bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

ABSTRACTPesticide‐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

ABSTRACTThe 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

ABSTRACTSubsurface 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

ABSTRACTIn 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

ABSTRACTNew 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

ABSTRACTUtilization 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.
Phosphorus Retention Mechanisms of a Water Treatment Residual
Authors: Ippolito J. A. , Barbarick K. A. , Heil D. M. , Chandler J. P. , Redente E. F. 
Published: June 2010

ABSTRACTWater treatment residuals (WTRs) are a by‐product of municipal drinking water treatment plants and can have the capacity to adsorb tremendous amounts of P. Understanding the WTR phosphorus adsorption process is important for discerning the mechanism and tenacity of P retention. We studied P adsorbing mechanism(s) of an aluminum‐based [Al2(SO4)3·14H2O] WTR from Englewood, CO. In a laboratory study, we shook mixtures of P‐loaded WTR for 1 to 211 d followed by solution pH analysis, and solution Ca, Al, and P analysis via inductively coupled plasma atomic emission spectroscopy. After shaking periods, we also examined the solids fraction by X‐ray diffraction (XRD) and electron microprobe analysis using wavelength dispersive spectroscopy (EMPA–WDS). The shaking results indicated an increase in pH from 7.2 to 8.2, an increase in desorbed Ca and Al concentrations, and a decrease in desorbed P concentration. The pH and desorbed Ca concentration increases suggested that CaCO3controlled Ca solubility. Increased desorbed Al concentration may have been due to Al OH−4formation. Decreased P content, in conjunction with the pH increase, was consistent with calcium phosphate formation or precipitation. The system appeared to be undersaturated with respect to dicalcium phosphate (DCP; CaHPO4) and supersaturated with respect to octacalcium phosphate [OCP; Ca4H(PO4)3·2.5H2O]. The Ca and Al increases, as well as OCP formation, were supported by MINTEQA2 modeling. The XRD and EMPA–WDS results for all shaking times, however, suggested surface P chemisorption as an amorphous Al–P mineral phase.
Recycling Soil Nitrate Nitrogen by Amending Agricultural Lands with Oily Food Waste
Authors: Rashid M. T. , Voroney R. P. 
Published: June 2010

ABSTRACTWith current agricultural practices the amounts of fertilizer N applied are frequently more than the amounts removed by the crop. Excessive N application may result in short‐term accumulation of nitrate nitrogen (NO3–N) in soil, which can easily be leached from the root zone and into the ground water. A management practice suggested for conserving accumulated NO3–N is the application of oily food waste (FOG; fat + oil + greases) to agricultural soils. A two‐year field study (1995–1996 and 1996–1997) was conducted at Elora Research Center (43°38′ N, 80° W; 346 m above mean sea level), University of Guelph, Ontario, Canada to determine the effect of FOG application in fall and spring on soil NO3–N contents and apparent N immobilization–mineralization of soil N in the 0‐ to 60‐cm soil layer. The experiment was planned under a randomized complete block design with four replications. An unamended control and a reference treatment [winter wheat (Triticum aestivumL.) cover crop] were included in the experiment to compare the effects of fall and spring treatment of oily food waste on soil NO3–N contents and apparent N immobilization–mineralization. Oily food waste application at 10 Mg ha−1in the fall decreased soil NO3–N by immobilization and conserved 47 to 56 kg NO3–N ha−1, which would otherwise be subject to leaching. Nitrogen immobilized due to FOG application in the fall was subsequently remineralized by the time of fertilizer N sidedress, whereas no net mineralization was observed in spring‐amended plots at the same time.
Methane Emissions of Rice Increased by Elevated Carbon Dioxide and Temperature
Authors: Allen Leon H. , Albrecht Stephan L. , Colón‐Guasp Wilfredo , Covell Stephen A. , Baker Jeffrey T. , Pan Deyun , Boote Kenneth J. 
Published: June 2010

ABSTRACTMethane (CH4) effluxes by paddy‐culture rice (Oryza sativa L.) contribute about 16% of the total anthropogenic emissions. Since radiative forcing of CH4 at current atmospheric concentrations is 21 times greater on a per mole basis than that of carbon dioxide (CO2), it is imperative that the impact of global change on rice CH4 emissions be evaluated. Rice (cv. IR72) was planted in sunlit, closed‐circulation, controlled‐environment chambers in which CH4 efflux densities were measured daily. The CO2 concentration was maintained at either 330 or 660 μmol mol−1 Air temperatures were controlled to daily maxima and minima of 32/23, 35/26, and 38/29°C at each CO2 treatment. Emissions of CH4 each day were determined during a 4‐h period after venting and resealing the chambers at 0800 h. Diurnal CH4 effluxes on 77, 98, and 119 d after planting (DAP) were obtained similarly at 4‐h intervals. Emissions over four‐plant hills and over flooded bare soil were measured at 53, 63, and 100 DAP. Emissions were negligible before 40 DAP. Thereafter, emissions were observed first in high‐CO2, high‐temperature treatments and reached a sustained maximum efflux density of about 7 mg m−2 h−1 (0.17 g m−2 d−1) near the end of the growing season. Total seasonal CH4 emission was fourfold greater for high‐CO2, high‐temperature treatments than for the low‐CO2, low‐temperature treatment, probably due to more root sloughing or exudates, since about sixfold more acetate was found in the soil at 71 DAP. Both rising CO2 and increasing temperatures could lead to a positive feedback on global warming by increasing the emissions of CH4 from rice.
Modeling Flow and Nitrate Fate at Catchment Scale in Brittany (France)
Authors: Conan Céline , Bouraoui Fayçal , Turpin Nadine , de Marsily Ghislain , Bidoglio Giovanni 
Published: June 2010

ABSTRACTIn the intensive pig‐farming (Sus scrofa) area of Brittany (western France), many surface and subsurface water resources are contaminated by nitrate (NO3) with concentrations that chronically exceed the European Community 50 mg L−1 drinking standard. To ensure sustainable water supply, the fate of NO3 must be considered in both surface water and ground water. The fate of N was investigated in a Britain catchment, the Coët‐Dan watershed, with an integrated management tool: the hydrological SWAT model coupled with the ground water model MODFLOW, and its companion contaminant and solute transport model MT3DMS. The model was validated with respect to water quantity during a 6‐yr period and for the NO3 concentration during a 44‐mo period, at two gauging stations in the catchment. The coupled models reproduced accurately the measurements. At the basin outlet, the Nash‐Sutcliffe coefficients were 0.88 for monthly flow for the entire period and 0.87 for monthly N load. Alternative scenarios were simulated and showed potential benefits of decreasing manure application from 210 to 170 kg N ha−1 as required by the European Commission Nitrates Directive.
Copper, Zinc, and Arsenic in Soil Surrounding Douglas‐Fir Poles Treated with Ammoniacal Copper Zinc Arsenate (ACZA)
Authors: Morrell J. J. , Keefe Donn , Baileys Randall T. 
Published: June 2010

ABSTRACTThe levels of copper, zinc, and arsenic in soil surrounding Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] utility poles treated with ammoniacal copper zinc arsenate (ACZA) were investigated at sites in Florida, Virginia, and New York. Copper levels were elevated near the poles and declined with both horizontal distance away from the pole and depth beneath the soil surface. Zinc levels were also elevated next to the poles, but the levels declined more slowly than did those of copper. Arsenic levels were elevated in soil immediately next to the poles but declined to near background levels farther away. The results indicate that metals can leach from ACZA‐treated poles, but do not migrate far in the soil, and thus the levels decline sharply with distance from the poles.
Long‐Term Effects of Nitrogen Fertilizer Use on Ground Water Nitrate in Two Small Watersheds
Authors: Tomer M. D. , Burkart M. R. 
Published: June 2010

ABSTRACTChanges in agricultural management can minimize NO3–N leaching, but then the time needed to improve ground water quality is uncertain. A study was conducted in two first‐order watersheds (30 and 34 ha) in Iowa's Loess Hills. Both were managed in continuous corn (Zea mays L.) from 1964 through 1995 with similar N fertilizer applications (average 178 kg ha−1 yr−1), except one received applications averaging 446 kg N ha−1 yr−1 between 1969 and 1974. This study determined if NO3–N from these large applications could persist in ground water and baseflow, and affect comparison between new crop rotations implemented in 1996. Piezometer nests were installed and deep cores collected in 1996, then ground water levels and NO3–N concentrations were monitored. Tritium and stable isotopes (2H, 18O) were determined on 33 water samples in 2001. Baseflow from the heavily N‐fertilized watershed had larger average NO3–N concentrations, by 8 mg L−1 Time‐of‐travel calculations and tritium data showed ground water resides in these watersheds for decades. “Bomb‐peak” precipitation (1963–1980) most influenced tritium concentrations near lower slope positions, while deep ground water was dominantly pre‐1953 precipitation. Near the stream, greater recharge and mixed‐age ground water was suggested by stable isotope and tritium data, respectively. Using sediment‐core data collected from the deep unsaturated zone between 1972 and 1996, the increasing depth of a NO3–N pulse was related to cumulative baseflow (r2 = 0.98), suggesting slow downward movement of NO3–N since the first experiment. Management changes implemented in 1996 will take years to fully influence ground water NO3–N. Determining ground water quality responses to new agricultural practices may take decades in some watersheds.
Behavior of 14C‐Atrazine in Argentinean Topsoils under Different Cropping Managements
Authors: Hang S. , Barriuso E. , Houot S. 
Published: June 2010

ABSTRACTAtrazine (6‐chloro‐N2–ethyl‐N4–isopropyl‐1,3,5‐triazine‐2,4‐diamine) behavior was studied in four surface soils during incubations in laboratory conditions. Soils were chosen in relation to their cropping management (tillage and no tillage) and crop rotation system (continuous soybean [Glycine max (L.) Merr.] and maize (Zea mays L.)–soybean rotation). A natural soil under brushwood was sampled as a reference. Atrazine use in field conditions was associated with maize cropping, thus only one soil received atrazine every other year. Atrazine behavior was characterized through the balance of 14C‐U‐ring atrazine radioactivity among the mineralized fraction, the extractable fraction, and the nonextractable bound residues. Soil organic matter capacity to form bound residues was characterized using soil size fractionation. Accelerated atrazine mineralization was only observed in the soil receiving atrazine in field conditions. Atrazine application every other year was enough to develop a microflora adapted to triazine ring mineralization. Bound residue formation was rapid and increased with soil organic matter content. The coarsest soil size fractions (2000–200 and 200–50 μm) containing the nonhumified organic matter presented the highest capacity to form bound residues. No effect of tillage system was observed, probably because of the uniform sampling depth at 20 cm, hiding the stratification pattern of soil organic matter in nontilled soils.
Biogeochemistry of Fluoride in a Plant–Solution System
Authors: Mackowiak C. L. , Grossl P. R. , Bugbee B. G. 
Published: June 2010

ABSTRACTFluoride (F−) pollutants can harm plants and the animals feeding on them. However, it is largely unknown how complexing and chelating agents affect F bioavailability. Two studies were conducted that measured F− bioavailability and uptake by rice (Oryza sativa L.). In the first study, rice was grown in solution culture (pH 5.0) with 0, 2, or 4 mM F− as KF to compare the interaction of F− with humic acid (HA) and with a conventional chelating agent, N‐hydroxyethylenthylenediaminetriacetic acid (HEDTA). In the second study, F was supplied at 0, 0.5, 1.0, and 2.0 mM KF with an additional 2 mM F− treatment containing solution Ca at 2× (2 mM Ca) the level used in the first study, to test the effect added Ca had on F− availability and uptake. Total biomass was greatest with HEDTA and F− < 1 mM Leaf and stem F concentrations increased exponentially as solution F− increased linearly, with nearly no F partitioning into the seed. Results suggest that F was taken up as HF0 while F− uptake was likely restricted. Additionally, F− competed with HA for Ca, thus preventing the formation of Ca–HA flocculents. The addition of soluble Ca resulted in the precipitation of CaF2 solids on the root surface, as determined by tissue analysis and energy dispersive X‐ray spectroscopy.
Aluminum Effect on Dissolution and Precipitation under Hyperalkaline Conditions
Authors: Qafoku Nikolla P. , Ainsworth Calvin C. , Szecsody James E. , Bish David L. , Young James S. , McCready David E. , Qafoku Odeta S. 
Published: June 2010

ABSTRACTThe high‐level radioactive, Al‐rich, concentrated alkaline and saline waste fluids stored in underground tanks have accidentally leaked into the vadose zone at the Hanford Site in Washington State. In addition to dissolution, precipitation is likely to occur when these waste fluids contact the sediments. The objective of this study was to investigate the solid phase transformations caused by dissolution and precipitation in the sediments treated with solutions similar to the waste fluids. Batch experiments at 323 K were conducted in metal‐ and glass‐free systems under CO2 and O2 free conditions. Results from X‐ray diffraction (XRD), quantitative X‐ray diffraction (QXRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and energy dispersive X‐ray fluorescence spectroscopy (EDXRF) indicated that significant solid phase transformations occurred in the sediments contacted with Al‐rich, hyperalkaline, and saline solutions. The XRD and QXRD analyses confirmed that smectite and most likely biotite underwent dissolution. The SEM and the qualitative EDS analyses confirmed the formation of alumino‐silicates in the groups of cancrinite and probably sodalite. The morphology of the alumino‐silicates secondary phases changed in response to changes in the Si/Al aqueous molar ratio. The transformations in the sediments triggered by dissolution (weathering of soil minerals) and precipitation (formation of secondary phases with high specific surface area and probably high sorption capacities) may play a significant role in the immobilization and ultimate fate of radionuclides and contaminants such as Cs, Sr, and U in the Hanford vadose zone.