Novel insights into PAHs accumulation and multi-method characterization of interaction between groundwater and surface water in middle Yangtze River: Hydrochemistry, isotope hydrology and fractionation effect

Weijie Liu; Xinli Xing; Yanmin Zou; Xin Li; Ying Gao; Ying Liu; Xianting Zhu; Shihua Qi

doi:10.1016/j.scitotenv.2024.178023

Novel insights into PAHs accumulation and multi-method characterization of interaction between groundwater and surface water in middle Yangtze River: Hydrochemistry, isotope hydrology and fractionation effect

Sci Total Environ. 2024 Dec 17:958:178023. doi: 10.1016/j.scitotenv.2024.178023. Online ahead of print.

Authors

Weijie Liu¹, Xinli Xing², Yanmin Zou¹, Xin Li¹, Ying Gao¹, Ying Liu¹, Xianting Zhu³, Shihua Qi⁴

Affiliations

¹ Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.
² Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China. Electronic address: xlxing@cug.edu.cn.
³ Hubei Geological Bureau, Wuhan 430034, China.
⁴ Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.

PMID: 39693653
DOI: 10.1016/j.scitotenv.2024.178023

Abstract

To meet the challenge of water quality protection and management in the middle Yangtze River and understand the accumulation mechanism of PAHs in aquatic complexity systems, caused by hydro-chemical changes, anthropogenic and geological activities, and intensive surface water-groundwater interaction, a comprehensive study is urgently needed. The study investigated the pollution levels, potential sources, accumulation mechanism, and groundwater- surface water interaction of polycyclic aromatic hydrocarbons (PAHs) in wet and dry seasons of the middle Yangtze River. There was no significant difference of PAHs accumulation between wet and dry seasons of the middle Yangtze River. PAHs occurrence in the middle Yangtze River was dominated by the input of tributary. Phenanthrene and Naphthalene were still the dominant species of PAHs. Coal combustion (CC) and biomass burning (BB) were the major contributor for the PAHs occurrence. However, the CC apportionment concentration increased by 6.18 ng·L^-1 from wet to dry season, suggesting higher density of coal consumption in dry season. The potential mechanism of PAHs occurrence was demonstrated by the mantel test and structural equation model (SEM). Results revealed that the pollution of the middle Yangtze River could be mainly affected by primary emission in wet and dry seasons due to the significant positive effect between eutrophication levels and PAHs pollution sources. Meanwhile, the difference in redox conditions could directly affect the fate of pollutants (including the valence state transformation of nitrogen and phosphorus). The stronger interaction of groundwater and surface water in dry season was presented by hydrochemistry and isotope hydrology (δ¹⁸O and δ²H). The similar result was also evidenced by fractionation effect of PAHs, because more similar behaviors of characteristic pollutants were observed in dry season. Consequently, PAHs can be considered as an effective geochemical tracer and further expanded their toxic effects through the surface water-groundwater interaction.

Keywords: Accumulation mechanisms; Polycyclic aromatic hydrocarbons (PAHs); Source apportionment; Structural equation model; Surface water-groundwater interaction; The middle Yangtze River.