High resolution dissolved heavy metals in sediment porewater of a small estuary: Distribution, mobilization and migration

Yurui Li; Zheng Wang; Yu Cai; Kai Xiao; Zhanrong Guo; Feng Pan

doi:10.1016/j.scitotenv.2023.167238

High resolution dissolved heavy metals in sediment porewater of a small estuary: Distribution, mobilization and migration

Sci Total Environ. 2023 Dec 20:905:167238. doi: 10.1016/j.scitotenv.2023.167238. Epub 2023 Sep 21.

Authors

Yurui Li¹, Zheng Wang¹, Yu Cai¹, Kai Xiao², Zhanrong Guo³, Feng Pan⁴

Affiliations

¹ Fujian Key Laboratory of Coastal Pollution Prevention and Control, College of the Environment & Ecology, Xiamen University, Xiamen 361102, PR China; Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, PR China; College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, PR China.
² State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, PR China.
³ College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, PR China. Electronic address: gzr@xmu.edu.cn.
⁴ Fujian Key Laboratory of Coastal Pollution Prevention and Control, College of the Environment & Ecology, Xiamen University, Xiamen 361102, PR China; Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, PR China. Electronic address: fengpan@xmu.edu.cn.

PMID: 37741402
DOI: 10.1016/j.scitotenv.2023.167238

Abstract

Identifying the distribution features, mobilization mechanisms and migration processes of heavy metals (HMs) in estuarine sediments is essential to predict their potential toxicity risk and for following contamination remediation. In this study, high-resolution dialysis (HR-Peeper) and a sequential extraction procedure were employed to determine the porewater dissolved iron (Fe), manganese (Mn), arsenic (As), chromium (Cr), vanadium (V), selenium (Se), molybdenum (Mo), nickel (Ni), zinc (Zn) and their geochemical species fractions in sediments of the Xixi River Estuary, Xiamen, China. The results showed that at estuarine sites with high TOC and TS content, sulfate reduction is the main diagenetic pathway of OC degradation and directly inhibits the reduction of Fe/Mn oxides. The mobility of most HMs in porewater profiles was influenced by multiple factors, such as the adsorption-desorption by Fe/Mn oxides, HM-sulfide co-precipitation, and the degradation of OM under different redox conditions. However, no environmental correlation and control factors of Ni and Zn have been found. In addition, the profile-averaged distribution of most HMs showed a seaward increasing trend, probably due to the severe industrial wastewater discharge and increasing salinity responsible for the competitive adsorption of HM ions. The overall positive fluxes of all HMs, together with the higher positive diffusion fluxes of some HMs such as Mn, Cr, V and Zn, suggest that the HMs mobility in small estuarine sediments should be seriously reconsidered due to its high contamination potential.

Keywords: Estuarine sediment; Exchange flux; HR-peeper; Heavy metals; Porewater.