Methylmercury in Industrial Harbor Sediments in Taiwan: First Observations on its Occurrence, Distribution, and Measurement

Chih-Feng Chen,Chiu-Wen Chen,Cheng-Di Dong,Guan-Ting Lin,Yun-Ru Ju

doi:10.3390/ijerph15081765

Abstract

The distribution of methylmercury (MeHg) and total mercury (T-Hg) in sediments of the estuaries and the basin in Kaohsiung Harbor (Taiwan) is studied. MeHg in the sediment samples was determined using gas chromatography-mass spectrometry. The certified reference material of sediments with respect to the method showed the recovery efficiency between 97.4 and 103.6% which confirmed the applicability of analysis method. The T-Hg and MeHg concentrations were between 149 to 9035 μg/kg and <0.31 to 17.7 μg/kg, respectively. The T-Hg and MeHg concentrations in the estuaries of Kaohsiung Harbor were relatively high. Results suggest that Hg in this studied area was likely contributed from the catchments of the rivers. The MeHg level was <0.01 to 2.66% of the T-Hg in the sediments. A positive correlation is obtained between MeHg, T-Hg, and total organic carbon in the sediments, whereas a negative correlation is observed between pH, oxidation-reduction potential, and MeHg concentration. The results further suggest that sediment characteristics contribute mainly to the distribution of MeHg.

Highlights

The presence of mercury (Hg) and methylmercury (MeHg) in the environment is a major ecological risk due to their extreme toxicity and highly bio-accumulative properties
The calibration factor based on the six-point calibration curve for MeHg showed acceptable relative standard deviation (RSD) values (4.1%)
The detection limit of the analytical procedure was estimated from three times standard deviation from repeated (n = 7) analysis of MeHg

Summary

Introduction

The presence of mercury (Hg) and methylmercury (MeHg) in the environment is a major ecological risk due to their extreme toxicity and highly bio-accumulative properties. Due to its low solubility in receiving waters, Hg is adsorbed on the water-borne suspended particles. The particle-bound Hg accumulates in the sediments. Mercury in sediments is generally in bivalent form complexed with chlorides, sulfides or organic matter [2]. The inorganic bivalent Hg may be transformed into MeHg via the biochemical actions of local microorganisms, such as sulfate-reducing bacteria (SRB), Fe(III)-reducing bacteria, and methanogenic microorganisms [3,4,5,6,7]. MeHg can bind to proteins and pass through the biological membrane, enabling its accumulation in the food web and biomagnification, which threatens the health of wildlife and human [2,8]. Sediments are the important niche and matrix for fishes and aquatic invertebrates, understanding the distribution of MeHg in aquatic sediments is necessary

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Results

Conclusion