Malathion-induced sublethal toxicity on the intestine of cricket frog (Fejervarya limnocharis)

The effect of malathion [diethyl(dimethoxythiophosphorylthio)succinate] at sublethal concentration (0.006 ppm) on intestinal parameters of cricket frog (Fejervarya limnocharis) was studied for 24 hrs to 240 hrs of exposure and remarkable histopathological alterations were observed. The study on intestinal parameters revealed acute pathological conditions in the intestinal wall. The toxic effect became evident as the cytoplasm of the cells disintegrated and the cells became empty and vacuolated. The cell membranes were also ruptured. Degenerative changes of the absorptive surface (villi) of the intestine in the different periods of exposure were pronounced. Severe atrophic nature (necrotic mucosa) of the intestine began from 48 hrs onwards to 96 hrs of exposure.     

Trimethylphenylammonium-Smectite as an Effective Adsorbent of Water Soluble Aromatic Hydrocarbons

Homoionic trimethylphenylammonium (TMPA)- and tetramethylammonium (TMA)-clays were prepared by Ion-exchange reactions using two smectite clays that differed in their cation exchange capacities and surface charge densities. These clays are referred to as a low-charge (SAC) and high-charge (SWa)-smectite. The organo-clays were evaluated as adsorbents of water soluble aromatic hydrocarbons including benzene, toluene, ethylbenzene, p-xylene, butylbenzene, and naphthalene. All of the aromatic hydrocarbons tested were effectively removed from water by the low-charge TMPA-smectite. The low-charge TMA-smectite was an effective adsorbent for benzene but was ineffective in the removal of the alkylbenzenes and naphthalene from water. The effect of surface charge on the adsorption properties of TMPA-smectite was pronounced. The uptake of benzene and toluene by the high-charge TMPA-smectite was greatly reduced as compared to the low-charge TMPAsmectite. These results suggest the utility of TMPA-smectite as a liner material for petroleum storage containers and waste disposal reservoirs. The use of TMPA-smectite in conjunction with Na-smectite would provide a barrier with the ability to impede the flow of water and to effectively adsorb dissolved organic contaminants.     

Airborne Emissions of Mercury from Municipal Solid Waste. I: New Measurements from Six Operating Landfills in Florida

Abstract

Mercury-bearing material enters municipal landfills from a wide array of sources, including fluorescent lights, batteries, electrical switches, thermometers, and general waste; however, the fate of mercury (Hg) in landfills has not been widely studied. Using automated flux chambers and downwind atmospheric sampling, we quantified the primary pathways of Hg vapor releases to the atmosphere at six municipal landfill operations in Florida. These pathways included landfill gas (LFG) releases from active vent systems, passive emissions from landfill surface covers, and emissions from daily activities at each working face (WF). We spiked the WF at two sites with known Hg sources; these were readily detected downwind, and were used to test our emission modeling approaches. Gaseous elemental mercury (Hg⁰) was released to the atmosphere at readily detectable rates from all sources measured; rates ranged from ～1–10 ng m^?2 hr^?1 over aged landfill cover, from ～8–20 mg/hr from LFG flares (LFG included Hg⁰ at μg/m³ concentrations), and from ～200–400 mg/hr at the WF. These fluxes exceed our earlier published estimates. Attempts to identify specific Hg sources in excavated and sorted waste indicated few readily identifiable sources; because of effective mixing and diffusion of Hg⁰, the entire waste mass acts as a source. We estimate that atmospheric Hg releases from municipal landfill operations in the state of Florida are on the order of 10–50 kg/yr, substantially larger than our original estimates, but still a small fraction of current overall anthropogenic losses.     

The addition of organic carbon and nitrate affects reactive transport of heavy metals in sandy aquifers

Organic carbon introduction in the soil to initiate remedial measures, nitrate infiltration due to agricultural practices or sulphate intrusion owing to industrial usage can influence the redox conditions and pH, thus affecting the mobility of heavy metals in soil and groundwater. This study reports the fate of Zn and Cd in sandy aquifers under a variety of plausible in-situ redox conditions that were induced by introduction of carbon and various electron acceptors in column experiments. Up to 100% Zn and Cd removal (from the liquid phase) was observed in all the four columns, however the mechanisms were different. Metal removal in column K1 (containing sulphate), was attributed to biological sulphate reduction and subsequent metal precipitation (as sulphides). In the presence of both nitrate and sulphate (K2), the former dominated the process, precipitating the heavy metals as hydroxides and/or carbonates. In the presence of sulphate, nitrate and supplemental iron (Fe(OH)(3)) (K3), metal removal was also due to precipitation as hydroxides and/or carbonates. In abiotic column, K4, (with supplemental iron (Fe(OH)(3)), but no nitrate), cation exchange with soil led to metal removal. The results obtained were modeled using the reactive transport model PHREEQC-2 to elucidate governing processes and to evaluate scenarios of organic carbon, sulphate and nitrate inputs.     

International comparative study of 3R and waste management policy developments

Reduce, reuse, and recycle (3R) policies form the basis of waste management and global warming countermeasures globally, so we conducted a comparative study of 3R and waste management policies in the European Union (EU), USA, Korea, Japan, China, and Vietnam. An international workshop for 3R and waste management policymakers was held in Kyoto, Japan, and a bibliographic survey was also conducted to collect data. 3R policies are clearly given priority in the hierarchy of waste management in every country studied. Thermal recovery, which includes power generation from waste heat and methane gas collected from organic waste, is also a priority; this is consistent with the increased use of countermeasures to reduce greenhouse gas (GHG) emissions. In the EU, waste management is characterized by practical and effective 3R policies through the development of realistic regulations and by the policymakers??desire to simplify management systems. The policy ideal in China, however, is the development of a circular economy that targets reductions in the amount and hazardousness of waste. Limits on the number of final disposal sites, strategies for procuring resources, and GHG emission countermeasures are closely linked with 3R policies, and further development of 3R policies in parallel with such issues is expected.     

Antioxidant responses of the earthworm Lampito mauritii exposed to Pb and Zn contaminated soil

The aim of this study was to provide fundamental data on the biochemical analysis of antioxidant defences in the earthworm exposed to low levels (75, 150, 300 mg kg(-1) soil) of Pb and Zn. In order to attain this objective, adult Lampito mauritii were exposed to different doses of Pb and Zn separately for 28 days and the concentrations of oxidized and reduced glutathione, activities of glutathione-S-transferase, glutathione peroxidase and glutathione reductase were assessed. Dose-dependent perturbations were observed in the glutathione-glutathione-S-transferase system and other antioxidant enzymes during the early phase of the exposure to Pb. In the Zn exposed earthworm, the glutathione-glutathione-S-transferase system remained stable and the stimulation of glutathione peroxidase and glutathione reductase activities occurred significantly only on day 14 at 300 mg Zn kg(-1). It is concluded that the antioxidants are directly involved in the adaptive response of Lampito mauritii for survival in metal contaminated soil.     

Organochlorine residues in roof timbers and possible implications for bats

In Britain, many species of bat regularly use buildings as roosts. DDT, DDE, dieldrin (HEOD) and gamma-HCH (lindane) have been detected in carcasses of bats that had died a short while before they were found. Roof timbers may be a source of this contamination. This study reports concentrations of organochlorines in (i) roof timbers known to have been treated in the past (spot samples; n - 17) and (ii) timbers before and after treatment with commercial permethrin formulations (pre-treatment and post-treatment samples, n = 11). Gamma-HCH was detected in 13 spot samples and HEOD in 6. Where present, mean (+/-1 SE) concentrations in wood were 15.6+/-6.5 microg g-1 WW (n = 13) and 25.0+/-11.8 microg g-1 WW (n = 6), respectively. DDT was not detected in any spot samples, but permethrin was detected in four (1264+/-567 microg g(-1) WW) samples, but not in the corresponding pre-treatment samples; in one other pair of samples, concentrations of gamma-HCH increased from 74 to 2468 microg g-1 WW after treatment. Both DDT and HEOD occurred in low (<2 microg g-1 WW) concentrations in five post-treatment samples and in one and zero pre-treatment samples, respectively; the highest dieldrin concentration measured was 30.9 microg g-1 WW. Permethrin was not detectable in any pre-treatment samples but was present in ten post-treatment samples in concentrations ranging from 93 to 2995 microg g-1 WW. The spot results suggest that low concentrations of organochlorines can persist in treated roof timbers for at least 13 years post-treatment. Occasionally, these pesticide residues in timber may be of sufficient magnitude to result in bats absorbing a substantial proportion of a lethal dose. Results also suggest that there is organochlorine contamination of permethrin formulations and that the solvents used in new applications of pesticide may re-mobilise organochlorines already present in wood.