The new maximum contaminant level (MCL) of 10 microg/L for arsenic in the US drinking water will take effect on January 22, 2006. The compliance cost is estimated to be approximately dollar 600 million per year using current treatment technologies. This research aims to develop an innovative ion exchange process that may help water utilities comply with the new MCL in a more cost-effective mann...

A pot experiment examined the biomass and As uptake of Medicago truncatula colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae in low-P soil experimentally contaminated with different levels of arsenate. The biomass of G. mosseae external mycelium was unaffected by the highest addition level of As studied (200 mg kg(-1)) but shoot and root biomass declined in both mycorrhizal and...

Arsenic and phosphorus are group 15 elements with similar chemical properties. Is it possible that arsenate could replace phosphate in some of the chemicals that are required for life? Phosphate esters are ubiquitous in biomolecules and are essential for life, from the sugar phosphates of intermediary metabolism to ATP to phospholipids to the phosphate backbone of DNA and RNA. Some enzymes that...

The haloalkaliphilic bacterium Alkalilimnicola ehrlichii is capable of anaerobic chemolithoautotrophic growth by coupling the oxidation of arsenite (As(III)) to the reduction of nitrate and carbon dioxide. Analysis of its complete genome indicates that it lacks a conventional arsenite oxidase (Aox), but instead possesses two operons that each encode a putative respiratory arsenate reductase (Ar...

The purpose of this study was a detailed characterization of Shewanella sp. O23S, a strain involved in arsenic transformation in ancient gold mine waters contaminated with arsenic and other heavy metals. Physiological analysis of Shewanella sp. O23S showed that it is a facultative anaerobe, capable of growth using arsenate, thiosulfate, nitrate, iron or manganite as a terminal electron acceptor...

Arsenic hyperaccumulator fern Pteris vittata L. produces large amounts of root exudates that are hypothesized to solubilize arsenic and maintain a unique rhizosphere microbial community. Total heterotrophic counts on rich or defined media supplemented with up to 400 mmol/L of arsenate showed a diverse arsenate-resistant microbial community from the rhizosphere of P. vittata growing in arsenic-c...

Effect of sodium arsenate (Na2HAsO4.7H2O) on the growth and activity of few oxidizing enzymes of mungbean seedlings was investigated and it was found to have drastic effects on the growth and biochemical metabolism of germinating mungbean (Vigna radiata (L.) Wilczek cv. B-105) seedlings. With the increase in concentration of sodium arsenate (5μM, 10μM and 20μM) significant decrease in seedling ...

Bacillus sp. CDB3 isolated from an arsenic contaminated cattle dip site possesses an uncommon arsenic resistance (ars) operon bearing eight genes in the order of arsRYCDATorf7orf8. We investigated the functions of arsA, arsT, orf7 and orf8 in arsenic resistance using a plasmid-based gene knockout approach in the ars gene deficient Escherichia coli strain AW3110. The CDB3 arsA gene was shown to ...

Mass balances of total arsenic and copper for a suburban lake in densely populated northern Virginia were calculated using date collected during 1998. Mass-balance terms were precipitation; stream inflow, including road runoff; stream outflow; and contributions from leaching of pressure-treated lumber. More mass of arsenic and copper was input to the lake than was output the 1998 lake-retention...