bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Elevated Carbon Dioxide on Soils in a Florida Scrub Oak Ecosystem
Authors: Johnson D.W. , Hungate B.A. , Dijkstra P. , Hymus G. , Drake B. 
Published: June 2010

ABSTRACTThe results of a 3‐yr study on the effects of elevated CO2on soil N and P, soil pCO2, and calculated CO2efflux in a fire‐regenerated Florida scrub oak ecosystem are summarized. We hypothesized that elevated CO2would cause (i) increases in soil pCO2and soil respiration and (ii) reduced levels of soil‐available N and P. The effects of elevated CO2on soil N availability differed according to the method used. Results of resin lysimeter collections and anion exchange membrane tests in the field showed reduced NO−3in soils in Years 1 and 3. On the other hand, re‐analysis of homogenized, buried soil bags after 1 yr suggested a relative increase in N availability (lower C to N ratio) under elevated CO2In the case of P, the buried bags and membranes suggested a negative effect of CO2on P during the first year; this faded over time, however, as P availability declined overall, probably in response to P uptake. Elevated CO2had no effect on soil pCO2or calculated soil respiration at any time, further suggesting that plant rather than microbial uptake was the primary factor responsible for the observed changes in N and P availability with elevated CO2
Sorption of Polycyclic Aromatic Compounds to Humic and Fulvic Acid HPLC Column Materials
Authors: Kollist‐Siigur Katrin , Nielsen Torben , Gr⊘n Christian , Hansen Poul Erik , Helweg Christian , Jonassen Kristoffer E.N. , J⊘rgensen Ole , Kirso Uuve 
Published: June 2010

ABSTRACTTwo different humic acids (HA) and a fulvic acid (FA) were chemically immobilized to a high performance liquid chromatography (HPLC) silica column material. The immobilization was performed by binding amino groups in HA/FA to the free aldehyde group in glutardialdehyde attached to the silica gel. The HPLC column materials were compared with a blank column material made by applying the same procedure but without immobilizing HA or FA. Also, a column was made by binding carbonyl groups in HA to amino groups attached to the silica gel. The humic substances were selected to secure appropriate variation of their structural features. The retention factors of 45 polycyclic aromatic compounds (PAC) to the four columns were determined by HPLC. The advantage of the technique is a large number of compounds can easily be studied. The binding procedure does not appear to cause a drastic selection between the HA molecules. The k′ values obtained for the two Aldrich HA columns agree in general reasonably. The retention or sorption of the compounds increased with the size of the PAC and the number of lipophilic substituents, but decreased when polar substituents were present. The PAC retention was much stronger to the two HA columns than to the FA and blank column, both for hydrophobic polycyclic aromatic hydrocarbons (PAH) and the polar PAC. Other factors impacting the PAC binding may be specific interactions with HA and the ionic strength of the aqueous phase. The technique has been applied to do direct determinations of Koc
TurfPQ, A Pesticide Runoff Model for Turf
Authors: Haith Douglas A. 
Published: June 2010

ABSTRACTEnvironmental assessments of golf courses and other turf systems must often rely on mathematical modeling. However, in the case of pesticide runoff, successful modeling applications are rare. Available models were developed for agricultural applications and have seen very limited testing for turf. TurfPQ is a pesticide runoff model developed exclusively for turf. The model is based on a curve number calculation for runoff volume and linear partitioning of pesticide into adsorbed and dissolved components during a precipitation or irrigation event. Calibration is optional, so the model can be applied, using default parameter values, to situations where runoff and chemical loss data are unavailable. TurfPQ was tested with default parameter values for 52 pesticide runoff events involving six pesticides measured in plot studies in four states. The model typically produced conservative overpredictions of pesticide runoff, particularly with strongly adsorbed pesticides. Mean predicted pesticide runoff was 3.2% of application, compared with an observed mean of 2.1%. TurfPQ captured the dynamics of the pesticide runoff events well with R2 = 0.76. Sensitivity analyses indicated that prediction errors could be reduced by better estimates of adsorption parameters and runoff curve numbers. However, even with default parameters, TurfPQ predictions are at least as accurate as those produced by more complex models.
Endosulfan Transport: II. Modeling Airborne Dispersal and Deposition by Spray and Vapor
Authors: Raupach M.R. , Briggs P.R. , Ahmad N. , Edge V.E. 
Published: June 2010

ABSTRACTEndosulfan (C9H6O3Cl6S; 6,7,8,9,10,10‐hexachloro‐1,5,5a,6,9,9a‐hexahydro‐6,9‐methano‐2,4,3‐benzodioxathiepin 3‐oxide) and other agricultural chemicals can be transported from farms to rivers by several airborne pathways including spray drift and vapor transport. This paper describes a modeling framework for quantifying both of these airborne pathways, consisting of components describing the source, dispersion, and deposition phases of each pathway. Throughout, the framework uses economical descriptions consistent with the need to capture the major physical processes. The dispersion of spray and vapor is described by similarity and mass‐conservation principles approximated by Gaussian solutions. Deposition of particles to vegetation is described by a single‐layer model incorporating contributions from settling, impaction, and Brownian diffusion. Vapor deposition to water surfaces is described by a simple kinetic formulation dependent on an exchange velocity. All model components are tested against available field and laboratory data. The models, and the measurements used for comparisons, both demonstrate that spray drift and vapor transport are significant pathways. The broader context, described in another paper, is an integrative assessment of all transport pathways (both airborne and waterborne) contributing to endosulfan transport from farms to rivers.
Pesticide Risk Reduction on Crops in the Province of Ontario
Authors: Gallivan G.J. , Surgeoner G.A. , Kovach J. 
Published: June 2010

ABSTRACTWe analyzed the changes in pesticide use and risk in the Province of Ontario, Canada, from 1973 to 1998 to monitor the success of Food Systems 2002, a program to reduce pesticide use by 50%. Pesticide risk was calculated by multiplying the amount of pesticide used (kilograms of active ingredient) by the Environmental Impact Quotient (EIQ), a score for the potential risk of pesticides to farmworkers, consumers, and the environment. Pesticide use increased by 46% from 1973 to 1983. From 1983, the baseline year for Food Systems 2002, to 1998, pesticide use decreased by 38.5% and risk declined 39.5%. The reductions in pesticide use and risk were primarily on corn (Zea mays L.) and tobacco (Nicotiana tabacum L.), the crops with the highest pesticide use in 1983. Total pesticide use on soybean [Glycine max (L.) Merr.] did not change, but the mean application rate (kg ha−1) decreased by 57%. Corn and soybean account for 65% of pesticide use, but have a relatively low pesticide use and risk per hectare and per tonne of production. Total pesticide use on tobacco, fruits, and vegetables was lower than on corn or soybean, but the pesticide use and risk per hectare were much higher. Small reductions in pesticide use on corn and soybean may allow a 50% reduction in pesticide use, but greater reductions in risk can be achieved by reducing the use of “high risk” pesticides on fruit and vegetables.
Spray Deposition of Two Insecticides into Surface Waters in a South African Orchard Area
Authors: Schulz Ralf , Peall Sue K.C. , Dabrowski James M. , Reinecke Adriaan J. 
Published: June 2010

ABSTRACTDrift from pesticide spray application can result in contamination of nontarget environments such as surface waters. Azinphos‐methyl (AZI) and endosulfan (END) deposition in containers of water was studied in fruit orchards in the Western Cape, South Africa. Additionally, attention was given to the contamination in farm streams, as well as to the resulting contamination of the subsequent main channel (Lourens River) approx. 2.5 km downstream of the tributary stream inlets. Spray deposit decreased with increasing distance downwind and ranged from 4.7 mg m−2within the target area to 0.2 mg m−2at 15 m downwind (AZI). Measured in‐stream concentrations of both pesticides compared well with theoretical values calculated from deposition data for the respective distances. Furthermore, they were in the range of values predicted by an exposure assessment based on 95th‐percentile values for basic drift deposition (German Federal Biological Research Centre for Agriculture and Forestry [BBA] and USEPA). Pesticide deposition in the tributaries was followed by a measurable increase of contamination in the Lourens River. Mortality of midges (Chironomusspp.) exposed for 24 h to samples obtained from the AZI trials decreased with decreasing concentrations (estimated LC50from field samples = 10 μg L−1AZI; lethal distance: LD50= 13 m). Mortality in the tributary samples averaged 11% (0.5–1.7 μg L−1AZI), while no mortality was discernible in the Lourens River samples (0.041 μg L−1). The sublethal endpoint failure to form tubes from the glass beads provided was significantly increased at all sites in comparison with the control (analysis of variance [ANOVA], Fisher's protected least significant difference [PLSD],p< 0.01).
EPIC Tile Flow and Nitrate Loss Predictions for Three Minnesota Cropping Systems
Authors: Chung S.W. , Gassman P.W. , Huggins D.R. , Randall G.W. 
Published: June 2010

ABSTRACTSubsurface tile drains are a key source of nitrate N (NO3–N) losses to streams in parts of the north central USA. In this study, the Erosion Productivity Impact Calculator (EPIC) model was evaluated by comparing measured vs. predicted tile flow, tile NO3–N loss, soil profile residual NO3–N, crop N uptake, and yield, using 4 yr of data collected at a site near Lamberton, MN, for three crop rotations: continuous corn (Zea mays L.) or CC, corn–soybean [Glycine max (L.) Merr.] or CS, and continuous alfalfa (Medicago sativa L.) or CA. Initially, EPIC was run using standard Soil Conservation Service (SCS) runoff curve numbers (CN2) for CC and CS; monthly variations were accurately tracked for tile flow (r2 = 0.86 and 0.90) and NO3–N loss (r2 = 0.69 and 0.52). However, average annual CC and CS tile flows were underpredicted by −32 and −34%, and corresponding annual NO3–N losses were underpredicted by −11 and −52%. Predicted average annual tile flows and NO3–N losses generally improved following calibration of the CN2; tile flow underpredictions were −9 and −12%, whereas NO3–N losses were 0.6 and −54%. Adjusting a N parameter further improved predicted CS NO3–N losses. Predicted monthly tile flows and NO3–N losses for the CA simulation compared poorly with observed values (r2 values of 0.27 and 0.19); the annual drainage volumes and N losses were of similar magnitude to those measured. Overall, EPIC replicated the relative impacts of the three cropping systems on N fate.
Effect of Dissolved Organic Matter from Sludge and Sludge Compost on Soil Copper Sorption
Authors: Zhou L.X. , Wong J.W.C. 
Published: June 2010

ABSTRACTInteraction of Cu with dissolved organic matter (DOM) is an important physicochemical process affecting Cu mobility in soils. The aim of this study was to investigate the effects of DOM from anaerobically digested dewatered sludge and sludge compost on the sorption of Cu on an acidic sandy loam and a calcareous clay loam. In the presence of DOM, Cu sorption capacity decreased markedly for both soils, especially for the calcareous soil. The Cu sorption isotherms could be well described by the Freundlich equation (r2 = 0.99), and the binding intensity parameter of soils in the presence of sludge DOM was lower than compost DOM. An increase in DOM concentration significantly reduced the sorption of Cu by both soils. Within the Cu and DOM concentration range studied, the decrease in Cu sorption caused by sludge DOM was consistently greater than that of compost DOM. This might be attributed to the greater amount of hydrophobic fraction of DOM in the compost. Moreover, the reduction of Cu sorption caused by DOM was more obvious in the soil with higher pH. In addition, the sorption of Cu increased with an increase in pH for both soils without the addition of DOM, while Cu sorption in the presence of DOM was unexpectedly decreased with an increase in pH at a pH >6.8. This implied that DOM produced by sludge or other C‐enriched organic wastes heavily applied on calcareous soils might facilitate the leaching loss of Cu because of the formation of soluble DOM–metal complexes.
Adsorption of Cadmium on Biosolids‐Amended Soils
Authors: Li Zhenbin , Ryan James A. , Chen Jiann‐Long , Al‐Abed Souhail R. 
Published: June 2010

ABSTRACTDebate exists over the biosolid phase (organic or inorganic) responsible for the reduction in phytoavailable Cd in soils amended with biosolids as compared with soils amended with inorganic salts. To test the importance of these two phases, adsorption isotherms were developed for soil samples (nine biosolids‐amended soils and their five companion controls) and two biosolids samples from five experimental sites with documented histories of biosolids application. Subsamples were treated with 0.7 M NaClO to remove organic carbon. Cadmium nitrate was added to both moist soil samples and their soil inorganic fractions (SIF) in a 0.01 M Ca(NO3)2 solution at three pH levels (6.5, 5.5, and 4.5), and equilibrated at 22 ± 1°C for at least 48 h. Isotherms of Cd adsorption for biosolids‐amended soil were intermediate to the control soil and biosolids. Decreasing pH did not remove the difference between these isotherms, although adsorption of Cd decreased with decreasing pH level. Organic matter removal reduced Cd adsorption on all soils but had little influence on the observed difference between biosolids‐amended and control soils. Thus, increased adsorption associated with biosolids application was not limited to the organic matter addition from biosolids; rather, the biosolids application also altered the adsorptive properties of the SIF. The greater affinity of the inorganic fraction of biosolids‐amended soils to adsorb Cd suggests that the increased retention of Cd on biosolids‐amended soils is independent of the added organic matter and of a persistent nature.
Laboratory Degradation Studies of Bentazone, Dichlorprop, MCPA, and Propiconazole in Norwegian Soils
Authors: Thorstensen Christian W. , Lode Olav 
Published: June 2010

ABSTRACTLaboratory degradation studies were performed in Norwegian soils using two commercial formulations (Tilt and Triagran‐P) containing either propiconazole alone or a combination of bentazone, dichlorprop, and MCPA. These soils included a fine sandy loam from Hole and a loam from Kroer, both of which are representative of Norwegian agricultural soils. The third soil was a highly decomposed organic material from the Froland forest. A fourth soil from the Skuterud watershed was used only for propiconazole degradation. After 84 d, less than 0.1% of the initial MCPA concentration remained in all three selected soils. For dichlorprop, the same results were found for the fine sandy loam and the organic‐rich soil, but in the loam, 26% of the initial concentration remained. After 84 d, less than 0.1% of the initial concentration of bentazone remained in the organic‐rich soil, but in the loam and the fine sandy loam 52 and 69% remained, respectively. Propiconazole was shown to be different from the other pesticides by its persistence. Amounts of initial concentration remaining varied from 40, 70, and 82% in the reference soils after 84 d for the organic‐rich soil, fine sandy loam, and loam, respectively. The organic‐rich soil showed the highest capacity to decompose all four pesticides. The results from the agricultural soils and the Skuterud watershed showed that the persistence of propiconazole was high. Pesticide degradation was approximated to first‐order kinetics. Slow rates of degradation, where more than 50% of the pesticide remained in the soil after the 84‐d duration of the experiment, did not fit well with first‐order kinetics.
Application of Calorimetry to Microbial Biodegradation Studies of Agrochemicals in Oxisols
Authors: Critter Silvana A.M. , Airoldi Claudio 
Published: June 2010

ABSTRACTCalorimetry was used to monitor the inhibitory effect caused by the bipyridynium diquaternary salts paraquat, diquat, and phosphamidon on microbial activity in a Red Latosol soil (Oxisol). The thermal effect was recorded on samples composed of 1.50 g of soil, 6.0 mg of glucose, 6.0 mg of ammonium sulfate, and different masses of an inhibitor ranging from zero to 8.00 mg, under a controlled moisture content of 35%. Thermal effects of each pollutant on the degradation curves of glucose in the soil were compared. Increasing amounts of the inhibitor caused a decrease in the thermal effect from −2234 to −1987 kJ mol−1for paraquat, −1670 to −1306 kJ mol−1for diquat, and −2239 to −589 kJ mol−1for phosphamidon. The last xenobiotic agent caused a significant inhibitory effect on the microbial activity of the soil. The results of relative efficiency, η = ΔH/ΔH′, referring to the enthalpic value with (ΔH) and without (ΔH′) agrochemical in the soil, exhibited a significant correlation. From this correlation obtained for the ranges 2.00 to 8.00, 1.30 to 8.00, and 1.20 to 5.80 mg of the agrochemicals paraquat, diquat, and phosphamidon, respectively, the following η values were calculated: 0.993 to 0.894, 0.668 to 0.522, and 0.896 to 0.236, respectively, during the degradation of glucose in the soil. The largest relative efficiency for paraquat implies that this agrochemical can be metabolized by microbial activity.
Phenanthrene Degradation in Soils Co‐Inoculated with Phenanthrene‐Degrading and Biosurfactant‐Producing Bacteria
Authors: Dean Stacy M. , Jin Yan , Cha Daniel K. , Wilson Sviatlana V. , Radosevich Mark 
Published: June 2010

ABSTRACTContaminant sorption within the soil matrix frequently limits biodegradation. However, contaminant bioavailability can be species‐specific. This study investigated bioavailability of phenanthrene (PHE) to two PHE‐degrading bacteria (Pseudomonas strain R and isolate P5‐2) in the presence of rhamnolipid biosurfactant and/or a biosurfactant‐producing bacterium, Pseudomonas aeruginosa ATCC 9027. Pseudomonas strain R mineralized more soil‐sorbed PHE than strain P5‐2, but in aqueous cultures the rate and extent of PHE mineralization by P5‐2 exceeded that by P strain R. In Fallsington sandy loam (fine‐loamy, mixed, active, mesic Typic Endoaquult) (high PHE‐sorption capacity) the addition of rhamnolipid increased PHE mineralization by P strain R. Phenanthrene mineralization in soils inoculated with P5‐2 was minimal and no enhancement in PHE degradation was observed when biosurfactant was added. Co‐inoculation of Fallsington sandy loam with the biosurfactant producer did not affect PHE mineralization by isolate P5‐2, but significantly enhanced PHE mineralization by P strain R. The enhancement of PHE mineralization could not be explained by P. aeruginosa–mediated PHE degradation. The addition of rhamnolipid at concentrations above the critical micelle concentration (CMC) resulted in enhanced PHE release from test soils. These results suggest that the PHE‐degrading strains were able to access different pools of PHE and that the biosurfactant‐enhanced release of PHE from soils did not result in enhanced biodegradation. The results also demonstrated that bacteria with the catabolic potential to degrade sorbed hydrophobic contaminants could interact commensally with surfactant‐producing strains by an unknown mechanism to hasten the biodegradation of aromatic hydrocarbons. Thus, understanding interactions among microbes may provide opportunities to further enhance biodegradation of soil‐bound organic contaminants.
Analysis of Irrigation Systems Using Sustainability‐Related Criteria
Authors: Manoliadis Odysseus G. 
Published: June 2010

ABSTRACTSustainable agricultural development as a desired goal in irrigation management is a result of recent public awareness of the scarcity of water for food production. In order to incorporate sustainability‐related criteria in the analysis of irrigation systems, the present study aims at introducing environmental indices that represent irrigation water conservation and satisfactory production and income for farmers under stress conditions. An experiment was conducted in Chania, Greece, during the irrigation periods of 1989 and 1990. The irrigation water delivered to 40 experimental plots and the relevant soil moisture content at the root zone were recorded. The data, collected in real time, were used for the calculation of the corresponding environmental indices. The variation of indices in time and space was high, and demonstrated that up to 13% of water was delivered to crops, 82% was yield loss, and 84% was economic return. The study indicated that environmental indices could be easily computed by means of routinely collected data, and could also be incorporated into decision‐making approaches, such as compromise programming, in order to develop policies for irrigation water allocation.
Nitrate and Chloride Loading to Groundwater from an Irrigated North‐Central U.S. Sand‐Plain Vegetable Field
Authors: Stites W. , Kraft G.J. 
Published: June 2010

ABSTRACTGroundwater pollution and associated effects on drinking water have increased with the expansion of irrigated agriculture in north‐central U.S. sand plains. Controlling this pollution requires an ability to measure and predict pollutant loading by specific agricultural systems. We measured NO3 and Cl loading to groundwater beneath a Wisconsin central sand plain irrigated vegetable field using both a budget method and a new monitoring‐based method. By relying on frequent monitoring of shallow groundwater, the new method overcomes some limitations of other methods. Monitoring‐based and budget methods agreed well, and indicated that loading to groundwater was 165 kg ha−1 NO3–N and 111 kg ha−1 Cl for sweet corn (Zea mays L.) in 1992, and 228 kg ha−1 NO3–N and 366 kg ha−1 Cl for potato (Solanum tuberosum L.) in 1993. Nitrate N loading was 56 to 60% of available N, or 66 to 70% of fertilizer N. Sweet corn NO3 loading was about typical for this region, but potato NO3 loading was probably 50% greater than typical because heavy rains provoked extra fertilizer application. Our results imply that typical NO3–N loading would be 119 kg ha−1 for sweet corn and 203 kg ha−1 for potato, even with strict adherence to University Extension fertilizer recommendations. To keep average groundwater NO3–N within the 10 mg L−1 U.S. drinking water standard, each irrigated vegetable field would need to be offset by five to eight times as much land supplying NO3–free groundwater recharge.