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Effect of bicarbonate and phosphate on arsenic release from mining-impacted sediments in the Cheyenne River watershed, South Dakota, USA

Lookup NU author(s): Dr Lucia Rodriguez Freire



This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


The mobilization of arsenic (As) from riverbank sediments affected by the gold mining legacy in north-central South Dakota was examined using aqueous speciation chemistry, spectroscopy, and diffraction analyses. Gold mining resulted in the discharge of approximately 109 metric tons of mine waste into Whitewood Creek (WW) near the Homestake Mine and Cheyenne River at Deal Ranch (DR), 241 km downstream. The highest concentrations of acid-extractable As measured from solid samples was 2020 mg kg−1 at WW and 385 mg kg−1 at DR. Similar sediment mineralogy between WW and DR was identified using XRD, with the predominance of alumino-silicate and iron-bearing minerals. Alkalinity measured in surface water at both sites ranged from 1000 to 2450 mg L−1 as CaCO3 (10–20 mM HCO3 at pH 7). Batch laboratory experiments were conducted under oxidizing conditions to evaluate the effects of NaHCO3 (0.2 mM and 20 mM) and NaH2PO3 (0.1 and 10 mM) on the mobilization of As. These ions are relevant for the site due to the alkaline nature of the river and nutrient mobilization from the ranch. The range of As(V) release with the NaHCO3 treatment was 17–240 μg L−1. However, the highest release (6234 μg L−1) occurred with 10 mM NaH2PO3, suggesting that As release is favored by competitive ion displacement with PO43− compared to HCO3. Although higher total As was detected in WW solids, the As(V) present in DR solids was labile when reacted with NaHCO3 and NaH2PO3, which is a relevant finding for communities living close to the river bank. The results from this study aid in a better understanding of As mobility in surface water sites affected by the mining legacy.

Publication metadata

Author(s): DeVore CL, Rodriguez-Freire L, Ali AM, Ducheneaux C, Artyushkova K, Zhou Z, Latta DE, Lueth VW, Gonzales M, Lewis J, Cerrato JM

Publication type: Article

Publication status: Published

Journal: Environmental Science: Processes & Impacts

Year: 2019

Volume: 21

Issue: 3

Pages: 456-468

Print publication date: 01/03/2019

Online publication date: 04/02/2019

Acceptance date: 17/01/2019

Date deposited: 16/02/2023

ISSN (print): 2050-7887

ISSN (electronic): 2050-7895

Publisher: Royal Society of Chemistry


DOI: 10.1039/C8EM00461G


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