Award: OCE-1434650

Project Outcomes We participated in the U.S. GEOTRACES cruise to the Arctic Ocean with the goal of studying the distribution and chemical forms of mercury (Hg), a toxic metal present at low but concerning concentrations. Of particular importance on this cruise was the investigation of various chemical forms of Hg that are present in the ocean: total Hg, composed mostly of inorganic Hg complexes; monomethylmercury; dimethylmercury; and elemental Hg. It is important to study these forms of Hg separately because their fate and behavior in the ocean are different. For example, elemental Hg is a dissolved gas that is produced in high enough concentrations to degas from the ocean and enter the atmosphere, representing a natural process of detoxification of Hg from the ocean. In contrast, monomethylmercury is produced within the ocean, possibly in association with sea ice, and is the form of Hg that accumulates in seafood and poses a risk to human and environmental health. Thus, in order to understand the potential health risks of monomethylmercury in seafood, we must gain an understanding of the chemical forms of Hg in seawater and how they interact with one another. We measured concentrations of different chemical forms of Hg in filtered water and suspended particles in the Arctic Ocean. The cruise track extended from Dutch Harbor, Alaska, north through the Bering Strait, traversed the Makarov Basin, reached the North Pole (Eurasian Basin), and returned southeast through the Canada Basin. The cruise track allowed us to test some fundamental questions regarding Hg cycling in the Arctic Ocean. Some highlights from our findings include: The ratio of monomethylmercury to total Hg in the Arctic Ocean is not greater than in other ocean basins. Indeed, we measured lower concentrations of both mono- and di-methylmercury in the Arctic Ocean compared to other basins. Arctic Ocean water contains Hg from human sources such as fossil fuel use and gold mining. Mercury inputs to the Arctic Ocean from Pacific Ocean water inflow is relatively low compared to other sources. Broader Impacts During this project we improved understanding of an important human and ecosystem health risk in the form of methylated Hg. This project supported dissertation research of a Ph.D. student at Wright State University, research of three Wright State undergraduate students, and a postdoctoral researcher at UC Santa Cruz. This research also promoted science education at the grade-school level. We engaged a class of seventh-graders at a Dayton-area middle school with our oceanographic research. This was done through classroom visits by Dr. Hammerschmidt and his Ph.D. student, Alison Agather, who talked with middle school students about oceanography and living at sea. Katlin Bowman, the postdoctoral researcher, was invited to blog for the Huffington Post during the expedition, to chronicle her research, the investigations and activities of other scientists aboard, life on a ship, and oceanography (https://www.huffingtonpost.com/author/katlin-bowman). This assignment stemmed from her personal blog (www.hginthesea.wordpress.com), which she started in 2011 as a Ph.D. student to document her work with the U.S. GEOTRACES program. She conveys her experiences and teaches oceanography with easily accessible language. To date, Bowman?s blog has had over 30,000 views. Bowman also contributed an article, "Journey to the North Pole," to the Times Publishing Group (http://www.tpgonlinedaily.com/journey-to-the-north-pole/). In addition to Bowman?s blog, Agather chronicled her experience as a first time sea-goer and GEOTRACES participant. Covering similar topics to a different audience, Agather?s blog had over 800 visitors with 2,700 views. While at sea, the Hg team participated in Coast Guard sponsored programs. We gave one of the weekly science lectures for the crew and scientists aboard. The lecture focused on Hg pollution and toxicity. Additionally, we guest-lectured in the Coast Guard?s on-board oceanography course, teaching two lectures on pollution and climate change. Katlin Bowman co-authored a children?s book about her experience. To the Top of the World: One Scientist?s Expedition to the North Pole is narrated from her perspective as a young female scientist on an expedition to the North Pole, and explains the basics of oceanography and Hg pollution with graphics, photos, and simple text for kids to easily understand. All proceeds from the book sales have been donated to four nonprofits: Falmouth STEM boosters in Massachusetts; the Woods Hole Public Library; a STEM school in Los Angeles; and Save Our Shores in California, a team that works to protect the coastline of Monterey Bay. Various public lectures and readings were organized to promote the book and Arctic GEOTRACES research, including readings and presentations at: Science Sunday at the Seymour Marine Discovery Center (Santa Cruz, CA; Bowman) Science on Tap, sponsored by UC Santa Cruz?s Women in Science and Engineering Club (Bowman) Scotts Valley, CA, Public Library local author event (Bowman) Bellbrook (Ohio) Middle School (Hammerschmidt & Agather) Nevin Coppock Elementary School (Tipp City, Ohio; Agather) Last Modified: 05/07/2018 Submitted by: Chad R Hammerschmidt