APPROACHES TO STUDY MERCURY CYLING
ANDREA GARCIA BRAVO
PhD in Environmental Sciences (2010)
Raymond L. Lindeman Awardee 2019
My main research interest is the fate of pollutants in the environment with a special emphasis on mercury biogeochemistry in rivers, lakes, ponds, wetlands, soils and the ocean. More specifically, I focus on the processes controlling the concentration of methylmercury in the landscape and its further biomagnification in food webs. I combine ecosystem, experimental, biogeochemical, molecular and “omics” approaches with the study of food web’s structure to investigate the environmental factors controlling Hg cycling in the environment and to determine the human exposure to this pollutant.
Mercury is a natural and widespread trace metal occurring in the environment but it is considered as a priority hazardous substance because it damages the central nervous system in severely exposed humans. Although all forms of mercury are toxic, human exposure to mercury takes place mainly via the intake of the organic form methylmercury, through fish consumption. Most mercury found in the environment is in the inorganic form Hg(II). However, essentially all the mercury accumulating in fish and other aquatic organisms is in methylmercury. Recent estimates indeed revealed that, in the European Union alone, the risk assessment of environmental exposure to methylmercury could save €8-9 billion per year by protecting children’s brain development.
The formation of methylmercury (i.e. Hg methylation) in aquatic ecosystems is therefore a key process of the mercury cycling. However, the formation of methylmercury in aquatic systems, a complex anaerobic biological process influenced by a wide variety of environmental factors, including temperature, pH, redox potential, the presence of inorganic and organic complexing agents, total microbial activity and the concentration of bioavailable Hg(II), still remains poorly understood. This lack of knowledge has impeded accurate predictions and effective management of methylmercury levels in the environment. As a deep understanding of all possible inputs and internal transformation processes that act as a source of methylmercury for aquatic ecosystems could help to draw effective management strategies to reduce human exposure to mercury, I focus my research on elucidating the main biological and chemical factors driving the formation and biomagnification of methylmercury in aquatic ecosystems.
The formation of methylmercury (i.e. Hg methylation) in aquatic ecosystems is therefore a key process of the mercury cycling. However, the formation of methylmercury in aquatic systems, a complex anaerobic biological process influenced by a wide variety of environmental factors, including temperature, pH, redox potential, the presence of inorganic and organic complexing agents, total microbial activity and the concentration of bioavailable Hg(II), still remains poorly understood. This lack of knowledge has impeded accurate predictions and effective management of methylmercury levels in the environment. As a deep understanding of all possible inputs and internal transformation processes that act as a source of methylmercury for aquatic ecosystems could help to draw effective management strategies to reduce human exposure to mercury, I focus my research on elucidating the main biological and chemical factors driving the formation and biomagnification of methylmercury in aquatic ecosystems.
