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Complex patterns in fish - sediment mercury concentrations in a contaminated estuary: The influence of selenium co-contamination?

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Jones, HJ and Swadling, KM and Butler, ECV and MacLeod, CK Complex patterns in fish - sediment mercury concentrations in a contaminated estuary: The influence of selenium co-contamination? Complex patterns in fish e sediment mercury concentrations in a, 137 (-). pp. 14-22. ISSN 002-326X

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Abstract

Environmental mercury (Hg) loads do not always correspond to Hg concentrations in resident fish and
selenium (Se) presence has been reported to play a pivotal role in mitigating Hg bioaccumulation. Total
mercury (THg), methylmercury (MeHg) and Se concentrations were measured in sediments and a
benthic fish species (Platycephalus bassensis) from a contaminated estuary (Derwent Estuary, Tasmania).
Elevated sediment concentrations of Se did not result in increased Se concentrations in fish, but low
concentrations of Se were associated with increased MeHg bioavailability (% MeHg) from sediments to
fish. Where MeHg (z99% of total Hg) concentration in fish was high Se uptake also increased, indicating
that maintaining positive Se:Hg ratios may reduce the toxicity of MeHg. MeHg was detectable in sediments
throughout the estuary, and a molar excess of THg over Se suggested that there was insufficient Se
to prevent methylation from the sediments. Se:Hg ratios of less than 1.0 in sediments, coupled with high
%MeHg fraction and high biotic sediment accumulation factors for MeHg (BSAFMeHg), indicated that the
lower region of the Derwent Estuary could be a hotspot for Hg methylation, despite having significantly
lower THg concentrations. In contrast, Hg bioavailability to fish from sediments close to the source may
be reduced by both inorganic Hg species complexation and lower methylation rates. There was a strong
association between THg and Se in estuarine sediments, suggesting that Se plays an important role in
sediment Hg cycling and should be a key consideration in any future assessments of Hg methylation,
bioavailability and bioaccumulation.

Item Type: Article
Keywords: Derwent Estuary, biotic sediment accumulation factors,Se:Hg ratios,methylmercury,Platycephalus bassensis
Journal or Publication Title: Complex patterns in fish e sediment mercury concentrations in a
Page Range: pp. 14-22
ISSN: 002-326X
Identification Number - DOI: 10.1016/j.ecss.2013.11.024
Additional Information:

Copyright 2013 Elsevier

Date Deposited: 11 Feb 2014 23:36
Last Modified: 18 Nov 2014 04:58
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