentrations in streams of the U.S. Midwest have been shown to decrease through the growing season due to a variety of chemical and physical factors. The occurrence of herbicide degradation products at the end of the growing season is not well known. This study was conducted to document the occurrence of commonly used herbicides and their degradation products in Illinois, Iowa, and Minnesota streams during base‐flow conditions in August 1997. Atrazine, the most frequently detected herbicide (94%), was present at relatively low concentrations (median 0.17 μg L−1). Metolachlor was detected in 59% and cyanazine in 37% of the samples. Seven of nine compounds detected in more than 50% of the samples were degradation products. The total concentration of the degradation products (median of 4.4 μg L−1) was significantly greater than the total concentration of parent compounds (median of 0.26 μg L−1). Atrazine compounds were present less frequently and in significantly smaller concentrations in streams draining watersheds with soils developed on less permeable tills than in watersheds with soils developed on more permeable loess. The detection and concentration of triazine compounds was negatively correlated with antecedent rainfall (April–July). In contrast, acetanalide compounds were positively correlated with antecedant rainfall in late spring and early summer that may transport the acetanalide degradates into ground water and subsequently into nearby streams. The distribution of atrazine degradation products suggests regional differences in atrazine degradation processes.
Macroinvertebrate Biomonitoring in Intermittent Coastal Plain Streams Impacted by Animal Agriculture
Authors: Davis Stephanie , Golladay Stephen W. , Vellidis George , Pringle Catherine M.
Published: June 2010

Little attention has been given to the ecology of intermittent coastal plain streams in the southeastern United States, and it is not known whether available macroinvertebrate biomonitoring methods reliably detect degradation in these streams. This study compared differences in biomonitoring metrics between reference and agricultural streams, and between the flow period (January–April) and the intermittent flow period (May–December). Percentages of crustaceans, isopods, and Ephemeroptera–Plecoptera–Trichoptera (EPT) were significantly higher at the reference site than the two most impacted sites during the flow period, probably resulting from the abundance of leaf litter and lower temperatures. During this same period, the agriculturally impacted sites had a significantly higher percentage of dipterans—a group that thrives in the silty, nutrient‐rich waters. Four metrics (percent Crustacea, Isopoda, Diptera, and EPT) had no overlap between values for the most impacted and the least impacted sites during the flow period, but no metrics were able to detect more discrete differences among sites. Sites were physically and biologically similar during the intermittent period when natural stresses (i.e., stagnant water, high temperatures, low dissolved oxygen) were high, with many metrics, such as percentages of dominant family, burrowers, chironomids, and dipterans becoming similar at all sites. Our findings indicate that development of a better understanding of invertebrate fauna in reference conditions and of the natural variation in intermittent streams is necessary to develop effective biomonitoring programs for these systems.
Phosphorus Sorption and Availability in Soils Amended with Animal Manures and Sewage Sludge
Authors: Siddique Muhammad Tariq , Robinson J. Stephen
Published: June 2010

Soils that receive large applications of animal wastes and sewage sludge are vulnerable to releasing environmentally significant concentrations of dissolved P available to subsurface flow owing to the gradual saturation of the soil's P sorption capacity. This study evaluated P sorption (calculated from Langmuir isotherms) and availability of P (as CaCl2–P and resin P) in soils incubated for 20 d with poultry litter, poultry manure, cattle slurry, municipal sewage sludge, or KH2PO4, added on a P‐equivalent basis (100 mg P kg−1). All the P sources had a marked negative effect on P sorption and a positive effect on P availability in all soils. In the cattle slurry– and KH2PO4–treated soils, the decreases in P sorption maximum (19–66%) and binding energy (25–89%) were consistently larger than the corresponding decreases (7–41% and 11–30%) in poultry litter–, poultry manure–, and sewage sludge–treated soils. The effects of cattle slurry and KH2PO4on P availability were, in most cases, larger than those of the other P sources. In the poultry litter, poultry manure, and sewage sludge treatments, the increase in soil solution P was inversely related (R2= 0.75) to the input of Ca from these relatively high Ca (13.5–42 g kg−1) sources. Correlation analyses implied that the magnitude of the changes in P sorption and availability was not related to the water‐extractable P content of the P sources. Future research on the sustainable application of organic wastes to agricultural soils needs to consider the non‐P‐ as well as P‐containing components of the waste.
Sediment Retention in Rangeland Riparian Buffers
Authors: Hook Paul B.
Published: June 2010

Controlling nonpoint‐source sediment pollution is a common goal of riparian management, but there is little quantitative information about factors affecting performance of rangeland riparian buffers. This study evaluated the influence of vegetation characteristics, buffer width, slope, and stubble height on sediment retention in a Montana foothills meadow. Three vegetation types (sedge wetland, rush transition, bunchgrass upland) were compared using twenty‐six 6‐ × 2‐m plots spanning 2 to 20% slopes. Plots were clipped moderately (10–15 cm stubble) or severely (2–5 cm stubble). Sediment (silt + fine sand) was added to simulated overland runoff 6, 2, or 1 m above the bottom of each plot. Runoff was sampled at 15‐s to >5‐min intervals until sediment concentrations approached background levels. Sediment retention was affected strongly by buffer width and moderately by vegetation type and slope, but was not affected by stubble height. Mean sediment retention ranged from 63 to >99% for different combinations of buffer width and vegetation type, with 94 to 99% retention in 6‐m‐wide buffers regardless of vegetation type or slope. Results suggest that rangeland riparian buffers should be at least 6 m wide, with dense vegetation, to be effective and reliable. Narrower widths, steep slopes, and sparse vegetation increase risk of sediment delivery to streams. Vegetation characteristics such as biomass, cover, or density are more appropriate than stubble height for judging capacity to remove sediment from overland runoff, though stubble height may indirectly indicate livestock impacts that can affect buffer performance.
Estimating Turf Pesticide Volatilization from Simple Evapotranspiration Models
Authors: Walden Rebecca R. , Haith Douglas A.
Published: June 2010

A previously developed model by Haith et al. (2002) related pesticide volatilization from turf to evapotranspiration (ET) by scaling factors determined from vapor pressures and heats of vaporization. Although the model provided volatilization estimates that compared well with field measurements, it relied on the Penman ET equation, requiring hourly temperature, wind speed, and solar radiation data, none of which are routinely available at field sites. The current study determined that the volatilization model works equally well with a simpler ET equation requiring only daily temperatures. Three daily temperature‐based ET models were evaluated as vehicles for estimating pesticide volatilization from turf: Hamon, Hargreaves–Samani, and a modified Priestley–Taylor. When compared with field volatilization measurements for eight pesticides, volatilization estimates produced from the Hargreaves–Samani model most closely approximated both the field observations and the previous estimates based on the more data‐intensive Penman model. Mean estimated volatilization exceeded mean observations by 15% and the coefficient of variation (R2) between estimates and observations was 0.65. The comparable values based on Penman ET were 17% and 0.63, respectively.
Gaseous Nitrogen Emissions and Mineral Nitrogen Transformations as Affected by Reclaimed Effluent Application
Authors: Master Y. , Laughlin R. J. , Shavit U. , Stevens R. J. , Shaviv A.
Published: June 2010

Irrigation with reclaimed effluent (RE) is essential in arid and semiarid regions. Reclaimed effluent has the potential to stimulate gaseous N losses and affect other soil N processes. No direct measurements of the N2 and N2O emissions from Mediterranean soils have been conducted so far. We used the 15N gas flux method in a field and a laboratory experiment to study the effect of RE irrigation on gaseous N losses and other N transformations in a Grumosol (Chromoxerert) soil. The fluxes of N2, N2O, and NH3 were measured from six Grumosol lysimeters following application of either fresh water or RE. The N fertilizer was applied either as 15NH4 or 15NO3 Only up to 0.3% from the applied N fertilizer was lost as N2O + NH3 Reclaimed effluent enhanced the losses of NH3, but did not affect those of N2O. Nitrification and denitrification were equally important to N2O production. Laboratory incubations were performed to both confirm the influence of the irrigation water type and to test the effect of moisture content. Significant quantities of N2 and N2O (up to 3.1% of the applied fertilizer) were emitted from saturated soils. Reclaimed effluent application did not induce higher N2O emissions, yet significantly more (approximately 33%) N2 was emitted from RE‐irrigated soils. Denitrification contributed up to 75% of the N2O amounts emitted from saturated soils. Reclaimed effluent application inhibited nitrification in the Grumosol by 15 to 25% and induced NO2 accumulation in soils incubated at a field‐capacity moisture content.
pH, Dissolved Oxygen, and Adsorption Effects on Metal Removal in Anaerobic Bioreactors
Authors: Willow Mark A. , Cohen Ronald R. H.
Published: June 2010

Anaerobic bioreactors were used to test the effect of the pH of influent on the removal efficiency of heavy metals from acid‐rock drainage. Two studies used a near‐neutral‐pH, metal‐laden influent to examine the heavy metal removal efficiency and hydraulic residence time requirements of the reactors. Another study used the more typical low‐pH mine drainage influent. Experiments also were done to (i) test the effects of oxygen content of feed water on metal removal and (ii) the adsorptive capacity of the reactor organic substrate. Analysis of the results indicates that bacterial sulfate reduction may be a zero‐order kinetic reaction relative to sulfate concentrations used in the experiments, and may be the factor that controls the metal mass removal efficiency in the anaerobic treatment systems. The sorptive capacities of the organic substrate used in the experiments had not been exhausted during the experiments as indicated by the loading rates of removal of metals exceeding the mass production rates of sulfide. Microbial sulfate reduction was less in the reactors receiving low‐pH influent during experiments with short residence times. Sulfate‐reducing bacteria may have been inhibited by high flows of low‐pH water. Dissolved oxygen content of the feed waters had little effect on sulfate reduction and metal removal capacity.
Effect of Nutrient Amendments on Indigenous Hydrocarbon Biodegradation in Oil‐Contaminated Beach Sediments
Authors: Xu Ran , Obbard Jeffrey P.
Published: June 2010

Nutrient amendment to oil‐contaminated beach sediments is a critical factor for the enhancement of indigenous microbial activity and biodegradation of petroleum hydrocarbons in the intertidal marine environment. In this study, we investigated the stimulatory effect of the slow‐release fertilizers Osmocote (Os; Scotts, Marysville, OH) and Inipol EAP‐22 (Ip; ATOFINA Chemicals, Philadelphia, PA) combined with inorganic nutrients on the bioremediation of oil‐spiked beach sediments using an open irrigation system with artificial seawater over a 45‐d period. Osmocote is comprised of a semipermeable membrane surrounding water‐soluble inorganic N, P, and K. Inipol, which contains organic N and P, has been used for oil cleanup on beach substrate. Nutrient concentrations and microbial activity in sediments were monitored by analyzing sediment leachates and metabolic dehydrogenase activity of the microbial biomass, respectively. Loss of aliphatics (n‐C12 to n‐C33, pristane, and phytane) was significantly greater (total loss between 95 and 97%) in oil‐spiked sediments treated with Os alone or in combination with other nutrient amendments, compared with an unamended oil‐spiked control (26% loss) or sediments treated with the other nutrient amendments (28–65% loss). A combination of Os and soluble nutrients (SN) was favorable for the rapid metabolic stimulation of the indigenous microbial biomass, the sustained release of nutrients, and the enhanced biodegradation of petroleum hydrocarbons in leached, oil‐contaminated sediments.
RDX Loss in a Surface Soil under Saturated and Well Drained Conditions
Authors: Ringelberg D. B. , Reynolds C. M. , Walsh M. E. , Jenkins T. F.
Published: June 2010

On military training ranges, low‐order, incomplete detonations deposit RDX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine) into surface soils. In this study, we evaluated RDX biodegradation in surface soils obtained from a military training range in Alaska. Two factors were compared: (i) soil water potential during the incubations; and (ii) the use of acetonitrile (ACN) as an RDX carrier to spike samples. Organic solvents have been used in laboratory studies to dissolve slightly water‐soluble contaminants before addition to soil. We added ACN to obtain final soil ACN concentrations of 0 mg kg−1 (0%), 1000 mg kg−1 (0.1%) and 10 000 mg kg−1 (1%). We then compared RDX attenuation in the soil under saturated and unsaturated conditions. RDX fell below the limit of detection within 3 wk of study initiation under the saturated condition. A maximum degradation rate of 0.15 mg RDX L−1 d−1 was measured. Under the unsaturated condition, 42% of the original RDX was still present at study termination (5 wk). The addition of acetonitrile at 0.1 or 1.0% had no affect on RDX loss in the saturated soil. In the unsaturated soil, however, ACN at 1.0% inhibited RDX loss by as much as 25%. These findings indicate that soil water potential and carrier solvent concentrations can impact the rate and extent to which RDX is attenuated in a surface soil.
Phosphogypsum Amendment Effect on Radionuclide Content in Drainage Water and Marsh Soils from Southwestern Spain
Authors: El‐Mrabet Rachid , Abril José‐María , Periáñez Raúl , Manjón Guillermo , García‐Tenorio Rafael , Delgado Antonio , Andreu Luis
Published: June 2010

Phosphogypsum (PG) is a residue of the phosphate fertilizer industry that has relatively high concentrations of 226Ra and other radionuclides. Thus, it is interesting to study the effect of PG applied as a Ca amendment on the levels and behavior of radionuclides in agricultural soils. A study involving treatments with 13 and 26 Mg ha−1 of PG and 30 Mg ha−1 of manure was performed, measuring 226Ra and U isotopes in drainage water, soil, and plant samples. The PG used in the treatment had 510 ± 40 Bq kg−1 of 226Ra. The 226Ra concentrations in drainage waters from PG‐amended plots were similar (between 2.6 and 7.2 mBq L−1) to that reported for noncontaminated waters. Although no significant effect due to PG was observed, the U concentrations in drainage waters (200 mBq L−1 for 238U) were one order of magnitude higher than those described in noncontaminated waters. This high content in U can be ascribed to desorption processes mainly related to the natural adsorbed pool in soil (25 Bq kg−1 of 238U). This is supported by the 234U to 238U isotopic ratio of 1.16 in drainage waters versus secular equilibrium in PG and P fertilizers. The progressive enrichment in 226Ra concentration in soils due to PG treatment cannot be concluded from our present data. This PG treatment does not determine any significant difference in 226Ra concentration in drainage waters or in plant material [cotton (Gossipium hirsutum L.) leaves]. No significant levels of radionuclides except 40K were found in the vegetal tissues.
Impact of Sample Preparation on Mineralogical Analysis of Zero‐Valent Iron Reactive Barrier Materials
Authors: Phillips D. H. , Gu B. , Watson D. B. , Roh Y.
Published: June 2010

Permeable reactive barriers (PRBs) of zero‐valent iron (Fe0) are increasingly being used to remediate contaminated ground water. Corrosion of Fe0 filings and the formation of precipitates can occur when the PRB material comes in contact with ground water and may reduce the lifespan and effectiveness of the barrier. At present, there are no routine procedures for preparing and analyzing the mineral precipitates from Fe0 PRB material. These procedures are needed because mineralogical composition of corrosion products used to interpret the barrier processes can change with iron oxidation and sample preparation. The objectives of this study were (i) to investigate a method of preparing Fe0 reactive barrier material for mineralogical analysis by X‐ray diffraction (XRD), and (ii) to identify Fe mineral phases and rates of transformations induced by different mineralogical preparation techniques. Materials from an in situ Fe0 PRB were collected by undisturbed coring and processed for XRD analysis after different times since sampling for three size fractions and by various drying treatments. We found that whole‐sample preparation for analysis was necessary because mineral precipitates occurred within the PRB material in different size fractions of the samples. Green rusts quickly disappeared from acetone‐dried samples and were not present in air‐dried and oven‐dried samples. Maghemite/magnetite content increased over time and in oven‐dried samples, especially after heating to 105°C. We conclude that care must be taken during sample preparation of Fe0 PRB material, especially for detection of green rusts, to ensure accurate identification of minerals present within the barrier system.
Treatment of Contaminated Soil with Phosphorus and Manganese Oxide Reduces Lead Absorption by Sprague–Dawley Rats
Authors: Hettiarachchi Ganga M. , Pierzynski Gary M. , Oehme Fredrick W. , Sonmez Osman , Ryan James A.
Published: June 2010

This study was conducted to determine the extent of Pb absorption into young rats (Rattus norvegicus var. Sprague–Dawley) fed untreated Pb‐contaminated soil or Pb‐contaminated soil treated with two different sources of P and P + Mn oxide. Data were compared from an in vitro, physiologically based extraction test (PBET) with the animal data to support the validity of the in vitro test to assess bioavailable Pb from a treated Pb‐contaminated soil. Soil with a total Pb concentration of 2290 mg kg−1 was used. Rats were fed 19 different test diets for 21 consecutive days. The test diets represented 95 g AIN93G rat meal kg−1 diet with varying proportions of silica sand or soil to provide low, medium, or high doses of Pb from either Pb acetate, treated, or untreated soil. Blood, liver, kidney, and bone Pb concentrations were examined. For all four tissues, Pb concentrations for the Pb acetate groups were significantly higher than concentrations for all the soil groups. In general, either triple superphosphate (TSP) or phosphate rock (PR) treatments resulted in significant reductions in tissue Pb concentrations compared with untreated soil. Blood and kidney Pb concentrations for the PR + Mn oxide group were significantly lower than those of the PR group at the low and high doses. Relative bioavailability of Pb, as measured in all tissues, was significantly reduced when comparing untreated with amended soil. Correlation between the in vitro and in vivo tests, based on bone and liver tissue, showed that the in vitro test is successful at predicting Pb bioavailability.
Dissolved Organic Carbon Dynamics in a Riparian Aquifer
Authors: Jacinthe P.‐A. , Groffman P. M. , Gold A. J.
Published: June 2010

The capacity of riparian soils to remove nitrate (NO−3) from ground water is well established, but the effects of ground water NO−3‐enrichment on C dynamics are not well studied. We incubated horizontal cores of aquifer material extracted from beneath moderately well‐drained (MWD) and poorly drained (PD) soils in a riparian forest in Rhode Island, USA for 132 d, and dosed (flow rate, 170 mL d−1; dissolved O2, 2 in PD and 5 mg L−1 in MWD cores) with ground water amended with either Br−, Br− + NO−3 (10 mg N L−1), or Br− + NO−3 + DOC (20 mg C L−1). The DOC was extracted from forest floor material and added during the first 56 d of the experiment. Addition of NO−3 had limited effect on CO2 production while DOC amendment had a significant effect in the PD but not in the MWD mesocosms. Total CO2 production (mg CO2–C kg−1 soil) was 6.3, 7.0, and 10.1 in the PD and 3.6, 4.0, and 4.5 in the MWD cores amended with Br−, Br− + NO−3, and Br− + NO−3 + DOC, respectively. Carbon balance (Cbal = DOCin − (DOCout + CO2–C) showed a net C retention of 8.0 mg C kg−1 soil in the DOC‐amended MWD cores (equivalent to 50% of the DOC added), and a net C loss of 8.3 mg C kg−1 soil in similarly treated PD cores. The lack of C retention in the PD cores was ascribed to reductive dissolution of minerals implicated in DOC sorption. These findings underscore that there is marked variation in C dynamics in riparian aquifers that has the potential to influence the fate of NO3− and DOC in the landscape.
Role of Active Floodplains for Nutrient Retention in the River Rhine
Authors: Venterink H. Olde , Wiegman F. , Van der Lee G. E. M. , Vermaat J. E.
Published: June 2010

We evaluated the importance of floodplains for nutrient retention in two distributaries of the river Rhine (Waal and IJssel) by monitoring N and P retention in a body of water during downstream transport. We hypothesized that (i) retention of P is much larger than retention of N and (ii) nutrient retention increases with an increasing amount of the discharge flowing through floodplains (QF). The second hypothesis was tested by comparing retention between the rivers Waal (low QF) and IJssel (high QF), as well as at different discharges. Total nitrogen (TN) did not decrease significantly during downstream transport in both rivers, whereas 20 to 45% of total phosphorus (TP) disappeared during transport in the river IJssel. This difference between N and P retention—supporting the first hypothesis—was probably caused by differences in sedimentation through a much lower proportion of N adsorbed to particles than of P (2–3% of N vs. 50–70% of P). Phosphorus retention was only observed in the IJssel and not in the Waal, and absolute P retention (g P s−1 km−1) in the IJssel increased with increasing QF The second hypothesis was, nevertheless, not fully supported, because the percentage P retention (% of P load) decreased (instead of increased) with increasing QF. The percentage P retention increased with decreasing river depth and flow velocity; it seemed related to the efficiency of sediment trapping.
Nutrient and Sediment Removal by a Restored Wetland Receiving Agricultural Runoff
Authors: Jordan Thomas E. , Whigham Dennis F. , Hofmockel Kirsten H. , Pittek Mary A.
Published: June 2010

Few studies have measured removal of pollutants by restored wetlands that receive highly variable inflows. We used automated flow‐proportional sampling to monitor the removal of nutrients and suspended solids by a 1.3‐ha restored wetland receiving unregulated inflows from a 14‐ha agricultural watershed in Maryland, USA. Water entered the wetland mainly in brief pulses of runoff, which sometimes exceeded the 2500‐m3water holding capacity of the wetland. Half of the total water inflow occurred in only 24 days scattered throughout the two‐year study. Measured annual water gains were within 5% of balancing water losses. Annual removal of nutrients differed greatly between the two years of the study. The most removal occurred in the first year, which included a three‐month period of decreasing water level in the wetland. In that year, the wetland removed 59% of the total P, 38% of the total N, and 41% of the total organic C it received. However, in the second year, which lacked a drying period, there was no significant (p> 0.05) net removal of total N or P, although 30% of the total organic C input was removed. For the entire two‐year period, the wetland removed 25% of the ammonium, 52% of the nitrate, and 34% of the organic C it received, but there was no significant net removal of total suspended solids (TSS) or other forms of N and P. Although the variability of inflow may have decreased the capacity of the wetland to remove materials, the wetland still reduced nonpoint‐source pollution.
Growth and Yield Responses of Potato to Mixtures of Carbon Dioxide and Ozone
Authors: Heagle A. S. , Miller J. E. , Pursley W. A.
Published: June 2010

Elevated carbon dioxide (CO2) concentrations in the atmosphere can stimulate plant growth and yield, whereas ground‐level ozone (O3) concentrations cause the opposite effect in many areas of the world. Recent experiments show that elevated CO2 can protect some plants from O3 stress, but this has not been tested for most crop species. Our objective was to determine if elevated CO2 protects Irish potato (Solanum tuberosum L.) from foliar injury and suppression of growth and yield caused by O3 An O3–resistant cultivar (Superior) and an O3–sensitive cultivar (Dark Red Norland) were exposed from within 10 d after emergence to maturity to mixtures of three CO2 and three O3 treatments in open‐top field chambers. The three CO2 treatments were ambient (370 μL L−1) and two treatments with CO2 added to ambient CO2 for 24 h d−1 (540 and 715 μL L−1). The O3 treatments were charcoal‐filtered air (15 nL L−1), nonfiltered air (45 nL L−1), and nonfiltered air with O3 added for 12 h d−1 (80 nL L−1). Elevated O3 and CO2 caused extensive foliar injury of Dark Red Norland, but caused only slight injury of Superior. Elevated CO2 increased growth and tuber yield of both cultivars, whereas elevated O3 generally suppressed growth and yield, mainly of Dark Red Norland. Elevated CO2 appeared to protect Dark Red Norland from O3–induced suppression of shoot, root, and tuber weight as measured at midseason but did not protect either cultivar from O3 stress at the final harvest. The results further illustrate the difficulty in predicting effects of O3 + CO2 mixtures based on the effects of the individual gases.
Removal of Selenate in Simulated Agricultural Drainage Water by a Rice Straw Bioreactor Channel System
Authors: Zhang Yiqiang , Frankenberger William T.
Published: June 2010

Removal of selenium (Se) from agricultural drainage water is important in protecting wetland wildlife. Three flow‐through bioreactor channel systems (BCSs), each with three channels filled with rice (Oryza sativa L.) straw, were set in the laboratory to determine removal of selenate [Se(VI)] (1020 μg L−1) from drainage water with a salinity of 10.4 dS m−1, a pH of 8.1, and a nitrate NO−3 range of 0 to 100 mg L−1 Results showed that the rice straw effectively reduced Se(VI) during 122 to 165 d of the experiments. Calculation of Se mass in the three BCSs showed that 89.5 to 91.9% of the input Se(VI) was reduced to red elemental Se [Se(0)], where 96.6 to 98.2% was trapped in the BCSs. Losses of each gram of rice straw were almost equal to the removal of 1.66 mg of Se from the drainage water as a form of red Se(0), indicating that rice straw is a very effective organic source for removing Se(VI) from drainage water.
The Role of Nitrilotriacetate in Copper Uptake by Tobacco
Authors: Wenger K. , Gupta S. K. , Furrer G. , Schulin R.
Published: June 2010

In growth chamber experiments we studied the effect of nitrilotriacetate (NTA) on Cu uptake by tobacco (Nicotiana tabacum L.). Plants were exposed for 6 d to 126 μM Cu and 500 μM NTA in nutrient solutions without and with 10 g L−1 montmorillonite. Approximately seven times less Cu was dissolved in the montmorillonite solutions than in the nutrient solutions alone. In the absence of NTA, montmorillonite effectively competed with plant roots for Cu, although Cu remained bound to the roots. Nitrilotriacetate increased Cu uptake and translocation into shoots of tobacco by a factor of 3.5 from the nutrient solution and by a factor of 26 from the montmorillonite nutrient solution. Neither growth reduction nor any other visible sign of Cu toxicity was found in the presence of NTA with Cu concentrations of 190 mg kg−1 in the shoots. In the absence of NTA, high Cu concentrations in root samples led to a brownish discoloration of the roots.
Assessing the Application of an Additive Model to Estimate Toxicity of a Complex Effluent
Authors: Ross Kirstin E. , Bidwell Joseph R.
Published: June 2010

A number of industries monitor levels of chemicals in their effluent, but few have undertaken prolonged biological monitoring of this wastewater. The focus of the present study was to determine whether past chemical data for effluent from a lead smelter could be used to estimate its past toxicity. Since the interactive effects of metals in effluents are often assumed to be additive, it was hypothesized that an additive model, 100/[Σ(metal concentration in effluent/EC50 for individual metal)], could be used to generate an EC50 from chemical data (where EC50 is the concentration of test material that affects 50% of the test organisms). To test the approach, a larval development toxicity test with the marine polychaete, Galeolaria caespitosa, was used to test 26 separate samples of effluent from a lead smelter, generating empirical EC50 values. EC50 values for each individual metal in the effluent were also generated using the larval development toxicity test. The concentrations of trace metals in each effluent sample were determined and, using the additive model, EC50 values were calculated. For the majority of effluent samples tested, the additive model underestimated toxicity, suggesting the presence of additional unidentified contaminants in the effluent samples. Additionally, a nonlinear rather than linear regression curve was found to best describe the relationship between the model and empirically derived EC50 values. This relationship was then used to estimate past trends in toxicity of the smelter effluent. Forty‐eight percent of the variability in measured toxicity was explained by the model, with the model underestimating toxicity in the majority of samples.
Sorption and Desorption of Cadmium by Different Fractions of Biosolids‐Amended Soils
Authors: Hettiarachchi Ganga M. , Ryan James A. , Chaney Rufus L. , La Fleur Cherie M.
Published: June 2010

To evaluate the importance of both the inorganic and organic fractions in biosolids on Cd chemistry, a series of Cd sorption and desorption batch experiments (at pH 5.5) were conducted on different fractions of soils from a long‐term field experimental site. The slope of the Cd sorption isotherm increased with rate of biosolids and was different for the different biosolids. Removal of organic carbon (OC) reduced the slope of the Cd sorption isotherm but did not account for the observed differences between biosolids‐amended soils and a control soil, indicating that the increased adsorption associated with biosolids application was not limited to the increased OC from the addition of biosolids. Removal of both OC and Fe/Mn further reduced the slopes of Cd sorption isotherms and the sorption isotherm of the biosolids‐amended soil was the same as that of the control, indicating both OC and Fe/Mn fractions added by the biosolids were important to the increased sorption observed for the biosolids‐amended soil samples. Desorption experiments failed to remove from 60 to 90% of the sorbed Cd. This “apparent hysteresis” was higher for biosolids‐amended soil than the control soil. Removal of both OC and Fe/Mn fractions was more effective in removing the observed differences between the biosolids‐amended soil and the control than either alone. Results show that Cd added to biosolids‐amended soil behaves differently than Cd added to soils without biosolids and support the hypothesis that the addition of Fe and Mn in the biosolids increased the retention of Cd in biosolids‐amended soils.
Kerogen in Aquifer Material and Its Strong Sorption for Nonionic Organic Pollutants
Authors: Ran Yong , Xiao Baohua , Huang Weilin , Peng Ping'an , Liu Dehan , Fu Jiamo , Sheng Guoying
Published: June 2010

Sorption of organic pollutants by subsurface materials has been found to not only correlate with the total organic carbon (TOC) content, but also depend on the types of soil and sediment organic matter (SOM). Characterization of geochemically heterogeneous SOM is key to elucidating sorption mechanisms and predicting pollutant transport in ground water systems. In this study, kerogen, a nonextractable organic material, was isolated with an acid demineralization procedure from a sandy aquifer material (Borden, Ontario, Canada) having a TOC content of approximately 0.021% (w/w). Petrographical examinations reveal that the kerogen has three major types of macerals including bituminite (Kerogen Type I and II), vitrinite (Type III), and fusinite (Type IV or charred kerogen). The solid‐state 13C nuclear magnetic resonance (NMR) spectrum shows two dominant peaks, aliphatic and aromatic carbons, for the isolated material. Sorption isotherms measured using phenanthrene, naphthalene, 1,3,5‐trichlorobenzene (TCB), and 1,2‐dichlorobenzene (DCB) as sorbates showed that both the isolated kerogen and the original sand exhibited nonlinear sorption and that the phenanthrene and TCB isotherms measured for the kerogen material are more nonlinear than the respective isotherms for the original sand. The single‐point organic carbon–normalized sorption capacity measured for the isolated kerogen can be several times greater than that measured for the original sand for a given sorbate. The study suggests that kerogen plays a major role in overall sorption isotherm nonlinearity and could yield higher‐than‐predicted sorption capacities for the subsurface material even though the content of this organic material is very low.
Enhancing Metolachlor Destruction Rates with Aluminum and Iron Salts during Zerovalent Iron Treatment
Authors: Satapanajaru T. , Comfort S. D. , Shea P. J.
Published: June 2010

Pesticide‐contaminated soil may require remediation to mitigate ground and surface water contamination. We determined the effectiveness of zerovalent iron (Fe0) to dechlorinate metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methyl ethyl) acetamide] in the presence of aluminum and iron salts. By treating aqueous solutions of metolachlor with Fe0, we found destruction kinetics were greatly enhanced when Al, Fe(II), or Fe(III) salts were added, with the following order of destruction kinetics observed: Al2(SO4)3> AlCl3> Fe2(SO4)3> FeCl3A common observation was the formation of green rusts, mixed Fe(II)–Fe(III) hydroxides with interlayer anions that impart a greenish‐blue color. Central to the mechanism responsible for enhanced metolachlor loss may be the role these salts play in facilitating Fe(II) release. By tracking Al and Fe(II) in a Fe0+ Al2(SO4)3treatment of metolachlor, we observed that Al was readily sorbed by the corroding iron with a corresponding release of Fe(II). The manufacturing process used to produce the Fe0also profoundly affected destruction rates. Metolachlor destruction rates with salt‐amended Fe0were greater with annealed iron (indirectly heated under a reducing atmosphere) than unannealed iron. Moreover, the optimum pH for metolachlor dechlorination in water and soil differed between iron sources (pH 3 for unannealed, pH 5 for annealed). Our results indicate that metolachlor destruction by Fe0treatment may be enhanced by adding Fe or Al salts and creating pH and redox conditions favoring the formation of green rusts.
Uptake Rates of Thorium Progeny in a Semiarid Environment
Authors: McClellan Yvonne , August Robert , Gosz James , Gann Steve , Parmenter Robert , Nelson Martin , Harper Mark
Published: June 2010

The release rates and transformation processes that influence the mobility, biological uptake, and transfer of radionuclides are essential to the assessment of the health effects in the food chain and ecosystem. This study examined concentrations of 232Th in both soil and vegetation at a closed military training site, Kirtland Air Force Base (KAFB), New Mexico. Brazilian sludge was intentionally introduced into the topsoil in the early 1960s to simulate nuclear weapon accidents. Soil (60) and vegetation (120) samples were collected from 1996 to 2000 and analyzed for radionuclides and progeny. High‐resolution γ‐ray spectroscopy was used to determine radionuclide activities. The results indicate that the thorium progeny were the predominant contaminant in soil and vegetation. Concentration ratios (CRs) were calculated based on actinium levels.
Nitrate Losses in Subsurface Drainage from a Corn–Soybean Rotation as Affected by Time of Nitrogen Application and Use of Nitrapyrin
Authors: Randall G. W. , Vetsch J. A. , Huffman J. R.
Published: June 2010

Subsurface drainage, a water management practice used to remove excess water from poorly drained soils, can transport substantial amounts of NO3 from agricultural crop production systems to surface waters. A field study was conducted from the fall of 1986 through 1994 on a tile‐drained Canisteo clay loam soil (fine‐loamy, mixed, superactive, calcareous, mesic Typic Endoaquoll) to determine the influence of time of N application and use of nitrapyrin [NP; 2‐chloro‐6‐(trichloromethyl) pyridine] on NO3 losses from a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. Four anhydrous ammonia treatments [fall N, fall N + NP, spring preplant N, and split N (40% preplant and 60% sidedress)] were replicated four times and applied at 150 kg N ha−1 for corn on individual drainage plots. Sixty‐two percent of the annual drainage and 69% of the annual NO3 loss occurred in April, May, and June. Flow‐weighted NO3–N concentrations in the drainage water were two to three times greater in the two years following the three‐year dry period compared with preceding and succeeding years. Nitrate N concentrations and losses in the drainage from corn were greatest for fall N with little difference among the other three N treatments. Nitrate losses from soybean were affected more by residual soil NO3 following corn than by the N treatments per se. Averaged across the four rotation cycles, flow‐normalized NO3–N losses ranked in the order: fall N > split N > spring N = fall N + NP. Under these conditions NO3 losses from a corn–soybean rotation into subsurface drainage can be reduced by 13 to 18% by either applying N in the spring or using NP with late fall–applied ammonia.
Biosolids Decomposition after Surface Applications in West Texas
Authors: Jaynes W. F. , Zartman R. E. , Sosebee R. E. , Wester D. B.
Published: June 2010

In a semiarid environment, climate is a critical factor in the decomposition of surface‐applied biosolids. This study examined the effect of 2‐ to 7‐yr exposure times on the composition of single applications of New York, NY biosolids in western Texas. Exposure time effects on organic matter, N, P, S, Cu, Cr, Pb, Hg, and Zn were studied near Sierra Blanca, TX. Due to organic matter decomposition, total organic C decreased from 340 g kg−1in fresh biosolids to 180 g kg−1in biosolids after 82 mo of exposure, whereas the inorganic ash content of the biosolids increased from 339 to 600 g kg−1Total N decreased from 50 to 10 g N kg−1and total S decreased from 12 to 6 g S kg−1Bicarbonate‐available P in the biosolids decreased from 0.9 to 0.2 g kg−1Successive H2O extractions yielded soluble P concentrations consistent with dicalcium phosphate (dical) for fresh biosolids and tricalcium phosphate (trical) for biosolids exposed for 59 months or more. Sparingly soluble phosphates, such as dical and trical, potentially yield >0.5 mg P L−1in runoff waters for extended periods after biosolids applications, especially after multiple applications. Selective dissolution of the biosolids indicated that as much as 66 to 78% of P exists as iron phosphates, 16 to 21% as Fe oxides, and 5 to 12% as insoluble Ca phosphates. Chemical analyses of ash samples suggest that Cu and Zn have been lost from biosolids through leaching or runoff and no losses of Pb, Cr, or Hg have occurred since application.
Spatial and Temporal Patterns of Campylobacter Contamination Underlying Public Health Risk in the Taieri River, New Zealand
Authors: Eyles Rebekah , Niyogi Dev , Townsend Colin , Benwell George , Weinstein Philip
Published: June 2010

New Zealand's freshwater ecosystems are subject to microbial contamination from a predominantly agricultural landscape. This study examines the spatial and temporal distribution of the human pathogen Campylobacter in the lower Taieri River, South Island (New Zealand). Enumeration of thermophilic Campylobacter from river samples was performed using a most probable number (MPN) method. Seasonal variation in Campylobacter levels was evident, with higher median levels detected in summer, when human exposure through recreational water use is maximal. Campylobacter levels varied significantly among the 10 sampling sites, increasing below a major tributary entering the river and then showing a downstream decrease. These changes probably resulted from inputs from adjacent farms and instream Campylobacter losses (settling, death). Two main peaks in the flux of Campylobacter were observed, one in winter and one in summer. A decrease in notified cases of campylobacteriosis in the human population was observed when levels of Campylobacter at the main recreational bathing site on the river were low. Continuing land use change and intensification in New Zealand may lead to further increases in microbial contamination of freshwaters, and an associated increase in waterborne enteric diseases such as campylobacteriosis.
Biosolids‐Derived Nitrogen Mineralization and Transformation in Forest Soils
Authors: Wang Hailong , Kimberley Mark O. , Schlegelmilch Mirko
Published: June 2010

Utilization of biosolids through land application is becoming increasingly popular among wastewater managers. To minimize the potential contamination of receiving waters from biosolids‐derived nitrogen (N), it is important to understand the availability of N after land application of biosolids. In this study, four secondary biosolids (two municipal and two pulp and paper industrial biosolids) were used in a laboratory incubation experiment to simulate N mineralization and transformation after land application. Municipal biosolids were from either aerobically or anaerobically digested sources, while pulp and paper industrial biosolids were from aerated wastewater stabilization lagoons. These biosolids were mixed with two New Zealand forest soils (top 100 mm of a volcanic soil and a brown soil) and incubated at two temperatures (10 and 20°C) for 26 wk. During incubation, mineralized N was periodically leached from the soil–biosolids mixture with 0.01MCaCl2solution and concentrations of NH4and NO3in leachate were determined. Mineralization of N from aerobically digested municipal biosolids (32.1%) was significantly more than that from anaerobically digested biosolids (15.2%). Among the two pulp and paper industrial biosolids, little N leached from one, while as much as 18.0% of total organic N was leached from the other. As expected, mineralization of N was significantly greater at 20°C (average 22.8%) than at 10°C (average 9.7%). It was observed that more N in municipal biosolids was mineralized in the brown soil, whereas more N in pulp and paper industrial biosolids mineralized in the volcanic soil. Transformation of NH4to NO3was affected by soil type and temperature.