The panel opened with a request to J. LaVelle (U.S. EPA) to enlarge upon his presentation of a bimodlal disposition for the plasma reduction of hexavalent chromium (and subsequent urine concentration) in an occupational group exposed to chromium. He replie(d that he did not know the size of the population that was exposed, but that the group consisted of workers at a dichromate plant, and the s...

phytoremediation of heavy metals is employed as a technological approach for a non-destructive remediation of contaminated soils. one of the most recently studied tree species used in phytoremediation applications are poplars. in this study, the one-year old rooted seedlings of populus nigra l. used to decontaminate hexavalent chromium-contaminated soils. five treatments of cr (vi) supply (were...

the objective of this work focuses on the use of a new natural lignocellulosic material based on palm stems for adsorbing of hexavalent chromium (cr(vi)) in water. the palm stems powder (psp) was characterized using different techniques. the influencing factors on the adsorption of cr(vi) ions was investigated such as ph. the results show that the increase of the temperature and the initial ads...

Washed cells of Enterobacter cloacae HO1 reduced hexavalent chromium (chromate: CrO4(2-) anaerobically. Chromate reductase activity was preferentially associated with the membrane fraction of the cells. Right-side-out membrane vesicles prepared from E. cloacae cells showed high chromate reductase activities when ascorbate-reduced phenazine methosulfate was added as an electron donor.

Plasmids determining resistance to arsenic, mercury, silver, and tellurium compounds in Escherichia coli and Pseudomonas aeruginosa were tested for resistance to 40 other metal compounds. Resistance to trivalent boron and hexavalent chromium compounds was a property of certain P. aeruginosa plasmids.

Reduction of toxic hexavalent was studied by using four resistant strains of E. coli ASU 3, 7, 8 and 18 isolated from wastewater of EL-Malah canal located in Assuit city, Egypt. They showed relatively high minimal inhibitory concentrations (MIC) and found to be plasmid mediated with 65 and 27 Kb. E. coli ASU 7 represents the best with high resistance and reducing power of Cr (VI), so it may be ...

In the different compartments of the environmental chromium occurs mainly in the oxidation states (III) and (VI). Although Cr(III) is an essential trace element for humans, Cr(VI) is highly cancerogenic and mutagenic. It is, therefore, necessary for risk assessment not only to determine total chromium, but also to determine chromium species, especially Cr(VI). Hexavalent chromium can be determi...

Chromium occurs in the environment primarily in two valence states, trivalent chromium (Cr III) and hexavalent chromium (Cr VI). Exposure may occur from natural or industrial sources of chromium. Chromium III is much less toxic than chromium (VI). The respiratory tract is also the major target organ for chromium (III) toxicity, similar to chromium (VI). Chromium (III) is an essential element in...

Hexavalent chromium is highly toxic to most living organisms and a known human carcinogen by the inhalation route of exposure. Therefore, treatment of Cr(VI) contaminated wastewater is essential before their discharge to the natural water bodies. Cr(VI) reduction to Cr(III) can be beneficial because a more mobile and more toxic chromium species is converted to a less mobile and less toxic form....