Hexavalent Chromium

Imamura, Greg; Alspach, Brent

doi:10.1201/b22226-4

Cited by 1 publication

(2 citation statements)

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“…Among the groundwater samples taken at depths between 280 and 400 m bls, 62.5% had Cr(VI) exceeding the Italian standard of 5 μg/L, 25% exceeding the North Carolina standard of 10 μg/L, and 10% had Cr(VI) exceeding the Chinese MCL standard of 50 μg/L . Less-saline and D- and 18 O-depleted groundwater seems to reflect paleo-recharge of meteoric water in deep aquifers.…”

Section: Resultsmentioning

confidence: 99%

“…The WHO has proposed 50 μg/L as the drinking water guideline for total Cr concentration . Hexavalent chromium-specific standards have been set in Italy (5 μg/L) and the U.S. state of California (10 μg/L), although the California standard was repealed in 2017 due to concerns about the economic feasibility of maintaining the MCL . North Carolina in the U.S. has set a state standard of 10 μg/L for Cr(VI), with a health advisory level of 0.07 μg/L.…”

Section: Introductionmentioning

confidence: 99%

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High Hexavalent Chromium Concentration in Groundwater from a Deep Aquifer in the Baiyangdian Basin of the North China Plain

Guo

Chen

et al. 2020

Environ. Sci. Technol.

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Hexavalent chromium (Cr(VI)) is known to occur naturally in shallow oxic groundwater, typically from aquifers associated with mafic and ultramafic formations, but information on the occurrence of Cr(VI) in deep groundwater from large sedimentary basins is limited. This study shows that groundwater from the Baiyangdian Lake Basin (BYB), home to the future second capital city of China, had high Cr concentration (>10 μg/L, up to 86 μg/L) in the deep aquifer (>150 m), while shallow groundwater had lower Cr concentration (<10 μg/L). Chromium occurred predominantly as Cr(VI) (>95%). Shallow groundwater was characterized by higher Mn and Fe concentrations relative to deep groundwater, likely indicating more reducing conditions. Sequential extraction experiments from aquifer sediments suggest that Cr(VI) may derive from silicate weathering and that Mn oxides in the aquifer play a major role in the formation of Cr(VI) in groundwater. Inverse correlations between Mn and Cr(VI) suggest that reductive dissolution of Mn oxides constrains Cr(VI) mobilization in the shallow groundwater, while oxic–suboxic conditions in the deep aquifer limit Mn solubility, which enhances oxidation of Cr(III) to Cr(VI) and promotes desorption of Cr(VI) under alkaline conditions. This study demonstrates the potential geogenic occurrence of high Cr(VI) concentration in deep groundwater from a nonmafic, large sedimentary basin containing Mn oxides in the aquifer sediments.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%