The distribution of methylmercury in estuary and harbor sediments

Chih-Feng Chen; Yun-Ru Ju; Chiu-Wen Chen; Cheng-Di Dong

doi:10.1016/j.scitotenv.2019.07.002

The distribution of methylmercury in estuary and harbor sediments

Sci Total Environ. 2019 Nov 15:691:55-63. doi: 10.1016/j.scitotenv.2019.07.002. Epub 2019 Jul 2.

Authors

Chih-Feng Chen¹, Yun-Ru Ju¹, Chiu-Wen Chen², Cheng-Di Dong³

Affiliations

¹ Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan.
² Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan. Electronic address: cwchen@nkust.edu.tw.
³ Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan. Electronic address: cddong@nkust.edu.tw.

PMID: 31319258
DOI: 10.1016/j.scitotenv.2019.07.002

Abstract

Methylmercury (MeHg) presents high toxicity to humans and can be accumulated to organisms via the food chains. In aquatic environments, MeHg is mainly formed by microorganism using the bioavailable inorganic mercury in sediment. In this study, a total of 120 surface sediments from 20 sites in the Kaohsiung Harbor were collected quarterly in the period from July 2016 to October 2017 and analyzed for total mercury (THg), bioavailable inorganic mercury (BIHg), MeHg, and several geochemical parameters. The concentrations of THg, BIHg, and MeHg in sediment were 455-5108, 7.0-1021, and 0.84-24.1 μg/kg dw, respectively. Results indicated that the percentage of MeHg to THg (MeHg ratio) in most sediment (85%) is <1.2%. Correlation analysis showed that MeHg in sediment was mainly controlled by BIHg (r = 0.759, p < 0.01), while the concentration of BIHg in sediment was mainly related to TOC (r = 0. 480, p < 0.01) and THg (r = 0.435, p < 0.01). The relationship between total bioavailable inorganic mercury (containing BIHg and the bioavailable inorganic mercury used in the synthesis of MeHg) and MeHg concentration in the sediments that collected from the estuary, harbor channel, and the entrance was established by a Michaelis-Menten model to predict the maximum value of MeHg. The efficiency of Hg methylation in the sediments of Kaohsiung Harbor is significantly affected by the total bioavailable inorganic mercury and the related environmental factors. In addition, changes in environmental conditions caused by local seasonality should also be an important factor to consider when assessing the efficiency of Hg methylation.

Keywords: Bioavailable inorganic mercury; MeHg; Methylation; Sediment properties.