THE MODIFICATION OF DISSOLVED ZINC DISTRIBUTIONS ALONG THE U.S. GEOTRACES WESTERN ARCTIC SECTION

Neil J Wyatt, Florida State University, Department of Earth, Ocean, and Atmospheric Science, Tallahassee, FL, United States, William M Landing, Florida State University, Earth, Ocean, and Atmospheric Science, Tallahassee, FL, United States, Jessica N Fitzsimmons, Texas A&M University, Department of Oceanography, United States, Robert M Sherrell, Rutgers University, Departments of Marine and Coastal Sciences and Earth and Planetary Sciences, New Brunswick, NJ, United States; Rutgers University, Department of Earth and Planetary Sciences, Piscataway, NJ, United States and Seth John, University of South Carolina, Department of Earth and Ocean Sciences, Columbia, United States
Abstract:
Zinc is the second most abundant trace metal in marine microorganisms, required for carbon and organic phosphorus acquisition, DNA replication and protein structure. We report a first comprehensive dataset of dissolved zinc (dZn) for the Western Arctic Ocean and identify the key biogeochemical interactions regulating dZn distributions in the upper water column. These measurements are timely, given ongoing climate change in the Arctic, and provide a baseline for predicting future observations of Arctic biogeochemistry upon environmental change. A dZn maximum was found in the halocline layer (25-225 m), indicating dZn serves as an effective tracer for advective Pacific inflow to the interior Arctic Ocean. Such inflow appears to be the dominant source of dZn to the upper water column of the Western Arctic. The modification of dZn in Pacific inflow by biological, sedimentary and margin exchange processes is examined by pairing dZn measurements with hydrographic and macronutrient data. Our findings suggest that these interactive processes maintain halocline Zn:Si ratios above that of the mixed layer, contributing to higher Zn:Si ratios in the upper water column of the Western Arctic Ocean than that observed for other ocean basins. Conversely, in non-halocline waters, including a station occupied at the geographic North Pole, Zn-macronutrient ratios reveal a hybrid-type dZn distribution for the Western Arctic Ocean with deep water concentrations on the order of 1 nM. These anomalously low dZn values, compared with deep waters from other ocean basins, are surprising and suggest that the underlying processes that control Zn cycling remain poorly understood.
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