Rare earth element input and transport in the near-surface zonal current system of the Tropical Western Pacific

Abstract

Continental sources and current transport play a major role in rare earth element (REE, and other trace element) input and distribution in the Tropical Western Pacific. Here, we present spatially highly resolved distributions of dissolved REE concentrations ([REE]) along three transects in the zonal (extra-)equatorial current system and the Solomon Strait of the Tropical Western Pacific. We use seawater [REE] in combination with direct physical oceanographic observations (e.g., current velocity data) to characterize the geochemical composition, origin and pathways of the complex surface and upper layer currents of the Tropical Western Pacific and to quantify the input fluxes of REEs. We identify Papua New Guinea (PNG) volcanic rocks, sediments, and/or river particles as the key source adding trace elements to the equatorial eastward zonal currents of the Tropical Western Pacific. Our and published data indicate temporal and spatial variability of this input and transport in the PNG source area and the equatorial eastward currents. The westward currents, on the other hand, lack this REE input signal suggesting lateral transport of preformed seawater [REE]. At the transition between these zonal eastward and westward currents, our data indicate lateral mixing of Eastern and Western Pacific source waters.