Disproportionately high rates of sulfide oxidation from mountainous river basins of Taiwan orogeny: Sulfur isotope evidence

Abstract

Sulfur isotopic tracing of river sulfate (SO 4 2-) suggests that sulfide oxidation accounts for 85 7% of the dissolved SO 4 2- in one of the largest river systems (the Kaoping) of the Taiwan orogeny in the high-discharge season. This corresponds to a basin-wide contribution of ∼1.2-1.6% of pyrite-derived SO 4 2- exported by rivers globally, from a river basin, which is only ∼0.003% of the global drainage area. Intense rainfall, high relief and active tectonics all favor intense physical weathering of the Kaoping basin, which promotes continuous exposure of fresh (sulfide) mineral surfaces for oxidative weathering. This coupling between physical and chemical weathering sustains disproportionately high sulfide oxidation, ∼400 times relative to surface area, in the Kaoping basin. © 2012 American Geophysical Union. All Rights Reserved.