bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphate and Trace Metal Availability from Sewage‐Sludge Incinerator Ash
Authors: Bierman Peter M. , Rosen Carl J.
Published: July 2010

Incineration is practiced to reduce sewage sludge volume, but disposal of the resulting ash remains an important waste‐management problem. The objectives of a field study conducted from 1987 to 1990 were to evaluate sewage‐sludge‐incinerator ash as a P fertilizer, determine trace metal availability, and assess the liming potential of the ash. The soil was an Estherville sandy loam (sandy, mixed, mesic Typic Hapludoll) with an initial pH of 5.7. Treatments compared P rates of 35, 70, and 140 kg ha−1 yr−1 from triple‐superphosphate fertilizer with equivalent ash rates based on citrate‐soluble (available) P. A control receiving no P application was included. Field corn (Zea mays L.) was grown the first 3 yr and sweet corn was grown in 1990. Limited effects on growth occurred the first 2 yr, but in 1989 and 1990 both ash and phosphate fertilizer significantly increased yield. Yield response to ash was equivalent to phosphate fertilizer for 1989 field corn, but significantly less for sweet corn in 1990. Ash and phosphate fertilizer both increased tissue P concentrations, but phosphate fertilizer was the more effective P source. Olsen's soil P extractant provided a more useful measure of plant available P than Bray P‐1 for ash‐amended soil. Ash increased diethylenetriaminepentaacetic‐acid (DTPA) extractable Cu, Zn, and Cd in the 0‐ to 15‐cm soil depth and slightly buffered soil pH. Concentrations of Cu and Zn in plant tissue were consistently higher, and Mn consistently lower, with ash than with phosphate fertilizer. In 1990, ash also significantly increased tissue Cd and Mo in sweet corn. Tissue trace metal concentrations were not in the range of anticipated phytotoxicity or animal health problems.
Cloudwater and Ozone Effects upon High Elevation Red Spruce: A Summary of Study Results from Whitetop Mountain, Virginia
Authors: Thornton F. C. , Joslin J. D. , Pier P. A. , Neufeld H. , Seiler J. R. , Hutcherson J. D.
Published: July 2010

This paper integrates the results of a number of studies on the effects of cloudwater and ozone (O3) on red spruce (Picea rubens Sarg.) seedlings, saplings, and mature trees at Whitetop Mountain, VA, over a 3‐yr period. These investigations consisted of (i) seedling chamber exclusion studies, (ii) mature tree branch chamber exclusion studies, and (iii) field experiments comparing responses of seedlings, saplings, and mature trees. The studies included treatments that: (i) excluded clouds and O3 (COE), (ii) excluded clouds and had ambient O3 (CE), and (iii) exposed plants to both clouds and O3 either with (CC) or without (AA) chambers. Seedlings and mature branches in the various treatments were compared with respect to growth rates, gas exchange rates, foliar nutrition, and chlorophyll and wax content. Soil solution, throughfall, and foliar responses of mature trees near the summit, receiving differing amounts of cloud exposure (low cloud and high cloud sites) were also monitored. Ozone was found to have minimal effects on the parameters measured, whereas cloudwater exposure was found to have adverse effects on several response parameters. Chambered seedlings that were exposed to cloudwater (AA and CC), and mature trees at the high cloud site had significantly lower foliar Ca and Mg concentrations than their counterparts, which were protected from exposure (seedlings) or received low cloud exposure (mature). A 3 to 5°C increase in cold tolerance was also measured in seedlings from which cloudwater was excluded. These findings suggest that cloudwater‐mediated effects are currently having a negative impact on the health of red spruce, and may be involved in red spruce decline in the eastern USA.
The Nitrogen Filtering Capability of Carolina Poplar in an Artificial Riparian Zone
Authors: O'Neill G. J. , Gordon A. M.
Published: July 2010

The extensive use of inorganic N fertilizers in agricultural operations has been identified as an important source of nonpoint NO3−‐N pollution, contaminating both ground and surface waters. The ability of trees planted in the riparian zone of streams draining agricultural areas, however, to filter NO3−‐N in drainage water and reduce loadings to watercourses has not been proven conclusively. This study evaluated the ability of Carolina poplar (Populus × canadensis Moench) to remove NO3−‐N from a saturated soil zone. An artificial riparian zone was designed to facilitate subsurface movement of NO3−‐N through the rooting zone of trees. A Mariotte container was used to maintain a saturation zone and to deliver two NO3−‐N concentrations (12.0 and 24.6 mg L−1) to the rooting zone. Planting densities of one and two poplar trees per compartment (0.48 m2) were compared with a control with no‐trees. Four sampling locations were used to monitor the NO3−‐N concentration of the soil solution as it moved through the tree rooting zone. The filtering of NO3−‐N from the soil solution followed a quadratic function. The one and two poplar tree densities filtered 11 and 14%, respectively, more NO3−‐N from the saturated soil zone than the control and over time, were able to lower the NO3−‐N concentration in the saturated soil zone over time. Tree roots showed a significant increase in dry weight and TKN% with increasing NO3−‐N concentration. These results indicate the N filtering capability of Carolina poplar with subsequent accumulation of the N in root biomass.
Hexavalent Chromium Extraction from Soils: Evaluation of an Alkaline Digestion Method
Authors: Vitale R. J. , Mussoline G. R. , Petura J. C. , James B. R.
Published: July 2010

The accurate quantification of total Cr(VI) in soils is relevant to human health concerns because Cr(VI) is significantly more toxic than Cr(III). Hot alkaline solution has been shown to extract soluble and insoluble forms of Cr(VI) from soils, but incomplete recovery of Cr(VI) spikes and the oxidation of soluble Cr(III) spikes in certain soils have been suggested as method deficiencies. A laboratory method study was performed to (i) test the method's accuracy, (ii) understand the soil chemical processes responsible for poor Cr(VI) spike recoveries, and (iii) develop definitive interpretations for Cr(VI) spike recovery data. Test results for >1500 field soil samples and the method study of eight diverse soil materials demonstrated dissolution of soluble and insoluble Cr(VI) spikes and the method's reliability for Cr(VI) characterization. Complete dissolution of K2CrO4, BaCrO4, and PbCrO4 spikes confirmed the extraction of soluble and insoluble Cr(VI) forms. Ancillary soil chemical parameters, including oxidation‐reduction potential (ORP) (reported herein as Eh), pH, S2−, and total organic C were quantified and interpreted to explain poor Cr(VI) spike recoveries. Highly reducing samples yielded 0% Cr(VI) spike recoveries, as predicted from Eh‐pH relationships, and unspiked soil samples contained no detectable Cr(VI). In soils containing Cr(VI) and in most aerobic soils without native Cr(VI), acceptable Cr(VI) spike recoveries were obtained. Ancillary parameter characterization demonstrated that strongly reducing samples cannot maintain Cr(VI) laboratory matrix spikes. Correct interpretation of poor Cr(VI) spike recovery data should avoid labeling these data as unacceptable method results without ancillary parameter characterization of such samples.
Soil, Groundwater, and Plant Resources in Sludge‐Treated Bigtooth Aspen Sapling Ecosystems
Authors: Hart James B. , Nguyen Phu V.
Published: July 2010

Sludge fertilization of a 10‐yr‐old coppice bigtooth aspen (Populus grandidentata Michx.) with 500 to 600 kg ha−1 N, and associated nutrients, resulted in plant, soil, and groundwater responses that are important silviculturally, ecologically, and environmentally. Results included: sapling biomass growth responses of 66% over 4 yr; ecologically significant and environmentally acceptable understory, ground flora, and regeneration responses; increased amounts of soil nutrients in available, cycling, and physiologically active forms; storage of nutrients in the forest floor but not the surface and subsurface soil; increased nutrients in soil water; and significant but environmentally acceptable levels of groundwater contamination. Responses are explained as perturbations in normal ecological processes. Aspen growth responses continued after 4 yr, but are expected to moderate to near unfertilized levels unless nutrients are reapplied.
Fate of Bromoxynil n‐Butyrate and iso‐Octanoate Applied as a Mixture to a Wheat Field
Authors: Grover R. , Smith A. E. , Cessna A. J.
Published: July 2010

Dissipation of bromoxynil (3,5‐dibromo‐4‐hydroxybenzonitrile), applied as a 1:1 mixture of the n‐butyrate and iso‐octanoate esters, in the air, crop, and soil components was measured in a spring wheat (Triticum aestivum L.) field, both during and following its application. Drift losses during spraying were <1% of the amount applied, with no phenol derivative being detected in air samples collected during application. Following application, cumulative vapor loss for the n‐butyrate and iso‐octanoate esters (phenol equivalent, p.e.) over the 5‐d postapplication period were estimated to be 16 and 7%, respectively. Little or no free phenol residues were detected in the air above the treated field. The crop canopy intercepted approximately 20% of the application. Ester deposits on plant surfaces were rapidly dissipated with >75% of the total ester residues on the crop being lost or hydrolyzed 24 h after treatment. There were no detectable residues in the seed or straw at harvest. In the soil, the half‐lives of n‐butyrate and iso‐octanoate were <1 and ∼4 d, respectively. Hydrolysis was, however, more rapid under moist soil conditions, with the n‐butyrate being converted more rapidly to phenol than the iso‐octanoate. Phenol breakdown was also moisture dependent but much slower, with >95% dissipation occurring only after 8 wk.
Anakeesta Stream Acidification and Metal Contamination: Effects on a Salamander Community
Authors: Kucken D. J. , Davis J. S. , Petranka J. W. , Smith C. K.
Published: July 2010

We examined how stream degradation can affect adjoining streamside communities by comparing the density, age structure, and microhabitats of salamanders in forests adjoining contaminated and noncontaminated sections of Beech Flats Creek in the Great Smoky Mountains National Park. A section of Beech Flats Creek was contaminated due to exposure of Anakeesta rock formations in 1963. Chronic changes that have occurred since then include a reduction in pH, an increase in metal concentrations, and a nearly complete elimination of all macroinvertebrates, salamander larvae, and fish. Comparisons of control and impacted plots indicate that two stream‐breeding species (Desmognathus quadramaculatus; Eurycea wilderae) have been nearly eliminated from impacted stream sections, while two other species (D. ochrophaeus; D. imitator) that breed in both streams and seepages have been reduced by about half. In contrast, terrestrial‐breeding species (Plethodon jordani; D. wrighti) appear to have increased markedly following the reduction in stream‐breeders. Juvenile P. jordani comprised a significantly greater percentage of the population on impacted plots compared with controls. Microhabitat use on control and impacted plots did not differ significantly for any species. Changes in the densities and age structure of terrestrial breeders on impacted plots may have been due to the elimination of D. quadramaculatus, which is a major predator on other salamanders, or to release from competition with adults of stream‐breeding species. Overall, our data indicate that stream contamination from Anakeesta exposure can alter the structure of streamside salamander communities both by directly eliminating species with biphasic life cycles, and by indirectly altering ecological interactions among community members.
Transport and Retention of Fecal Bacteria at Sewage‐Polluted Fractured Rock Sites
Authors: Malard Florian , Reygrobellet Jean‐Louis , Soulié Michel
Published: July 2010

In 1991 to 1993, a bacteriological investigation was made of the numbers of fecal bacteria present in groundwater of a limestone site located in the Lez Basin, Southern France. Sampling was carried out in closely spaced 60‐m deep wells located on either side of a sewage‐polluted river to determine the spatio‐temporal distribution of total coliforms, fecal coliforms, and fecal streptococci in groundwater. High differences in fecal bacteria concentrations observed between wells were largely attributable to two types of infiltration mechanisms controlling the groundwater recharge. A quick infiltration process promoted channelized flow of bacterial contaminants through large vertical fractures connected to enlarged bedding joints. In such conductive channels, the reduction of fecal bacteria concentrations resulted only from the flushing and dilution ability of groundwater. However, in the less permeable parts of the site, clogging of the small‐sized fissures of the unsaturated zone by sludge particles might reduce the seepage rates and remove bacterial contaminants from percolating water. This straining effect was considered as a temporary retention process because fecal bacteria were eluted by subsequent rainwater percolation. Results of another bacteriological survey carried out on a thinly fissured gneiss aquifer contaminated by percolating sewage from numerous septic tanks also demonstrated that a similar accumulation and elution cycle had to be considered to explain the temporal pattern of well contamination.
Toxic Metal Accumulation from Agricultural Use of Sludge: Are USEPA Regulations Protective?
Authors: McBride M. B.
Published: July 2010

The new USEPA regulations for the use of sewage sludges will permit concentrations of particular toxic metals to increase locally on agricultural land by a factor of a hundred or more above present soil concentrations. Short‐term field experiments have shown that the adsorptive properties of sludges themselves often prevent excessive uptake of many of these metals into crops, a protection attributable largely to the added organic matter. This protection cannot be considered to be permanent or effective for all toxic metals, as indicated by data from old sludged sites. Differences in degree of protection are evident for greenhouse and field experiments, largely attributable to different rooting patterns and degree of sludge mixing in these two situations. The USEPA reliance on field data for metal uptake by corn (Zea mays L.) has led to an underestimation of phytoxicity thresholds applicable to a wider range of crops, in part because corn is able to root deeply and is metal‐tolerant. Also, the decision to use 50% yield reduction and plant top (rather than root) concentrations of heavy metals as phytotoxicity indicators may have obscured incipient toxicity. Long‐term field observations (several decades) often show that sludge‐applied metals can remain sufficiently available, even in nonacid soils when total metal concentrations are below the proposed EPA limits, to harm sensitive crops and microbes. It is concluded that the ultimate impact of toxic metals from sewage sludges at levels approaching the proposed USEPA limits on various soil‐crop systems is potentially harmful.
Reductive Dechlorination of Carbon Tetrachloride Mediated by Cationic Water‐Soluble Metalloporphyrins
Authors: Lewis Thomas A. , Morra Matthew J. , Habdas Jan , Czuchajowski Leszek , Brown Paul D.
Published: July 2010

Microbial degradation of halogenated pollutants in wastewaters may be limited by toxic contaminant concentrations or poor membrane permeability of the target compound. Extracellular catalysts can be used in wastewater treatment schemes to overcome these limitations. Water soluble porphyrins with functional groups suitable for immobilization were synthesized as catalysts for reductive dehalogenation of organic contaminants. Synthesized mesosubstituted porphyrins contained (with one exception) three N‐methyl‐4‐pyridinium substituents and a phenyl substituent having the ‐OH, ‐OCH3, ‐NH2, or ‐C(O)OCH2C6H4‐CH=CH2 group located in the p‐position. Catalytic activity was assessed by measuring carbon tetrachloride disappearance in reactions containing a synthetic porphyrin, dithiothreitol, and tris buffer (pH 8.2). Porphyrins metallated with Co or Ni had higher catalytic activities than those metallated with Fe. Changes in meso substituents also altered catalytic activity, with aminophenyl substitution resulting in porphyrins catalyzing the highest rates of carbon tetrachloride disappearance. Although chloroform, dichloromethane, and carbon monoxide were found to be breakdown products, no methane was detected and <40% of the carbon tetrachloride could be recovered in identified volatile products. When 14C carbon tetrachloride was used as substrate, approximately 80% of the label was found in the aqueous phase of the reaction mixture. Synthetic porphyrins have potential utility in wastewater treatment as catalysts for reductive dehalogenation, but further identification of degradative products is necessary.
Cadmium and Lead Deposition around a Swedish Battery Plant as Recorded in Oak Tree Rings
Authors: Eklund Mats
Published: July 2010

In this study, results from the elemental analysis of Cd and Pb in oak (Quercus robur L.) tree rings are compared with emission estimations based on company and official statistics for the major producer of Ni‐Cd accumulators in Sweden, NIFE. The NIFE plant in Fliseryd was in operation from 1910 to 1974, handling and thereby emitting large quantities of Cd. In 1942, the company also took up recycling Pb from various sources. The Cd and Pb content in control trees, situated far from point sources, varied between 20 and 30 µg/kg without any obvious temporal trend for Cd and 20 to 200 μg/kg with an increasing temporal trend for Pb during the 20th century. These values represent regional background levels resulting from natural and diffuse sources. Cores from 18 trees, situated less than 2 km away from the factory were sampled. The variation in absolute figures between different trees was in some cases large, but the temporal trend within each tree showed a consistent similarity to the trend of the estimated emissions. The Cd values were up to one magnitude higher than in the reference trees, and the highest values were always found in the latest segment, formed from 1980 to 1990. A significant uptake through the roots from the polluted soil after the factory close down must therefore have taken place. The Pb content of the sampled trees in a few cases exceeded 3000 μg/kg, but the highest values were never found in the latest 10‐yr segment. Despite large intertree variation and difficult interpretations, the tree‐ring analysis seems to have great potential as a tool for the study of both temporal and spatial dimensions of historical Cd and Pb emissions.
Old and New Water in Subsurface Flow from a Forest Soil Block
Authors: Turton Donald J. , Barnes Donald R. , de Jesus Návar Jose
Published: July 2010

In order to understand how infiltrating water mixes with water and solutes already present in the soil, percentages of old and new water in subsurface flow from a forest soil block subjected to simulated rainfall were studied. A rainfall simulator was used to apply simulated rainfalls of four intensities 6.3, 4.3, 2.8, and 1.3 cm h−1. Each intensity was repeated four times. Sodium bromide was added to the first replicate, but not the two following replicates to insure that old and new water had different chemical signatures. Subsurface flow was measured at four depths, 14, 26, 44, and 64 cm using a system of collection troughs and tipping buckets. Discrete water samples for bromide analysis were taken at 1‐ to 10‐min intervals throughout each simulation. Old water percentages declined as the block was wetted and reached a minimum when peak subsurface flow was achieved. Minimum old water percentages during the simulations ranged from 0% for the 6.3 cm h−1 simulation to 28% for the 1.3 cm h−1 simulation. After rainfall stopped subsurface flow declined rapidly and old water percentages increased. Total subsurface flow was composed of 8.0, 3.7, 3.9, and 31% old water for simulated intensities of 6.3, 4.3, 2.8, and 1.3 cm h−1, respectively, indicating a trend of increasing old water with decreasing rainfall intensity. Rapid subsurface flow through soil macropores was the most likely mechanism of new water release.
Numerical and Field Evaluation of Soil Water Sampled by Suction Lysimeters
Authors: Wu L. , Baker J. M. , Allmaras R. R.
Published: July 2010

Porous cup suction‐lysimeters are widely used for extracting soil water in solute transport monitoring, bat it is not clear how the sampled concentration can change with the ambient solute concentration, or with applied suction inside the lysimeter. This research was designed to numerically evaluate soil water sampled by suction lysimeters and to test simulation results with field observations. An axisymmetric three‐dimensional finite element model (SWMS_2D) was used to simulate soil water sampled by suction lysimeters in a Zimmerman fine sand (mixed, frigid Argic Udipsamments). To test the simulated results, KBr was uniformly spread on the soil surface. After 183 mm rainfall, suction was applied to the lysimeters (with ceramic cups at a depth of 0.8 m) to withdraw soil water; soil column samples were also removed from the surrounding soil and sectioned to determine solute concentration in situ using a bromide electrode. Simulation showed that when there is a concentrated solute band near a porous cup, as can occur with banded fertilizers, the concentration of sampled soil water in the lysimeter is considerably higher than the resident concentration in the soil at the same depth. The influence of a concentrated solute band on the concentration of sampled soil water decreased as the distance to the cup increased. Variations in applied suction (25, 35, and 45 kPa) appear to have little influence on the amount and concentration of field lysimeter extracted soil water. The measured amount of water in the lysimeter (78.4 mL) was comparatively more than the simulated amount (53.9 mL) when the mean water content of nine soil columns was used as an initial condition for the simulation, but was within the range of simulated amounts (32.5–91.5 mL) when the lower and upper 95% limits of the measured soil‐water content profiles were used as initial conditions for the simulations. Measured Br− concentration of the sampled water (3.13 × 10−4 M) was lower than the simulated concentration (4.66 × 10−4 M) when the geometric means of each layer from the nine soil column Br− concentrations were used as the initial conditions. The difference between measured and simulated concentration may have been due to variability in soil hydraulic properties.
Physical Characteristics of Alkaline Stabilized Sewage Sludge (N‐Viro Soil) and Their Effects on Soil Physical Properties
Authors: Logan T. J. , Harrison B. J.
Published: July 2010

The N‐Viro process for alkaline stabilization of municipal sewage sludge combines dewatered sludge with one or more alkaline industrial byproducts and destroys pathogens by a combination of high pH, heat, and drying. The final product, N‐Viro Soil, is a soil‐like material that is being used as an agricultural lime substitute, soil amendment, and soil substitute. Physical characteristics of 28 N‐Viro Soils were determined and compared to those of mineral soils. The N‐Viro Soils have an average solids content of 62%, particle density of 1.96 Mg/m3, bulk density of 0.59 Mg/m3, and total porosity of 70%. Mean moisture retention was 66, 58, 34, and 31% (v/v) at saturation, 5.9, 33, and 1.5 MPa, respectively. Available water content was 27% by volume (60 cm water tension, 1.5 MPa). Noncompacted and compacted saturated hydraulic conductivities were high, 3 × 10−2 and 9 × 10−4 cm/s, respectively. Mean weight diameter (MWD) of water stable aggregates was 2.0 mm. Fifty‐six percent of the materials were >2 mm in diam., almost all of this (88%) in sizes <16 mm. Of the <2‐mm fraction, 69% was >0.5 mm. The N‐Viro Soils have a shrinkage of 58%, and Atterberg liquid limit, plastic limit, and plasticity index of 76, 64, and 18% water (w/w), respectively. The N‐Viro Soils are similar in physical attributes to those of medium to fine textured, porous soils with granular, stable aggregates, and nonplastic consistency. The moisture retention characteristics are those of a fine textured soil dominated by fine pores and low to medium available water holding capacity, and these materials are highly permeable, even when compacted. N‐Viro Soil was applied to the Miamian silt loam (fine, mixed, mesic Typic Hapludalf) in the field at a rate of 500 Mg/ha (dry solids), and changes in physical properties were measured 1 yr after application. All effects of N‐Viro Soil were statistically significant (P = 0.01), except total porosity, 33 KPa moisture holding capacity, 0.5‐ to 0.25‐mm water stable aggregates, and pocket penetrometer measurements, and all of the effects were beneficial.
Minespoil Amendment with Dry Flue Gas Desulfurization By‐Products: Element Solubility and Mobility
Authors: Stehouwer R. C. , Sutton P. , Fowler R. K. , Dick W. A.
Published: July 2010

Greenhouse column studies of 8 mo duration investigated the solubility and mobility of salts and trace elements in dry flue gas desulfurization (FGD) by‐products used for minespoil reclamation. Three minespoils were amended with two dry FGD by‐products (lime injection multistage burners ash, LIMB; and, pressurized fluidized bed combustion ash, PFBC) using amounts from 0 to 320 g k−1. Two of the minespoils also received sewage sludge amendment of 60 g kg−1. Columns were planted with ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreber). Leachate analyses and pH determinations from column mixes were done at the beginning and the conclusion of the experiments. Both FGD by‐products were effective in raising pH of the spoil materials. The largest LIMB amendment raised pH to near 12 and resulted in the formation of ettringite [(Ca6Al2(SO4)3(OH)12·26 H20)]. Leachate pH, electrical conductivity, dissolved organic C, Ca, Mg, and S tended to increase with increased FGD amendment, while Al, Fe, Mn, and Zn decreased. Changes in leachate As, B, Cu, Ni, and Se depended on interactions among the type of FGD, the type of spoil, and the presence of sewage sludge, with pH being the most important variable. Overall, with FGD amendments of 120 g kg−1 or less, leachate concentrations of most elements of environmental concern were less than drinking water standards. The amount of FGD by‐product that can be applied to a minespoil is probably limited by soluble salts and initially high pH levels rather than by trace element loading of spoil or water.
Urban Waste Compost: Effects on Physical, Chemical, and Biochemical Soil Properties
Authors: Giusquiani P. L. , Pagliai M. , Gigliotti G. , Businelli D. , Benetti A.
Published: July 2010

A long‐term field experiment was conducted to determine the effect of the additions of urban waste compost on the physical and chemical properties and enzymatic activities in a calcareous soil (Fluventic Xerochrept). Total porosity (pores >50 µm measured on thin soil sections from undisturbed samples by image analysis) was greater in the plots treated with compost than the control plots due to a larger amount of elongated pores. In the amended plots total and humified organic C, Pb, Cu, and Zn showed a significant increase compared with nonamended plots. Enzymatic activities (L‐asparaginase, arylsulphatase, dehydrogenase, phosphodiesterase, and alkaline phosphomonoesterase) were significantly enhanced by the compost addition thus indicating no inhibiting influence of the heavy metals present. The increased levels of the arylsulphatase, dehydrogenase, phosphodiesterase, and phosphomonoesterase activities were significantly correlated with total porosity: the first three with pores ranging from 50 to 1000 µm, mainly with pores 50 to 200 µm in size, and phosphomonoesterase only with pores whose size was <500 µm. L‐asparaginase activity was not correlated with porosity. Only arylsulphatase, dehydrogenase, and phosphodiesterase were negatively correlated with bulk density.
Model for Biomethylation and Volatilization of Selenium from Agricultural Evaporation Ponds
Authors: Gao Suduan , Tanji Kenneth K.
Published: July 2010

Selenium has evapoconcentrated to hazardous levels in agricultural evaporation ponds in the San Joaquin Valley of California. Microbial methylation and volatilization is one of the pathways by which high Se concentrations may be dissipated from these ponds. To obtain a more complete understanding of this potential remediation process, kinetic models are developed to evaluate the factors affecting Se biomethylation such as temperature and organic C sources (carbohydrates and proteins) using experimental data from the literature. By assuming that dimethylselenide (DMSe, (CH3)2Se) formation is irreversible and follows first‐order kinetics, the experimental data are described reasonably well using temperature‐ and organic matter‐characteristics, except deviations occurred at a higher temperature (35°C). Proteins are known to stimulate Se volatilization dramatically as compared with carbohydrates as the energy source. This stimulatory property appears to depend on the ability of microorganisms to absorb protein hydrolysis products, a source of methyl groups. A coupled reaction mechanism is proposed in which proteins provide methyl groups for Se methylation to form volatile DMSe. The model fitted experimental data successfully. The volatility of DMSe through the air‐water interface was evaluated using a two‐layer film model. The predicted half‐life of DMSe in water ranged from 1 to 3 d when assuming that wind speed was <3 m s−1 and the water body was 1 m deep. An opportunity exists to enhance Se volatilization by fungi, bacteria, microalgae, and other indigenous microbes found in evaporation ponds as a remediation technique. Additional knowledge on the fate of DMSe both in the water and in the atmosphere, however, is needed to evaluate this dissipation strategy in high Se water bodies.
Persistence and Fate of Anthracene and Benzo(a)pyrene in Municipal Sludge Treated Soil
Authors: Goodin J. D. , Webber M. D.
Published: July 2010

Greenhouse studies using pots and microcosms were conducted to investigate the persistence and fate of nonlabeled and 14C‐labeled anthracene (ANT) and benzo(a)pyrene (B(a)P) in sludge treated soil. Results indicated that ANT degraded rapidly (t1/2 ≈ 3 wk) from the experimental systems, but that B(a)P was persistent. Cropping did not affect the persistence of either compound. On completion of the experiments (≤21 wk), ≤ 10% of the ANT added to soil was recovered intact, whereas 78% of the B(a)P added to soil was recovered intact. Most (≥ 85%) of the 14C added to soil as labeled ANT and B(a)P was accounted for. Recoveries of 14CO2 indicated significant mineralization of ANT, but not of B(a)P. Trivial amounts (≤0.2%) of were recovered as volatile organics and in plant materials, but large amounts were recovered from soil. A considerable proportion of the ANT derived 14C in soil was not extracted with acetone/hexane, which indicated that it had been converted to bound residue. A much smaller proportion of B(a)P than of ANT derived 14C in soil was converted to bound residue. No evidence was obtained for uptake of intact ANT or B(a)P by ryegrass (Lolium multiflorum Lam.), soybean [Glycine max (L.) Merr.], and cabbage (Brassica oleracea var. capitata L.).
Cause and Remediation of Hydrogen Sulfide Emissions from a Sodium‐Based Flue Gas Desulfurization Sludge Disposal Pond
Authors: Ainsworth C. C. , Rai D. , Smith S. C.
Published: July 2010

A flue gas desulfurization (FGD) sludge disposal pond with a history of H2S emissions to the atmosphere was studied to determine the cause of emissions and remediation strategies. The pond receives sludge and associated waters from a single‐pass Na2CO3 flue gas scrubber unit. The pond water is a sodic alkaline brine with large SO3 and S2O3 concentrations (>5000 mg L−1), and hence, an elevated chemical O2 demand. The pond water H2S concentrations are small as a result of periodic H2O2 additions. The sediments, however, have as much as 3500 mg L−1 H2S in the pore water. The production of H2S appeared to originate from the sediments and diffuses through the anoxic water column with little oxidation. Large concentrations of the reduced sulfur species SO3 and S2O3 were present as a result of the flue gas desulfurization process and incomplete oxidation of H2S. The pond was reconstructed to circulate the water through an air injection system that was designed to oxidize the SO3 and S2O3 to SO4, and thereby reduce the chemical O2 demand. After the installation of the air injection system, emissions of H2S ceased and the concentrations of SO3 and S2O3 were reduced by at least a factor of 10 within 3 to 4 wk. The production of H2S in the sediments, however, did not appear to be affected, nor did it appear that it will be reduced in the future by the air injection system.
Effect of Chemical Amendments on Ammonia Volatilization from Poultry Litter
Authors: Moore P. A. , Daniel T. C. , Edwards D. R. , Miller D. M.
Published: July 2010

Ammonia (NH3) volatilization from poultry litter results in a buildup of atmospheric NH3 in chicken houses, which is detrimental to both farm laborers and birds. Ammonia loss from litter is detrimental to the external environment because it results in acid rain, as well as low N/P ratios in litter, which increase the likelihood of excessive P runoff into adjacent water bodies. The objectives of this study were to determine the effect of various chemical amendments on NH3 volatilization and selected litter characteristics after 42 d. A laboratory study was conducted using the following amendments: Ca(OH)2 (calcium hydroxide), Al2(SO4)3·18H2O (alum), alum + CaCO3, FeSO4·7H2O (ferrous sulfate), and MLT (Multi‐purpose Litter Treatment, commercial product). Ammonia‐free air was continuously passed through air‐tight chambers containing amended litter and any NH3 volatilized from the litter was trapped in boric acid solutions, which were titrated daily for NH3 content. The study was carried out for 42 d. At this time, the litter was analyzed for pH, electrical conductivity (EC), soluble, organic C (SOC), metals, and soluble and total forms of N and P. The results of this study indicated that the addition of alum to poultry litter dramatically reduces NH3 volatilization (up to 99% less volatilization than controls). Decreases in volatilization resulted in higher total and soluble N in litter, which increased N/P ratios. Several of the compounds studied (particularly alum) were effective in decreasing water‐soluble P levels in litter. Therefore, we are proposing the use of alum as a litter amendment in poultry houses.
Aerobic Acetate Degradation near the Capillary Fringe of Roadside Soil: Field Simulations from Soil Microcosms
Authors: Ostendorf D. W. , DeGroot D. J. , Pollock S. J. , Gagnon P. J.
Published: July 2010

We studied the aerobic degradation of acetate in a roadside soil to assess the reduction of O2 demand imposed by an alternative highway deicing agent on groundwater. Aseptic uniform sand samples adjacent to the capillary fringe of a state highway shoulder in southeastern Massachusetts were placed in sterile serum bottles at 5°C, forming a series of aerobic soil microcosms. The samples were dosed with a reagent‐grade glacial acetic acid solution, then sampled at various time intervals and analyzed by ion chromatography in a laboratory determination of the microbial degradation kinetics. The aerobic reaction rates were slower than those observed in loamy sand near the ground surface in an earlier study. A steady state transport model for the alternative highway deicing agent calcium magnesium acetate [CMA; Ca0.3 Mg0.7(C2H3O2)2] was derived, including infiltration and degradation. Simulations were run using the observed microcosm kinetics for a range of assumed snowmelt rates. The resulting profiles suggest that microbial activity within the uniform sand near the capillary fringe has the potential to reduce O2 demand by CMA on groundwater for slow (<5×10−7 m/s) snowmelt rates at 5°C under aerobic conditions. More rapid infiltration passes more CMA to the underlying aquifer.
Soil Water Balance Changes in Engineered Soil Surfaces
Authors: Sackschewsky M. R. , Kemp C. J. , Link S. O. , Waugh W. J.
Published: July 2010

Permanent disposal of radioactive waste requires the construction of isolation barriers that minimize both recharge and erosion. Recharge can be prevented by storing precipitation near the surface so that it will be returned to the atmosphere via evapotranspiration. Erosion can be reduced with gravel mulch, but thick gravel layers may increase recharge. Gravel mixed into the surface soil may provide erosion protection without increasing recharge. To compare the effects that erosion control has on infiltration, two lysimeter experiments were conducted to examine the effects of sand and gravel mulches and gravel admixtures, using two precipitation regimens and with or without vegetation. Sand and gravel mulch increased soil‐column water storage and decreased evapotranspiration compared with a plain soil surface. Gravel admixtures did not significantly affect the soil water balance compared with plain soil surfaces. Vegetation increased evapotranspiration and decreased soil moisture storage compared with nonvegetated treatments. Irrigation greatly increased evapotranspiration but had little effect on soil water storage. Drainage was detected from sand and gravel‐mulch lysimeters, but not from lysimeters with a plain‐soil or gravel‐admixture surface. Results are significant for isolation barrier designs in arid sites: (i) a nonvegetated gravel‐mulch surface eventually will result in recharge, even under low precipitation (160 mm/yr); and (ii) a soil column with a plain‐soil or gravel‐admixture surface is capable of recycling all water back to the atmosphere, even under high‐precipitation (450 mm/yr).
Impact of Long‐Term Tillage Systems for Continuous Corn on Nitrate Leaching to Tile Drainage
Authors: Randall G. W. , Iragavarapu T. K.
Published: July 2010

Information is lacking on the long‐term impact of tillage systems on NO3 losses to surface and groundwater. An 11‐yr (1982–1992) study was conducted to assess NO3 losses to subsurface, tile drainage for corn (Zea mays L.) grown with continuous conventional tillage (CT) and no tillage (NT) on a poorly drained Webster clay loam soil (fine‐loamy, mixed, mesic Typic Haplaquoll) at Waseca, MN. Nitrogen was applied at an annual application rate of 200 kg ha−1. Mean annual subsurface drain flow during the 11‐yr period was 35 mm higher for NT (315 ram) compared with CT (280 mm). Flow‐weighted nitrate‐nitrogen (NO3‐N) concentrations increased dramatically in the wet years (1990 and 1991) following the dry period of 1987 to 1989. Flow‐weighted NO3‐N concentrations during the 11‐yr period averaged 13.4 and 12.0 mg L−1 for CT and NT, respectively. Although subsurface drain flow was 12% higher with NT, NO3‐N losses were about 5% higher with CT mainly due to higher NO3‐N concentrations with CT in the last 2 yr. Corn grain yields and N removal were significantly higher in 6 out of 11 yr with CT compared with NT with no difference between tillage systems in the other 5 yr. Grain yields averaged 8.6 Mg ha−1 with CT and 7.3 Mg ha−1 with NT during the 11‐yr period. Multiple regression equations showed that annual flow‐weighted NO3‐N concentration is best predicted from residual soil NO3 in the 0‐ to 1.2‐m profile and spring rainfall while NO3‐N flux can be predicted well from May and June rainfall. Results from this long‐term study indicate that on this poorly drained soil, CT had a positive effect on corn grain yield and N removal compared with NT, but tillage systems had minimal impact on NO3 losses to subsurface drain flow. Higher drain flow with NT does not necessarily result in higher NO3‐N fluxes lost via subsurface drainage.
Cation Exchange Behavior of Bauxite Refining Residues from Western Australia
Authors: Wong J. W. C. , Ho G. E.
Published: July 2010

Over 60 million tonnes per year of bauxite refining residue (red mud) is produced worldwide. Its high Na concentration inhibits plant growth and hence reclamation. The cation‐exchange capacity (CEC) of red mud and the cation exchange equilibria between Na+ and several other cations were measured to elucidate the mechanism of Na release from red mud. The CECs obtained by using K+ and NH+4 were significantly higher than those obtained using Ca2+ and Ba2+. This unusual cation exchange phenomenon can be attributed to the presence of zeolitic minerals in red mud. Cation exchange equilibria show that Na+ originally present in red mud was preferentially adsorbed by the mud over other cations. At high cation fractions in red mud (>0.1), the mud selectively sorbed monovalent over divalent cations, with the following order of selectivity: K+ > Li+ > NH+4 > Ba2+ ≥ Ca2+ > Mg2+. The exchange of Na+ has been found to have significant negative correlations with the radius of hydration and Debye‐Huckei parameter. Divalent cations have little ability to exchange Na+ from zeolitic exchange sites. Incremental extraction of Na+ in red mud shows that K+ and NH+4 displaced 99 (63%) and 57 (44%) cmolc kg−1 red mud whereas Ca2+ and Mg2+ could only displace 33 and 29 cmolc kg−1 red mud, respectively, out of a total of 99 cmolc Na kg−1 red mud. In a reverse process 95% of K+ adsorbed on red mud was readily replaced by Na+. The experimental evidence suggests that the release of Na+ from red mud is due to cation exchange.
Agricultural Water Quality Program Policy Considerations
Authors: Harris B. L. , Nipp T. L. , Waggoner D. K. , Weber A.
Published: July 2010

Congress, in dealing with the Coastal Zone Management Act and Amendments, and the Clean Water Act reauthorization, has placed increased attention on agricultural point and nonpoint‐source pollution. A structure (“tiered and targeted”) for integrating voluntary, incentive‐based, and regulatory approaches to address agricultural point and nonpoint‐source pollution is proposed, in keeping with the administration's commitment to use voluntary programs to the extent possible, but applying regulatory programs where necessary. The focus of this article is on agricultural sources of nonpoint‐source pollution and the appropriate mix of federal, state, and local programs for necessary control actions. Specific suggestions are offered for improving existing programs and appropriate roles are suggested for land‐grant universities in responding to pollution demands.
Nonlinear Regression of Breakthrough Curves to Obtain Retardation Factors in a Natural Gradient Field Study
Authors: Widmer S. K. , Spalding R. F. , Skopp J.
Published: July 2010

An investigation of the fate and transport of trace quantities of commonly detected herbicides and herbicide degradates in groundwater under aquifer conditions was conducted in a shallow sand and gravel aquifer. Herbicides and a conservative tracer (bromide) were injected into the aquifer and the plumes monitored for 2 to 3 mo using an array of downgradient multilevel samplers (MLSs). Breakthrough curves were fitted to the advection‐dispersion and exponentially modified Guassian (EMG) equations. Coefficients of determination were high for both models (generally >0.90). Comparison of the breakthrough curves for the conservative tracer and each herbicide provides a measure of retardation in the aquifer. A retardation factor (R) may be calculated from the first central moment of the data or from peak parameters obtained from the fitted curves, such as: (i) the time required to reach half‐maximum concentration, (ii) the centroid of the curve, or (iii) model parameters such as the apparent transport velocity. Comparison of the retardation factors shows small differences due to the method of calculation both within and between models. The similarities in the retardation factors and the fitted curves suggest that both the EMG and the advection‐dispersion model describe the data well. The detection of differences in herbicide retardation factors varied with the method of calculating R.
Ingested Soil: Bioavailability of Sorbed Lead, Cadmium, Cesium, Iodine, and Mercury
Authors: Sheppard S. C. , Evenden W. G. , Schwartz W. J.
Published: July 2010

Ingestion of soil, inadvertent or otherwise, is an important route of exposure for contaminants that are not geochemically or biologically mobile. There is little known about the bioavailability of these contaminants, especially when the contaminants are sorbed onto native soil particles. We investigated this with in vitro acid‐extraction and enzymolysis experiments and with in vivo single and chronic exposure studies with mice (Mus musculus). The only anion studied was 125I, and soil in the diet had no effect on the carcass 125I content. The bioavailability of the cations tested decreased in the order of 134Cs > 203Hg > 115Cd = 210Pb, and the effect of soil in the diet on concentrations in the carcass decreased in the same order. Soil in the diet significantly decreased the bioavallability of 134Cs, by more than four‐fold, whereas the effect on 210Pb was only ≈1.1‐fold and was not significant. The results of the in vitro digestions ordered the elements in the same way as observed in the in vivo analyses. These results indicate that for contaminants that are not very mobile and are sorbed onto native soil particles, the presence of soil in the diet does not markedly affect bioavailability in the gut.
Spatial Analysis of Plutonium‐239 + 240 and Americium‐241 in Soils around Rocky Flats, Colorado
Authors: Litaor M. Iggy
Published: July 2010

Plutonium and americium contamination of soils around Rocky Flats, Colorado resulted from past outdoor storage practices. Four previous studies produced four different Pu isopleth maps. Spatial estimation techniques were not used in the construction of these maps and were also based on an extremely small number of soil samples. The purpose of this study was to elucidate the magnitude of Pu‐239 + 240 and Am‐241 dispersion in the soil environment east of Rocky Flats using robust spatial estimation techniques. Soils were sampled from 118 plots of 1.01 and 4.05 ha by compositing 25 evenly spaced samples in each plot from the top 0.64 cm. Plutonium‐239 + 240 activity ranged from 1.85 to 53 560 Bq/kg with a mean of 1924 Bq/kg and a standard deviation of 6327 Bq/kg. Americium‐241 activity ranged from 0.18 to 9990 Bq/kg with a mean of 321 Bq/kg and a standard deviation of 1143 Bq/kg. Geostatistical techniques were used to model the spatial dependency and construct isopleth maps showing Pu‐239 + 240 and Am‐241 distribution. The isopleth configuration was consistent with the hypothesis that the dominant dispersal mechanism of Pu‐239 + 240 was wind dispersion from west to east. The Pu‐239 + 240 isopleth map proposed by this study differed significantly in the direction and distance of dispersal from the previously published maps. This isopleth map as well as the Am‐241 map should be used as the primary data for future risk assessment associated with public exposure to Pu‐239 + 240 and Am‐241.