Mercury contamination in the riparian ecosystem during the reservoir discharging regulated by a mega dam

Yaseen Mir, Shengjun Wu, Maohua Ma, Yiguo Ran, Kai Zhu, Chirangano Mangwandi, Zakaria Ahmed Mirza*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Mercury (Hg) is extremely poisonous and can be absorbed through touch, inhalation, or consumption. In the living environment, Hg in contaminated sediment can be transferred into grass by the direct absorption through the roots or shoots. The intake of Hg due to Hg emissions may pose a threat to living bodies especially to human beings. The present study aims to provide a novel insight about total mercury (THg) and methyl mercury (MeHg) in a riparian grass (Cynodon dactylon (L).Pers) and sediments during the discharging phase (summertime at145 m water level) in Three Gorges Reservoir (TGR-China); where C. dactylon is a dominant perennial herb in the riparian zone. Yet, the potential risk of Hg contamination in the riparian ecosystem is not thoroughly assessed in the dam regulated reservoir. This study was conducted in the riparian zones of the reservoir formed by a mega dam (Three Gorge Dam)which regulates the water levels during the summer and winter period in the TGR. Our results showed that riparian sediments were acting as a sink for THg and MeHg. Insignificant correlation of THg and MeHg was found between the amphiphyte C. dactylon and its surrounding sediments in the TGR. Bioconcentration factors values for MeHg were found higher than 1 inall study locations in the riparian zones in TGR, which could be due to action of certain bacteria/purely chemical-based methylation on inorganic form of Hg.Additionally, translocation factor indices also high-lighted that the amphiphyte C. dactylon was MeHg accumulator in riparian zones. These results suggested that since riparian sediment was found acting as thesink for THg and MeHg during discharging phase,MeHg contamination in the amphiphyte C. dactylon in riparian zones was not caused by the riparian sediments but by other factors, for instance, the anthropogenic activities in the TGR. Finally, this study leads to conclude that amphiphyte C. dactylon can be used as bio-monitoring agent for Hg pollution in the TGR.
Original languageEnglish
Pages (from-to)4405–4422
Number of pages8
JournalEnvironmental Geochemistry and Health
Volume44
Early online date28 Jan 2022
DOIs
Publication statusEarly online date - 28 Jan 2022

Keywords

  • THg
  • sediment
  • cynodomacatulon
  • ENVIRONMENTAL CONTAMINATION
  • MeHg

ASJC Scopus subject areas

  • Pollution

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