Hydrogeological controls on chromium enrichment along the groundwater flow path in the Baiyangdian Catchment, North China Plain

Chao Liu; Huaming Guo; Wendi Fan; Rui Xu; Shuangbao Han; Bingying Gao; Bo Zhao; Chunping Jiang

doi:10.1016/j.scitotenv.2023.164890

Hydrogeological controls on chromium enrichment along the groundwater flow path in the Baiyangdian Catchment, North China Plain

Sci Total Environ. 2023 Oct 1:893:164890. doi: 10.1016/j.scitotenv.2023.164890. Epub 2023 Jun 16.

Authors

Chao Liu¹, Huaming Guo², Wendi Fan¹, Rui Xu¹, Shuangbao Han³, Bingying Gao¹, Bo Zhao¹, Chunping Jiang¹

Affiliations

¹ State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China; Key Laboratory of Groundwater Conservation of MWR & School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, China.
² State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China; Key Laboratory of Groundwater Conservation of MWR & School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, China. Electronic address: hmguo@cugb.edu.cn.
³ Center for Hydrogeology and Environmental Geology, China Geological Survey, Baoding 071051, China.

PMID: 37329913
DOI: 10.1016/j.scitotenv.2023.164890

Abstract

Although the natural occurrence of high chromium (Cr) groundwater has been intensively investigated in bedrock or sedimentary aquifers, the impacts of hydrogeological conditions on dissolved Cr distribution are poorly understood. In this study, groundwater samples from recharge mountain area (Zone I) through runoff area (Zone II) to discharge area (Zone III) were taken from bedrock and sedimentary aquifers approximately along the flow path in Baiyangdian (BYD) catchment, China, to reveal how hydrogeological conditions and hydrochemical evolution contributed to Cr enrichment in groundwater. Results showed that dissolved Cr was dominated by Cr(VI) species (>99 %). Around 20 % of studied samples had Cr(VI) exceeding 10 μg/L. Groundwater Cr(VI) was of natural origin, which generally increased along the flow path, and high concentrations (up to 80.0 μg/L) were observed in deep groundwater of Zone III. At the local scales, geochemical processes including silicate weathering, oxidation, and desorption under weakly alkaline pH, predominately contributed to Cr(VI) enrichment. Principal component analysis showed that oxic conditions were the principal control of Cr(VI) in Zone I, and geochemical processes (especially Cr(III) oxidation and Cr(VI) desorption) predominantly enhanced groundwater Cr(VI) enrichment in Zones II and III. However, at the regional scale, Cr(VI) enrichment was dominantly facilitated by the low flow rate and recharge of paleo-meteoric water due to the long-term water-rock interaction in the BYD catchment.

Keywords: Groundwater flow path; Hexavalent chromium; Hydrogeological conditions; Suboxic oxidation.