Seminar by Dr. Hannah Horowitz from University of Washington
19 April 2019
10:00 — 11:00
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 a global scale.