bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Beneficial Use of Wood‐Fired Boiler Ash on Oat and Bean Growth
Authors: Krejsl J. A. , Scanlon T. M.
Published: July 2010

An evaluation on the effects of pulp and paper mill combined boiler ashes on growth and nutrient uptake by oat (Avena sativa L., var. 501) and bean (Phaseolus vulgaris L., var. blue pole) was conducted in a greenhouse. Ash with a calcium carbonate equivalent of 29.1% and a pH of 12.1 was applied at the rates 30, 40, and 50 dry Mg ha−1 to Chehalis silty clay loam (fine‐silty, mixed, mesic Cumulic Ultic Haploxerolls), with pH 5.4. An agricultural dolomitic lime treatment of 7.4 Mg ha−1 and a nonamended control were also included. Plants grown on ash‐amended soil had higher biomass compared to plants grown on lime and control treatments. Ash treatments 30, 40, and 50 dry Mg ha−1 increased the bean (stems and leaves) dry matter (DM) yield over the control by 49, 57, and 64%, respectively. The lime treatment increased the bean DM yield by 31% compared with the control. The ash rate 30 dry Mg ha−1, equivalent to the recommended agronomic lime rate 7.4 Mg ha−1, increased oat (shoots) DM yields over the control by 45%, while the lime treatment increased biomass by 8% over control. The highest ash treatment, 50 Mg ha−1, produced the lowest oat biomass. The ash was as effective as dolomitic lime in raising soil pH. Ash‐amended soils contained higher concentrations of P, S, and B for plant growth compared to lime and nonamended soils. Soil Zn, Fe, Mn, and Cu concentrations decreased as ash application rates increased. Oat and bean plants grown in the ash‐amended soil had increased concentrations of K, S, and B and decreased concentrations of Mn and Cu compared with plants grown in the nonamended control soil. Overall, oat and bean benefited from the increased nutrient availability and soil pH caused by the application of boiler ash.
Optimizing Nitrogen and Irrigation Inputs for Corn Based on Nitrate Leaching and Yield on a Coarse‐Textured Soil
Authors: Sexton B. T. , Moncrief J. F. , Rosen C. J. , Gupta S. C. , Cheng H. H.
Published: July 2010

A study was conducted on a Verndale sandy loam soil (coarse loamy over sandy, mixed, frigid Udic Argiboroll) during 1991 and 1992 at Staples, MN, to assess the influence of irrigation scheduling and N source and rate on corn (Zea mays L.) yield and nitrate leaching. Nitrogen sources were urea and turkey manure. Soils were irrigated to field capacity (i) at a fixed trigger deficit throughout the season, or (ii) at a variable trigger deficit based on crop growth stage. Leaching losses were calculated from measured daily fluxes of water percolation and soil water NO3‐N concentrations and from a seasonal N mass balance. Based on yield response curves, maximum corn grain yields were obtained at 202 and 234 kg N ha−1 urea in 1991 and 1992, respectively. This resulted in growing season leaching losses of 72 and 55 kg N ha−1 in 1991 and 1992, respectively. The rate at 95% of the maximum crop yield is suggested to substantially reduce nitrate leaching past the root zone. Using this guideline, nitrate leaching would be reduced by 35% compared with nitrate leaching at the maximum yield. When a variable available water deficit was used to schedule irrigation compared with a fixed deficit schedule (at 95% of maximum yield N rate), nitrate leaching was reduced 46%. At equivalent N rates, turkey manure produced equal or greater crop yields as that from urea applications; however, nitrate leaching was equal to or less than urea.
Atrazine Concentrations in Near‐Surface Aquifers: A Censored Regression Approach
Authors: Liu Shiping , Yen Steven T. , Kolpin Dana W.
Published: July 2010

In 1991, the U.S. Geological Survey (USGS) conducted a study to investigate the occurrence of atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) and other agricultural chemicals in near‐surface aquifers in the midcontinental USA. Because about 83% of the atrazine concentrations from the USGS study were censored, standard statistical estimation procedures could not be used. To determine factors that affect atrazine concentrations in groundwater while accommodating the high degree of data censoring, Tobit models were used (normal homoscedastic, normal heteroscedastic, lognormal homoscedastic, and lognormal heteroscedastic). Empirical results suggest that the lognormal heteroscedastic Tobit model is the model of choice for this type of study. This model determined the following factors to have the strongest effect on atrazine concentrations in groundwater:percent of pasture within 3.2 km, percent of forest within 3.2 km (2 mi), mean open interval of the well, primary water use of a well, aquifer class (unconsolidated or bedrock), aquifer type (unconfined or confined), existence of a stream within 30 m (100 ft), existence of a stream within 30 m to 0.4 km (0.25 mi), and existence of a stream within 0.4 to 3.2 km. Examining the elasticities of the continuous explanatory factors provides further insight into their effects on atrazine concentrations in groundwater. This study documents a viable statistical method that can be used to accommodate the complicating presence of censored data, a feature that commonly occurs in environmental data.
Bromide and Nitrogen‐15 Tracers of Nitrate Leaching under Irrigated Corn in Central Nebraska
Authors: Kessavalou Anabayan , Doran John W. , Powers William L. , Kettler Timothy A. , Qian Jin H.
Published: July 2010

Nitrate leaching from agricultural fields into groundwater has caused environmental and health concerns. A study was conducted during 1992–1993 in the Central Platte Valley of Nebraska to assess the nitrate leaching potential under recommended center‐pivot irrigation and fertilizer best management practices for continuous corn (Zea mays L.). At time of planting corn, potassium bromide (KBr) and double‐labeled 15N ammonium nitrate (10 atom% 15NH415NO3) tracers were applied at rates of 200 kg Br ha−1 and 30 kg N ha−1 to four 6.1 by 3.7 m plots that were representative of major soil types on the 32.1‐ha field. Soil and plants sampled 7 wk after planting and at harvest in 1992, and in the spring of 1993, were analyzed for Br and N content and a mass balance was determined. At corn harvest, 41% (81.9 kg ha−1) of the applied Br loss from the top 1.2 m of soil was attributed to leaching. Also, 54% (16.2 kg ha−1) of the tracer applied was lost from the system; 41% (12.3 kg ha−1) through leaching; and 13% (3.9 kg ha−1) through denitrification and volatilization. By time of planting in the spring of 1993, 70% (139.3 kg ha−1) of the applied Br and 46% (13.8 kg ha−1) of the fertilizer N leached below 1.2 m. High negative correlations were found between soil clay and silt contents, and Br or NO3 leaching. Despite use of best management practices for irrigation water and N applications, large amounts of nitrate can be lost through leaching under irrigated corn in this subhumid climate on fine‐ to medium‐textured soils.
Chemistry and Phytotoxicity of Soil Trace Elements from Repeated Sewage Sludge Applications
Authors: Berti W. R. , Jacobs L. W.
Published: July 2010

Municipal sewage sludges, or biosolids, can be applied to croplands to supply and recycle nutrients and organic C. Trace elements in sludges, however, may be of environmental concern. This study examines the long‐term consequences to crops and soil when loading phytotoxic levels of one or more trace elements to cropland. Municipal sewage sludges containing trace elements, including high concentrations of Cd, Cr, Cu, Pb, Ni, and Zn, were applied to cropland from 1977 to 1986 at three rates plus an untreated control. Plant and soil samples were collected between 1985 and 1990. These results report on yield and metal uptake of corn (Zea mays L.), sorghum‐sudangrass (Sorghum bicolor L. Moench × S. sudanese P. Stapf.), and soybean (Glycine max L.). Yields of all crops were reduced on one or more sludge treatments because of phytotoxic concentrations of soil trace elements, probably Zn and Ni. Phytotoxicity has continued since the last sludge application. Chemical fractionation of surface soils was performed using a sequential extraction technique and trace elements were measured in each of eight fractions. Cadmium, Ni, and Zn occupied soil fractions that were potentially available for plant uptake. Copper and Cr loadings increased the environmental availability of these two elements to a smaller extent. Loadings of Pb to the levels seen in this study did not appear to significantly increase its environmental availability. The Toxicity Characteristic Leaching Procedure (TCLP) and guidelines used to characterize hazardous wastes were inappropriate to use when testing soils for potential phytotoxic concentrations of trace elements or uptake of these elements into the food chain.
Stabilization of Lead in Acidic Mine Filtercake by Addition of Alkaline Tailings
Authors: Davis Andy , Link Timothy E. , Baugh Kim , Witham Richard
Published: July 2010

The potential for disposal of acidic Pb‐bearing process waste in an alkaline tailings pond was assessed to ascertain if Pb would become stabilized as opposed to diluted during mixing. This study demonstrated that codisposal of the filtercake residue, consisting of ferrihydroxide, lead sulfate and lead oxide phases (pH = 6.2, Pb = 43 000 mg/kg), with tailings containing abundant calcium and strontium carbonate (pH = 9.8, Pb = 2400 mg/kg) would result in Pb stabilization. The leachable Pb was greater (p < 0.05%) for a sand‐filtercake mixture compared with the tailings‐filtercake at analogous ratios, demonstrating reactivity between filter cake and tailings. Stabilization occurs because abundant remnant calcite in the tailings neutralizes the acidic filtercake, facilitating sorption of Pb to ferrihydroxide at the pH of the filtercake/tailings mix and a >98.5% decrease in Pb solubility. Sorption (KdPb = 28 600 at pH 7.7) and possible precipitation of Ce‐Pb and Ln‐Pb oxides limit Pb solubility. These data suggest that disposal of acidic filtercake in an alkaline tailings pond would reduce Pb solubility to levels below relevant environmental standards.
Decomposition of Biosolids in a Disposal Site Soil
Authors: Gilmour John T. , Roman Fernando , Clark Mark D.
Published: July 2010

The objectives of this study were to determine if residual biosolids in a disposal site soil altered fresh biosolid decomposition and characterize the decomposition behavior of the residual biosolids in that soil. This information is requisite to predicting the impact of residual biosolids on release of N via net N mineralization from fresh and residual biosolids at the disposal site. Aerobically digested municipal sewage sludge from Laredo, TX, was incubated in LaGloria silty clay loam soil (coarse‐silty, mixed, hyperthermic fluventic Ustochrepts) from three locations within the disposal area. Sites 1 and 2 had been amended with biosolids at disposal rates of 647 and 418 Mg ha−1, respectively, over a 7‐yr period while Site 3 was the control. Carbon dioxide evolution was monitored for 62 d and decomposition of fresh biosolid was evaluated using first‐order kinetics for simultaneous and sequential decomposition models. Decomposition of the “active” and “total” residual biomass pools was also assessed. Decomposition of the fresh biosolid was characterized as a two phase (rapid and slow fractions) process. The rate constants for these phases and percentages of biosolid in the rapid fraction were independent of previous additions for this biosolid/soil combination. The active pool or the residual biosolid that was most labile was from 6 to 10% of the total residual biosolid C pool. First‐order rate constants for the total pool of residual biosolids approached those that have been used for more labile portions of soil organic matter.
Retention of Zero‐Valent Iron Colloids by Sand Columns: Application to Chemical Barrier Formation
Authors: Kaplan Daniel I. , Cantrell Kirk J. , Wietsma Thomas W. , Potter Margaret A.
Published: July 2010

Chemical barriers are an emerging technology used for the in situ remediation of groundwater. They are placed in the subsurface environment perpendicular to groundwater flow where they selectively remove targeted groundwater contaminants while permitting water and other nontargeted constituents to pass through freely. A novel approach to emplacing chemical barriers is by the injection of zero‐valent iron (Fe0) colloids into the subsurface. The objective of this study was to determine the effect of influent Fe0 colloid concentration and injection rate on colloid retention by columns of sand. Suspensions of Fe0 colloids (2 ± 1 µm) were injected into coarse‐grain sand that simulated a simplified aquifer matrix. Influent colloid injection rate (P ≤ 0.01) and concentration (P ≤ 0.05) had a significant effect on colloid retention by the sand. Efficiency of the column to retain colloids decreased as the concentration of retained colloids increased. Colloids were uniformly distributed throughout 1‐m long columns at concentrations >3 g kg−1. Based on filtration theory, gravitational settling was clearly the primary mechanism controlling colloid retention; diffusion, electrostatic attraction, and interception were less important mechanisms. These results were rationalized as follows: the high density of the colloids (7.6 g cm−3) enhanced gravitational settling, the fast experimental flow rates minimized diffusion, the weak surface charge of the colloids and sediments minimized electrostatic attraction, and the small size of the colloids relative to the sand particles (640 µm) minimized interception.
Stream Channel Changes Associated with Mining and Grazing in the Great Basin
Authors: Sidle Roy C. , Sharma Ashish
Published: July 2010

Characteristics of channel morphology and streambed sediment were sampled at 5‐ and 10‐m intervals, respectively, along a 6.4‐km reach of Birch Creek in 1989 and 1992. In this case study we evaluate changes in these channel features using kernel regression analysis. The watershed is located high in the Toiyabe Mountains of central Nevada and has experienced historical grazing and more recent (1986–1989) mining for gold. Exclusion of grazing in the incised lower 1 km of the channel since 1990 did not lead to substantial geomorphic recovery by 1992. The bankfull width did decrease a bit in the grazing exclosure, but baseflow width increased. In both years, bankfull width was about 4 m greater in the exclosure compared with the upstream reaches, reflecting the long‐term grazing influences. The shift of grazing pressure into wet riparian areas upstream apparently caused decreases in thalweg depth, increases in fine sediment deposition in the channel, and loss of pool volume in these upstream areas. Some of these changes in substrate sediment could be attributed to inputs from the mine dumps; however, since either fine sediment did not increase or D50 did not decrease in the vicinity of the mines, the changes appear to be more related to recent changes in grazing patterns. Increased fine deposition also occurred in reaches with high volumes of large woody debris. Because of the episodic nature of peakflows that occur in the Great Basin, it may take many years for the full impacts of mining and grazing to be assimilated by the fluvial and riparian systems.
Retention of Inorganic Carbon‐14 by Isotopic Exchange in Soils
Authors: Sheppard S. C. , Evenden W. G.
Published: July 2010

Carbon‐14 is present naturally and is a waste product of the nuclear industry. It is readily incorporated into biological materials and potential impacts have to be considered carefully. From underground waste repositories, much of any 14C released will be inorganic and will pass rapidly through most terrestrial environments because of gaseous transfer. However, there will be some 14C retained in soils, in both organic and inorganic forms. This study addresses retention of inorganic 14C through isotopic exchange with soil carbonates. An outdoor study with incubations lasting up to 24 mo was conducted. A carbonated sandy soil was used unamended, amended with additional carbonate, or amended with ground alfalfa (Medicago sativa L.). One set of soil containers was left open and another set gamma‐sterilized and sealed. Volatilization of some of the 14C happened within minutes, with 98% lost in the alfalfa‐amended soils and 56% lost in the carbonate‐amended soil. However, the fractions remaining in all the soils had residence half‐times of over 1000 d. Much of this retained 14C was still inorganic and had undergone isotopic exchange with the solid 12C minerals in the soil. A progressive extraction method was used to monitor the degree of isotopic exchange, and in certain treatments the exchange process was still measurably progressing after 12 mo of incubation. Clearly, assessments of the impacts of 14C releases to the terrestrial environment must account for these long‐term reactions and retention of 14C in soils.
Assessing Soil Quality for Environmental Purposes: Roles and Challenges for Soil Scientists
Authors: Sims J. T. , Cunningham S. D. , Sumner M. E.
Published: July 2010

Soil quality is emerging as an issue of vital importance to the use and management of land, water, and air. Clearly, we must maintain soils in a clean state that is suitable for agriculture, that minimizes the pollution of water and air, and that allows for the safe and productive use of wastes and by‐products as soil amendments. We must also remediate many unclean soils that have been severely impacted by anthropogenic activities. It can be argued that to sensibly approach these complex tasks we must first begin to develop a consensus on the proper means to assess soil quality from an environmental perspective. In doing so we must recognize that conceptual and mechanistic interpretations of soil quality will vary with the intended use of the land and will not always be the same for nonagricultural and agricultural systems. Measures of soil quality important for environmentally sound agronomic crop production will not always be the most appropriate for contaminated soils where cost‐effective remediation is often the primary objective. This paper raises some fundamental questions about the changing role of soil scientists who now must contribute more than ever to the research, technology transfer, and public policy critical to soil and environmental quality. The need for soil scientists to take a proactive role in framing, from all perspectives, the debate on soil quality and environmental issues is emphasized, as is the need for new approaches to quantify the environmental risks posed by soils in agricultural and nonagricultural settings.
Heavy Metal Displacement in a Sandy Soil at the Field Scale: II. Modeling
Authors: Streck Thilo , Richter Jörg
Published: July 2010

Although several studies have tested leaching models on field‐scale data, a comparable case study on heavy metal transport has not yet been undertaken. Data concerning heavy metal displacement after 29 yr of controlled wastewater irrigation were used to compare several simple modeling approaches to predict total and solution phase concentration profiles in the soil. Approaches employed comprise parallel soil column (PSC) models and the application of the convection dispersion equation at the field scale (CD). The PSC simulations were either realized by one‐dimensional (ID) simulations at points in the field where soil properties had been determined experimentally (grid model; GM) or by the Monte‐Carlo (MC) method. Sorption was described with an extended Freundlich equation as a function of the spatially variable soil properties organic C content and pH. The CD simulations were based on conventional sorption isotherms of mixed samples determined in laboratory batch experiments. Cadmium profiles predicted by the PSC models agree very well with measured profiles, while leaching of Zn was somewhat underestimated. Grid model and MC simulations yielded largely similar results if correlation of random variables was considered in the MC simulations. In the PSC simulations no parameters were fitted to the measured concentration profiles. Agreement between CD simulations and measured data could only be achieved by adjusting the dispersion length to a value in the upper range of values found in the literature.
Heat and Water Transfer in Compacted and Layered Soils
Authors: Nassar I. N. , Horton Robert
Published: July 2010

Clay material is frequently used to cover landfills or to line hazardous waste disposal landfills. The cover of a landfill is usually exposed to solar radiation, which can cause desiccation and shrinkage of the landfill cover. This study presents two nonisothermal conditions (small and large surface temperature amplitudes) to evaluate heat and water transfer in closed soil columns. The small surface temperature amplitude ranged from 1.0 to 11.0°C, and the large surface temperature amplitude ranged from 15.0 to 16.0°C. Both uniformly compacted and layered soil columns were exposed to small temperature amplitudes, but large temperature amplitudes were used only with uniformly compacted soil columns. Clarinda clay (fine, montmorillonitic, mesic Vertic Argiaquoll) and Fayette silty clay loam (fine‐silty, mixed, mesic Typic Hapludalf) soils were moistened to initial gravimetric water contents of 0.281 and 0.187 kg kg−1, respectively. The moistened soil was packed into polyvinyl chloride columns (0.75 m in diameter and 0.30 m long). For uniform compacted soil columns, the bulk densities were 1.45 and 1.67 Mg m−3 for Clarinda and Fayette soils, respectively. In the layered soil columns, the bulk densities of the upper layers (0.05 m thick) were similar to the densities in uniform compacted soil. The bulk density of the lower layers (0.25 m thick) was 1.0 Mg m−3. A numerical model of coupled heat and water transfer predicted soil temperature and water distributions well in comparison with the measured distributions for all of the conditions. Predicted net water transfer in layered soil revealed that thermal water transfer is significant in comparison with isothermal water transfer.
Nitrate Leaching from Soil Core Lysimeters Treated with Urine or Feces under Orchardgrass: Measurement and Simulation
Authors: Jabro J. D. , Fales S. L. , Fox R. H. , Stout W. L.
Published: July 2010

The ability of the N submodel, LEACHN, of the Leaching Estimation And CHemical Model (LEACHM model) to simulate nitrate‐nitrogen (NO3‐N) leaching from orchardgrass (Dactylis glomerata L.) pasture was evaluated using field data from a 2‐yr experiment. Leaching data were collected from an experiment conducted in central Pennsylvania on Hagerstown silt loam soil (fine, mixed, mesic, Typic Hapludalf). Nitrate losses below the 1‐m depth from N‐fertilized orchardgrass sod were measured with intact soil core lysimeters (0.6‐m diam. by 1‐m long). Five N fertilizer treatments consisted of a control, urine application in the spring, urine application in the summer, urine application in the fall, and feces application in the summer. Calibration N transformation rate constants from previous work with inorganic fertilizer and manure treatments under corn were used to evaluate the LEACHN model under pasture conditions. Statistical analysis indicated that the model accurately predicted annual NO3‐N leaching below the 1‐m depth for three to five of the five treatments in each year. The model failed to produce accurate predictions for the control and feces treatments in 1993 to 1994. The simulation error in these two treatments appeared to be related to soil N transformation rate constants in the model. Other reasons for discrepancies between measured and simulated NO3‐N leaching for some months may have been due to restricted water flow associated with frozen soil or a heavy snowpack during winter. Results demonstrate the potential of the LEACHN model to predict NO3‐N leaching under pasture conditions using N transformation rate constants determined through the calibration process from corn (Zea mays L.) fields on similar soils.
The Sorption of Pyrene and Anthracene to Humic Acid‐Mineral Complexes: Effect of Fractional Organic Carbon Content
Authors: Onken B. M. , Traina S. J.
Published: July 2010

Carbon‐normalized distribution coefficients (Koc) of organic solutes appear to increase as the amount of organic C in a system decreases. This study was conducted to determine the effect of fractional organic C content (foc) on the sorption of anthracene and pyrene. Batch‐sorption experiments were conducted on reagent CaCO3, a geologic calcite, and a montmorillonite to measure anthracene and pyrene sorption. An organic C‐free mineral surface and two surface loadings of humic acid (HA) were evaluated. The Koc of anthracene and pyrene varied with foc as well as with the underlying mineral surface. The sorption of anthracene and pyrene to all HA‐mineral complexes increased with increases in foc, while Koc for the compounds decreased. In higher foc systems (>3 × 10−5), isotherms were C‐type curves indicative of partitioning. In lower foc systems (<3 × 10−5), isotherms were commonly L and S‐type curves indicative of adsorption and condensation. Sources of potential experimental artifact examined were loss of HA from the mineral surface to solution, dissolution of CaCO3 during the experiment, and loss of NOS to experimental glassware or volatilization. None were found to contribute to the observations made. Our results suggest that adsorption‐condensation of pyrene and anthracene created more surface excess than predicted by partitioning alone as evidenced by the large experimental Koc values obtained.
Modification of AGNPS for Agricultural Land and Climate Conditions in Central Germany
Authors: Rode M. , Frede H.‐G.
Published: July 2010

Until recently, no suitable computer model was available to quantify P and N yields of nonpoint sources into surface water in central German watersheds. The event‐based erosion and nutrient transport model AGNPS (Version 3.65), developed in the USA, was adapted to central German landscape conditions and linked to a GIS. Drawing on a 2‐yr program of water quality measurements and on hydrologic data collected during 33 yr, this modified model was tested in two medium‐sized agricultural watersheds in the state of Hesse, Germany. With deviations of 1.7 and 3.8%, runoff volumes for all observed and simulated flood events showed a high level of agreement in both watersheds. Peak flows showed larger errors averaging 14.8 and 24%. Only for one of the two watersheds were sediment and total P yield computed satisfactorily, with average errors of 5% (sediment) and 6% (total P). Deviations for the second watershed were considerably greater. The same is true for the dissolved P and N yields. In the case of small events, AGNPS consistently overestimated the particulate P yield in both watersheds. However, the model correctly registered the overall dynamics of the system as well as the differences of sediment and total P yield between the two watersheds. The modified AGNPS model can thus be employed by environmental agencies as a useful planning tool.
Thermotolerant Clostridia as an Airborne Pathogen Indicator during Land Application of Biosolids
Authors: Dowd Scot E. , Widmer Kenneth W. , Pillai Suresh D.
Published: July 2010

Since biosolids could harbor a variety of potentially infectious microorganisms, there are concerns of human exposure to these microbial pathogens in population centers surrounding sites where biosolids are land applied. A field study was conducted at a large commercial biosolid application site to determine if thermotolerant clostridia could be employed as a microbial indicator in determining the presence of such fecal contamination in aerosols. Even though the applied biosolids harbored as much as 107 MPN fecal and total coliforms per gram wet weight, these traditional indicators were undetectable at locations having the greatest potential for aerosolization. Thermotolerant clostridia and bacteriophages, however, were detectable in 73% and 53% of the samples, respectively. Hydrogen sulfide producing bacteria as a group, were detected in 93% of the samples. Even at sites directly in the vicinity of the biosolid application, thermotolerant clostridia were detected in 26% of the samples, as compared with the fecal and total coliforms which were detected in only 1 out of 15 (6.6%) samples. Since municipal sewage sludges usually undergo anaerobic digestion before land disposal, it would favor the selection of thermotolerant clostridia within these biosolids. Moreover, clostridla also could be ribotyped using the 16S–23S interspacer region length polymorphism to identify the origins or sources of aerosol contamination. Thermotolerant clostridia could thus serve as a reliable indicator to determine the presence of microbial pathogens and biosolid derived microbial populations in aerosols being generated from biosolid application programs.
Cloudwater and Precipitation Chemistry at Popocatepetl Volcano: A High Elevation Site
Authors: Baez A. P. , Belmont R.D. , Azpra E. , Torres M. B. , Padilla H. G.
Published: July 2010

Cloud and rain water were collected at Tlamacas (3900 m above sea level), a site on the northern flanks of Popocatepetl volcano, 70 km southeast of Mexico City. Ten cloud events were sampled in September 1992 (five from 9–11 September, five from 29–30 September), eight from 19–21 July (1994) and three from 25–26 July (1995). During 9 to 11 September, cloud production was orographic, while during 29 to 30 September cloud production was associated with a cold front. On 19 to 21 July 1994 and 25 to 26 July 1995, cloud production was orographic. The results showed that cloudwater had a higher ionic concentration than rainwater, with two exceptions, in agreement with previous studies.

The ionic concentrations in cloud and rain water seem to indicate a clear dependency on air mass origin and trajectories. Clouds in which back trajectories show passage over zones with little or no pollution produced cloudwater with low ionic concentrations (29 and 30 September).

On 10 Sept. 1992, the winds had a strong easterly component, eliminating significant contamination from crater fumaroles. This meteorological situation yielded extremely clean rainwater.
Changes in Microbial Activity after Abandonment of Cultivation in a Semiarid Mediterranean Environment
Authors: Garcia C. , Roldan A. , Hernandez T.
Published: July 2010

Several organic matter fractions together with biological and biochemical parameters that might serve as markers of microbial activity were determined in an area previously dedicated to agriculture but where the soils had been abandoned for different lenghts of time (3 to 45 yr). Recently abandoned agricultural soils showed lower organic matter levels than soils not exposed to anthropic activity (natural soils). During the years immediately following abandonment the soils show lower levels of total organic C, humic substances and labile fractions of organic matter than natural soils. Soils abandoned for longer than 15 yr begin to recover their organic fractions after the appearance of spontaneous vegetation. The lower slopes appear to accumulate a greater quantity of total organic C and some labile fractions of C, such as water soluble C. Soil abandonment has a negative influence on soil microbial activity, biomass C and oxidoreductases such as dehydrogenase and catalase, although these values begin to rise again after several years. Soils abandoned for long periods of time and in the process of recovery show higher oxidoreductase values than natural soils. The activity of hydrolases belonging to the N, C, and P cycles (ureases and proteases, β‐glucosidase, and phosphatase) point to the negative influence of the agricultural practices, indicating that human activity does not favor adequate establishment of the cycles of these important nutrients. The cessation of agricultural activity leads to the recovery of soil hydrolase activities. Except in isolated cases, the hydrolase activities values determined did not appear to be affected by the position on the slope of the plot from which the samples were taken.
Potential Movement of Dithiopyr following Application to Golf Courses
Authors: Hong Song , Smith A. E.
Published: July 2010

Research was conducted to evaluate the potential movement of dithiopyr [S,S‐dimethyl2‐(difluoromethyl)‐4‐(2‐methylpropyl)‐6‐(trifluoromethyl)‐3,5‐pyridinedicarbothioate] from golf courses. Dithiopyr was applied as granule and emulsifiable concentrate (EC) formulations to ‘Penncross’ creeping bentgrass (Agrostis stolonifera L.) and ‘Tifdwarf’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] in simulated greens. Less than 0.6% of the dithiopyr was transported through the rooting media (a mixture containing at least 97% coarse sand by weight with sphagnum peat moss). Dithiopyr concentrations in the leachate, transported through the greens, did not exceed 3 µg L−1. Most of the dithiopyr (11–31%) was detected in the top 0 to 12.5 cm of rooting media at the end of the greenhouse experiments and as much as 20% of the applied dithiopyr was removed with the leaf clippings over the duration of the greenhouse experiments. The highest concentration of dithiopyr transported in the runoff water from simulated golf course fairways did not exceed 40 µg L−1. Generally, the concentration of dithiopyr in the runoff water was higher when applied as an EC formulation compared with the granule formulation at 1 d after treatment (DAT). The dithiopyr concentration, in the runoff water, had decreased to near 9 µg L−1 at the 8 DAT sampling period and less than 2.0% of the applied dithiopyr was transported from the simulated fairways.
Sorption and Desorption of Atrazine, Deethylatrazine, and Hydroxyatrazine by Soil and Aquifer Solids
Authors: Moreau C. , Mouvet C.
Published: July 2010

Adsorption kinetics and adsorption/desorption isotherms of atrazine (AT), and its degradation products, deethylatrazine (DEA) and hydroxyatrazine (HyA) on solids from two depths of a gleyic planosol and the underlying sandy aquifer were studied using laboratory batch systems. Adsorption of the three molecules decreased with the sampling depth of the solid. Atrazine and DEA were not adsorbed on the aquifer solids, whereas HyA was. For all three solids, the adsorption increased in the order DEA < AT << HyA. Adsorption equilibrium was reached after 72 h for the upper soil sample (0‐0.33 m) and after 24 h for the deeper soil sample (0.9–1.05 m) for all three molecules. For HyA, equilibrium was reached after 24 h for the aquifer solid (6–7 m). High pressure liquid chromatography (HPLC) analyses showed no significant degradation of the three molecules after 72 h. The adsorption isotherms of the three molecules were described by Freundlich equations. The Kfads values ranged from 3.1 to 0.4 L kg−1 for AT, 1.5 to 0.3 L kg−1 for DEA and 7.9 to 0.9 L kg−1 for HyA. The Koc values suggested that the affinity for the organic matter bound to the solid increased in the order DEA < AT << HyA. The desorption isotherms were also described by Freundlich equations. The Kfdes value was 7.5 L kg−1 for AT in the upper soil sample and ranged from 0.1 to 31.1 L kg−1 for DEA and from 0.7 to 96.8 L kg−1 for HyA, depending on the sample. In the upper soil sample, desorption was hysteretic and DEA and HyA formed nonextractable residues, HyA more so than DEA. For the deeper soil sample for all three compounds and the aquifer solids for HyA, adsorption was completely reversible and did not lead to the formation of nonextractable residues.
Destruction of 2,4,6‐Trinitrotoluene by Fenton Oxidation
Authors: Li Z. M. , Comfort S. D. , Shea P. J.
Published: July 2010

Past disposal practices at munitions production facilities have generated numerous acres of 2,4,6‐trinitrotoluene (TNT)‐contaminated soil. We determined the potential of the Fenton reagent (Fe2+ and H2O2) to remediate TNT contamination in water, aqueous extracts of contaminated soil, and soil‐water slurries. The effects of H2O2 and Fe2+ concentrations, solution pH, temperature, and initial TNT concentration on transformation and mineralization rates were evaluated. Treating an aqueous TNT solution (70 mg TNT L−1) with Fenton reagent (1% H2O2, 80 mg Fe2+ L−1) in the dark resulted in 100% destruction of TNT within 24 h. This coincided with 40% mineralization. Subsequent exposure to light resulted in >90% mineralization. We observed generation of 2,4,6‐trinitrobenzoic acid and 1,3,5‐trinitrobenzene within 15 min following Fenton oxidation of TNT. This indicates that initial TNT destruction likely occurs by methyl group oxidation and decarboxylation. Subsequent transformations involve nitro moiety removal with ring hydroxylation and cleavage, as evidenced by the stoichiometric recovery of TNT‐nitrogen as NO−3 and production of oxalic acid as the primary C‐containing end product. Upon exposure to light, Fe(II) was regenerated and the oxalate produced from 14C‐TNT oxidation disappeared; this coincided with a decrease in solution 14C activity. Similar observations were made when 14C‐oxalic acid was the starting substrate. Fenton oxidation was also effective in destroying TNT in aqueous extracts of contaminated soil and soil‐water slurries. Experimental data provide evidence that the Fenton reagent can effectively remediate TNT‐contaminated water and soil.
Anaerobic Transformation of Alachlor, Propachlor, and Metolachlor with Sulfide
Authors: Stamper David M. , Traina Samuel J. , Tuovinen Olli H.
Published: July 2010

The purpose of this work was to elucidate microbiological and abiotic transformations relevant to the environmental fate of the acetanilide herbicides alachlor [2‐chloro‐2′,6′‐diethyl‐N‐methoxymethyl)acetanilide], propachlor (2‐chloro‐N‐isopropyl‐acetanilide), and metolachlor [2‐chloro‐2′‐ethyl‐6′‐methyl‐N‐(1‐methyl‐2‐methoxyethyl)‐acetanilide]. Several attempts to retrieve aerobic and anaerobic microbial cultures capable of degrading alachlor from agricultural soils and pond sediments were unsuccessful with the exception of sulfate‐reducing bacteria that partially transformed acetanilide herbicides during active sulfate reduction. The transformation products of alachlor and propachlor were more hydrophobic than the parent compounds. The transformations were associated with the activity of sulfate‐reducing bacteria because the reactive species was sulfide and possibly other reduced S species produced during the bacterial reduction of sulfate. Transformation could be duplicated under abiotic conditions by reacting Na2S with alachlor, propachlor, and metolachlor. One of the reaction products of the abiotic reaction between alachlor and sulfide was identified by mass spectroscopy as a S‐substituted dimer of alachlor. This compound was formed by the nucleophilic substitution of chloride by reduced S, with the subsequent oxidation to a disulfide.
Consequences of Rising Atmospheric Carbon Dioxide Levels for the Belowground Microbiota Associated with White Oak
Authors: Ringelberg David B. , Stair Julia O. , Almeida Jonas , Norby Richard J. , O'Neill Elizabeth G. , White David C.
Published: July 2010

The consequences for belowground microbiota under conditions of rising atmospheric CO2 are largely unknown. In this research we examined the microbiota associated with white oak (Quercus alba L.). It was our hypothesis that an increase in CO2 level would induce a change in the rhizosphere‐associated microbial abundance and community composition. To provide an in situ estimation of microbial abundance and community composition, ester‐linked polar lipid fatty acid (PLFA) technology was utilized. This technology, based on the quantitative measurement of membrane lipid fatty acids, has been utilized in the accurate identification and description of bacterial isolates and communities. Initial experiments demonstrated that a clear distinction in lipid patterns and microbial biomass existed between sterile roots and those of roots containing an associated viable microbiota. Statistical approaches were then used to determine what differences existed between individual PLFA and PLFA patterns obtained from white oak fine roots and bulk soils. An analysis of variance (ANOVA) showed significant differences to exist in the relative percentages of individual prokaryotic PLFA collected under ambient vs. elevated CO2 and between those associated with fine roots and bulk soils. Multivariate statistics showed distinct differences in the patterns of prokaryotic PLFA detected in the rhizosphere vs. the surrounding bulk soil, but did not identify differences related to elevated CO2 exposures. An artificial neural network recognized PLFA patterns unique to three different CO2 exposures: ∼35, ∼50, and ∼65 Pa. Results of the three statistical tests were viewed as supportive of the hypothesis describing significant differences in individual PLFA and patterns of PLFA as a result of elevated CO2 exposure.
Spatial Variability of Canopy Throughfall and Groundwater Sulfate Concentrations under a Pine Stand
Authors: Böttcher J. , Lauer S. , Strebel O. , Puhlmann M.
Published: July 2010

Calculation of solute flux into groundwater by recharge must account for the spatial variability of water flux and recharge solute concentration. Solute concentration of the recharge can be characterized by sampling the uppermost groundwater. In an earlier study under pine (Pinus silvestris L.) on sandy soil, solute concentrations at the water table along a transect fluctuated in a recurrent pattern, probably caused by heterogenous solute input via canopy throughfall. To obtain more insight into the spatial variability of deposition processes and solute concentrations in recharge, transect sampling of the uppermost groundwater was repeated in 1989, and again in 1993. Solute deposition by throughfall was also measured in 1993. The data were analyzed by spectral and time series methods. Sulfate (SO4) concentrations in canopy throughfall and uppermost groundwater showed recurrent fluctuations corresponding to canopy coverage of the ground. Sulfate maxima coincided with canopy edges. The dominant fluctuation frequency of SO4 concentrations in 1993 was lower than in 1989 because of canopy enlargement by pine tree growth. Detailed analysis of the 1993 SO4 concentrations revealed superimposed fluctuations with a frequency valid for the 1989 canopy edge distribution. This can be attributed to an actual patterned SO4 retrieval from solid aluminum‐hydroxo‐sulfate (Al‐OH‐SO4) phases, stored in the subsoil under previous higher SO4 deposition rates.
Trace Metal Geochemistry in Spodosols of the Northeastern United States
Authors: Jersak Joseph , Amundson Ronald , Brimhall George
Published: July 2010

Long‐term or postglacial (≈ 12 000‐year) net fluxes of Pb, Cu, Zn, Ni, Cr, and Co through three Spodosols, formed from different parent materials, were calculated using mass‐balance modeling. Metal contents in vegetation and O horizons were also estimated and measured, respectively. Total metal contents in mineral horizons were fractionated into different operationally defined pedogenic phases using a sequential extraction technique. With few exceptions, the three soils had significant leaching losses for all trace metals (from 7–508 kg ha−1), the greatest losses generally occurring in the E and upper horizons. The magnitude of losses by leaching varied with parent material, as a result of differences in weatherabilities of mineral suites. Combined metal contents in vegetation and O horizons, which may originate from anthropogenic additions as well as mineral weathering, are significantly large in some cases; however, these metal amounts are apparently not large enough to offset long‐term leaching losses from the underlying mineral soil profiles. Some B and C horizons had net accumulations of extractable Pb, Cu, and/or Ni‐bearing phases. Based on the sequential extraction procedure used, the extractable metal forms are probably pedogenic Fe oxide‐ and/or organic‐bound phases. One soil apparently gained Cu (≈38 kg ha−1), which may have been from atmospheric deposition.
A Novel Approach Using Solid Phase Extraction Disks for Extraction of Pesticides from Water
Authors: Koskinen W. C. , Barber B. L.
Published: July 2010

Pressures to reduce hazardous solvent use in traditional procedures for pesticide extractions from water have increased the use of solid phase extraction (SPE) technology. We have expanded the use of SPE disks beyond the procedural techniques previously used. Pesticides are sorbed onto preconditioned SPE disks placed directly into the water in the sample collection bottle and then eluted off the disks by solvents in the same bottle, bypassing the laboratory extraction process and reducing costs by eliminating the need for expensive vacuum filtering glassware. We determined atrazine (6‐chloro‐N‐ethyl‐N′‐[1‐methylethyl]‐1,3,5‐triazine‐2,4‐diamine), acetochlor (2‐chloro‐N‐[ethoxymethyl]‐N‐[2‐ethyl‐6‐methylphenyl]acetamide), and alachlor (2‐chloro‐N‐[2,6‐diethylphenyl]‐N‐[methoxymethyl]acetamide) recovery from water as a function of contact time, degree of mixing, and disk size. Shaking 47‐mm C8 extraction disks in 500 mL water for 20 h, followed by elution with ethyl acetate in the same sample collection bottle, resulted in >70% recovery of the three herbicides (1 µg L−1) compared to >90% recovery for atrazine achieved with traditional vacuum‐filtering extraction. This research suggests a simpler approach for pesticide extraction from water samples compared to current methods, and may allow for in‐field extraction of some pesticides.
Postwar Nitrogen Use Efficiency in West German Agriculture and Groundwater Quality
Authors: van der Ploeg R. R. , Ringe H. , Machulla Galina , Hermsmeyer D.
Published: July 2010

Rising NO3 concentrations in groundwater are of general concern in Germany. To estimate the role that agriculture has played in this contamination, national statistical data on fertilizer and fodder use and on agricultural productivity for 1951 to 1990 were analyzed. With use of assumptions about the N content of fertilizers, fodder, and agricultural products, an attempt was made to estimate the yearly N turnover and N‐use efficiency in West German agriculture during this period. The analysis showed that from 1951 to 1990 the use of commercial N fertilizer increased from 27.4 to 107.8 kg ha−1 and of N present in animal feeds from 72.4 to 158.0 kg ha−1. At the same time, the estimated N content of farm produce only increased from 24.1 to 57.2 kg ha−1. As a consequence, agricultural N surplus increased from 7.2 kg ha−1 in 1951 to 94.6 kg ha−1 in 1990. The analysis also showed that during the 1951 to 1990 period, N‐use efficiency in crop production decreased from 100% in 1951 to 81.4% in 1990. Nitrogenuse efficiency in livestock production changed little and varied time‐independently between 12.4 and 17.3%. For agriculture as a whole, N‐use efficiency decreased from 77.0% in 1951 to 38.0% in 1990. The results indicate that low N‐use efficiency in livestock production, together with an excess of farm manure, is the main reason for the NO3 problem that Germany is facing.