bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immobilization of Cesium‐137 and Uranium in Contaminated Sediments Using Soil Amendments
Authors: Seaman John C. , Meehan T. , Bertsch P.M. 
Published: June 2010

ABSTRACTBatch and dynamic leaching methods were used to evaluate the effectiveness of hydroxyapatite (HA), illite, and zeolite, alone and in combination, as soil additives for reducing the migration of cesium‐137 (137Cs+) and uranium (U) from contaminated sediments. Amendment treatments ranging from 0 to 50 g kg−1were added to the sediment and equilibrated in 0.001MCaCl2After equilibration, the treatment supernatants were analyzed for137Cs+, U, PO4, and other metals. The residual sediments were then extracted overnight using one of the following: 1.0MNH4Cl, 0.5MCaCl2, or the Toxicity Characteristic Leaching Procedure (TCLP) extractant. Cesium was strongly sorbed to the contaminated sediments, presumably due to interlayer fixation within native illitic clays. In fact,137Cs+was below detection limits in the initial equilibration solutions, the CaCl2extract, and the TCLP solution, regardless of amendment. Extractants selective for interlayer cations (1.0MNH4Cl) were necessary to extract measurable levels of137Cs+Addition of illitic clays further reduced Cs+extractability, even when subjected to the aggressive extractants. Zeolite, however, was ineffective in reducing Cs+mobility when subjected to the aggressive extractants. Hydroxyapatite was less effective than illite at reducing NH+4–extractable Cs+Hydroxyapatite, and mixtures of HA with illite or zeolite, were highly effective in reducing U extractability in both batch and leaching tests. Uranium immobilization by HA was rapid with similar final U concentrations observed for equilibration times ranging from 1 h to 30 d. The current results demonstrate the effectiveness of soil amendments in reducing the mobility of U and Cs+, which makes in‐place immobilization an effective remediation alternative.
In Situ Stabilization of Soil Lead Using Phosphorus
Authors: Hettiarachchi G.M. , Pierzynski G.M. , Ransom M.D. 
Published: June 2010

ABSTRACTIn situ stabilization of Pb‐contaminated soils can be accomplished by adding phosphorus. The standard remediation procedure of soil removal and replacement currently used in residential areas is costly and disruptive. This study was carried out to evaluate the influence of P and other soil amendments on five metal‐contaminated soils and mine wastes. Seven treatments were used: unamended control; 2500 mg of P/kg as triple superphosphate (TSP), phosphate rock (PR), acetic acid followed by TSP, and phosphoric acid (PA); and 5000 mg of P/kg as TSP or PR. A significant reduction in bioavailable Pb, as determined by the physiologically based extraction test (PBET), compared with the control upon addition of P was observed in all materials tested. Increasing the amount of P added from 2500 to 5000 mg/kg also resulted in a significantly greater reduction in bioavailable Pb. Phosphate rock was equally or more effective than TSP or PA in reducing bioavailable Pb in four out of five soils tested. Preacidification produced significantly lower bioavailable Pb compared with the same amount of P from TSP or PR in only one material. Reductions in Pb bioavailability as measured by PBET were evident 3 d after treatment, and it may indicate that the reactions between soil Pb and P occurred in situ or during the PBET. No further reductions were noted over 365 d. X‐ray diffraction data suggested the formation of pyromorphite‐like minerals induced by P additions. This study suggests that P addition reduced bioavailable Pb by PBET and has potential for in situ remediation of Pb‐contaminated soils.
Assessment of Metal Availability in Smelter Soil Using Earthworms and Chemical Extractions
Authors: Conder Jason M. , Lanno Roman P. , Basta Nicholas T. 
Published: June 2010

ABSTRACTChemical immobilization is a relatively inexpensive in situ remediation method that reduces soil contaminant solubility, but the ability of this remediation treatment to reduce heavy metal bioavailability and ecotoxicity to soil invertebrates has not been evaluated. Our objectives were to (i) assess the ability of chemical immobilization amendments (municipal sewage sludge biosolids and rock phosphate) to reduce metal bioavailability and toxicity in a toxic metal‐contaminated smelter soil and (ii) evaluate soil extraction methods using Ca(NO3)2 solution or ion‐exchange membranes coated with diethylenetriaminepentaacetic acid (DTPA) as surrogate measures of metal bioavailability and ecotoxicity. We treated a soil contaminated by Zn and Pb milling and smelting operations and an uncontaminated control soil with lime‐stabilized municipal biosolids (LSB), rock phosphate (RP), or anaerobically digested municipal biosolids (SS) and evaluated lethality of the remediated soils to earthworm (Eisenia fetida Savigny). Lime‐stabilized municipal biosolids was the only remediation amendment to successfully immobilize lethal levels of Zn in the smelter soil (14‐d cumulative mortality ≤15%). Calcium nitrate–extractable Zn in the lethal Zn smelter soil–amendment combinations was 11.5 to 18.2 mmol/kg, compared with the nonlethal LSB amended soil (0.62 mmol/kg). The Ca(NO3)2–extractable Zn‐based median lethal concentration (LC50) of 6.33 mmol/kg previously developed in Zn‐spiked artificial soils was applicable in the remediated smelter soils despite a 14‐fold difference in total Zn concentration. Chelating ion‐exchange membrane uptake among the soils was highly variable (mean CV = 39%) compared with the Ca(NO3)2–extraction (mean CV = 1.9%) and not well related to earthworm toxicity.
Factors Controlling Sediment and Phosphorus Export from Two Belgian Agricultural Catchments
Authors: Steegen A. , Govers G. , Takken I. , Nachtergaele J. , Poesen J. , Merckx R. 
Published: June 2010

ABSTRACTSediment and total phosphorus (TP) export vary through space and time. This study was conducted to determine the factors controlling sediment and TP export in two agricultural catchments situated in the Belgian Loess Belt. At the outlet of these catchments runoff discharge was continuously measured and suspended sediment samples were taken during rainfall events. Within the catchments vegetation type and cover, soil surface parameters, erosion features, sediment pathways, and rainfall characteristics were monitored. Total P content and sediment characteristics such as clay, organic carbon, and suspended sediment concentration were correlated. Total sediment and TP export differ significantly between the monitored catchments. Much of the difference is due to the occurrence of an extreme event in one catchment and the morphology and spatial organization of land use in the catchments. In one catchment, the direct connection between erosive areas and the catchment outlet by means of a road system contributed to a high sediment delivery ratio (SDR) at the outlet. In the other catchment, the presence of a wide valley in the center of the catchment caused sediment deposition. Vegetation also had an effect on sediment production and deposition. Thus, many factors control sediment and TP export from small agricultural catchments; some of these factors are related to the physical catchment characterisics such as morphology and landscape structure and are (semi)permanent, while others, such as vegetation cover and land use, are time dependent.
Effects of Dissolved Organic Matter from Animal Waste Effluent on Chlorpyrifos Sorption by Soils
Authors: Huang Xinjiang , Lee Linda S. 
Published: June 2010

ABSTRACTThe increased use of animal waste–derived effluents for irrigation could result in the enhanced movement of pesticides through complexation with dissolved organic materials. Batch equilibrium studies were conducted to measure the interaction among soil, chlorpyrifos [O,O‐diethyl O‐(3,5,6‐trichloro‐2‐pyridyl) phosphorothioate], and dissolved organic matter (DOM) from poultry, swine, and cow waste–derived lagoon effluents. All DOM was found to have a strong affinity for chlorpyrifos, resulting in reduced sorption of chlorpyrifos by soil, thus the potential for DOM‐enhanced mobility. Effluent DOM was observed to sorb to soils. Thus, for increasingly higher soil mass to solution volume ratios, the effect of chlorpyrifos association with water‐borne DOM on sorption decreases significantly. For high soil mass to solution volume ratios typical of soil profiles in the landscape, the potential for DOM‐enhanced transport will be greatly attenuated. Dissolved organic matter concentration and the nonpolar nature of DOM in the lagoon effluent decreased with increasing residence time in the cells of the lagoon system, thus reducing the potential for DOM‐enhanced transport.
Anaerobic Degradation of Atrazine and Metolachlor and Metabolite Formation in Wetland Soil and Water Microcosms
Authors: Seybold C.A. , Mersie W. , McNamee C. 
Published: June 2010

ABSTRACTThe half‐lives, degradation rates, and metabolite formation patterns of atrazine (6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine) and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] were determined in an anaerobic wetland soil incubated at 24°C for 112 d. At 0, 7, 14, 28, 42, 56, and 112 d, the soil and water were analyzed for atrazine and metolachlor, and their major metabolites. The soil oxidation–reduction potential reached −200 mV after 14 d. Degradation reaction rates were first‐order for atrazine in anaerobic soil and for metolachlor in the aqueous phase. Zero‐order reaction rates were best fit for atrazine in the aqueous phase and metolachlor in anaerobic soil. In anaerobic soil, the half‐life was 38 d for atrazine and 62 d for metolachlor. In the aqueous phase above the soil, the half‐life was 86 d for atrazine and 40 d for metolachlor. Metabolites detected in the anaerobic soil were hydroxyatrazine and deethylatrazine for atrazine, and relatively small amounts of ethanesulfonic acid and oxanilic acid for metolachlor. Metabolites detected in the aqueous phase above the soil were hydroxyatrazine, deethylatrazine, and deisopropylatrazine for atrazine, and ethanesulfonic acid and oxanilic acid for metolachlor. Concentrations of metabolites in the aqueous phase generally peaked within the first 25 d and then declined. Results indicate that atrazine and metolachlor can degrade under strongly reducing conditions found in wetland soils. Metolachlor metabolites, ethanesulfonic acid, and oxanilic acid are not significantly formed under anaerobic conditions.
Degradation of Soil Fumigants as Affected by Initial Concentration and Temperature
Authors: Ma Q.L. , Gan J. , Papiernik S.K. , Becker J.O. , Yates S.R. 
Published: June 2010

ABSTRACTSoil fumigation using shank injection creates high fumigant concentration gradients in soil from the injection point to the soil surface. A temperature gradient also exists along the soil profile. We studied the degradation of methyl isothiocyanate (MITC) and 1,3‐dichloropropene (1,3‐D) in an Arlington sandy loam (coarse‐loamy, mixed, thermic Haplic Durixeralf) at four temperatures and four initial concentrations. We then tested the applicability of first‐order, half‐order, and second‐order kinetics, and the Michaelis–Menten model for describing fumigant degradation as affected by temperature and initial concentration. Overall, none of the models adequately described the degradation of MITC and 1,3‐D isomers over the range of the initial concentrations. First‐order and half‐order kinetics adequately described the degradation of MITC and 1,3‐D isomers at each initial concentration, with the correlation coefficients greater than 0.78 (r2 > 0.78). However, the derived rate constant was dependent on the initial concentration. The first‐order rate constants varied between 6 and 10× for MITC for the concentration range of 3 to 140 mg kg−1, and between 1.5 and 4× for 1,3‐D isomers for the concentration range of 0.6 to 60 mg kg−1, depending on temperature. For the same initial concentration range, the variation in the half‐order rate constants was between 1.4 and 1.7× for MITC and between 3.1 and 6.1× for 1,3‐D isomers, depending on temperature. Second‐order kinetics and the Michaelis–Menten model did not satisfactorily describe the degradation at all initial concentrations. The degradation of MITC and 1,3‐D was primarily biodegradation, which was affected by temperature between 20 and 40°C, following the Arrhenius equation (r2 > 0.74).
Seasonal Leaching and Biodegradation of Dicamba in Turfgrass
Authors: Roy J.W. , Hall J.C. , Parkin G.W. , Wagner‐Riddle C. , Clegg B.S. 
Published: June 2010

ABSTRACTThe leaching of surface‐applied herbicides, such as dicamba (2‐methoxy‐3,6‐dichlorobenzoic acid), to ground water is an environmental concern. Seasonal changes in soil temperature and water content, affecting infiltration and biodegradation, may control leaching. The objectives of this study were to (i) investigate the leaching of dicamba applied to turfgrass, (ii) measure the degradation rate of dicamba in soil and thatch in the laboratory under simulated field conditions, and (iii) test the ability of the model EXPRES (containing LEACHM) to simulate the field transport and degradation processes. Four field lysimeters, packed with sandy loam soil and topped with Kentucky bluegrass (Poa pratensis L.) sod, were monitored after receiving three applications (May, September, November) of dicamba. Concentrations of dicamba greater than 1 mg L−1 were detected in soil water. Although drying of the soil during the summer prevented deep transport, greater leaching occurred in late autumn due to increased infiltration. From the batch experiment, the degradation rate for dicamba in thatch was 5.9 to 8.4 times greater than for soil, with a calculated half‐life as low as 5.5 d. Computer modeling indicated that the soil and climatic conditions would influence the effectiveness of greater degradation in thatch for reducing dicamba leaching. In general, EXPRES predictions were similar to observed concentration profiles, though peak dicamba concentrations at the 10‐cm depth tended to be higher than predicted in May and November. Differences between predictions and observations are probably a result of minor inaccuracies in the water‐flow simulation and the model's inability to modify degradation rates with changing climatic conditions.
Oxidation Kinetics of the Combustible Fraction of Construction and Demolition Wastes
Authors: Chang Ni‐Bin , Lin Kuen‐Song , Sun Y.‐P. , Wang H.Paul 
Published: June 2010

ABSTRACTProper disposal of construction and demolition wastes (CDW) has received wide attention recently due to significantly large quantities of waste streams collected from razed or retrofitted buildings in many metropolitan regions. Burning the combustible fractions of CDW (CCDW) and possibly recovering part of the heat content for economic uses could be valuable for energy conservation. This paper explores the oxidation kinetics of CCDW associated with its ash characterization. Kinetic parameters for the oxidation of CCDW were numerically calculated using thermal gravimetric analysis (TGA) and the resultant rate equations were therefore developed for illustrating the oxidation processes of CCDW simultaneously. Based on three designated heating rates, each of the oxidation processes can be featured distinctively with five different stages according to the rate of weight change at the temperature between 300 K and 923 K. In addition, Fourier transform infrared (FTIR) spectroscopy was employed, associated with a lab‐scale fixed‐bed incinerator for monitoring the composition of flue gas. Carbon dioxide (CO2) was found as a major component in the flue gas. The fuel analysis also included an ash composition analysis via the use of X‐ray powder diffraction (XRD), atomic absorption (AA) spectroscopy, inductively coupled plasma–atomic emission spectroscopy (ICP–AES), and scanning electron microscopy–energy dispersive spectroscopy (SEM–EDX). The ash streams were identified as nonhazardous materials based on the toxicity characteristic leaching procedure (TCLP). Overall, the scientific findings gained in this study will be helpful for supporting a sound engineering design of real‐world CCDW incineration systems.
The Influence of Vegetation on Sedimentation and Resuspension of Soil Particles in Small Constructed Wetlands
Authors: Braskerud B.C. 
Published: June 2010

ABSTRACTWhen initiatives to mitigate soil erosion are insufficient or fail, constructed surface flow wetlands (CWs) could be a final buffer to reduce pollution before reaching recipients. The objective of this study was to determine the influence of CW vegetation on the retention of soil particles from arable land. Retention was measured with water flow‐proportional sampling systems in the inlet and outlet, sedimentation traps, and sedimentation plates in four small CWs over a period of 5 yr. The surface area of the CWs was 265 to 900 m2, and the average hydraulic loads were 1.2 to 3.4 m d−1 Watershed areas were 0.5 to 1.5 km2 Annual soil particle retention was 30 to 80% or 14 to 121 kg m−2 Results show that macrophytes stimulate sediment retention by mitigating resuspension of CW sediment. Five years after construction, resuspension had decreased approximately 40% and was negligible. As vegetation cover increases, the influence of macrophytes on soil particle retention reaches a level where other factors, such as hydraulic load and sediment load, were more important. Macrophytes increased the hydraulic efficiency by reducing short‐circuit or preferential flow. However, vegetation did not have any influence on the clay concentration in the sediment. Hence, a possible stimulation of particle flocculation was not detected. Vegetation makes it possible to use the positive effect of a short particle settling distance in shallow ponds by hindering resuspension.
Phosphorus Sorption Characteristics of Estuarine Sediments under Different Redox Conditions
Authors: Pant H.K. , Reddy K.R. 
Published: June 2010

ABSTRACTPhosphorus (P) plays a major role in eutrophication of aquatic systems. Estuarine sediments could function as sources or sinks for P to the overlying water column depending upon their physico–chemical characteristics. Understanding of P sorption phenomena in estuarine sediments is important in regulating the P availability in estuaries. Phosphorus sorption characteristics of sediments from the Indian River Lagoon, Florida, USA, were determined to examine the role of selected physico–chemical properties of the sediments on soluble reactive P status in estuary water. Mean equilibrium P concentrations (EPCo) of 0.75 mg L−1 and mean P sorption maxima (Smax) of 32.2 mg kg−1 were obtained under anaerobic conditions, compared with EPCo of 0.05 mg L−1 and Smax of 132.7 mg kg−1 under aerobic conditions. The higher EPCo values under anaerobic conditions and the greater Smax values under aerobic conditions were associated with amorphous and poorly crystalline iron. These results suggest that sediments enriched with amorphous and poorly crystalline forms of iron act as an excellent reservoir for P by adsorbing excessive P in aerobic sediment zones and releasing it upon burial under anaerobic conditions. This study also indicates that P compounds in sediments independently maintain equilibrium with P in solutions. Thus, heterogeneous systems like soil and sediment simply behave as a mixture of homogeneous surfaces as far as their P sorption characteristics are concerned, and hence can be successfully described by the Langmuir and Freundlich models.
Screening for Organotin Compounds in European Landfill Leachates
Authors: Mersiowsky I. , Brandsch R. , Ejlertsson J. 
Published: June 2010

ABSTRACTAs industrial chemicals, organotin compounds are predominantly applied as polyvinyl chloride (PVC) stabilizers and biocides. They are widely encountered in environmental samples and may be introduced into landfills by disposal of municipal solid waste or sewage sludge. In the present study, leachate samples were obtained from several sanitary landfill sites in Sweden, Italy, and Germany. These samples were analyzed by means of a highly sensitive and species‐selective method for methyltin, butyltin, and octyltin species. In total, twelve samples from eight different landfill sites at various ages were investigated. The findings of all target compounds range between less than the limit of detection at 0.1 μg/L and, at maximum, 4 μg/L. Only octyltin compounds can be attributed to PVC products with any certainty, whereas for methyltin and butyltin compounds alternative and less distinct sources exist. Organotin compounds are subject to microbial transformation, such as dealkylation and methylation processes. Consequently, caution should be exercised when attributing findings to potential sources and deriving any predicted environmental concentrations.
Degradation of Biomacromolecules during High‐Rate Composting of Wheat Straw–Amended Feces
Authors: Veeken A. H. M. , Adani F. , Nierop K. G. J. , de Jager P. A. , Hamelers H. V. M. 
Published: June 2010

ABSTRACTPig (Sus scrofa) feces, separately collected and amended with wheat straw, was composted in a tunnel reactor connected with a cooler. The composting process was monitored for 4 wk and the degradation of organic matter was studied by two chemical extraction methods, 13C cross polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) and pyrolysis gas chromatography–mass spectrometry (GC–MS). Wet‐chemical extraction methods were not adequate to study the degradation of specific organic compounds as the extraction reagents did not give selective separation of hemicellulose, cellulose, proteins, and lignins. A new method was proposed to calculate the contribution of four biomacromolecules (aliphatics, proteins, polysaccharides, and lignin) from the 13C CPMAS NMR spectrum. Pyrolysis GC–MS allowed identification of the composition of the biomacromolecules. The biomacromolecules showed different rates of degradation during composting. High initial degradation rates of aliphatics, hemicellulose, and proteins were observed, where aliphatics were completely degraded and hemicellulose and proteins were partly recalcitrant during the four weeks of composting. The degradation rate of cellulose was much lower and degradation was not completed within the four weeks of composting. Lignin was not degraded during the thermophilic stage of composting but started to degrade slowly during the mesophilic stage. A combination of 13C CPMAS NMR and pyrolysis GC–MS gave good qualitative and semiquantitative assessments of the degradation of biomacromolecules during composting.