![]() This chemical transport model tracks mercury from its emissions sources to where it is chemically transformed in the atmosphere and then ultimately to where it is deposited, mainly through rainfall or uptake into forest ecosystems. Using a series of land use change scenarios, they adjusted the model to quantify the role of deforestation. In past work, they had built a model to probe the role vegetation plays in mercury uptake. The researchers launched their study to fill in that missing piece. However, it doesn't directly consider impacts of deforestation. A global treaty, the 2013 Minamata Convention, calls on nations to reduce human-made emissions. Many studies of mercury focus on industrial sources, like burning fossil fuels, small-scale gold mining, and metal smelting. In this way, forests reduce the amount of toxic methylmercury in oceans. The forests are doing a sort of ecosystem service, in that they are sequestering mercury for longer timescales," says Feinberg, who is now a postdoc in the Blas Cabrera Institute of Physical Chemistry in Spain. "In soils, mercury is much more tightly bound than it would be if it were deposited in the ocean. This can lead to risky levels of methylmercury in the fish humans eat. Methylmercury, a potent neurotoxin, can be taken up by fish and bioaccumulated through the food chain. ![]() ![]() Mercury becomes a serious concern for humans if it ends up in water bodies, where it can become methylated by microorganisms. Mercury largely stays within a leaf until it falls to the forest floor, where the mercury is absorbed by the soil. But unlike carbon dioxide, mercury doesn't play an essential biological function for plants. Plant leaves take up mercury from the atmosphere, in a similar way as they take up carbon dioxide. Mercury, a trace element, hasn't received the same attention, partly because the terrestrial biosphere's role in the global mercury cycle has only recently been better quantified. Over the past few decades, scientists have generally focused on studying deforestation as a source of global carbon dioxide emissions. The paper appears today in Environmental Science and Technology. needs to be part of the solution," says senior author Noelle Selin, a professor in IDSS and MIT's Department of Earth, Atmospheric and Planetary Sciences.įeinberg and Selin are joined on the paper by co-authors Martin Jiskra, a former Swiss National Science Foundation Ambizione Fellow at the University of Basel Pasquale Borrelli, a professor at Roma Tre University in Italy and Jagannath Biswakarma, a postdoc at the Swiss Federal Institute of Aquatic Science and Technology. But 10 percent of the global anthropogenic source is substantial, and there is a potential for that to be even greater in the future. ![]() "Countries have put a lot of effort into reducing mercury emissions, especially northern industrialized countries, and for very good reason. ![]() While this is significant, the researchers emphasize that reforestation alone should not be a substitute for worldwide pollution control efforts. The team also estimates that global reforestation efforts could increase annual mercury uptake by about 5 percent. Curbing Amazon deforestation could thus have a substantial impact on reducing mercury pollution. The researchers' model shows that the Amazon rainforest plays a particularly important role as a mercury sink, contributing about 30 percent of the global land sink. "We've been overlooking a significant source of mercury, especially in tropical regions," says Ari Feinberg, a former postdoc in the Institute for Data, Systems, and Society (IDSS) and lead author of the study. However, if the current rate of deforestation remains unchanged or accelerates, the researchers estimate that net mercury emissions will keep increasing. The world's vegetation, from the Amazon rainforest to the savannahs of sub-Saharan Africa, acts as a sink that removes the toxic pollutant from the air. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |