Effects of water-sediment interaction and irrigation practices on iodine enrichment in shallow groundwater

JOURNAL OF HYDROLOGY

卷:543

Article

Li, Junxia^1,2  Wang, Yanxin^1,2  Xie, Xianjun^1,2  DePaolo, Donald J.^3,4 

[1] China Univ Geosci, State Key Lab Biogeol & Environm Geol, Wuhan 430074, Peoples R China

[2] China Univ Geosci, Sch Environm Studies, Wuhan 430074, Peoples R China

[3] Univ Calif Berkeley, Earth & Planetary Sci, Berkeley, CA 94720 USA

[4] Lawrence Berkeley Natl Lab, Energy Geosci Div, Berkeley, CA 94720 USA

关键词: Vertical mixing;    Water-sediment interaction;    Groundwater;    Iodine;    Datong basin;   

DOI  :  10.1016/j.jhydrol.2016.10.002

来源: Elsevier

【 摘 要 】

High iodine concentrations in groundwater have caused serious health problems to the local residents in the Datong basin, northern China. To determine the impact of water-sediment interaction and irrigation practices on iodine mobilization in aquifers, isotope (H-2, O-18 and Sr-87/Sr-86) and hydrogeochemical studies were conducted. The results show that groundwater iodine concentrations vary from 14.4 to 2180 mu g/L, and high iodine groundwater (>150 mu g/L) mainly occurs in the central area of the Datong basin. Sediment iodine content is between <0.01 and 1.81 mg/kg, and the co-occurrence of high iodine and high DOC/TOC concentrations of groundwater and sediment samples in the deeper aquifer indicates that the sediment enriched in iodine and organic matter acts as the main source of groundwater iodine. The Sr-87/Sr-86 values and groundwater chemistry suggest that aluminosilicate hydrolysis is the dominant process controlling hydrochemical evolution along groundwater flowpath, and the degradation of TOC/iodine-rich sediment mediated by microbes potentially triggers the iodine release from the sediment into groundwater in the discharge area. The vertical stratification of groundwater O-18 and H-2 isotope reflects the occurrence of a vertical mixing process driven by periodic surface irrigation. The vertical mixing could change the redox potential of shallow groundwater from sub-reducing to oxidizing condition, thereby affecting the iodine mobilization in shallow groundwater. It is postulated that the extra introduction of organic matter and O-2/NO3/SO4 could accelerate the microbial activity due to the supplement of high ranking electron acceptors and promote the iodine release from the sediment into shallow groundwater. (C) 2016 Published by Elsevier B.V.

【 授权许可】

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