bluuebunny/crossref_metadata_2025 huggingface dataset:
One‐Time Dormant Season Application of Gas Well Brine on Forest Land
Authors: DeWalle David R. , Galeone Daniel G.
Published: July 2010

Gas well brine was applied to forest land at loading rates of 1.52, 0.69, and 0.17 kg Cl m−2 of ground surface in November 1985 to test the feasibility of one‐time, dormant season brine applications on forest land. The number and species of woody and herbaceous plants on the treated plots and adjacent control plot were measured in July 1985 and July 1986. Both pan and suction lysimeters were used to follow changes in macro‐ and micropore soil water chemistry, respectively, at 70‐cm soil depths. Little mortality of overstory trees occurred in any of the treatments, but the number of understory red maple (Acer rubrum L.) and flowering dogwood (Cornus florida L.) saplings was reduced 30 to 40% on the plot receiving 1.52 kg Cl m−2. Several species of herbaceous plants were also eliminated from all treated plots; however, the majority of understory woody and herbaceous plants survived. Chloride, Ba, Pb, As, Se, and Cd were found in soil water at 70‐cm depths at concentrations exceeding Safe Drinking Water Act limits immediately after brine application. Concentrations of elements in macropore soil water declined to safe levels within 3 mo of treatment, except for Se. Micropore soil water, extracted under negative pressures, remained at or slightly above Safe Drinking Water Act limits for As, Se, Ba, and Cd 8 mo after treatment. Mobility of Pb and Cd in the soil appeared to be enhanced by complexation of these metals with Cl in the brine.
Streams in the New Jersey Pinelands Directly Reflect Changes in Atmospheric Deposition Chemistry
Authors: Morgan Mark D.
Published: July 2010

The major ion chemistry of precipitation and four undisturbed streams was measured in the New Jersey Pinelands (Pine Barrens) in 1970–1972 and 1984–1988. Over the interval, the sea salt corrected concentration of Ca and SO4 significantly declined in precipitation and all streams. Analytical problems prevented analysis of the change in precipitation H, but H significantly declined in all streams. The change in precipitation and stream water Mg and K was less consistent, but was generally toward lower concentrations in 1984–1988. After examining the potential contribution of analytical artifacts and changes in watershed characteristics and hydrology to these results, it was concluded that the changes in precipitation chemistry was real and resulted in direct changes in stream chemistry between 1970–1972 and 1984–1988. The direct effect of precipitation on stream water chemistry in the New Jersey Pinelands suggests that this region is an ideal locality to investigate future long‐term linkages between precipitation and surface water.
Content and Fractionation of Heavy Metals in Water Treatment Sludges
Authors: Elliott H. A. , Dempsey B. A. , Maille P. J.
Published: July 2010

The composition and distribution of Cd, Cu, Cr, Ni, Pb, and Zn in eight alum and FeCl3 coagulation sludges were investigated using a five‐step chemical fractionation procedure to assess potential impacts following soil incorporation. The mean total metal levels (mg kg−1 dry wt.) for these sludges were Cd (<2), Cu (234), Cr (187), Ni (102), Pb (230), and Zn (557), which are well below maximum allowable levels for land‐applied wastes. Two individual FeCl3 sludges had Ni levels slightly above maximum allowable concentrations. Mean total Cr and Ni concentrations in the FeCl3 sludges were, respectively, 5.4 and 3.1 times the corresponding alum sludge levels, reflecting elevated concentrations in the FeCl3 coagulant. The Cu, Cr, Ni, Pb, and Zn in sludges were predominantly bound within the oxide or silicate components. A small portion of the sludge Cd was in a readily exchangeable form, whereas the dilute acid extractable and organically bound fractions contained the majority of non‐residual Cd. Fractionation results suggest sludge Cd would potentially be mobile under acidic soil conditions, but the total Cd levels were very low (1–2 mg kg−1 compared with an allowable maximum of 25 mg kg−1). Although fractionation data must be interpreted cautiously, the results suggest most metals in water treatment sludges occur predominantly in weakly mobile, nonbioavailable forms.
Treatment of Chlordane‐Contaminated Water by the Activated Rotating Biological Contactor
Authors: Sabatini David A. , Smith John W. , Moore Larry W.
Published: July 2010

The insecticide chlordane (1,2,4,5,6,7,8,8‐octachloro‐2,3,3a,4,7,7a‐hexahydro‐4,7‐methanoindene) has been detected as a contaminant in groundwaters and surface waters. This study investigated the removal characteristics of chlordane using the activated rotating biological contactor (ARBC). Chlordane concentrations ranged from 0.1 to 4.6 mg/L with organic supplement levels of 500 and 175 mg/L of BOD5. The chlordane removal efficiencies ranged from 75 to 96% and the organic removal efficiencies (BOD5) ranged from 95 to 99%. Shock loadings of chlordane did not significantly hinder chlordane or organic removal efficiencies. Mass balances of the chlordane throughout the study showed 58 to 89% of the influent chlordane was not accounted for in the effluent, the system or waste solids. The relatively low volatility of chlordane and the low adsorption of the chlordane to the biomass indicates biological transformation as the primary removal mechanism in this study.
Sensitivity of Twenty Soybean Cultivars to Simulated Acid Rain
Authors: Banwart W. L. , Finke R. L. , Porter P. M. , Hassett J. J.
Published: July 2010

Efforts to assess the effect of acid rain on soybean [Glycine max (L.) Merr.] have shown variable results. Simulated acid rain has been reported to cause increases, decreases, and no significant effect on yield. Although few parameters were identical among the diverse studies reported in the literature, one common difference was the choice of cultivar. In this study, 20 soybean cultivars were screened to determine their relative sensitivity to simulated acid rain. Soybean was grown in 1984, 1985, and 1986 in field plots in east central Illinois. Plots were protected from ambient rain and treated twice weekly with simulated rain of pH 5.6 (control) or pH 3.0. Early in each growing season visible leaf injury was noted for all 20 cultivars, and level of injury was significantly higher for plants receiving the more acidic treatment (pH 3.0). Average yield for the 20 cultivars was approximately the same when plants were treated with simulated rain of pH 3.0 as when plants were treated with stimulated rain of pH 5.6. Over all 3 yr, the group V cultivars Essex and Forrest yielded more grain and had more chaff dry matter, pods per hectare, and pods per plant with the more acidic pH treatment than with the control treatment. Only ‘Williams 82’ yielded significantly less with the more acidic pH treatment than with the control treatment. The results suggest soybean cultivars may respond differently to applications of highly acidified rainfall, but none of the cultivars tested were extremely sensitive to growth and yield reduction.
Temporal Solubility Trends of Aluminum and Iron Leached from Coal Spoils and Contaminated Soil Materials
Authors: Karathanasis A. D. , Thompson Y. L. , Evangelou V. P.
Published: July 2010

Column leaching experiments were conducted over a period of 5 mo on selected spoil, soil, and sediment samples collected from acid mine watersheds with low buffering capacity in Kentucky. Evaluation of effluent compositions over time suggested that at different stages of leaching these samples may release different levels of Al and Fe. These levels appeared to be controlled by the solubility of characteristic sequences of basic Al‐sulfate, Al‐hydroxide, and alumino‐silicate minerals, or Fe‐sulfate and Fe‐hydroxide minerals, which are sample specific. Jurbanite‐jurbanite, jurbanite‐alunite, and jurbanite‐alunite‐microcrystalline gibbsite appeared to be the dominant mineral sequences controlling the solubility of Al. Similarly, the jarosite‐amorphous Fe(OH)3 and amorphous Fe(OH)3‐goethite sequences appeared to control the solubility of Fe. Alternating water saturation and desaturation cycles appeared to cause more drastic changes in the above relationships than different flow rates simulating rain events of different intensity. The findings suggest that understanding temporal relationships among the sequence of mineral phases controlling Al and Fe solubility is essential for realistic modeling of Al and Fe release into aquifers.
Batch Leaching Studies of Rundle Oil Shale
Authors: Jones David R.
Published: July 2010

The leaching of Fe, Mn, Al, Zn, Cd, Pb, Ni, Cn, As, and Se from samples of raw and retorted Kerosene Creek seam oil shale and Telegraph Creek seam claystone from the Rundle oil shale deposit, Australia, was studied over the pH range 2 to 9.5. Low pH values were used to simulate the effects of possible acidification that might occur by oxidation of pyrite contained in the solids. The variation in leachate composition with pH highlighted the shortcomings of any batch test that seeks to categorize the behavior of a waste material solely on the basis of extraction at a single pH value. In this context, the results provided by the Resource Conservation and Recovery Act (RCRA) toxicity and American Society for Testing and Materials (ASTM) leach tests were compared. The RCRA test would not have identified As as being a potential problem in leachate from the retorted shale because, at pH 5, this element (in the form of arsenate) is strongly adsorbed to the shale matrix. The natural pH of a slurry of this waste is, however, greater than 9. Under these conditions, As is the trace element present in the highest concentrations in the leachate.
Modeling Linked Watershed and Lake Processes for Water Quality Management Decisions
Authors: Summer R. M. , Alonso C. V. , Young R. A.
Published: July 2010

A physically based modeling approach is used to link watershed with lake processes and to simulate their responses to land management and weather conditions. Components of the watershed model, AGNPS (agricultural nonpoint‐source model), are hydrology, erosion, sediment transport, transport of nitrogen and phosphorus, and chemical oxygen demand. Using a cellular structure, runoff, sediment, and chemical variables from the watershed provide input to a lake model. This one‐dimensional model of water bodies simulates temperature stratification, mixing by wind, sedimentation, inflow density current, and algal growth. Unsteady advection‐diffusion equations characterize the dynamics of suspended sediment, soluble and sediment‐attached N and P, and chlorophyll. This model, AGNPS‐LAKE, is driven by random generation of weather conditions on a daily basis. Resulting impacts of alternative management plans are simulated by changing agricultural practices and land use, thereby modifying inflow characteristics to a lake. Modeling capabilities are being tested on eutrophic lakes in Minnesota for the purpose of simulating long‐term trends and impacts of best management practices.
Nitrate Leaching from Systematically Tiled Potato Fields in New Brunswick, Canada
Authors: Milburn P. , Richards J. E. , Gartley C. , Pollock T. , O'Neill H. , Bailey H.
Published: July 2010

Flow volumes and NO3‐N concentrations of drain discharge from five systematically tiled, commercial potato (Solatium tuberosum L.) fields were measured from April to December, 1987 and 1988, to assess the potential for NO3‐N leaching associated with current production practices. The sites, located in New Brunswick, Canada, ranged from 3 to 10 ha and varied in fertilizer application rate, cropping practices, rainfall, and duration of data collection (the latter due to site access difficulties in the spring). Three of the five sites were representative of intense potato rotations, whereas the remaining two were representative of land conversions into potato production from more passive, low input production systems. Ten site‐years of data were collected. Drain outflow volumes averaged 75 and 115 mm per unit area in 1987 and 1988, respectively. Considerable drain flow occurred during snowmelt each year before data collection began. Measured NO3‐N concentrations ranged from 1 to 65 mg L−1 and there were substantial changes in NO3‐N concentrations within flow events. The flow‐weighted average annual nitrate concentrations of the drainage effluent, , were ≥ 10 mg L−1 for potato site‐years, regardless of whether the sites were established potato rotation fields or not. The concentrations of the established potato rotation sites also remained > 10 mg L−1 for the first non‐potato year following potato. The concentration of one potato rotation site was more than double that of the other two potato rotation sites. Incubation studies showed the soil at this site had considerably more potential to mineralize N than the other two sites. Total NO3‐N leaching for the potato site‐years for the measured April to December periods ranged from 5 to 33 kg N ha−1. More work, under controlled conditions, is required to determine both dormant and growing season NO3‐N leaching associated with various potato production systems.
Aluminum‐ and Calcium‐Binding Affinities of Some Organic Ligands in Acidic Conditions
Authors: Tam Shuk‐Ching , McColl John G.
Published: July 2010

The Al‐ and Ca‐binding affinities of organic ligands containing carboxylic and/or phenolic groups were studied at pH 4.5, using an ion‐pairing chromatographic technique. The ligands were loaded individually in an anion exchange column and were eluted with a solution containing the pairing ion (Al or Ca). Retention data thus obtained were normalized using data from a NaCl elution (i.e., without the pairing ion) and were used as a measure of binding affinity. At pH 4.5, the Al‐binding affinity of the following combinations of α, β‐ substituent groups was found to decrease in the order: . The Ca‐binding affinity, on the other hand, showed a different order: . The binding of Al to ligands containing the important group combinations is responsible for the more effective Al mobilization in the environment, the extent of Al availability in biological systems and the interference of Al on Fe and Ca.
Aerobic and Anaerobic Degradation of Alachlor in Samples from a Surface‐to‐Groundwater Profile
Authors: Pothuluri J. V. , Moorman T. B. , Obenhuber D. C. , Wauchope R. D.
Published: July 2010

Estimates of pesticide degradation rates in subsoils are needed to improve models predicting pesticide movement to groundwater. Biodegradation rates of the herbicide alachlor [2‐chloro‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide] in surface soil, vadose zone, and aquifer samples collected from a single site near Plains, GA were determined in the laboratory under aerobic and anaerobic conditions. Degradation was described by first‐order kinetics during 126 d of incubation. Under aerobic conditions the halflife (t1/2) of alachlor in the surface soil (t1/2 = 23 d) was less than in the vadose zone (t1/2 = 73 to 285 d) and aquifer samples (t1/2 = 320 to 324 d). Alachlor in anaerobic samples degraded less rapidly in the surface (0 to 0.6 m) and the next deepest (0.6 to 2.4 m) subsoil than under aerobic conditions (t1/2 = 100 and 144 d, respectively). Degradation in anaerobic aquifer samples was very slow (t1/2 = 337 to 553 d). Addition of organic nutrients enhanced aerobic degradation in subsurface soils and one aquifer sample, indicating that nutrient availability limits biodegradation. Total aerobic microbial populations ranged from 6.6 × 103 to 2.5 × 106 cells per gram of soil in the subsoils and aquifer samples, but were not correlated with aerobic or anaerobic degradation rates. The lower degradation rates in vadose zone and aquifer materials may be due to less microbial activity or the absence of alachlor degraders.
Atrazine and Bromide Movement through a Silt Loam Soil
Authors: Starr J. L. , Glotfelty D. E.
Published: July 2010

The movement of agrochemicals through soil to groundwater is affected by soil properties, soil management, timing of leaching events, and kinetics of the transformation processes. This study was conducted to determine the pattern(s) of movement of Br and atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) through a field soil as affected by plow‐ and conservation‐till corn (Zea mays L.), under severe leaching conditions. The soil surface inside double‐ring infiltrometers was sprayed with chemicals, 1 wk later 10 cm of solution was applied under ponded flow conditions, and soll cores removed the next day for chemical analysis. The distribution patterns of Br and atrazine with soil depth were quite similar, with the largest proportion of the chemicals observed in the surface horizon, yet all cores showed some movement of chemicals to the deepest sampling depth (90 cm). However, on average <50% of the applied water, Br, and atrazine could be found. Two quite different processes seem to be involved in the movement of these chemicals through this soil: one‐dimensional movement through the soil matrix and rapid downward movement through macropores—bypassing most of the soil matrix. These and other findings have major implications regarding the potential for contamination of groundwater by agrochemicals.
Behavior of Toluene Added to Sludge‐Amended Soils
Authors: Jin Y. , O'Connor G. A.
Published: July 2010

Toluene is a priority pollutant that can be introduced to soils in a variety of wastes, including some municipal sludges. Laboratory experiments were conducted to study the behavior of toluene in two soils in the presence and absence of municipal sludge. Sludge additions increased toluene adsorption in two soils because of increased organic C content. The source of organic C (soil or sludge) and soil clay content also influenced toluene adsorption. Toluene adsorption‐desorption was reversible in one soil, but slightly hysteretic in the other soil. An air‐flow incubation system was used to evaluate toluene volatilization and degradation. The primary fate of surface‐applied toluene in both soils was volatilization. Toluene volatilization rates were independent of sludge treatments. Toluene degradation was negligible in all treatments because of rapid volatilization losses. Despite increased toluene adsorption in the presence of sludge and reduced volatilization in saturated soils, gaseous transfer dominated all soils and treatments so that no toluene remained after 10 d.
Precipitation Nutrient Inputs in Semiarid Environments
Authors: Emmerich William E.
Published: July 2010

Seasonal and spatial variations in precipitation nutrient inputs were suggested by differences in storm type and air mass origin into southeastern Arizona. Wet precipitation NO3‐N, NH4‐N, PO4‐P, and K inputs were collected at seven sites to determine seasonal and spatial variations in nutrient inputs. Total nutrient inputs and concentrations in summer precipitation were significantly greater than in winter precipitation. Higher summer total inputs and concentrations were attributed to storm type and air mass origin rather than precipitation amount, as summer precipitation accounted for 56% of the precipitation and 79, 69, 66, and 73% of the NO3‐N, NH4‐N, PO4‐P, and K, respectively. Spatial variability in nutrient inputs was limited to specific nutrients, seasons, and sites and attributed to precipitation variability and localized sources. Generally, the air masses and storm types that produced seasonal differences in nutrient inputs and concentrations affected all sites uniformly.
Biodegradation of Land‐Applied Sludge
Authors: Boyle Michael
Published: July 2010

The economic and environmental costs of sludge disposal are escalating rapidly. There is a need to increase the rate of decomposition during and after sludge formation. Sludge formation often determines which environmental factors and enzymatic reactions are effective in further degrading this complex substrate. From activated waste treatment through anaerobic digestion to land application, there is a decrease in the volume but an increase in the stabilization of the remaining organic material. Before we can design better methods for land disposal or “engineer” better microbial decomposers, the limitations of sludge decay must first be addressed.
Nature of Dissolved Organic Matter in the Drainage Basin of a Boreal Humic River in Northern Finland
Authors: Heikkinen Kaisa
Published: July 2010

The nature of dissolved organic matter in river, brook, and peat mining water in the drainage basin of the humic Kiiminkijoki River, located in an area of minerotrophic peatlands in northern Finland in the boreal region, was studied by gel filtration. Special emphasis was paid to changes in the nature of high molecular weight organic Fe‐P colloids that result from peat mining. The river water is organically colored, with high organic matter and Fe concentrations. High apparent molecular weight (HAMW) organic colloids are important for the transport of Fe and P in the basin. The gel filtration data suggest that the DOM in the water consist mainly of fulvic acids (FA), although humic acids (HA) are also important. The proportion of dissolved organic C (DOC) and Fe in the HAMW organic colloids increases with increasing DOC and iron concentrations in the river water. The apparent molecular weight of the DOM is higher than in the lakes in the area of ombrotrophic peatlands in southern Finland. Color in this humic water increases with DOC and Fe concentrations. The effect of Fe on color values can be seen in filtered (<1.2 µm) river water and in all the gel filtration fractions. The results indicate an increase in the mobilization of HAMW organic Fe‐P colloids in the peatlands of the area following drainage and peat mining. The average ratio of Fe to DOC in the HAMW organic fraction is higher in the peat mining water than in the Keihäsoja brook in a natural peaty urea. It is possible that the Fe to DOC ratio in these colloids transported in the river increases following drainage and peat mining, especially under low flow conditions in summer. This may lead to gradual changes in the detritus food webs of the river ecosystem.
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

As 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

Agricultural 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

Leaching 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

The 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

A 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

The 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

Determination 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

Acidity 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

Cohesion 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

The 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

An 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

This 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

A 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

The 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

Growth 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

Given 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.
Sulfometuron Persistence and Movement in Soil and Water in North Dakota
Authors: Lym Rodney G. , Swenson Orval R.
Published: July 2010

The lateral movement, soil persistence and aqueous hydrolysis of sulfometuron [2‐([{[(4,6‐dimethyl‐2‐pyrimidinyl)amino]carbonyl]} amino]sulfonyl)‐benzoic acid] was evaluated. Sulfometuron applied at 140 g a.i. ha−1 from slopes to nontarget areas was minimal and was not detected in the 0‐to‐30‐cm‐soil depth, when sampled up to 120 cm downslope from the treated area on 2, 8, or 16% slopes 1 yr after treatment. The highest sulfometuron concentration found downslope from the treated area was less than 1 µg kg−1 regardless of the slope. Sulfometuron moved beyond the soil column (70 cm deep) in Fairdale loam [fine‐loamy, mixed (calcareous), frigid, Mollic Udifluvents], Felor silty clay loam (fine‐loamy, mixed, Typic Agriborolls), and Barnes stony loam (fine‐loamy, mixed, Udic Haploborolls) soils when leached with 45.7 cm of water for 48 h compared to only 35 to 50 cm deep when leached with the same amount of water over 9 wk. Solfometuron degradation increased as soil temperature and moisture increased. Sulfometuron was detected for an average of 429 d in Felor silty clay loam at pH 6.1, 8°C, and 45% field capacity but only 218 d in the same soil at 90% field capacity and 16°C. Degradation was slower in Renshaw and Sioux sandy loam [(undifferentiated soil mixture) fine‐loamy over sandy or sandy skeletal, mixed Udic Haploborolls and sandy‐skeletal, mixed Udortheutic Haploborolls] with a pH of 7.4 and averaged >700 d, regardless of environmental conditions. Sulfometuron hydrolysis was similar regardless of solution pH with an average of 63% 14C‐sulfometuron remaining after 28 d in water at pH 5, 7, and 9. The average halflife of 14C‐sulfometuron was 31 and 65 d in ultraviolet‐irradiated and dark control samples, respectively.