the potential of citrobacter freundii, a gram negative bacteria for the remediation of hexavalentchromium (cr(vi)) and trivalent chromium (cr(iii)) from aqueous solutions was investigated. bioremediationof cr(vi) involved both biosorption and bioreduction processes, as compared to only biosorption processobserved with respect to cr(iii) bioremediation. in the case of cr(vi) bioremediation studi...

The capabilities of a “universal platform” for the deployment of analytical sensors in the field for long-term monitoring of environmental contaminants were expanded in this investigation. The platform was previously used to monitor trichloroethene in monitoring wells and at groundwater treatment systems (1,2). The platform was interfaced with chromium (VI) and conductivity analytical systems t...

Some compounds of hexavalent chromium are well-established carcinogens. Chromium enters mammalian cells in the hexavalent form and is reduced to chromium (III). Treatment of purified DNA with chromium (III) produces DNA-DNA interstrand crosslinks (DDC) which obstruct the progression of DNA polymerases in vitro. DDC were also detected in chromate-treated cultured normal human lung cells using th...

Hexavalent chromium (Cr(VI)), a commonly used industrial metal, is a well known human lung carcinogen. Epidemiology and animal studies suggest that the particulate Cr(VI) compounds, specifically the water insoluble compounds, are the more potent carcinogens; however, the carcinogenic mechanism remains unknown. Here we summarize recent Cr(VI)-induced human tumour, in vivo, cell culture and in vi...

The United States Environmental Protection Agency (EPA) intends to add either chromium or hexavalent chromium to the list of hazardous air pollutants under Section 112 of the Clean Air Act. A preliminary assessment performed by EPA has identified several categories of stationary sources as emitters of significant quantities of chromium to the atmosphere and for which the proposal o f national e...

A trivalent chromium electroplating process has been io use commercially in North America since its introduction in 1975. Based upon years of laboratory and in-plant experience and testing, many process performance characteristics and physical properties of deposits have been determined. This paper compares the performance of trivalent chromium with hexavalent chromium processes. Factors such a...

II ADIOACTIVE hexavalent chromium is a widely used agent for labeling platelets and studying their survival. Since platelet viability appears to be unaffected by chromium labeling, it is assumed that platelet function also remains intact. This assumption is basic to interpretation of platelet survival studies with chromium labeling. Accordingly, we examined the in vitro function of platelets th...

Quantitative electron microscopy was used to evaluate interactive effects of chromium additions and phosphate nutrient status on the diatom Cyclotella meneghiniana. Cells of differing phosphate status were exposed to hexavalent chromium for 7 days and morphological changes in both phosphate alone and phosphate and chromium treatments were observed. Changes in chloroplast relative volume and num...

Chromium (vi) – tolerant bacterial strains, namely, Bacillus sp., Pseudomonas sp., Escherichia coli and Staphylococcus sp. were isolated from the oxidation ditch of a sewage treatment plant. All the isolates tolerated high concentrations of up to 500 μg/ml chromium (vi) in nutrient broth. The growth responses of the bacterial isolates to different concentrations of chromium (vi) were carried ou...

The toxicity of chromium (Cr) to biota is related to its chemical forms and consequently to the redox conditions of soils. Hexavalent Cr[Cr(VI)] may undergo natural attenuation through reduction processes. In this study, the reduction kinetics of Cr(VI) in seven soils and its relationships with soil properties were investigated with laboratory incubation experiments. The results indicate that t...