Trace metals (Fe, Zn, Cu, Co, Ni and Mn) act as essential micronutrients for phytoplankton, serving as the foundation of the marine food web. Not all trace elements act as micronutrients, with some metals (Pb and Cd) instead having toxic effects on the marine environment. Studying the distribution of trace metals throughout the global ocean is critical to estimating ecosystem health and understanding biogeochemical processes. Metals can be partitioned into three size classes: soluble, colloidal, and particulate. Dissolved metals (<0.2 um) consist of both soluble (“truly dissolved;” <0.003 um ~10 kDa) and colloidal phases (0.003 – 0.2 um). Colloids are tiny particles that are still small enough to pass through the 0.2 um dissolved filter membrane; they are considered an intermediary between soluble and particulate. The size partitioning of trace metals is important because it impacts the fate and lifetime of different elements, particularly their bioavailability. In this study, the concentration of colloidal trace metals in the central Pacific Ocean is compared to the colloidal composition of trace elements in the South Pacific, Atlantic, and Arctic Oceans. Seawater samples were collected on the US GEOTRACES GP15 Pacific Meridional Transect cruise conducted along the 152°W meridian of the central Pacific Ocean, from Alaska to Tahiti in Fall 2018. This cruise was the first basin-scale meridional trace element analysis in the Pacific Ocean covering, a wide range of biogeochemical features, allowing for the analysis of differences in inter-basin colloidal composition.

Primary Presenter: Catherine Kaylor, Texas A&M University (catiekaylor@tamu.edu)

Authors:

Catherine Kaylor, Texas A&M University  (catiekaylor@tamu.edu)

Nathan Lanning, Texas A&M University   (nlann1@tamu.edu)

Jessica Fitzsimmons, Texas A&M University  (jessfitz@tamu.edu)