Sr fluxes and isotopic compositions in the headwaters of the Yangtze River, Tongtian River and Jinsha River originating from the Qinghai-Tibet Plateau

The 87Srex flux forcing changes in seawater Sr isotopic composition is 1.13 × 106 mol a− 1 for the HTJR at Yibin, being far lower than those in the Ganges and Brahmaputra and merely accounting for 1.36% of the total carried by the global rivers. Therefore, impact of the HTJR on steady increase of seawater 87Sr/86Sr ratio since 40 Ma may be very small.