Award: OCE-1459270

Lead (Pb) is a toxic element that was dispersed throughout the environment from numerous anthropogenic sources (smelting, gasoline, paint) in large quantities throughout the 20th century. In the oceans, dissolved Pb and its isotopes have been used for several decades to trace water masses using the differences in the concentrations and isotopic ratios found in various water masses. These water masses would have accumulated Pb in surface waters from the atmosphere as it was deposited during a given period of time and then have been carried by currents throughout the worlds oceans. This project concentrated on measuring the concentration of dissolved Pb in the Arctic Ocean. The Arctic Ocean is the worlds smallest ocean that receives water from both the Pacific and Atlantic Oceans through the Bering and Fram Straits respectively as well as freshwater from several large arctic rivers. The Arctic Ocean is surrounded by several marginal seas; the Beaufort, Chukchi, East Siberian, Laptev and Barents and their respective shelves. The input of accumulated dissolved Pb from both the Atlantic and Pacific as well as atmospheric transport of Pb from northern countries bordering the Arctic created the potential for Pb from around the world to be transported into the Arctic. Surface waters in the northern hemishere oceans have reached as high as 150 pM/L dissolved Pb in the past 100 years and we expected to find higher concentrations in the Arctic in some older, deeper water masses. Our results from this project inidcate that although the potential for high concentrations of dissolved Pb exist from sources entering the Arctic Ocean, the surrounding shelves, continental slopes and marginal seas appear to be an effective at scavenging (removing) dissolved Pb from the water column. Concentrations of dissolved Pb from this study (352 samples from 26 water column profiles and surface water) were generally less that 10 pM, most less than 5 pM. These concentrations would be analogous to >500 m deep in most of the worlds oceans. While more work must still be done to interpret our data by comparing our data with other datasets generated from other researchers who participated in this project we can say that we are struck by the uniformity of the concentrations of dissolved Pb in the Arctic Ocean. Last Modified: 07/01/2019 Submitted by: Robert D Rember