Novel insights into source apportionment of dissolved organic matter in aquifer affected by anthropogenic groundwater recharge: Applicability of end-member mixing analysis based optical indices

Xu Cao; Wei He; Mengqing Fan; Wei He; Yuanyuan Shi; Tongyan An; Xiaorui Chen; Zhanhao Zhang; Fei Liu; Yi Zhao; Pengpeng Zhou; Cuibai Chen; Jiangtao He

doi:10.1016/j.scitotenv.2022.160885

Novel insights into source apportionment of dissolved organic matter in aquifer affected by anthropogenic groundwater recharge: Applicability of end-member mixing analysis based optical indices

Sci Total Environ. 2023 Mar 10:863:160885. doi: 10.1016/j.scitotenv.2022.160885. Epub 2022 Dec 14.

Authors

Xu Cao¹, Wei He², Mengqing Fan¹, Wei He³, Yuanyuan Shi², Tongyan An², Xiaorui Chen¹, Zhanhao Zhang¹, Fei Liu¹, Yi Zhao¹, Pengpeng Zhou¹, Cuibai Chen¹, Jiangtao He¹

Affiliations

¹ Ministry of Education Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China.
² Beijing Municipal Research Institute of Eco-Environment Protection, Beijing 100037, China.
³ Ministry of Education Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China. Electronic address: wei.he@cugb.edu.cn.

PMID: 36526179
DOI: 10.1016/j.scitotenv.2022.160885

Abstract

The composition and main sources of dissolved organic matter (DOM) in groundwater may change significantly under long-term anthropogenic groundwater recharge (AGR); however, the impact of AGR on quantitative sources of groundwater DOM has seldom been reported. This study evaluated the applicability of optical indices combined with mixing stable isotope analysis in R (MixSIAR) in end-member mixing analysis (EMMA) of groundwater DOM. Fluorescent indices, including C1%, C2%, and C3%, were more sensitive to AGR than other absorbance indices, as indicated by the significant difference between the dominant area of artificial groundwater recharged by surface water and the dominant area of natural groundwater recharged by atmospheric precipitation (NGRP). BIX-C1% was selected as the optimal dual index after the screening protocol of groundwater DOM for EMMA. Our results showed that DOM in the aquifer was mainly subject to autochthonous DOM and the contribution of background groundwater to AGRSW and NGRP groundwater accounted for 36.15% ± 32.41% and 55.46% ± 37.17% (p < 0.05), respectively. Therefore, AGR significantly changed the native DOM in the groundwater. In allochthonous sources of DOM, sewage and surface water contributed 29.54% ± 24.87% and 21.32% ± 28.08%, and 24.79% ± 15.56% and 15.21% ± 14.20% to AGRSW and NGRP groundwater, respectively. The contribution of surface water to AGRSW groundwater was significantly higher than that to NGRP groundwater (p < 0.05), indicating that AGR introduced significantly more DOM from surface water to groundwater. This study provides novel insights into the quantitative source apportionment of DOM in groundwater under long-term AGR, which will facilitate the environmental risk assessment of present AGR measures and the sustainable management of clean water.

Keywords: Anthropogenic groundwater recharge (AGR); Dissolved organic matter; End-member mixing analysis (EMMA); Optical indices.