Mercury contamination in aquatic ecosystems under a changing environment: Implications for the Three Gorges Reservoir

Feiyue Wang,JinZhong Zhang

doi:10.1007/s11434-012-5490-7

Feiyue Wang, JinZhong Zhang

Open Access

https://doi.org/10.1007/s11434-012-5490-7

Copy DOI

Journal: Science Bulletin	Publication Date: Oct 11, 2012
Citations: 29	License type: CC BY 2.0

Affiliation: University of Manitoba

Abstract

Mercury is one of the primary contaminants of global concern. As anthropogenic emissions of mercury are gradually placed under control, evidence is emerging that biotic mercury levels in many aquatic ecosystems are increasingly driven by internal biogeochemical processes, especially in ecosystems that have been undergoing dramatic environmental changes. Here we review the unique properties of mercury that are responsible for the exceptional sensitivity of its biogeochemical cycles to changes in climatic, geochemical, biological and ecological processes. We show that, due to rapid climate warming, a shift from sources-driven to processes-driven mercury bioaccumulation is already happening in the Arctic marine ecosystem. We further suggest that such a shift might also be operating in the Three Gorges Reservoir due to changes in these biogeochemical processes induced by the damming. As a result, the effectiveness of mercury emission control is expected to be followed by long delays before ensuing reduction is seen in food-web levels, making it all the more pressing to control and reduce mercury emissions to the reservoir. Long-term monitoring and targeted studies are urgently needed to understand how biotic mercury levels in the reservoir are responding to changes in mercury emissions and in biogeochemical processes.

Highlights

SPECIAL TOPICS: Mercury contamination in aquatic ecosystems under a changing environment: Implications for the Three Gorges Reservoir
As anthropogenic emissions of mercury are gradually placed under control, evidence is emerging that biotic mercury levels in many aquatic ecosystems are increasingly driven by internal biogeochemical processes, especially in ecosystems that have been undergoing dramatic environmental changes
We further suggest that such a shift might be operating in the Three Gorges Reservoir due to changes in these biogeochemical processes induced by the damming

Summary

SPECIAL ISSUE Toxic Metal Pollution

SPECIAL TOPICS: Mercury contamination in aquatic ecosystems under a changing environment: Implications for the Three Gorges Reservoir. In addition to systems where a shift in the paradigm is driven by climate-induced changes such as in the Arctic Ocean, such a shift from source-driven to process-driven Hg bioaccumulation could be prompted by drastic environmental changes due to large-scale engineering operations such as the Three Gorges Reservoir on the Yangtze River Such a change in the paradigm would have major implications for Hg contamination and remediation in the region. Hg possesses many unique properties, which make its biogeochemical cycles exceptionally sensitive to climatic (e.g., temperature, light, hydrology), geochemical (e.g., pH, pe, complexing ligands), biological (e.g., feeding behavior of an organism) and ecological (e.g., organic carbon flux, microbial processes, and food web structure and dynamics) processes. Any changes in these bottomup or top-down processes would have a major effect on the Hg levels in an ecosystem, in top predators

Signs from the Arctic Ocean

There is no doubt that the significant increase in Hg

Before impoundment

Conclusions

Findings

Scavenging and sedimentation