Abstract: Tibetan Plateau is an ideal place to study the relationship between tectonic uplift,surface weathering and climate change. Here, the role of sulfuric acid in carbonate and silicate weathering and its effects on the corresponding CO₂ consumption flux and climate change were investigated in Niyang River catchment using hydrochemical method and forward model. The results showed that: (1) The hydrochemical type of Niyang River was characterized by HCO₃·SO₄Ca·Mg and HCO₃·SO₄Ca. The cations in river water were mainly derived from weathering of carbonate and silicate, contributing to 79.4% and 11.7% of the total water cation, respectively. (2) There was substantial chemical weathering of sulfide minerals in the catchment, with weathering rate (13.5 t·km^-2·a^-1) being three times as high as that of the silicate mineral weathering (4.46 t·km^-2·a^-1). (3) The net CO₂ emissions during chemical weathering of carbonateresulted by sulfuric acid, to a large extent, could offset the CO₂ consumption caused bycarbonate silicate mineral weathering in Niyang River catchment.

Key words: Karst slope, soil mechanical composition, leakage of underground soil, rainfall, shallow fissure