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

Abstract

[1] 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 Â 10 3 mol y À1. Based on this riverine flux, the estimated oceanic residence time of Pt is 24 AE 10 kyrs. A 50% release and 50% uptake of Pt in estuaries would modify this to 16 kyrs and 45 kyrs, respectively.

Improving the Voltammetric Quantification of Ill-Defined Peaks Using Second Derivative Signal Transformation: Example of the Determination of Platinum in Water and Sediments

“…A major challenge in any environmental study of Pt is the need for extremely sensitive analytical techniques that allow measuring its ultra-trace concentrations of 10 2 -10 -1 ng g -1 in sediments and 10 2 -10 -2 pM in waters [4][5][6][7] . Two analytical techniques, inductively-coupled plasma mass spectrometry (ICP-MS) and voltammetry, have been mostly used for the determination of Pt in water and sediments since they provide the sensitivity needed.…”

“…The use of ICPMS offers the advantage of a direct and rapid analysis of sediment digests and freshwater, provided the isobaric interference of 179 Hf 16 O on 195 Pt, the commonly monitored Pt isotope, is taken into account. 6,8 ICPMS has also been used for the analysis of Pt in seawater 9,10 where an anion exchange resin is used for the removal of sea-salts and preconcentration of Pt, and high-purity concentrated acids are used in the elution step 9 making the procedure expensive, contamination-sensitive, time-consuming, and thus unsuitable for routine analysis. The analysis of natural waters using voltammetry, however, appears to be more straightforward since no prior preconcentration step or removal of salts is required and is capable of determining Pt down to about 30 fM in seawater.…”

Accumulation of Platinum Group Elements in Hydrogenous Fe–Mn Crust and Nodules from the Southern Atlantic Ocean

“…Possible sources of platinum group elements in the ocean can be riverine fluxes, hydrothermal processes, cosmic dust flux, and halmyrolysis of oceanic basalts. If riverine and cosmic inputs have been estimated in some works [59,60], the influence of hydrothermal process and basalt halmyrolysis are significantly less studied [61]. Ferromanganese deposits in the ocean are a significant sink of metals entering the ocean and indicate the source of the metal supply.…”

“…Platinum elements in the ocean are not a chemically coherent group, and the seawater PGE composition is not inherited by ferromanganese deposits. Thus, palladium is mobile in seawater and its residence time in the ocean is longer (10-100 thousand years, [62]) than that of platinum (10-22 thousand years, [60]) and iridium (2-20 thousand years, [9]). Pd does not accumulate in ferromanganese deposits.…”

New insights on the dissolved platinum behavior in the Atlantic Ocean

“…Platinum is a highly siderophile metal (Lorand et al 2008) and, as such, is one of the least abundant elements at the Earth's surface with a typical crustal abundance of 0.5 ng g -1 (Rudnick and Gao 2003). In natural waters, dissolved Pt typically displays picomolar and subpicomolar concentrations (Obata et al 2006;Soyol-Erdene and Huh 2012;Cobelo-García et al 2013;Cobelo-García et al 2014a,b). Current interest on the investigation of the environmental Pt geochemistry relies on the fact that its cycle at the Earth's surface is greatly impacted by anthropogenic activities, amounting up to, at least, 80% of its total mobilization (Sen and Peucker-Ehrenbrink 2012).…”