bluuebunny/crossref_metadata_2025 huggingface dataset:
Low‐Temperature Chromium(VI) Biotransformation in Soil with Varying Electron Acceptors
Authors: Tseng Julia K. , Bielefeldt Angela R.
Published: June 2010

Effective and low‐cost strategies for remediating chromium (Cr)‐contaminated soil are needed. Chromium(VI) leaching from contaminated soil into ground water and surface water threatens water supplies and the environment. This study tested indigenous Cr(VI) microbial transformation in batch systems at 10°C in the presence of various electron acceptors. The effects of carbon addition, spiked Cr(VI), and mixing highly contaminated soil with less contaminated soil were investigated. The results indicated that Cr(VI) can be biotransformed in the presence of different electron acceptors including oxygen, nitrate, sulfate, and iron. Sugar addition had the greatest effect on enhancing Cr(VI) removal. Less dissolved organic carbon (DOC) was consumed per amount of Cr(VI) transformed under anaerobic conditions [0.8–93 mg DOC/mg Cr(VI)] compared with aerobic conditions [1.4–265 mg DOC/mg Cr(VI)]. Toxicity of high concentrations (<160 mg/L) of spiked Cr(VI) were not evident. At Cr(VI) concentrations > 40 mg/L, aerobic conditions promoted faster Cr(VI) reduction than anaerobic conditions with nitrate or sulfate present. Biotransformation of Cr(VI) in highly contaminated soil (22 000 mg Cr/kg) was facilitated by mixing with less‐contaminated soil. The study results provide a framework for evaluating indigenous Cr(VI) microbial transformation and enhance the ability to develop strategies for soil treatment.
Soil Quality at a National Scale in New Zealand
Authors: Sparling G. P. , Schipper L. A.
Published: June 2010

New Zealand is a signatory to international conventions on environmental performance, and soil quality information is needed for reporting both at a national and regional level. Soil quality was measured at 222 sites in five regions of New Zealand (12 soil orders and 9 land‐use categories). Topsoil (0–100 mm) properties measured were total carbon and nitrogen, potentially mineralizable N, pH, Olsen P, cation exchange capacity, bulk density, total porosity, macroporosity, and total available and readily available water. Our objectives were to gauge the representativeness of the sample, determine the contribution from land use or soil order to variability, rationalize the data set, and identify concerns for long‐term sustainable land use. Soil and land use combinations were both under‐ or overrepresented in the data set compared with national distribution. Soil order and land‐use categories explained 55 to 76% of the variance in soil properties. Total C contents of pastures were comparable with indigenous forest soils, but pastures were less acidic and with higher N and P contents. Plantation forests had characteristics similar to indigenous forests on comparable soils. Cropland soils comprised <1% of the national land cover and generally had high inorganic fertility and low organic matter, with evidence of compaction. Seven characteristics (total C, total N, mineralizable N, pH, Olsen P, bulk density, and macroporosity) explained 87% of the total variability. The findings are being used by monitoring agencies to raise awareness about soil quality in the wider community, set land management guidelines, and develop policies.
pH‐Dependent Release of Cadmium, Copper, and Lead from Natural and Sludge‐Amended Soils
Authors: Sukreeyapongse Orathai , Holm Peter E. , Strobel Bjarne W. , Panichsakpatana Supamard , Magid Jakob , Hansen Hans Christian Bruun
Published: June 2010

The pH‐dependent release of cadmium, copper, and lead from soil materials was studied by use of a stirred flow cell to quantify their release and release rates, and to evaluate the method as a test for the bonding strength and potential mobility of heavy metals in soils. Soil materials from sludge‐amended and nonamended A horizons from a Thai coarse‐textured Kandiustult and a Danish loamy Hapludalf were characterized and tested. For each soil sample, release experiments with steady state pH values in the range 2.9 to 7.1 and duration of 7 d were performed. The effluent was continuously collected and analyzed. Release rates and total releases were higher for the Hapludalf than the Kandiustult and higher for the sludge‐amended soils than the nonamended soils. With two exceptions the relative release rates (release rate/total content of metal in soil) plotted vs. steady state pH followed the same curves for each metal, indicating similar bonding strengths. These curves could be described by a rate expression of the form: relative release rate = k[H+]a, with specific a (empirical constant) and k (rate constant) parameters for each metal demonstrating that metal release in these systems can be explained by proton‐induced desorption and dissolution reactions. With decreasing pH, pronounced increases in release rates were observed in the sequence cadmium > lead > copper, which express the order of metal lability in the soils. The flow cell system is useful for comparison of metal releases as a function of soil properties, and can be used as a test to rank soils with respect to heavy metal leaching.
The Role of Condensed Organic Matter in the Nonlinear Sorption of Hydrophobic Organic Contaminants by a Peat and Sediments
Authors: Ran Yong , Huang Weilin , Rao P. S. C. , Liu Dehan , Sheng Guoying , Fu Jiamo
Published: June 2010

This study examines the effect of soil organic matter heterogeneity on equilibrium sorption and desorption of phenanthrene, naphthalene, 1,3,5‐trichlorobenzene (1,3,5‐TCB), and 1,2‐dichlorobenzene (1,2‐DCB) by soils and sediments. Two estuary sediments, a Pahokee peat (PP; Euic, hyperthermic Lithic Haplosaprist), and two subsamples (base‐ and acid‐treated peat [TP] and acid‐treated peat [FP]) of the peat were used as the sorbents. The contents of black carbon particles were quantified with a chemical extraction method. Petrographical examinations revealed the presence of the condensed soil and sediment organic matter (SOM) in Pahokee peat. The Freundlich isotherm model in two different forms was used to fit both sorption and desorption data. The results show that the sorption and desorption isotherms are generally nonlinear and that the apparent sorption–desorption hysteresis is present for phenanthrene and TCB. Detailed analysis of sorption data for the tested sorbent–sorbate systems indicates that black carbon is probably responsible for sorption isotherm nonlinearity for the two sediments, whereas the humic substances and kerogen may play the dominant role in nonlinear sorption by the peat. This investigation suggests that the microporosity of SOM is important for the hydrophobic organic contaminant (HOC) sorption capacity on the peat.
Tree‐Ring Strontium‐90 and Cesium‐137 as Potential Indicators of Radioactive Pollution
Authors: Kagawa Akira , Aoki Toru , Okada Naoki , Katayama Yukio
Published: June 2010

To examine whether tree rings can be used to detect or assess local historical 90Sr or 137Cs fallout, such as that resulting from the Hiroshima atomic bomb, radial distribution of 90Sr and 137Cs in trees was examined. We studied a gymnosperm [Japanese cedar, Cryptomeria japonica (L. f.) D. Don] and an angiosperm (Japanese persimmon, Diospyros kaki Thunb.) tree species from the vicinity of the atomic bomb hypocenter, and from other locations in Japan. A significant amount of 137Cs was detected in tree rings formed before 1945, indicating lateral migration of Cs. In contrast, the specific activity of 90Sr in the Hiroshima Japanese cedar showed the highest level in 1945, due to relatively immobile characteristics of Sr compared with Cs. Strontium‐90 and Sr analyses in tree rings helped identify and distinguish between residual 90Sr activity from the Hiroshima atomic bomb and the atmospheric nuclear testing. This indicates the possibility of detecting or assessing previous local 90Sr pollution through with tree‐ring analysis.
Acid–Base Accounting to Predict Post‐Mining Drainage Quality on Surface Mines
Authors: Skousen J. , Simmons J. , McDonald L. M. , Ziemkiewicz P.
Published: June 2010

Acid–base accounting (ABA) is an analytical procedure that provides values to help assess the acid‐producing and acid‐neutralizing potential of overburden rocks prior to coal mining and other large‐scale excavations. This procedure was developed by West Virginia University scientists during the 1960s. After the passage of laws requiring an assessment of surface mining on water quality, ABA became a preferred method to predict post‐mining water quality, and permitting decisions for surface mines are largely based on the values determined by ABA. To predict the post‐mining water quality, the amount of acid‐producing rock is compared with the amount of acid‐neutralizing rock, and a prediction of the water quality at the site (whether acid or alkaline) is obtained. We gathered geologic and geographic data for 56 mined sites in West Virginia, which allowed us to estimate total overburden amounts, and values were determined for maximum potential acidity (MPA), neutralization potential (NP), net neutralization potential (NNP), and NP to MPA ratios for each site based on ABA. These values were correlated to post‐mining water quality from springs or seeps on the mined property. Overburden mass was determined by three methods, with the method used by Pennsylvania researchers showing the most accurate results for overburden mass. A poor relationship existed between MPA and post‐mining water quality, NP was intermediate, and NNP and the NP to MPA ratio showed the best prediction accuracy. In this study, NNP and the NP to MPA ratio gave identical water quality prediction results. Therefore, with NP to MPA ratios, values were separated into categories: <1 should produce acid drainage, between 1 and 2 can produce either acid or alkaline water conditions, and >2 should produce alkaline water. On our 56 surface mined sites, NP to MPA ratios varied from 0.1 to 31, and six sites (11%) did not fit the expected pattern using this category approach. Two sites with ratios <1 did not produce acid drainage as predicted (the drainage was neutral), and four sites with a ratio > 2 produced acid drainage when they should not have. These latter four sites were either mined very slowly, had nonrepresentative ABA data, received water from an adjacent underground mine, or had a surface mining practice that degraded the water. In general, an NP to MPA ratio of <1 produced mostly acid drainage sites, between 1 and 2 produced mostly alkaline drainage sites, while NP to MPA ratios > 2 produced alkaline drainage with a few exceptions. Using these values, ABA is a good tool to assess overburden quality before surface mining and to predict post‐mining drainage quality after mining. The interpretation from ABA values was correct in 50 out of 52 cases (96%), excluding the four anomalous sites, which had acid water for reasons other than overburden quality.
Nitrogen and Phosphorus Availability in Composted and Uncomposted Poultry Litter
Authors: Preusch P. L. , Adler P. R. , Sikora L. J. , Tworkoski T. J.
Published: June 2010

Poultry litter applications to land have been based on crop N requirements, resulting in application of P in excess of plant requirements, which may cause degradation of water quality in the Chesapeake Bay watershed. The effect of litter source (the Delmarva Peninsula and Moorefield, West Virginia) and composting of poultry litter on N mineralization and availability of P in two soil types (sandy loam and silt loam) was determined in a controlled environment for 120 d. Nitrogen mineralization (percent total organic N converted to inorganic nitrogen) rates were higher for fresh litter (range of 42 to 64%) than composted litter (range of 1 to 9%). The N mineralization rate of fresh litter from the Delmarva Peninsula was consistently lower than the fresh litter from Moorefield, WV. The N mineralization rate of composted litter from either source was not significantly different for each soil type (7 to 9% in sandy loam and 1 to 5% in silt loam) even though composting conditions were completely different at the two composting facilities. Litter source had a large effect on N mineralization rates of fresh but not composted poultry litter. Composting yielded a more predictable and reliable source of mineralizable N than fresh litter. Water‐extractable phosphorus (WEP) was similar in soils amended with composted litter from WV and fresh litter from both sources (approximately 10 to 25 and 2 to 14 mg P kg−1for sandy loam and silt loam, respectively). Mehlich 1–extractable phosphorus (MEP) was similar in soils amended with WV fresh litter and composted litter from both sources (approximately 100 to 140 and 60 to 90 mg P kg−1for sandy loam and silt loam, respectively). These results suggest that the composting process did not consistently reduce WEP and MEP, and P can be as available in composted poultry litter as in fresh poultry litter.
Seasonal Variation in Microbial Communities and Organic Malodor Indicator Compound Concentrations in Various Types of Swine Manure Storage Systems
Authors: Merrill L. , Halverson L. J.
Published: June 2010

Anaerobic manure storage systems are one of the major contributors to the odor and environmental pollution associated with swine (Sus scrofa) production systems. The microbial ecology of manure storage systems and the relationships between microbial communities and odor production are largely unknown. In this study, we used community fatty acid methyl ester (FAME) analysis to generate lipid profiles to assess seasonal differences among microbial communities inhabiting various types of outdoor swine manure storage systems. Concurrently, we measured manure concentrations of several malodor indicator compounds as well as pH, temperature, and solids content. Principal components analysis (PCA) showed that there are differences in FAME profiles among the swine manure storage systems examined and most of the variation was in the relative abundance of 18:0, 18:1ω7t, 18:1ω7c/ω9t/ω12t, and 16:1ω7t/i15:0 2OH FAMEs. The PCA of the FAME profiles revealed that the phototrophic systems were more similar to each other and that the nonphototrophic systems were more similar to each other than they were to phototrophic lagoons. There were seasonal changes in the FAME profiles in the phototrophic systems and the concrete nonphototrophic basin (CNPB), and in one phototrophic system, the FAME profiles more closely resembled a CNPB FAME profile during the winter than the other phototrophic lagoons. In the phototrophic lagoon systems, there was a direct correlation between the abundance of the FAMEs identified in the PCA and manure concentrations of phenol, p‐cresol, and 4‐ethyl phenol. In the CNPB, there was a negative correlation between the total phenolics concentration and the 18:1ω7t FAME. Our results indicate that community FAME profiles could be used as a diagnostic tool for obtaining preliminary evidence that management practices are altering the system's microbial community to one that favors less air pollution potential.
Paper Mill Residuals and Compost Effects on Soil Carbon and Physical Properties
Authors: Foley B. J. , Cooperband L. R.
Published: June 2010

Use of organic by‐products as soil amendments in agricultural production exemplifies a strategy for converting wastes to resources. The overall objective of this research was to evaluate the short‐ and intermediate‐term effects of repeatedly amending sandy soil with paper mill residuals (PMR) and composted PMR in a vegetable rotation in Wisconsin's Central Sands. Specifically, we investigated the effects of PMR and composted PMR on total soil C and related these to changes in water‐holding capacity and plant‐available water (PAW). Amendment effects on irrigation requirements were estimated with a simple soil water balance model. The experimental design was replicated five times as a randomized complete block with four organic amendments: raw PMR, PMR composted alone (PMRC), PMR composted with bark (PMRB), and peat applied at two rates and a nonamended control. All amended treatments significantly increased total soil C relative to the nonamended control following applications in 1998 and 1999. One year following the second serial amendment, all PMR treatments increased PAW by 5 to 45% relative to the control. There was a significant positive linear relationship between total soil C and PAW. All amended treatments reduced the average amount of irrigation water required for potato production by 4 to 30% and the number of irrigation events by 10 to 90%. There was a clear trend of greater reduction in irrigation requirements with more carbon added. The cumulative effects of repeated additions of PMRB suggest that certain composts might sustain elevated PAW and reduce irrigation requirements beyond one year.
Retention and Runoff Losses of Atrazine and Metribuzin in Soil
Authors: Selim H. M.
Published: June 2010

Minimizing herbicide runoff and mobility in the soil and thus potential contamination of water resources is a national concern. Metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] and atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine] dynamics in surface soils and in runoff waters were studied on six 0.2‐ha sugarcane (Saccharum spp.) plots of a Commerce silt loam (finesilty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquept) during three growing seasons under different best management practices. Metribuzin was applied in the spring as a postemergence herbicide and atrazine was applied following winter harvest. Both herbicides were applied on top of the sugarcane rows as 0.6‐ or 0.9‐m band width application, or broadcast application, where the entire area was treated. Maximum effluent concentrations were measured from the broadcast treatment and ranged from 600 to 1100 μg L−1 for atrazine and 250 to 450 μg L−1 for metribuzin. Atrazine runoff losses were highest for the broadcast treatment (2.8–11% of that applied) and lowest for the 0.6‐m band treatment (1.9–7.6%), with a similar trend for metribuzin losses. Measured extractable herbicides from the surface soil exhibited a sharp decrease with time and were well described with a simple first‐order decay model. For atrazine, estimates for the decay rate (λ) were higher than for metribuzin. Results based on laboratory adsorption–desorption (kinetic–batch) measurements were consistent with field observations. The distribution coefficients (Kd) for atrazine exhibited stronger retention over time in comparison with metribuzin on the Commerce soil. Moreover, discrepancies between adsorption isotherm and desorption indicated slower release and that hysteresis was more pronounced for atrazine compared with metribuzin.
Reduction of Ammonia Emission by Shallow Slurry Injection
Authors: Hansen Martin N. , Sommer Sven G. , Madsen Niels P.
Published: June 2010

Ammonia (NH3) emission from livestock production causes undesirable environmental effects and a loss of plant‐available nitrogen. Much atmospheric NH3 is lost from livestock manure applied in the field. The NH3 emission may be reduced by slurry injection, but slurry injection in general, and especially on grassland, increases the energy demand and places heavy demands on the slurry injection techniques used. The reduction in NH3 emission, injection efficiency, and energy demand of six different shallow slurry‐injection techniques was examined. The NH3 emission from cattle slurry applied to grassland was reduced by all the injectors tested in the study, but there were major differences in the NH3 reduction potential of the different types of injectors. Compared with the trailing hose spreading technique, the NH3 loss was reduced by 75% when cattle slurry was injected using the most efficient slurry injection technique, and by 20% when incorporated by the least efficient injection technique. The reduction in NH3 emission was correlated with injection depth and the volume of the slot created. The additional energy demand for reducing ammonia emissions by slurry injection was approximately 13 000 kJ ha−1 for a 20% reduction and 34 000 kJ ha−1 for a 75% reduction. The additional energy demand corresponds to additional emissions of, respectively, 5.6 and 14.5 kg CO2 per ha injected.
Pesticide Volatilization from Soil
Authors: Wolters André , Linnemann Volker , Herbst Michael , Klein Michael , Schäffer Andreas , Vereecken Harry
Published: June 2010

A comparison was drawn between model predictions and experimentally determined volatilization rates to evaluate the volatilization approaches of European registration models. Volatilization rates of pesticides (14C‐labeled parathion‐methyl, fenpropimorph, and terbuthylazine and nonlabeled chlorpyrifos) were determined in a wind‐tunnel experiment after simultaneous soil surface application on Gleyic Cambisol. Both continuous air sampling, which quantifies volatile losses of 14C‐organic compounds and 14CO2 separately, and the detection of soil residues allow for a mass balance of radioactivity of the 14C‐labeled pesticides. Recoveries were found to be >94% of the applied radioactivity. The following descending order of cumulative volatilization was observed: chlorpyrifos > parathion‐methyl > terbuthylazine > fenpropimorph. Due to its high air–water partitioning coefficient, nonlabeled chlorpyrifos was found to have the highest cumulative volatilization (44.4%) over the course of the experiment. Volatilization flux rates were measured up to 993 μg m−2 h−1 during the first hours after application. Parameterization of the Pesticide Emission Assessment at Regional and Local Scales (PEARL) model and the Pesticide Leaching Model (PELMO) was performed to mirror the experimental boundary conditions. In general, model predictions deviated markedly from measured volatilization rates and showed limitations of current volatilization models, such as the uppermost compartment thickness, making an enormous influence on predicted volatilization losses. Experimental findings revealed soil moisture to be an important factor influencing volatilization from soil, yet its influence was not reflected by the model calculations. Future versions of PEARL and PELMO ought to include improved descriptions of aerodynamic resistances and soil moisture dependent soil–air partitioning coefficients.
Use of Additives to Enhance the Removal of Phenols from Water Treated with Horseradish and Hydrogen Peroxide
Authors: Tonegawa Masami , Dec Jerzy , Bollag Jean‐Marc
Published: June 2010

Use of additives, such as polyethylene glycol (PEG), selected surfactants, chitosan gel, or activated carbon, has been shown to enhance enzymatic treatment of water polluted with organic compounds. In this study, additives were used to facilitate the removal of 2,4‐dichlorophenol (2,4‐DCP) from water using minced horseradish (Armoracia rusticana P. Gaertn. et al.) as a carrier of peroxidase activity. The specific objectives of the study were to (i) enhance the pollutant removal activity of minced horseradish by the addition of PEG and other additives (e.g., Tween 20, Triton X‐100, and rhamnolipid); (ii) eliminate colored reaction products by the addition of chitosan; and (iii) eliminate color by amending treated water with activated carbon. The disappearance of 2,4‐DCP in horseradish‐treated water samples amended with PEG or various surfactants (75–90%) was greatly increased over that observed in nonamended samples (29%). The effect of PEG depended on its average molecular weight. As indicated by visible spectrophotometry, enclosing horseradish pieces between two sealed chitosan films completely eliminated colored reaction products; however, the decolorization was accompanied by a reduction in 2,4‐DCP removal (from 95 to 60%). On the other hand, commercially available activated carbon completely removed colored reaction products from the treated water without reducing the removal efficiency. Based on the results obtained, it can be concluded that the use of additives may considerably improve the quality of wastewater treated by plant materials.
Size and Performance of Anoxic Limestone Drains to Neutralize Acidic Mine Drainage
Authors: Cravotta Charles A.
Published: June 2010

Acidic mine drainage (AMD) can be neutralized effectively in underground, anoxic limestone drains (ALDs). Owing to reaction between the AMD and limestone (CaCO3), the pH and concentrations of alkalinity and calcium increase asymptotically with detention time in the ALD, while concentrations of sulfate, ferrous iron, and manganese typically are unaffected. This paper introduces a method to predict the alkalinity produced within an ALD and to estimate the mass of limestone required for its construction on the basis of data from short‐term, closed‐container (cubitainer) tests. The cubitainer tests, which used an initial mass of 4 kg crushed limestone completely inundated with 2.8 L AMD, were conducted for 11 to 16 d and provided estimates for the initial and maximum alkalinities and corresponding rates of alkalinity production and limestone dissolution. Long‐term (5–11 yr) data for alkalinity and CaCO3 flux at the Howe Bridge, Morrison, and Buck Mountain ALDs in Pennsylvania, USA, indicate that rates of alkalinity production and limestone dissolution under field conditions were comparable with those in cubitainers filled with limestone and AMD from each site. The alkalinity of effluent and intermediate samples along the flow path through the ALDs and long‐term trends in the residual mass of limestone and the effluent alkalinity were estimated as a function of the computed detention time within the ALD and second‐order dissolution rate models for cubitainer tests. Thus, cubitainer tests can be a useful tool for designing ALDs and predicting their performance.
Solubilization of Manganese and Trace Metals in Soils Affected by Acid Mine Runoff
Authors: Green C. H. , Heil D. M. , Cardon G. E. , Butters G. L. , Kelly E. F.
Published: June 2010

Manganese solubility has become a primary concern in the soils and water supplies in the Alamosa River basin, Colorado due to both crop toxicity problems and concentrations that exceed water quality standards. Some of the land in this region has received inputs of acid and trace metals as a result of irrigation with water affected by acid mine drainage and naturally occurring acid mineral seeps. The release of Mn, Zn, Ni, and Cu following saturation with water was studied in four soils from the Alamosa River basin. Redox potentials decreased to values adequate for dissolution of Mn oxides within 24 h following saturation. Soluble Mn concentrations were increased to levels exceeding water quality standards within 84 h. Soluble concentrations of Zn and Ni correlated positively with Mn following reduction for all four soils studied. The correlation between Cu and Mn was significant for only one of the soils studied. The soluble concentrations of Zn and Ni were greater than predicted based on the content of each of these metals in the Mn oxide fraction only. Increases in total electrolyte concentration during reduction indicate that this may be the result of displacement of exchangeable metals by Mn following reductive dissolution of Mn oxides.
Response of Soil Microbiological Activities to Cadmium, Lead, and Zinc Salt Amendments
Authors: Stuczynski T. I. , McCarty G. W. , Siebielec G.
Published: June 2010

Heavy metal pollution of soil has been recognized as a major factor impeding soil microbial processes. From this perspective, we studied responses of the soil biological activities to metal stress simulated by soil amendment with Zn, Pb, and Cd chlorides. The amounts of heavy metal salts added to five metal‐polluted soils and four nonpolluted soils were selected to match the total metal concentrations typically found in polluted soils of the Silesia region of Poland. From the perspective of soil quality, metal mobility in amended soils could not be described by simple functions of pH or organic matter. Reaction of Pb with the soil caused strong immobilization with less than 1% of the Pb amendment recovered by 0.01 M CaCl2 extractions. Immobilization of Cd was also significant, whereas immobilization of the Zn amendment was much weaker than that of Cd or Pb. The Zn amendment had substantial inhibitory effect on soil dehydrogenase, acid and alkaline phosphatase, arylsulfatase, urease, and nitrification potential. Generally, Cd and Pb had limited or stimulatory effect on most of these biological activities, with an exception of Pb strongly inhibiting soil urease. The effect of the metal amendments on biological activities could not be satisfactorily accounted for by metal toxicity because no strong relationship was observed between extractable metal content and the degree of inhibition. The Zn amendment had a significant effect on soil pH, resulting in confounding effects of pH and Zn toxicity on activities. Metal amendment experiments seem to be of limited utility for meaningful assessment of metal contamination effects on soil quality.
Soil Chemical Changes under Irrigated Mango Production in the Central São Francisco River Valley, Brazil
Authors: Heck R. J. , Tiessen H. , Salcedo I. H. , Santos M. C.
Published: June 2010

Irrigated areas in Brazil's Central São Francisco River Valley have experienced declines in productivity, which may be a reflection of changes in soil chemical properties due to management. This study was conducted to compare the chemical composition of soil solutions and cation exchange complexes in a five‐year‐old grove of irrigated mango (Mangifera indica L. cv. Tommy Atkins) with that of an adjacent clearing in the native caatinga vegetation. A detailed physiographic characterization of the area revealed a subsurface rock layer, which was more undulating than the current land surface, and identified the presence of a very saline and sodic (1045 μS cm−1, sodium adsorption ratio [SAR] = 5.19) ground water table. While changes in concentrations of Ca, Mg, and K could be attributed to direct management inputs (fertilization and liming with dolomite), increases in Na suggested average annual capillary rise from the ground water table of 28 L m−2 Accordingly, soil salinity levels appeared to be more dependent on surface elevation than the elevation of the rock layer or sediment thickness. The apparent influence of land surface curvature on water redistribution and the solution chemistry was more pronounced under irrigated mango production. In general, salinity levels had doubled in the mango grove and nearly tripled under the canopies, after only five years of irrigation. Though critical saline or sodic conditions were not encountered, the changes observed indicate a need for more adequate monitoring and management of water and salt inputs despite the excellent water quality of the São Francisco River.
Electron Affinity Coefficients of Nitrogen Oxides and Biodegradation Kinetics in Denitrification of Contaminated Stream Water
Authors: Kim Seung‐Hyun , Chung Jong‐Bae , Jeong Byeong‐Ryong , Lee Young‐Deuk , Prasher Shiv O.
Published: June 2010

During the dry season in Korea, rivers become more vulnerable to contamination by biochemical oxygen demand (BOD) and nitrogen. It is hypothesized that the natural characteristics of the streams in Korea allow the contaminated water to be treated at the tributaries. Downstream river water quality in Korea may be improved by spraying the contaminated stream water from the tributaries over the surrounding floodplains. The consequent water filtration through the soil could remove the contaminants through aerobic and denitrifying reactions. In this study, the kinetics parameters of the denitrifying reaction in floodplain filtration were determined using contaminated stream water. For the electron donor the Monod kinetics was used, while the competitive Michaelis–Menten model was employed for the electron acceptors. The parameters to the competitive Michaelis–Menten model were found using continuous denitrifying reactions, instead of the batch reactions employed in previous studies, to match the conditions needed to apply the competitive Michaelis–Menten kinetics. From the result, it was found that continuous reactions as well as batch reactions could be used to determine the affinity coefficients in denitrification. The results of this study also showed that the affinity coefficient of NO−2, using continuous reactions, was similar to that of other studies in the literature found via batch reactions, whereas the affinity coefficient of N2O was much larger than that acquired with batch reactions. The parameters obtained in this study will be used in future work to simulate the contaminant behaviors during floodplain filtration using a mathematical model.
Phytase, High‐Available‐Phosphorus Corn, and Storage Effects on Phosphorus Levels in Pig Excreta
Authors: Baxter Christopher A. , Joern Brad C. , Ragland Darryl , Sands Jason S. , Adeola Olayiwola
Published: June 2010

Phosphorus‐based land application limits for manure have increased the importance of optimizing diet P management and accurately characterizing the bioavailability of manure P. We examined the effects of pig (Sus scrofa) diets formulated with high‐available‐P corn and phytase on P levels in excreta and slurry stored for 30, 60, 90, 120, and 150 d. Twenty‐four pigs (approximately 14 kg each) were fed one of four low‐P diets: (i) normal corn, no phytase (control); (ii) normal corn with 600 phytase units kg−1 (PHY); (iii) high‐available‐P corn, no phytase (HAP); and (iv) high‐available‐P corn with 600 phytase units kg−1 (HAP + PHY). Fresh fecal and stored slurry dry matter (DM) was analyzed for total phosphorus (TP), dissolved molybdate‐reactive phosphorus (DRP), dissolved organic phosphorus (DOP), acid‐soluble reactive phosphorus (ASRP), acid‐soluble organic phosphorus (ASOP), and phytate phosphorus (PAP). The PHY, HAP, and HAP + PHY diets significantly (α = 0.05) decreased fecal TP 19, 17, and 40%, respectively, compared with the control. Dissolved reactive P was 36% lower in the HAP + PHY diet compared with the other diets. Relative fractions (percent of TP) of DRP, DOP, ASOP, and PAP in slurry generally decreased with storage time up to 150 d, with the largest decreases occurring within 60 to 90 d. Diet‐induced differences in relative fractions of DRP, DOP, ASRP, and PAP were significant when averaged across storage times, simulating a mixed‐age slurry. Relative fractions of DRP in simulated mixed‐age slurries were higher in HAP and HAP + PHY diets, indicating that diet may affect P losses under certain P‐based application scenarios.
Decomposition and Plant‐Available Nitrogen in Biosolids
Authors: Gilmour John T. , Cogger Craig G. , Jacobs Lee W. , Evanylo Gregory K. , Sullivan Dan M.
Published: June 2010

This research combines laboratory and field studies with computer simulation to characterize the amount of plant‐available nitrogen (PAN) released when municipal biosolids are land‐applied to agronomic crops. In the laboratory studies, biosolids were incubated in or on soil from the land application sites. Mean biosolids total C, organic N, and C to N ratio were 292 g kg−1, 41.7 g kg−1, and 7.5, respectively. Based on CO2 evolution at 25°C and optimum soil moisture, 27 of the 37 biosolids–soil combinations had two decomposition phases. The mean rapid and slow fraction rate constants were 0.021 and 0.0015 d−1, respectively, and the rapid fraction contained 23% of the total C assuming sequential decomposition. Where only one decomposition phase existed, the mean first order rate constant was 0.0046 d−1 The mean rate constant for biosolids stored in lagoons for an extended time was 0.00097 d−1 The only treatment process that was related to biosolids treatment was stabilization by storage in a lagoon. Biosolids addition rates (dry basis) ranged from 1.3 to 33.8 Mg ha−1 with a mean value of 10.6 Mg ha−1 A relationship between fertilizer N rate and crop response was used to estimate observed PAN at each site. Mean observed PAN during the growing season was 18.9 kg N Mg−1 or 37% of the biosolids total N. Observed PAN was linearly related to biosolids total N. Predicted PAN using the computer model Decomposition, actual growing‐season weather, actual analytical data, and laboratory decomposition kinetics compared well with observed PAN. The mean computer model prediction of growing‐season PAN was 19.2 kg N Mg−1 and the slope of the regression between predicted and observed PAN was not significantly different from unity. Predicted PAN obtained using mean decomposition kinetics was related to predicted PAN using actual decomposition kinetics suggesting that mean rate constants, actual weather, and actual analytical data could be used in estimation of PAN. There was a linear relationship between predicted N mineralization for the growing season and for the first year. For this study, the mean values for the growing season and year were 27 and 37% of the organic N, respectively.
Characterization of Sewage Sludge Organic Matter Using Solid‐State Carbon‐13 Nuclear Magnetic Resonance Spectroscopy
Authors: Smernik Ronald J. , Oliver Ian W. , Merrington Graham
Published: June 2010

Six sewage sludges from five sewage treatment plants in Australia were characterized using solid‐state 13C nuclear magnetic resonance (NMR) spectroscopy. Spectra were acquired both before and after removal of mineral components through treatment with hydrofluoric acid (HF). Carbon mass balance indicated that little organic matter was lost on HF treatment, which significantly improved NMR sensitivity and spectral resolution, and decreased acquisition time and hence cost of NMR analysis. Two NMR techniques were used, the standard cross polarization (CP) technique and Bloch decay (BD). The BD technique had not been applied previously to the analysis of sewage sludge. For each sludge sample, both before and after HF treatment, the BD spectrum contained significantly more alkyl carbon. Spin counting, another technique applied to sewage sludge here for the first time, showed that the BD spectra of the HF‐treated sludges were quantitative, while approximately 30% of the CP NMR signal went undetected. The discrepancy between CP and BD spectra was attributed to the presence of alkyl carbon with such high molecular mobility that the efficiency of cross polarization is affected. This study shows that sewage sludge organic matter is significantly different in chemistry to soil organic matter and has implications for the application of sewage sludge to agricultural land.
Pesticide Removal from Container Nursery Runoff in Constructed Wetland Cells
Authors: Stearman G. Kim , George Dennis B. , Carlson Kris , Lansford Stacey
Published: June 2010

The increased use of pesticides by container nurseries demands that practices for removal of these potential contaminants from runoff water be examined. Constructed wetlands may be designed to clean runoff water from agricultural production sites, including container nurseries. This study evaluated 14 constructed wetlands cells (1.2 by 4.9 m or 2.4 by 4.9 m, and 30 or 45 cm deep) that collected pesticide runoff from a 465‐m2 gravel bed containerized nursery in Baxter, TN. One‐half of the cells were vegetated with bulrush, Scirpus validus The cells were loaded at three rates or flows of 0.240, 0.120, and 0.060 m3 d−1 Herbicides—simazine (Princep) [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine] and metolachlor (Pennant) [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐2‐methoxy‐1‐methylethyl‐acetamide]—were applied to the gravel portion of the container nursery at rates of 4.78 and 2.39 kg ha−1, respectively, 9 July 1998, and at rates of 2.39 and 1.19 kg ha−1, respectively, 17 May 1999. Pesticides entering the wetland and wetland cell water samples were analyzed daily to determine pesticide removal. At the slower flow rate, which corresponds to lower mass loading and greater hydraulic retention times (HRTs), a greater percentage of pesticides was removed. During the 2‐yr period, cells with plants removed 82.4% metolachlor and 77.1% simazine compared with cells without plants, which removed 63.2% metolachlor and 64.3% simazine. At the lowest flow rate and mass loading, wetland cells removed 90.2% metolachlor and 83% simazine. Gravel subsurface flow constructed wetlands removed most of the pesticides in runoff water with the greatest removal occurring at lower flow rates in vegetated cells.
Selenium Removal and Mass Balance in a Constructed Flow‐Through Wetland System
Authors: Gao S. , Tanji K. K. , Lin Z. Q. , Terry N. , Peters D. W.
Published: June 2010

A field study on the removal of Se from agricultural subsurface drainage was conducted from May 1997 to February 2001 in the Tulare Lake Drainage District (TLDD) of San Joaquin Valley, California. A flow‐through wetland system was constructed consisting of ten 15‐ × 76‐m unlined cells that were continuously flooded and planted with either a monotype or combination of plants, including sturdy bulrush [Schoenoplectus robustus(Pursh) M.T. Strong], baltic rush (Juncus balticusWilld.), smooth cordgrass (Spartina alternifloraLoisel.), rabbitsfoot grass [Polypogon monspeliensis(L.) Desf.], saltgrass [Distichlis spicata(L.) Greene], cattail (Typha latifoliaL.), tule [Schoenoplectus acutus(Muhl. ex Bigelow) Á. Löve & D. Löve], and widgeon grass (Ruppia maritimaL.). One cell had no vegetation planted. The objectives of this research were to evaluate Se removal efficiency of each wetland cell and to carry out a mass balance on Se. The inflow drainage water to the cells had average annual Se concentrations of 19 to 22 μg L−1dominated by selenate [Se(VI), 95%]. Average weekly water residence time varied from about 3 to 15 d for Cells 1 through 7 (target 7 d), 19 to 33 d for Cells 8 and 9 (target 21 d), and 13 to 18 d for Cell 10 (target 14 d). Average weekly Se concentration ratios of outflow to inflow ranged from 0.45 to 0.79 and mass ratio (concentration × water volume) from 0.24 to 0.52 for year 2000, that is, 21 to 55% reduction in Se concentration and 48 to 76% Se removal in mass by the wetland, respectively. The nonvegetated cell showed the least Se removal both in concentration and in mass. The global mass balance showed that on the average about 59% of the total inflow Se was retained within the cells and Se outputs were outflow (35%), seepage (4%), and volatilization (2%). Independent measurements of the Se retained in the cells totaled 53% of the total Se inflow: 33% in the surface (0–20 cm) sediment, 18% in the organic detrital layer above the sediment, 2% in the fallen litter, <1% in the standing plants, and <1% in the surface water. Thus, about 6% of the total Se inflow was unaccounted for in the internal compartments.
The Capacity of Duckweed to Treat Wastewater
Authors: Körner Sabine , Vermaat Jan E. , Veenstra Siemen
Published: June 2010

Duckweed species are promising macrophytes for use in sustainable wastewater treatment due to their rapid growth, ease of harvest, and feed potential as a protein source. This paper reviews growth rates of different duckweed species on wastewater and ammonia toxicity to duckweed and summarizes insights into the mechanism of organic matter and nutrient removal. Results were gained from laboratory experiments in small, shallow, duckweed‐covered semicontinuous batch systems. Growth rates on different types of wastewater vary considerably among different species. Ammonia is toxic for duckweed in both the ionized and un‐ionized forms. Duckweed, however, can be used to treat wastewater containing very high total ammonia concentrations as long as certain pH levels are not exceeded. The degradation of organic material is enhanced by duckweed through both additional oxygen supply and additional surface for bacterial growth. The duckweed mat with attached bacteria and algae is, independent of the loading rates, responsible for three‐quarters of the total nitrogen (N) and phosphorus (P) loss in very shallow systems. Based on our results we suggest that full‐scale pilot plants with duckweed should be shallower than the range encountered in the literature. A harvesting schedule that allows doubling times of 2 to 3.5 d, maintenance of a full coverage, and plug flow conditions are recommended.
Atmospheric Deposition of Pesticides to an Agricultural Watershed of the Chesapeake Bay
Authors: Kuang Zhihua , McConnell Laura L. , Torrents Alba , Meritt Donald , Tobash Stephanie
Published: June 2010

The Choptank River watershed, located on the Delmarva Peninsula of the Chesapeake Bay, is dominated by agricultural land use, which makes it vulnerable to runoff and atmospheric deposition of pesticides. Agricultural and wildlife areas are in close proximity and off‐site losses of pesticides may contribute to toxic effects on sensitive species of plants and animals. High‐volume air samples (n = 31) and event‐based rain samples (n = 71) were collected from a single location in the watershed representing regional background conditions. Surface water samples were collected from eight stations in the tidal portion of the river on five occasions during 2000. Chlorothalonil, metolachlor, atrazine, simazine, endosulfan, and chlorpyrifos were frequently detected in the air and rain, with maximal concentrations during the period when local or regional crops were planted. The wet deposition load to the watershed was estimated at 150 ± 16, 61 ± 7, and 51 ± 6 kg yr−1 for chlorothalonil, metolachlor, and atrazine, respectively. The high wet deposition load compared with the estimated annual usage for chlorothalonil (13%) and endosulfan (14–90%) suggests an atmospheric source from outside the watershed. Net air–water gas exchange fluxes for metolachlor varied from −44 ± 19 to 9.3 ± 4.1 ng m−2 d−1 with negative values indicating net deposition. Wet deposition accounted for 3 to 20% of the total metolachlor mass in the Choptank River and was a more important source to the river than gas exchange. Estimates of herbicide flux presented here are probably a low estimate and actual rates may be significantly higher in areas closer to pesticide application.
Spatial Distribution of DDT in Sediments from Estuarine Rivers of Central Florida
Authors: Ouyang Ying , Nkedi‐Kizza Peter , Mansell Robert S. , Ren Jim Y.
Published: June 2010

Sediments may act as both a carrier for and a potential source of contaminants such as toxic organics in aquatic environments. This study investigated the spatial distribution of the pesticide DDT [1,1,1‐trichloro‐2,2‐bis(p‐chlorophenyl)ethane] in sediments from the Cedar and Ortega Rivers located in the lower St. Johns River basin, Florida, USA, using field measurements and three‐dimensional kriging analysis. High DDT concentrations were found near the junction of the Cedar and Ortega Rivers and at the north end of the Ortega River in the upper 0.5 m of the sediments, indicating that the sediment was enriched with DDT in the top layer although use of this chlorinated compound was banned in 1972. Further study revealed that the influence of sediment grain size or texture on DDT contamination was negligible in this river system and no linear correlations existed among DDT and its metabolites such as DDD [1,1‐dichloro‐2,2‐bis(p‐chlorophenyl)ethane] and DDE [1,1‐dichloro‐2,2‐bis(p‐chlorophenyl)ethylene]. Comparison of three‐dimensional distribution of DDT content to the Florida sediment quality assessment guideline or probable effect level (PEL) showed several “hot spots” in the Ortega River sediments, where DDT contents exceeded the PEL value of 4.78 μg kg−1 Such contamination may pose a significant hazard to aquatic life.