Chemosphere (v.60, #2)

Kinetics of carbosulfan hydrolysis to carbofuran and the subsequent degradation of this last compound in irrigated rice fields by Luís Pedro de Melo Plese; Lourival Costa Paraiba; Luiz Lonardoni Foloni; Luiz Roberto Pimentel Trevizan (149-156).
The objectives of this work were estimate the reaction rates of hydrolysis of carbosulfan to carbofuran and subsequent degradation of this last compound in irrigated rice fields, and the respective half life, in aquatic environment and soil solution, by mean of numerical solution of differential ordinary linear equations system that describes the kinetics of insecticide concentrations. The results indicated that the carbosulfan and carbofuran have low persistence in water and medium persistence in soil solution of tropical irrigated rice fields. However, both compounds can be found in laminar water and soil solution in concentration above environmental and human safety limits.
Keywords: Kinetic; Rice; Carbamate; Carbosulfan; Carbofuran; Oryzophagus oryzae; Model;

We studied the characteristic gram-stain of Tc insolubilizing bacteria using various antibiotics, and the fate of insoluble Tc in a water column above flooded paddy soil to clarify Tc behavior in paddy fields. The formation of insoluble Tc in water column samples was inhibited by the addition of antibiotics, especially reagents against gram-negative bacteria. For a sample without antibiotics, insoluble Tc formation increased with time, and the maximum amount of insoluble Tc was observed on day 4 of incubation with 95mTc. In contrast, concentrations of ferrous ion decreased with time. These results suggested that gram-negative bacteria were mainly responsible for insoluble Tc formation, and that these bacteria were able to transform soluble Tc to insoluble forms under oxidizing conditions.
Keywords: Gram-negative bacteria; Insoluble technetium; Water column; Paddy field;

Paclobutrazol is a plant growth regulator that is used to counter alternate bearing habit of mango (Mangifera indica L.). The uptake and persistence of paclobutrazol residues in mango fruits and soil respectively, was studied following its application at tree basin soil @5 and 10 g a.i. per tree for three consecutive years. Residues of paclobutrazol were found in unripe mango fruits at levels below permissible level while the same was generally not detected in fully mature mango fruits ready for harvest. There was no effect of consecutive yearly applications on the amount of paclobutrazol residues in mango fruit. However, the residues of paclobutrazol were found in tree basin soil (0–15 cm) at the end of each season and there was a small increase in the amount of residues corresponding to the number of yearly applications that had been made. GC–MS analysis confirmed that the sample peaks obtained corresponded to paclobutrazol residues present in mango and soil.
Keywords: Uptake; Dissipation; Mango; Soil; Paclobutrazol;

Passive air sampling theory for semivolatile organic compounds by Michael E. Bartkow; Kees Booij; Karen E. Kennedy; Jochen F. Müller; Darryl W. Hawker (170-176).
The mathematical modelling underlying passive air sampling theory can be based on mass transfer coefficients or rate constants. Generally, these models have not been inter-related. Starting with basic models, the exchange of chemicals between the gaseous phase and the sampler is developed using mass transfer coefficients and rate constants. Importantly, the inter-relationships between the approaches are demonstrated by relating uptake rate constants and loss rate constants to mass transfer coefficients when either sampler-side or air-side resistance is dominating chemical exchange. The influence of sampler area and sampler volume on chemical exchange is discussed in general terms and as they relate to frequently used parameters such as sampling rates and time to equilibrium. Where air-side or sampler-side resistance dominates, an increase in the surface area of the sampler will increase sampling rates. Sampling rates are not related to the sampler/air partition coefficient (K SV) when air-side resistance dominates and increase with K SV when sampler-side resistance dominates.
Keywords: Passive air sampling; SPMDs; PUF; Rate constants; Mass transfer coefficients; Air-side resistance;

Partitioning microbial respiration between jet fuel and native organic matter in an organic-rich long time-contaminated aquifer by G.C. Bugna; J.P. Chanton; T.B. Stauffer; W.G. MacIntyre; E.L. Libelo (177-187).
The relative importance of jet fuel biodegradation relative to the respiration of natural organic matter in a contaminated organic-rich aquifer underlying a fire training area at Tyndall Air Force Base, Florida, USA was determined with isotopic measurements. Thirteen wells were sampled and analyzed for BTX (benzene, toluene, xylene), dissolved inorganic carbon (DIC) and CH4 concentrations, and δ13C and 14C of DIC. Results range from non-detectable to 3790 ppb, 1.4–24 mM, 0.2–776 μM, +5.8‰ to −22‰, and from 52 to 99 pmc, respectively. Residual fuel was confined to two center wells underlying the fire training area. DIC and CH4 concentrations were elevated down-gradient of the contamination, but also at sites that were not in the apparent flow path of the contaminated groundwater. DIC exhibited greatest δ13C enrichment at highest DIC and CH4 concentrations indicating that CH4 production was an important respiration mode. Radiocarbon-depleted DIC was observed at sites with high hydrocarbon concentrations and down-gradient of the site. The results indicate that while natural attenuation was not rapidly reducing the quantity of free product overlying the aquifer at the site of contamination, it was at least constraining its flow away from the spill site. Apparently under the conditions of this study, BTX was degraded as rapidly as it was dissolved.
Keywords: Stable carbon isotope; Radiocarbon; Aquifer; Jet fuel; Petroleum hydrocarbon; Biodegradation;

Fate and bioavailability of arsenic in organo-arsenical pesticide-applied soils. by Dibyendu Sarkar; Rupali Datta; Saurabh Sharma (188-195).
A laboratory incubation study was conducted to estimate geochemical speciation and in vitro bioavailability of arsenic as a function of soil properties. Two chemically-variant soil types were chosen, based on their potential differences with respect to arsenic reactivity: an acid sand with minimal arsenic retention capacity and a sandy loam with relatively high concentration of amorphous Fe/Al-oxides, considered a sink for arsenic. The soils were amended with dimethylarsenic acid (DMA) at three rates: 45, 225, and 450 mg/kg. A sequential extraction scheme was employed to identify the geochemical forms of arsenic in soils, which were correlated with the “in vitro” bioavailable fractions of arsenic to identify the most bioavailable species. Arsenic bioavailability and speciation studies were done at 0 time (immediately after spiking the soils with pesticide) and after four-months incubation. Results show that soil properties greatly impact geochemical speciation and bioavailability of DMA; soils with high concentrations of amorphous Fe/Al oxides retain more arsenic, thereby rendering them less bioavailable. Results also indicate that the use of organic arsenicals as pesticides in mineral soils may not be a safe practice from the viewpoint of human health risk.
Keywords: Dimethylarsenic acid; Geochemical speciation; Bioavailability; Soil properties;

Evaluation of pesticides and metals in fish of the Dniester River, Moldova by Yelena Sapozhnikova; Natalia Zubcov; Sarah Hungerford; Luke A. Roy; Nina Boicenco; Elena Zubcov; Daniel Schlenk (196-205).
The Dniester River is one of the largest rivers in Eastern Europe and receives input from numerous anthropogenic activities. In October 2001, fish samples (Abramis brama, Rutilus rutilus heckeli, Perca fluviatilis, Chondrostoma nasus, Carassius auratus gibelio, and Cyprinus carpio) were collected and analyzed for metals and various pesticides. Maximum total DDT pesticide concentrations were between 27.7 and 34.2 ng/g wet weight in muscles and gonads, respectively. DDE isomers comprised up to 70% of total DDT measurement in fish tissues, indicating historical rather than recent DDT pollution. Chlordane and lindane were also detected in amounts up to 37 and 76 ng/g wet weight in gonads, respectively. Among organophosphorous pesticides, malathion showed extremely high concentrations—3 μg/g wet weight in muscles and 46 μg/g wet weight in gonads, indicating recent exposure. Copper concentrations in muscles (1.8–7.2 μg/g) exceeded Threshold Effect Concentrations for copper in fish. Detection of high concentrations of malathion and copper in fish tissues indicated potential anthropogenic stress for more sensitive aquatic biota, likely from agricultural sources in the Dniester River.
Keywords: Pesticides; Metals; Fish; Dniester River; Moldova;

Heavy metal binding capacity (HMBC) of municipal solid waste landfill leachates by Marnie L. Ward; Gabriel Bitton; Timothy Townsend (206-215).
This research describes the use of a toxicity assay for the identification of metal toxicity, bioavailability and heavy metal binding capacity (HMBC) of municipal solid waste (MSW) landfill leachates. MetPLATE, an assay specific for heavy metal toxicity, was used to determine the HMBC of MSW leachates collected from 14 sites in Florida, with a wide range of chemical and physical characteristics. The leachates displayed a low toxicity which was attributed to the site-specific parameters, including, high concentrations of both organic and inorganic ligands. The HMBC test was undertaken to measure the effect of these site-specific parameters on metal toxicity. The potential for MSW leachate to bind and, thus, detoxify heavy metals was investigated with copper, zinc, and mercury. The HMBC values obtained ranged from 3 to 115, 5 to 93 and 4 to 101 for HMBC-Cu+2, HMBC-Zn+2, and HMBC-Hg2, respectively. Additionally, the high strength leachates displayed the highest binding capacities, although the landfills sampled represented a wide range of characteristics. For comparison, the HMBC values reported with local lake water, Lake Alice and Lake Beverly, and a wastewater treatment plant effluent were all below 3. A partial fractionation of MSW leachate samples from sites 1, 5 and 8, was conducted to further investigate the influence of selected site-specific physico-chemical parameters on metal binding. The fractionation revealed that the HMBC of the leachate samples was heavily influenced by the concentration of solids, organics and hardness.
Keywords: Heavy metal binding; Municipal solid wastes; Landfill leachates; MetPLATE assay; Heavy metals;

Distribution patterns of particulate trace metals in the water column and nepheloid layer of the Gulf of Riga by Rita Poikāne; Jacob Carstensen; Ingela Dahllöf; Juris Aigars (216-225).
The dynamics (fate) of trace metals in suspended particulate matter within the Gulf of Riga has not yet been adequately addressed in the scientific literature. Therefore, during a two year period (2001–2002) samples of suspended particulate matter and surface sediments for trace metal analysis were collected in the Gulf of Riga and the Daugava river, and these data were combined with background information from the national marine monitoring program in Latvia. This paper presents a descriptive study of solid phase trace metals (aluminium, iron, cadmium, chromium, copper, manganese, nickel, lead and zinc) dynamics and their spatial distribution within the Gulf of Riga based on Principal Component Analysis and Cluster analysis. Fluvial particulate matter and particulate Al, Fe, Cr and Ni were brought into the Gulf of Riga mainly during spring flood and thereafter quickly diluted by the water masses of the Gulf of Riga. Fine-grained suspended material and particulate Al and Fe were well mixed and evenly distributed through all deepwater basins of the Gulf of Riga. The increase of particulate Mn below the thermocline in August and a strong negative correlation with dissolved oxygen concentrations suggested that particulate Mn in the water column and the sediments were regulated mainly by changing oxic–anoxic conditions in the sediments of the Gulf of Riga. The observed correlation between Al and Fe in the water column is in contrast to that observed in the nepheloid layer where Fe correlated with Mn, obviously due to fast diagenetic processes on sediment surface. The observed negative correlation of Cd and Zn with total carbon and total nitrogen in the nepheloid layer might indicate different sedimentation mechanisms of these elements, however, this assumption is still inconclusive.
Keywords: Particulate matter; Sediments; Principal component analysis; Cluster analysis; Daugava river;

Mercury in lakes and lake fishes on a conservation-industry gradient in Brazil by N. Mirlean; S.T. Larned; V. Nikora; V. Tavares Kütter (226-236).
Mercury contamination in freshwater food webs can be severe and persistent, and freshwater fish are a major source of mercury contamination in humans. Northern hemisphere studies suggest that the primary pathway by which freshwater fish accumulate mercury is the food web, and that atmospheric deposition is the primary route by which mercury enters freshwater systems. Levels of atmospheric deposition are closely linked to proximity to sources of mercury emissions. These propositions have not been tested in the southern hemisphere. In this study, we measured mercury levels at three lakes in southern Brazil and assessed relationships between mercury in precipitation, lake water, sediment and fish tissues at sites close to (industrial and suburban areas) and distant from (protected conservation area) sources of mercury emissions. We also assessed relationships between mercury in fish species and their trophic habits. Mercury concentrations in sediment and lake water did not vary among lakes. In contrast, mercury in precipitation at the study lakes increased with proximity to industrial sources. Mercury in fish tissue generally increased along the same gradient, but also varied with trophic level and preferred depth zone. Atmospheric mercury deposition to these closed lakes may be directly linked to concentrations in fish, with surface-feeding piscivorous species attaining the highest concentrations.
Keywords: Fish; Lake; Mercury contamination; Sediment; South America; Trophic level;

Phosphorus is an essential and often limiting nutrient in both marine and freshwater ecosystems. However, its oversupply is of great concern in many environments due to its role in eutrophication. The concentration and distribution of sediment bound phosphorus species not only record its input into the environment, but also suggest their possible sources. It is recognized that the features of phosphorus behaviour have not been extensively studied in urban environments. In this study, phosphorus in solid waste and sediments from drainage canals within the industrial belt of Delhi were fractionated into five operationally defined forms, i.e., exchangeable or loosely sorbed phosphorus (Exch-P), Fe-bound phosphorus (Fe–P), authigenic apatite, CaCO3-bound phosphorus and biogenic apatite (Acet-P), detrital apatite (Det-P) and organic-bound phosphorus (Org-P), in order to assess the potential bioavailability status in these systems.
Keywords: Eutrophication; Exchangeable; Authigenic; Detrital and organic phosphorus;

Laboratory batch studies were conducted to characterize the sorption behavior of three pharmaceutically active substances (carbamazepine, diclofenac, and ibuprofen) in different sediment types. The sediments were natural sandy sediments from the water saturated zone and the unsaturated zone in the Berlin (Germany) area. They are characterized as medium and fine-grained sands, both with low organic carbon content. The results of the experiments show that sorption coefficients were generally quite low. Distribution coefficients (K d values) determined by the batch experiments varied from 0.21 to 5.32 for carbamazepine, 0.55 to 4.66 for diclofenac, and 0.18 to 1.69 for ibuprofen. Comparison of the organic carbon normalized sorption coefficient K OC values based on correlation equations with actual experimental data revealed that the calculated data for carbamazepine is of the same order as the experimental data. For diclofenac and ibuprofen the calculated values are much higher than the experimental data, showing a much higher mobility of diclofenac and ibuprofen in natural aquifer sediments than indicated by correlation equations based on octanol water distribution coefficients.
Keywords: Pharmaceuticals; Mobility; Freundlich; Nernst; Isotherm;

An investigation was conducted to evaluate the stability or leachability of arsenic immobilized by microbial sulfate reduction. Anoxic solid-phase samples taken from a bioreactor previously used to treat metal and As contaminated water using sulfate reducing bacteria (SRB) were subjected to the toxicity characteristic leaching procedure (TCLP) and long-term column leaching tests. The results from TCLP experiments showed that the concentration of As leached from solid-phase sulfide material (SSM) samples after an 18 h extraction time was <300 μg l−1, which is below the current maximum Australian TCLP leachate value for As, and thus would not be characterized as a hazardous waste. In terms of percent total As leached, this was equivalent to <8.5% for SSM samples initially containing 61.3 mg kg−1 As. The levels of As extracted by the TCLP was found to be significantly lowered or underestimated in the presence of dissolved oxygen, with As concentrations increasing with decreasing headspace-to-leachant volume ratios. The concentration of As was also consistently higher in nitrogen purged extractions compared to those performed in air. This was attributed to the dissolution of Fe–sulfide precipitates and subsequent oxidation of Fe(II) ions and precipitation of ferric(hydr)oxides, resulting in the adsorption of soluble As and corresponding decrease in As concentrations. According to the experimental data, it is recommended that TCLP tests for As leachability should be performed at least in zero-headspace vessels or preferably under nitrogen to minimize the oxidation of Fe(II) to ferric(hydr)oxides. In long-term leaching studies (∼68 days), it was found that the low solubility of the SSM ensured that rate of release of As was relatively slow, and the resulting leachate concentrations of As were below the current Australian guideline concentration for arsenic in drinking water.
Keywords: Arsenic; TCLP; Sulfate reduction; Leaching; Extraction; Sulfide;

Enhancement of p,p′-DDT photodegradation on soil surfaces using TiO2 induced by UV-light by Xie Quan; Xu Zhao; Shuo Chen; Huimin Zhao; Jingwen Chen; Yazhi Zhao (266-273).
Enhancement of p,p′-DDT photodegradation on soil surfaces using TiO2 induced by UV-light was mainly investigated in this work. After being spiked with p,p′-DDT, soil samples loaded with different doses of TiO2 (0%, 0.5%, 1%, 2%, and 3% wt) were exposed to UV-light irradiation for 24 h. The results indicated that the photodegradation of p,p′-DDT followed the pseudo-first-order kinetics. TiO2 accelerated the photodegradation of p,p′-DDT significantly as indicated by the half-life reduction from 23.3 h to 10.4 h, corresponding to the TiO2 content from 0% to 3% respectively. In addition, the effects of soil pH, photon flux and humic substances on p,p′-DDT degradation were investigated. The photodegradation rate increased with the increase of the soil pH and photon flux. The humic substances (2% wt) inhibited the p,p′-DDT photodegradation by reducing the amount of light available to excite the p,p′-DDT and TiO2 or by quenching radicals capable of oxidizing p,p′-DDT. p,p′-DDE, p,p′-DDD and DDMU were main degradation intermediates and they were further degraded in the presence of TiO2.
Keywords: p,p′-DDT; Soil surfaces; Photodegradation; TiO2; Humic substances; UV-light;

Distribution of PCNs, PCBs, and other POPs together with soot and other organic matter in the marine environment of the Grenlandsfjords, Norway by N. Johan Persson; Örjan Gustafsson; Thomas D. Bucheli; Rasha Ishaq; Kristoffer Næs; Dag Broman (274-283).
The apparently dissolved concentration of polychlorinated naphthalenes (PCNs) and three planar polychlorinated biphenyls (pPCBs) were sampled and analysed in the water column of a marine fjord system. We also measured how much of these persistent organic pollutants (POPs) were associated with suspended particles. The field observations showed that an unexpectedly high portion of the pollutants were particle-associated. The factor of deviation from model predictions had positive linear regression on the soot carbon:particulate organic carbon ratio of the particles, and on estimates of the soot–water distribution coefficient for the PCNs. The spatial distribution of surface sediment concentrations of PCNs and polycyclic aromatic hydrocarbons (PAH) were found to consistently follow the sediment content of soot (f SC) to a larger extent than the bulk organic matter (f OC). There were no systematic differences in the strength of correlation of sediments concentrations of other POPs, i.e. octachlorostyrene and organochlorine pesticides with sediment concentration to f SC and f OC. Mechanisms possible of generating these types of observations, e.g. adsorption to soot carbon in the marine particle, are discussed.
Keywords: POPs; Partitioning models; Soot; Water; Sediment;

Sorption of tylosin onto swine manure by Angela C. Kolz; Say Kee Ong; T.B. Moorman (284-289).
Sorption of tylosin was conducted on manure solids (<2 mm) and colloidal materials (<1.2 μm) collected from open (OL) and covered (CL) anaerobic swine manure lagoons. The aqueous concentration of tylosin in the sorption studies bracket the levels expected in lagoons, between 1 mg l−1 and 30 mg l−1. Sorption isotherms were found to be slightly non-linear for 2 mm solids, with Freundlich distribution coefficients (K f) of 39.4 with n  = 1.32 for CL slurry and 99.5 with n  = 1.02 for OL. These values are comparable to those reported for loam soils, but higher than those reported for sandy or clay soils and lower than those reported for fresh manure. Normalization of K d to the organic carbon content of the solids gave K oc values of 570 l kg−1 and 818 l kg−1, for CL and OL solids, respectively. The K d and K f values were not significantly different between colloids and 2 mm solids in OL slurry, but were significantly different in CL due to the non-linearity of the colloid isotherm. Based on the K d values obtained and comparing the K d values of other antibiotics, tylosin is strongly sorbed to manure, and would be more mobile than tetracyclines, but less mobile than sulfonamides, olaquindox, and chloramphenicol. However, tylosin mobility may be facilitated through transport with colloidal manure materials.
Keywords: Tylosin; Antibiotic; Sorption; Swine manure; Environmental fate;