The concentrations and distribution of mercury in aquatic ecosystem of Baihua Reservoir

1Introduction Thebiogeochemicalcycleofmercuryinaqueous systemisthekeyfactorleadingtotheexpansionof mercurypollutiononaglobalscaleandthesafetyof fishconsumers.Dissolvedgaseousmercury(DGM)e vasionisconsideredasoneofthemostimportantmer curysourcesforatmosphere.Atthesametime,this procedurewillreducetheHgburdeninthewatercol umnandmaythusdecreasemethylmercuryproduction andaccumulationinfish(Nriagu,1994).TheBaihua ReservoirissituatedinGuizhouProvince,andithas sufferedseriousmercurycontaminationfr…     

Methylmercury and total mercury distribution in the sediments of Baihua Reservoir, Guizhou Province, China

Mercury is an important pollutant in lakes. Methylmercury （MeHg）, the most toxic mercury species, which can be formed from inorganic mercury in lakes, can be bioaccumulated into high concentration in food chain and result in a potential threat to human beings. Sediments play an important role for the Hg biogeochemistry in the aquatic systems： Mercury methylation has been shown to be fastest in the surfacial sediments, where the microbial activity is highest. The formation of MeHg in lakes suggests that sediments and/or near-shore wetlands can be the sources of MeHg in aquatic environments. The Baihua Reservoir, located in the suburb of Guiyang, was impounded in 1966. From the 1970s to the 1990s, Guizhou Organic Chemical Plant which used inorganic mercury as catalyst to produce acetic acid, was responsible for the discharge of waste water with high mercury content.     

Human exposure to mercury as a consequence of landscape management and socio-economical behaviors： Three case studies in Canada

In direct continuation with the acquired knowledge of ecosystem approach for the presence of mercury in the Amazon, we have launched in 2001 the NSERC-supported pan-Canadian COMERN project. This Collaborative Mercury Research Network addresses the urgent need for the development of a framework enabling researchers, political stakeholders, and communities concerned by the mercury question to evolve towards an interdisciplinary association capable of synergistically combining our knowledge on Hg into an original synthesis. We are presenting a simple integrated indicator representative of the specific susceptibility of an ecosystem to Hg bioaccumulation and subsequent transfer to humans. This indicator includes three concepts： （1） the sensitivity to bioaccumulation, induced and influenced by factors such as the Hg loading, the different transport and methylation processes, and human activities; （2） the vulnerability of the populations exposed to Hg through consumption of local and market fish; and （3） the adaptability of the ecosystem and the people living into it, an evaluation of its resilience, or its capacity to recover and/or to cope with the contamination, taking into account the social and political resources within the communities impacted.