Hexavalent Chromium Sources and Distribution in California Groundwater

Abstract

Groundwater resources in California represent a confluence of high-risk factors for hexavalent chromium contamination as a result of industrial activities, natural geology, and, potentially, land use. Here, we examine state-wide links in California between groundwater Cr(VI) concentrations and chemicals that provide signatures for source attribution. In environmental monitoring wells, Cr(VI) had the highest co-occurrence and also clustered with 1,4-dioxane and several chlorinated hydrocarbons indicative of the metal plating industry. Additionally, hotspots of Cr(VI) co-occurring with bromoform result from volatile organic compound remediation using in situ chemical oxidation that inadvertently oxidizes naturally occurring Cr(III). In groundwater supply wells, which are typically free of industrial inputs, Cr(VI) correlates with dichlorodiphenyldichloroethylene (DDE), vanadium, and ammonia and clusters with nitrate and dissolved oxygen, suggesting potential links between agricultural activities and Cr(VI). Specific controls on Cr(VI) vary substantially by region: from the metal plating industry around Los Angeles and the San Francisco Bay areas to natural redox conditions along flow paths in the Mojave Desert and to correlations with agricultural practices in the Central Valley of California. While industrial uses of Cr lead to the most acute cases of groundwater Cr(VI) contamination, oxidation of naturally occurring Cr affects a larger area, more wells, and a greater number of people throughout California.

Bioelectrochemical Systems for Removal of Selected Metals and Perchlorate from Groundwater: A Review

“…Limit/Guideline Value (µg L −1 ) Country/Organization Massachusetts (USA) [82] Hexavalent chromium (Cr(VI)) is a toxic heavy metal, found in effluents from industries such as electroplating, steel and metal alloys production, leather tanning, cement, dye/pigment manufacturing, mining, photographic materials, paints, and fungicide production [6,83]. Its accumulation in the environment is a serious threat since Cr(VI) is a known mutagen, teratogen, and carcinogen, besides being also highly corrosive [84,85].…”

“…Groundwater contamination is a highly important issue, due to the exploitation of this resource for water supply (drinking, irrigation, industrial process water). Several contaminants can be detected in groundwater and consequently limit its use: nitrate [1], perchlorate [2,3], arsenic [4,5], chromium [6], cadmium [4,7], and vanadium [8] are widely diffused. Those contaminants can be naturally occurring or the consequence of anthropic activities [9].…”

FeS@rGO nanocomposites as electrocatalysts for enhanced chromium removal and clean energy generation by microbial fuel cell

“…On the other hand, Cr(III) is more stable and less toxic than Cr(VI), which is relatively more corrosive, water-soluble, and mobile [5]. Therefore, the reduction/ transformation of Cr (VI) into Cr(III) is necessary before the discharge of industrial effluents in the environment.…”

Macroscopic Poly Schiff Base-Coated Bacteria Cellulose with High Adsorption Performance

“…Hexavalent chromium (Cr(VI)), a typical toxic contaminant, is normally discharged by industrial plants, which has strong teratogenicity and carcinogenicity [1][2][3]. Various technologies have been developed and, among them, adsorption is a popular choice for Cr(VI) owing to its feasibility of operation and cost effectiveness [4][5][6][7][8][9][10][11].…”