期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 701, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2019.134842
关键词
Hg fractionation; Sedimentary methylmercury; Organo-Hg compounds; Hg bioaccumulation; Gastropod; Mangrove sediment
资金
- Council of Scientific and Industrial Research (CSIR)-NIO [OLP1712]
- NIO, Goa
This study investigated the linkage between mercury (Hg) speciation in the surficial sediments from a mangrove ecosystem of the Zuari Estuary, west coast of India, with Hg bioaccumulation in gastropods collected from the same area. Multiple operationally defined protocols and methods were used for determination of Hg speciation study in the mangrove sediments. Moderately low concentrations of Hg were observed in the sediments, ranging from 37.3 +/- 1.9 to 79.6 +/- 4.0 mu g/kg. Geochemical fractionation showed that a significant part of sedimentary Hg was present within the structure of the sediment (residual fraction) and not bioavailable. Non-residual Hg was primarily associated with oxidizable (sedimentary organic matter (SOM) or sulfide) binding phase of the sediments, and ranged from 9.2 +/- 0.3 to 78.5 +/- 3.9 mu g/kg. Concentration of methylmercury (MeHg) (a neurotoxin) in the sediments varied from 1.7 +/- 0.1 to 4.4 +/- 0.1 mu g/kg. L-Cysteine, a suitable complexing ligand, extractable Hg concentration in the sediments ranged from 4.3 +/- 0.1 to 15.9 +/- 0.3 mu g/kg. Statistical analysis suggested that MeHg was adsorbed on Fe/Mn oxyhydroxide phases in the sediments. L-Cysteine was found to extract sedimentary MeHg and thermodynamically less stable Hg-SOM complexes from the sediments. Concentrations of bioaccumulated Hg in soft tissues of the gastropod, Pirenella cingulata, ranged from 57.6 +/- 4.4 to 224.4 +/- 7.2 mu g/kg. Positive correlations existed between the concentration of bioaccumulated Hg in the gastropods and the concentrations of Hg associated with the oxidizable phase, sedimentary MeHg and L-Cysteine extracted Hg in the sediments. This study indicated that operationally defined Hg species can be useful in estimating bioavailable Hg to obligatory deposit feeder in tropical mangrove systems. (C) 2019 Elsevier B.V. All rights reserved.
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