环境地球化学国家重点实验室知识库

This study examined for the first time the Hg isotope composition in rain samples from a single precipitation event at Lhasa City (China) on the Tibetan Plateau, the "world's third pole". Large variations of both mass-dependent fractionation (MDF, delta Hg-202 from -0.80 parts per thousand to -0.42 parts per thousand) and mass-independent fractionation (MIF, Delta Hg-199 from 0.38 parts per thousand to 0.76 parts per thousand) were observed, with the latter increasing with time. Our results demonstrated that the large variation of Hg isotope ratios likely resulted from mixing of locally emitted Hg and long-term transported Hg, which were characterized by different Hg isotope signatures and mainly leached by below-cloud scavenging and in-cloud scavenging processes, respectively. Our findings demonstrated that Hg isotopes are a powerful tool for investigating the dynamics of precipitation events and emphasized the importance of systematic monitoring studies of the chemical and isotope variability of Hg and other elements during rainfall events.