Suppression of inhibition of substrate photodegradation by scavengers of hydroxyl radicals: the solvent-cage effect of bromide on nitrate photolysis

In this paper we show that bromide scavenges the ^·OH radicals formed upon photolysis of nitrate, before they leave the solvent cage. Bromide can thus inhibit the in-cage recombination between ^·OH and ^·NO₂. The consequence is an increased generation of ^·NO₂ and nitrite and of Br₂ ^?· + ^·OH, compared to ^·OH alone in the absence of bromide. We show that this effect compensates for the lower reactivity of Br ₂ ^?· compared to ^·OH toward certain organic substrates, e.g. phenol and tryptophan. Our findings could lead to a deep revision of the present views of the role of bromide in saltwater photochemistry.     

Effect of trichloroethylene (TCE) inhalation on biotransformation enzymes of rat lung and liver

Trichloroethylene (TCE) is widely used as an industrial solvent and cleaning fluid. In the present study the toxic effects of TCE inhalation on pulmonary and hepatic biotransformation enzymes in rats have been investigated by assay of aniline hydroxylase (AH), aminopyrine-N-demethylase (APD), benzo-a-pyrene hydroxylase (BH) and glutathione-s-transferase (GST) activities and glutathione (GSH) contents in liver as well as lungs of exposed animals. In both organs phase I and phase II drug metabolizing enzymes have been found to be increased along with decrease in GSH contents following TCE inhalation. Pulmonary as well as hepatic MFO's seem to be activated by inhaled TCE probably in an attempt for its rapid detoxification and reduced glutathione is used during its biotransformation.     

Best management practices to prevent cross-media transfers during soil cleanup

Cleanup activities often focus on the initial and final concentration levels of contaminants. What happens in-between, during implementation of treatment technologies, has raised major concerns by several environmental groups. To address this issue, the U.S. Environmental Protection Agency (EPA) has undertaken the task of developing a guidance that would identify the potential for cross-media transfer during implementation of various soil treatment technologies and recommend best management practices (BMPs) to prevent or control these cross-media transfers. The soil treatment technologies have been grouped into seven major categories in this effort. This article provides some details of the seven soil treatment technology groups and the general BMPs recommended in the draft BMP guidance document. One case history of existing control practices is also presented in this article and compared with the recommended BMPs.     

The effect of iron on the biological activities of erionite and mordenite

Epidemiological data has demonstrated that environmental and/or occupational exposure to mineral particulates may result in the development of pulmonary fibrosis, bronchogenic carcinoma and malignant mesothelioma many years following exposure. It has been suggested that the genotoxic effects of fibrous particulates, such as asbestos, is due in part to the generation of reactive oxygen species (ROS) from iron associated with the particulates. However, the molecular mechanisms by which mineral particulates induce ROS that results in genotoxic damage remains unclear. The naturally occurring zeolites, erionite and mordenite share several physiochemical properties but they elicit very different biological responses, with erionite, a fibrous particulate, being highly toxic, and mordenite, a nonfibrous particulate, being relatively benign. We are using these natural zeolites as a model system to determine what physicochemical properties of these zeolites are responsible for their biological response(s) and to evaluate the parameters that influence these responses. The purpose of the present study was to determine the mutagenic potential of erionite and mordenite and to determine whether this mutagenic potential was modulated by iron. The results of this study using the Chinese hamster ovary cell line AS52 demonstrated that erionite was more cytotoxic than mordenite. However, the cytotoxicity of both zeolites was increased in the presence of physiological concentrations of ferrous chloride. Ferrous ions (5-20 microM) significantly (p<0.001) increased the cytotoxicity of mordenite, but only at the highest concentration (16 microg/cm(2)) of mordenite tested. Conversely, only the highest concentration (20 microM) of ferrous ion significantly (p<0.001) increased the cytotoxicity of erionite, but this enhanced cytotoxicity occurred over a wider concentration range (6-16 microg/cm(2)) of erionite. Mordenite was not mutagenic at any of the concentrations tested, and the mutagenic potential of mordenite was not enhanced by the addition of ferrous ion. Conversely, erionite was mutagenic in a dose-response manner at concentrations greater than 6 microg/cm(2) and the mutagenic potential of erionite was significantly enhanced by the addition of ferrous ions. These results suggest that while the cytotoxicity of mordenite and erionite may be related to the ability of these fibers to transport iron into a cell, the different coordination state of iron associated with the two fiber surfaces is critical for inducing genotoxic damage.     

Remediation of sulfidic wastewater by catalytic oxidation with hydrogen peroxide

Oxidation of sulfide in aqueous solution by hydrogen peroxide was investigated in the presence of hydrated ferric oxide catalyst. The ferric oxide catalyst was synthesized by sol gel technique from ferric chloride and ammonia. The synthesized catalyst was characterized by Fourier transform infrared spectroscopy, X-Ray di raction analysis, scanning electrom microscope and energy dispersive X-ray analysis. The catalyst was quite e ective in oxidizing the sulfide by hydrogen peroxide. The e ects of sulfide concentration, catalyst loading, H2O2 dosing and temperature on the kinetics of sulfide oxidation were investigated. Kinetic equations and activation energies for the catalytic oxidation reaction were calculated based on the experimental results.     

Phytoremediation of cadmium-contaminated soil by Bidens pilosa L.: impact of pine needle biochar amendment

Environmental Science and Pollution Research - The objective of the present study was to evaluate the feasibility of pine needle biochar as a soil amendment to promote the growth of Bidens pilosa...     

pH-conditioning for simultaneous removal of arsenic and iron ions from groundwater

The effects of some commonly used pH conditioners, viz., lime, banana ash, the carbonate and the bicarbonate of sodium and potassium and their binary mixture, on simultaneous removal of arsenic and iron ions from water have been studied. KHCO₃ has been found to be the most suitable pH conditioner for the purpose. About 80 mg/L KHCO₃ can remove both arsenate and iron ions from initial 250 μg/L and 20 mg/L to below their respective guideline values of the WHO for drinking water, retaining the final pH in the acceptable range for drinking. The simultaneous removal of arsenate and iron by the pH-conditioners decreases in the order: Lime > KHCO₃ > NaHCO₃ > K₂CO₃ > Na₂CO₃ > ash. However, lime requires post-treatment correction of highly alkaline pH. The arsenate ion is removed predominantly through goethite or ferrihydrite in the presence of the bicarbonates and through ferric hydroxide in the presence of the more alkaline pH-conditioners. KHCO₃ is more advantageous over the more basic substances including NaHCO₃, because with it, one not only needs the smallest dose but also can avoid careful adjustment of the dose for regulating the initial and the final pH. The paper clearly demonstrates the potential of KHCO₃ to substitute the currently used pH-conditioners, viz., ash, lime and NaHCO₃ for simultaneous removal of arsenate and iron ions.     

Implications of endocrine-disrupting chemicals on polycystic ovarian syndrome: A comprehensive review

Environmental Science and Pollution Research - Polycystic ovarian syndrome (PCOS) is a complex multifactorial disorder of unknown pathogenesis in which genetic and environmental factors contribute...     

Sustainable extraction of hazardous metals from crystal glass waste using biodegradable chelating agents

Journal of Material Cycles and Waste Management - Extraction of hazardous metals from dumped crystal glass waste was investigated for site decontamination and resource recovery. Mechanically...     

Optimization of process parameters using response surface methodology for maximum liquid yield during thermal pyrolysis of blend of virgin and waste high-density polyethylene

Journal of Material Cycles and Waste Management - The pyrolytic fuel generated by high-density polyethylene (HDPE) has the potential to replace fossil fuels as a primary source of energy. Thermal...