Quantitative identification of groundwater contamination sources by combining isotope tracer technique with PMF model in an arid area of northwestern China

Qianqian Zhang; Huiwei Wang; Zhifang Xu; Gan Li; Mingnan Yang; Jingtao Liu

doi:10.1016/j.jenvman.2022.116588

Quantitative identification of groundwater contamination sources by combining isotope tracer technique with PMF model in an arid area of northwestern China

J Environ Manage. 2023 Jan 1;325(Pt B):116588. doi: 10.1016/j.jenvman.2022.116588. Epub 2022 Oct 26.

Authors

Qianqian Zhang¹, Huiwei Wang², Zhifang Xu³, Gan Li⁴, Mingnan Yang², Jingtao Liu²

Affiliations

¹ Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China; Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China. Electronic address: zhangqianqian@mail.cgs.gov.cn.
² Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China.
³ Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China.
⁴ College of Forestry, Southwest Forestry University, Kunming, 650233, China.

PMID: 36308954
DOI: 10.1016/j.jenvman.2022.116588

Abstract

Nowadays, groundwater quality has deteriorated because of intensive human activities. It is important to accurately identify the pollution source for controlling the deterioration of groundwater quality. However, the accuracy of the current source analysis method needs to be improved. In this study, we combined hydrochemical method, isotope tracing technique and PMF model, for the first time, to trace the source of groundwater pollution in Beichuan River basin, Qinghai Province, China. According to the results, there were 35.8% of Fe, 34.1% of total hardness, 24.3% of SO₄^2- and 8.09% of NO₃^- samples exceeded the Grade III standards for Groundwater quality in China, which indicated that the groundwater in the study area has been significantly affected by human activities. Hydrochemical method suggested that the chemical component originated from rock weathering, cation exchange and mineral dissolution. Based on isotope tracing technique (δ¹⁵N-NO₃^-, δ¹⁸O-NO₃^-, δ³⁴S-SO₄^2- and δ¹⁸O-SO₄^2-), the primary sources of nitrate and sulfate in groundwater were soil nitrogen and oxidation of sulﬁde minerals in the forest area, domestic sewage and oxidation of sulﬁde minerals in the urban and industrial area, and mixed sources in the village and agricultural area. Finally, the pollution source of groundwater was distinguished by combining the PMF model, isotope tracing technique and hydrochemical method. Results showed that the main pollutant of groundwater is domestic sewage in the urban, village and industrial area. The contribution rates to groundwater pollution were 60.7%, 60.8% and 57.8%, respectively. However, in the forest and agricultural area, the main source changed to water-rock interaction and chemical fertilizer, and the contribution rates to groundwater quality were 53.5% and 61.0%, respectively. Our results suggested that the coupling tracing methodology can improve the accuracy of source resolution in the water environment and it can be applied to other areas of the world.

Keywords: Groundwater; Hydrochemistry; Isotope; PMF model; Pollution sources.

MeSH terms

China
Environmental Monitoring / methods
Groundwater*
Humans
Nitrates / analysis
Nitrogen Isotopes / analysis
Sewage / analysis
Sulfides / analysis
Water / analysis
Water Pollutants, Chemical* / analysis

Substances

Sewage
Water Pollutants, Chemical
Nitrogen Isotopes
Nitrates
Sulfides
Water