Review of mercury pollution research in Southeast Asian marine environments

Mercury (Hg) is a global pollutant of widespread concern, and modern Hg levels have been much elevated compared to pre-industrial levels. The majority of environmental Hg assessment has occurred in the developed world within the temperate region, but recent years we have witnessed increases in research activities in polar, subtropical, and tropical biomes. East Asia is currently the biggest emitter of anthropogenic Hg, while intense research is ongoing in China, Korea, and Japan, relatively little has been done in the neighboring regions. Southeast (SE) Asia is a geographic region mostly within tropical biomes and neighboring two large global Hg emitters (i.e., China and India), and contains vast marine resources that would be prone to Hg contamination. The region consists of 10 countries of different economic and development status, and has a population near 700 million, a rapid industrialization and commercialization occurring in the region, including Hg-emitting activities such as coal burning and artisanal gold mining. Here, we identified 31 published studies since 1980s reporting marine Hg pollution in SE Asia, but the majority of the studies did not measure the neurotoxic form of Hg, methylmercury, while the majority of studies in SE Asia were concentrated in a few countries, namely Malaysia, Thailand, and Vietnam. Recommendations are provided to propel the Hg biogeochemical cycling studies in this rapidly developing region on the planet.