The impact of resuspension on sediment mercury dynamics, and methylmercury production and fate: A mesocosm study

The objective of this study was to investigate the effects of resuspension on the fate and bioaccumulation of mercury (THg) and methylmercury (MeHg) in shallow estuarine environments, using mesocosms. Two 4-week experiments were conducted in July (Experiment 1) and October (Experiment 2) of 2001 wit...

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Bibliographic Details
Published in:Marine chemistry 2006-12, Vol.102 (3), p.300-315
Main Authors: Kim, Eun-Hee, Mason, Robert P., Porter, Elka T., Soulen, Heather L.
Format: Article
Language:English
Subjects:
Bioaccumulation
Brackish
Earth sciences
Earth, ocean, space
Exact sciences and technology
External geophysics
Geochemistry
Marine
Mercenaria mercenaria
Mercury
Mercury stable isotopes
Methylmercury
Mineralogy
Physical and chemical properties of sea water
Physics of the oceans
Sediment resuspension
Silicates
Water geochemistry
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Summary:The objective of this study was to investigate the effects of resuspension on the fate and bioaccumulation of mercury (THg) and methylmercury (MeHg) in shallow estuarine environments, using mesocosms. Two 4-week experiments were conducted in July (Experiment 1) and October (Experiment 2) of 2001 with Baltimore Harbor sediments. Hard clams, Mercenaria mercenaria, were introduced into sediments for Experiment 2. Tidal resuspension (4 h on and 2 h off cycles) was simulated, with 3 replicate tanks for each treatment—resuspension (R) and non-resuspension (NR). Sediment cores were collected during the experiments for THg, MeHg, organic content and AVS analyses, and for the determination of methylation/demethylation using Hg stable isotopes ( 199Hg(II) and CH 3 199Hg(II)). Zooplankton samples were collected once a week while clams were taken before and after Experiment 2 for THg and MeHg analyses. Our results suggest that the interplay between Hg methylation and MeHg degradation determines the overall MeHg pool in sediments. Sediment resuspension does not appear to directly impact the Hg transformations but can lead to changes in the association to Hg binding phases, influencing Hg methylation. The bioaccumulation results indicate that sediment resuspension can play an important role in transferring sediment MeHg into organisms.
ISSN:0304-4203
1872-7581
DOI:10.1016/j.marchem.2006.05.006