Boron isotopic compositions of brine, sediments, and source water in Da Qaidam Lake, Qinghai, China

The isotopic compositions of boron in Da Qaidam Lake, Quinghai, have been determined by using the technique of thermal ionization mass spectrometry of cesium tetraborate. The brines are enriched in 11B, with an average δ11B of +5.49 ± 2.34%., compared with those of lake sediments and boron minerals produced by the lake. The apparent isotopic fractionation factors between brine and lake sediments as well as boron minerals are 0.988 ± 0.001 and 0.986 ± 0.001, respectively. Source water δ11B values range from −11.72 to + 16.69%., depending on their origin.