bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tillage Effects on Sediment and Soluble Nutrient Losses from a Maury Silt Loam Soil
Authors: Blevins R. L. , Frye W. W. , Baldwin P. L. , Robertson S. D. 
Published: July 2010

AbstractAs the role of nonpoint‐source contamination of surface waters becomes more evident, increasingly more attention is focused on the effects of agricultural practices on soil erosion and water quality. Tillage systems are known to affect the amount of water moving over the surface and through the soil. This study compared the contributions of three tillage systems used in corn (Zea mays L.) production with (i) sediment losses and surface runoff and (ii) the potential for nonpoint‐source surface water pollution from N and P fertilizers and triazine herbicides. Tillage treatments were no‐tillage, chisel‐plow tillage, and conventional tillage (moldboard plow plus secondary tillage). The study site was on a Maury silt loam (Typic Paleudalfs). Over the 4‐yr period, conventional tillage runoff volume was 576.7 kL ha−1, chisel‐plow 205.7 kL ha−1, and no‐tillage 239.9 kL ha−1. Total soil loss from conventional tillage was 19.79 Mg ha−1, chisel plow 0.71 Mg ha−1, and no‐tillage 0.55 Mg ha−1. Amounts of NO−3, soluble P, and atrazine leaving the plots in surface runoff were greatest from conventional tillage and about equal from chisel‐plow and no‐tillage. The magnitudes of the losses in surface runoff water were small for all chemicals measured.
Nitrogen Status of Forest Floor, Soils, and Vegetation following Municipal Wastewater Sludge Application
Authors: Aschmann S. G. , McIntosh M. S. , Angle J. S. , Hill R. L. , Weil R. R. 
Published: July 2010

AbstractAgricultural land near urban areas is commonly used as disposal sites for municipal wastewater sludge. As available agricultural land decreases in the Northeast, the feasibility of applying sludge to established hardwood forests is increasingly being considered. A major concern with this practice is the potential for the large quantities of nitrogen in sludge to be detrimental to the forest ecosystem. The objective of this study was to evaluate changes in nitrogen storage in several components of a hardwood forest amended with municipal sludge. In June 1986, aerobically digested liquid sludge was surface applied to a Maryland hardwood forest at rates of 0, 3, 6, and 12 dry Mg ha−1, corresponding to nitrogen Ioadings of 0, 200, 400, and 800 kg N ha−1, respectively. Soils from the 0 to 10 and 10 to 20 cm soil depth were analyzed for extractable NO3‐N and NH4‐N in the spring and fall of 1986 and 1987. Standing litter, litterfall, and leaves of five overstory and seven understory species were analyzed for total nitrogen annually. The first year following sludge application, total extractable nitrogen in the surface 10 cm of soil ranged from 28 mg kg−1 soil in the control to 125 mg kg−1 under the 800 kg N ha−1 treatment. Within two years, total extractable N in the soil surface was not significantly different among treatments. Nitrogen concentration in litterfall increased with increasing sludge rates but only during the second year after sludge was applied. Nitrogen in the standing litter of the 800 kg N ha−1 increased in response to sludge the first year after application, indicating that decomposition was accelerated in sludge‐treated plots. The second year after sludge application, foliar nitrogen concentration was increased with increasing sludge rate in two of five tree species and four of seven understory species. The total nitrogen uptake was small compared with the total available nitrogen. Low rainfall in 1986 and 1987 may have limited nitrogen uptake by the vegetation.
Leaching of Chlorsulfuron and Metsulfuron Methyl in Three Swedish Soils Measured in Field Lysimeters
Authors: Bergström Lars 
Published: July 2010

AbstractLeaching of the herbicides chlorsulfuron (2‐chloro‐N‐[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)aminocarbonyl]benzenesulfonamide) and metsulfuron methyl (methyl 2‐[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)aminocarbonyl]‐aminosulfonyl]benzoate) was studied using field lysimeters containing either undisturbed soil monoliths or packed soil. Three soil types were represented, two sandy soils and one clay soil. Each herbicide was applied at two rates, 4 and 8 g a.i. ha−1, representing normal and double doses of the compounds for spring cereals. All lysimeters received supplementary watering in addition to natural rainfall. With the exception of a single sample that had a chlorsulfuron concentration (14 ng L−1) just above the detection limit, neither compound was detectable in leachate from lysimeters receiving the normal dose of the herbicides. For both herbicides at double dose, levels above the minimum detectable were found in selected lysimeters, reaching 43 and 21 ng L−1 for chlorsulfuron and metsulfuron methyl, respectively. Converted to fluxes over the 7‐mo period, considerably less than 1% of the applied chlorsulfuron and metsulfuron methyl appeared in leachate.
Evaluating Pesticide Migration in Tile‐Drained Soils with a Transfer Function Model
Authors: Utermann J. , Kladivko E. J. , Jury W. A. 
Published: July 2010

AbstractThe interpretation and prediction of chemical outflow in tile drains as a result of solute migration through both unsaturated and saturated soil can be an important tool for understanding and reducing groundwater pollution risk. A simple analytical solution for predicting pesticide transport in tile‐drained soils, based on the transfer‐function concept, is presented and tested in screening scenarios for chemicals with widely varying fate properties under different hypothetical transport characteristics for the individual soil layers. The inherent soil travel time variability of the two layers is embodied in probability density functions (pdf). The unsaturated zone is represented by either a unimodal or a bimodal pdf, the latter describing both preferential and matrix flow of solutes at the field scale. The saturated travel time pdf is derived from cumulative travel time distributions calculated by streamline functions. Sensitivity analysis focused on chemical outflow in tile drains as a function of travel time variability in the unsaturated and saturated soil, assuming linear equilibrium adsorption and first order decay in either the entire soil or the preferential and/or slow flow regions of the unsaturated soil, respectively. The tile drain outflow clearly reflects the time‐delayed travel time characteristics of the unsaturated soil. Compared with a Gaussian‐like pdf, a bimodal pdf for the unsaturated zone affects primarily the shortest travel times of highly retarded and short‐lived chemicals. Screening scenarios with 10 different pesticides exhibit a strong influence of preferential flow on both the early arrival time in the tile and the total residual mass fraction, whereas the total residence time is nearly independent of travel time characteristics of the unsaturated soil.
Microbial Transformation of 1,2‐Dibromo‐3‐Chloropropane (DBCP)
Authors: Bloom Raanan A. , Alexander Martin 
Published: July 2010

AbstractA once widely used nematicide that is now banned, 1,2‐dibromo‐3‐chloropropane (DBCP), persists in groundwaters and is a significant pollutant in some water supplies. A study was conducted to determine whether a means for the biodegradation of this persistent compound could be devised. DBCP was not converted to organic products, halide, or CO2 in unamended samples of soil, subsoil material, or groundwaters in 60 d, and no microorganism could be isolated that was able to use the compound as a C source for growth. However, cell suspensions of Pseudomonas putida and of bacteria grown in solutions containing chlorinated fatty acids or 3‐chloro‐1‐propanol cometabolized DBCP in the presence of O2 with the formation of halide but not CO2. Pseudomonas putida had the greatest activity. DBCP was also converted aerobically to organic products and CO2 by soil suspensions incubated with methane. The compound was also converted anaerobically to organic products but not CO2 in suspensions of soil, but no anaerobic transformation was observed in samples of groundwater or aquifer solids. We suggest that biological treatment may be used as a means to destroy this pollutant.
Comparison of the Pesticide Root Zone Model Simulated and Measured Pesticide Mobility under Two Tillage Systems
Authors: Sauer T. J. , Fermanich K. J. , Daniel T. C. 
Published: July 2010

AbstractThe USEPA's Pesticide Root Zone Model (PRZM) was evaluated to determine its ability to predict pesticide movement in the unsaturated zone of a Plainfield sand (Typic Udipsamments) profile under no‐till (NT) and moldboard plow (MB) tillage practices. Atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] distribution in the root zone was measured by analysis of soil cores taken from nonirrigated field plots. The mobility of carbofuran (2,3‐dihydro‐2,‐dimethyl‐7‐benzofuranyl methylcarbamate) and chlorpyrifos [O,O‐diethyl‐O‐(3,5,6‐trichloro‐2‐pyridyl) phosphorothioate] was measured using intact soil columns extracted from adjacent field plots and subjected to a typical irrigation schedule. Predicted depth of pesticide penetration, depth to peak concentration, and amount of pesticide leached from the root zone were compared with measured pesticide distributions and leaching patterns. Acceptable agreement between PRZM simulations and measured data was obtained early in the growing season whereas the model generally predicted greater‐than measured pesticide penetration at later sampling dates.
Interference of Soluble Silica in the Determination of Orthophosphate‐Phosphorus
Authors: Ciavatta Claudio , Antisari Livia Vittori , Sequi Paolo 
Published: July 2010

AbstractDetermination of P concentration in dilute solutions is currently Used to assess P loadings to fresh and marine waters from nonpoint sources. The aim was to ascertain possible P overestimates from interferences caused by the presence of silica. The commonly used methods of Murphy and Riley, Dick and Tabatabai, and the Italian “Instituto di Ricerca Sulle Acque” (IRSA) were tested for possible interferences caused by Si/P ratios (1000–5000) similar to those reported to occur in soil solutions and in groundwaters. The three methods overestimated P concentration due to the presence of Si in the solutions, especially if the spectrophotometric readings were taken more than 10 min from the addition of the reagents. The least interference occurred with the procedure of Murphy and Riley, which is therefore recommended.
A Modified Hydrogen Peroxide Oxidation Method for Determination of Potential Acidity in Pyritic Overburden
Authors: O'Shay Tracey , Hossner L. R. , Dixon J. B. 
Published: July 2010

AbstractAcidity that develops in mine spoil after exposure to the environment commonly results from oxidation of iron disulfides, mainly the minerals pyrite and marcasite. It is often necessary to quantify the acid‐producing potential of overburden sediments prior to surface mining or during the reclamation process. To prevent excessive acidity problems from occurring on the spoil surface, or to correct acidity problems that may have occurred after leveling of the spoil, a rapid, accurate, and reproducible potential acidity method is required. Potential acidity determinations made by the rapid peroxide oxidation procedure were highly variable for east Texas overburden samples. Potential acidity determinations of overburden using a modified method were found to be accurate and reproducible. Modifications included grinding of the sample to <149µm, leaching with 1 M CaCl2 to remove residual acid prior to oxidation with H2O2, increasing the volume of H2O2 used to oxidize the sample, the use of Cu as a catalyst to decompose excess H2O2, and the removal of acidity from the sample with 1 M CaCl2 prior to titration. Recovery of standard pyrite addition by the original potential acidity method was 61 to 171% and by the modified method it was 97 to 102%. Potential acidity values obtained from samples using the modified method were compared with potential acidity values calculated from nonsulfate S, pyritic Fe, and total S data. The modified potential acidity method gave the lowest acidity estimate of three alternative methods investigated.
A Conceptual Model of Changes in Root Cohesion in Response to Vegetation Management
Authors: Sidle Roy C. 
Published: July 2010

AbstractCohesion contributed by plant root systems is an important factor in determining the stability of steep, vegetated slopes subject to shallow landslides. The effects of vegetation removal on root cohesion can be simulated by two functional relationships: (i) root deterioration as described by an exponential decay function and (ii) regrowth of newly planted or invading vegetation as described by a sigmoid relationship. The rates of these simultaneous functions determine the temporal changes in net rooting strength. The general root strength model developed in this paper is adapted to specific silvicultural systems such as clearcutting, partial cutting, shelterwood cutting, and thinning. The models simulate the long‐term effects of vegetation management on root cohesion by overlaying the impacts of a prior vegetation removal on a more recent removal. Examples presented for specific silvicultural systems indicate that vegetation and site conditions that promote rapid root strength deterioration and slow regrowth may depress net rooting strength over several management rotations. Progressively shorter clearcut or partial cut rotations can cause a steady temporal decline in root strength. Longer intervals between initial and final shelterwood cuttings promote greater rooting strength than short intervals.
Water‐Soluble Fractions of Heavy Metals during Composting of Municipal Solid Waste
Authors: Leita Liviana , De Nobili Maria 
Published: July 2010

AbstractThe need to assess the limitations of compost use on agricultural soils has created a demand for information on the availability of metals in municipal solid waste compost. This study was done to determine the water‐extractable fractions of Cd, Zn, Cu, and Pb and investigate changes in water‐soluble organic C during the complete composting of a pile of ground municipal solid waste. Samples were collected every 3 to 5 d for 60 d. The progressive increase in total heavy metals concentrations during the composting period was not accompanied by a corresponding increase in the water‐extractable amounts of metals. The water‐extractable fractions of Pb and Zn decreased rapidly with composting time, and a more complex behavior was observed for Cu and Cd. No relationship was found between pH and extractable fractions of all metals, even if higher amounts of Pb and Zn were extracted when the pH of the composting material was below neutrality. Total soluble C concentration of extracts rapidly decreased during the first days of composting. There was a significant correlation between water‐extractable Pb (r = 0.99***) and Zn (r = 0.98**), and water‐soluble C of nonhumic decomposition products. The water‐extractable fraction of Cu was significantly correlated only with water‐soluble humic C (r = 0.94**).1 No correlation was found for the water‐extractable fraction of Cd. The degree of stabilization reached by organic matter appears to be important in determining potential mobility of heavy metals.
Determination of Total Metals in Sewage Sludges by Ion Chromatography
Authors: Basta N. T. , Tabatabai M. A. 
Published: July 2010

AbstractAn accurate and precise ion chromatographic (IC) method for determination of total Cu, Mn, Ni, Pb, and Zn was developed. The method consists of three steps: (i) digestion of the soil sample using HNO3, HClO4, and HF; (ii) extraction of the metals by using dithizone in CHCl3; and (iii) destruction of the metal‐dithizonate complex with HNO3 and determination of the metals by IC. The IC system consisted of a guard (HPIC‐CG5) column and separator (HPIC‐CS5) column followed by postcolumn reaction with 4‐(2‐pyridylazo) resorcinol (PAR) to form colored metal complexes. The absorbance of the metal‐PAR complexes was measured by a UV‐VIS detector at 520 nm. Two different eluents were required for separation of these metals. Simultaneous determination of Cd, Cu, Mn, and Zn was achieved by using an eluent containing 4 mM 2,6‐pyridinedicarboxylic acid and 50 mM HOAc‐NaOAc buffer (pH 4.8). Simultaneous determination of Cu, Ni, Pb, and Zn was accomplished by using an eluent containing 40 mM oxalic acid and 50 mM HOAc‐LiOAc buffer (pH 4.8). Results by the IC method for determination of total Cu, Mn, Ni, Pb, and Zn in several diverse sewage sludges were in good agreement with those obtained by atomic absorption spectrophotometry (AA). Results also showed that the proposed IC method is precise and has the same degree of precision as that of AA. Also, the sensitivity and detection limits of IC for these metals are similar to those of flame AA.
Modeling Selenium Transport in Steady‐State, Unsaturated Soil Columns
Authors: Alemi M. H. , Goldhamer D. A. , Nielsen D. R. 
Published: July 2010

AbstractThis study was conducted to characterize batch adsorption of selenate (SeO2−4), selenite (SeO2−3), and selenomethionine (Se‐CH2CH2CHNH2COOH)2 and transformations of Se in the presence of microbial activity in Punoche loam (fine‐loamy, mixed, calcareous, thermic Typic Torriorthents). The effects of sterilization, enhanced microbial activity, and aerobic vs. anaerobic conditions on the transport of pulse‐fed Se in soil columns were also investigated. Selenate was rapidly leached in the soil columns compared with selenomethionine and selenite both of which invaded the columns to only a limited extent. Adsorption was highest for selenite and least for selenate. Selenate was transformed to reduced and less mobile forms when soil was C‐enriched, particularly with smaller water fluxes and under anaerobic conditions. Systems of partial differential equations (PDEs) involving equilibrium adsorption of Se are set up to simulate transport of selenate, selenite, and selenomethionine under sterilized conditions. The transport model is solved by an iterative procedure using a finite difference scheme. Experimentally determined adsorption parameters of selenite and selenomethionine did not produce a satisfactory fit when used in simulation of these Se species in column studies. The Se transport model adequately simulated Se concentrations in soil solution under sterilized conditions when the adsorption coefficients derived from batch experiments were adjusted. No transport modeling was considered for nonsterilized conditions.
Identification of Copper Contamination in Sediments by a Microscale Partial Extraction Technique
Authors: Mesuere Karel , Martin Rachel Edelstein , Fish William 
Published: July 2010

AbstractA H2O2/HNO3 microscale extraction procedure is described for the partial removal of metals from sediments. The procedure is carried out at room temperature for approximately 24 h, and requires only 50 mg of dried sample and 1 mL of extraction solution for a single extraction. The characteristics of the procedure were investigated in detail for Cu‐contaminated sediment samples taken from stormwater runoff detention ponds and a background soil sample. The H2O2/HNO3 microextraction was compared to a more commonly employed HCl extraction. Taken collectively the data indicate that the procedure extracts Cu in excess of native levels in a systematic way over the range of total Cu concentration investigated. Copper concentrations derived by this method appear to be useful indicators of anthropogenic contamination provided an appropriate background sample is used to determine native levels of Cu.
Trace Metal Movement in an Aeric Ochraqualf following 14 Years of Annual Sludge Applications
Authors: Dowdy R. H. , Latterell J. J. , Hinesly T. D. , Grossman R. B. , Sullivan D. L. 
Published: July 2010

AbstractThe potential for movement of sewage sludge‐borne trace metals beyond the zone of soil incorporation poses a real concern for society. To address this concern, we sampled an Aeric Ochraqualf (Blount Series) after 14 yr of massive, sludge additions (765 Mg ha−1 cumulative sludge applications, dry wt. basis). Cadmium, Zn, and Cu concentrations in each genetic horizon to a depth of 1.0 m were determined by atomic absorption spectroscopic analyses of 4.0 M HNO3 extracts. In addition, ped surfaces (cutans) and intra‐ped material (s‐matrix) from prismatic structural units of the lower B and upper C horizons were analyzed to determine the partitioning of trace metals in this highly structured profile. Cadmium concentrations in the subsoil of sludge‐treated areas were consistently and significantly higher (∼0.4 mg kg−1) than levels present in the control areas. Similarly, Zn concentrations in the 0.32 to 0.51 m region (Bt1) were increased (∼12 mg kg−1) with sludge applications; no increases in Cu levels were observed. Significantly more Cd (0.08 mg kg−1) was present in cutans removed from ped surfaces in the upper B horizon than was observed in the s‐matrix for sludge‐treated areas. Cutans also contained more sludge‐borne Zn than the associated s‐matrix. The evidence suggests that small amounts of sludge‐borne Cd and Zn moved out of the tillage zone into the subsoil of this highly structured agricultural soil over a 14‐yr period of massive sludge additions.
Long‐Term Correlations between Mining Activity and Levels of Lead and Cadmium in Tree‐Rings of Eastern Red‐Cedar
Authors: Guyette Richard P. , Cutter Bruce E. , Henderson Gray S. 
Published: July 2010

AbstractGrowth increments of eastern red‐cedar (Juniperus virginiana L.) from sites in the Pb mining district of southeast Missouri were subjected to multielemental analysis. Three chronologies, two of Pb and one of Cd, were constructed from heartwood growth increments of 27 trees on sites in the mining district and on control sites. No significant increases in Pb and Cd were found in growth increments of trees on control sites. Lead in the xylem of trees growing in acid soils of the mining district increased from 3.1 µmol kg−1 in growth increments formed before 1900 to 7.8 µmol kg−1 in increments formed after 1900. Cadmium was detected in 46% of the wood formed after 1900 vs. 3% of the wood formed before 1900. Lead and Cd were found only in wood grown on acid soils (pH <4.6) and not in wood grown in more basic soils. Lead and Cd concentrations in growth increments are found to be highly correlate with Pb production. Lead in sapwood was also found to correlate with soil pH on acid sites in both the mining district and in the control sites.
Biodegradability of Polyhydroxybutyrate(co‐hydroxyvalerate) and Starch‐Incorporated Polyethylene Plastic Films in Soils
Authors: Barak Phillip , Coquet Yves , Halbach Thomas R. , Molina J. A. E. 
Published: July 2010

AbstractGiven the extremely low rates of microbial decomposition of most common plastics, the manufacture of biodegradable plastics is of interest as a means of managing the solid waste stream, as well as for specialty applications in pharmaceuticals and agriculture. In order to evaluate the biodegradability of several plastics commercially developed for enhanced biodegradability, plastic films of two types—(i) polyhydroxybutyrate copolymerized with hydroxyvalerate (PHBV) and (ii) low density polyethylene (LDPE) incorporated with a starch filler—were incubated for 44 d under moist, aerobic conditions in two soils, an acid sand and a calcareous sandy loam. Biodegradability of the plastics was evaluated based on evolution of CO2‐C upon incubation and by microscopic examination after 44‐and 150‐d incubation under the same conditions. Biodegradation of polyhydroxybutyrate films ranged from 5% to near complete biodegradation during the 44‐d incubation, depending on soil type, film thickness, and the nature of chemical additives to the polymer. Granules of embedded starch exposed at the surface of starch‐incorporated polyethylene films were degraded within 14 d, after which no further biodegradation could be detected; no gross deformations of the plastic film were associated with the loss of surface starch.