Impacts of anthropogenic change on pollution and climate
Human activity impacts both sources of pollutants, as well as the chemical and physical processes determining the pathways from sources to societal impacts. In this talk I will focus on the mercury cycle as an example of the full biogeochemical cycle of a pollutant. Mercury (Hg) adversely affects human health on a global scale through fish consumption. It remains cycling in the ocean for decades to centuries, such that present-day and future environmental loadings are influenced by the past. I first quantify historical emissions of mercury to the environment from commercial activities using substance flow analysis. This work more than doubles previous estimates of total anthropogenic mercury emissions, helping lead a paradigm shift in the attribution of human vs. natural environmental Hg, with regulatory consequences. I examine the effects of commercial mercury releases on our understanding of historical and recent observed trends using a state-of-the-art 3-D chemical transport model. I then briefly discuss how a detailed understanding of the atmospheric chemistry of mercury is needed to predict how mercury emissions are transported and deposited to surface ecosystems. Finally, I develop modeling tools to assess current national and global mercury regulations. I end with future research directions, where I will investigate the impacts of climate and anthropogenic change on 1) the biogeochemistry of toxic pollutants; 2) aerosol-chemistry-climate feedbacks; and 3) air quality on a regional to global scale.