Solute Sources and Mechanism of Boron Enrichment in the Tataleng River on the Northern Margin of the Qaidam Basin

The Tataleng River (TTR), as an important tributary of the Da Qaidam Salt Lake (DQSL) and Xiao Qaidam Salt Lake (XQSL) in the Qaidam Basin (QB), has an exceptionally high B content. However, the solute sources and the provenance of B in the TTR are still unclear, which significantly hinders a deeper understanding of the source–sink processes of the boron deposits in the QB. In this study, water samples were collected from tributaries, mainstreams, mud volcanoes, hot springs, and rainwater in the TTR area. Through hydrochemical analysis, forward modeling, and B isotope geochemistry methods, combined with the previous research results, some findings were obtained. The hydrochemical type of TTR is Ca–Mg–Cl, and the major mechanism of controlling chemical composition is rock weathering. The solute sources in the TTR are mainly from dissolution of evaporites (75.9