Dissolved platinum in major rivers of East Asia: Implications for the oceanic budget

Abstract

Dissolved platinum concentrations of eleven large pristine river systems in East Asia (∼200 samples) were determined to better constrain the oceanic platinum budget. Most samples had concentrations less than 1.4 pM; relatively high concentrations up to 5.8 pM were measured in only approximately 6% of the samples. The median Pt concentrations of the individual river systems had only a small range, from 0.18 pM (Duman) to 0.63 pM (Huang He), and the difference in Pt yield mainly resulted from the difference in runoff. The rivers draining the eastern Tibetan Plateau - the Salween, Mekong, Chang Jiang (Yangtze), Hong (Red), and Huang He (Yellow) - had higher Pt yield than the rivers of the Russian Far East - the Amur, Lena, Yana, Indigirka, and Kolyma. If the discharge-weighted mean Pt concentration of our samples (0.36 pM) is extrapolated globally, the estimated riverine flux of dissolved Pt to the ocean is 13 × 10 3 mol y -1. Based on this riverine flux, the estimated oceanic residence time of Pt is 24 ± 10 kyrs. A 50% release and 50% uptake of Pt in estuaries would modify this to 16 kyrs and 45 kyrs, respectively. © 2012. American Geophysical Union. All Rights Reserved.