Trace elements(and their isotopes)in carbonates are commonly used to reconstruct paleoenvironment and paleoclimate.Understanding the processes and mechanisms of element incorporation into carbonates is thus crucial fo...Trace elements(and their isotopes)in carbonates are commonly used to reconstruct paleoenvironment and paleoclimate.Understanding the processes and mechanisms of element incorporation into carbonates is thus crucial for using such geochemical parameters as paleoclimate proxies.In contrast to laboratory-based experimental results,the partitioning of trace metals between solid and solution phases in natural carbonate precipitation systems has rarely been reported.In this study,we investigated the partition coefficients of metal ions between solid and solution in the channel of the natural Baishuitai travertine system,Yunnan,China.Our results show that the partition coefficients of Li+,Na+,Mg2+,Sr2+and Ba2+are<1,that of Ni2+is approximately 1,and those of Co2+,Mn2+,Zn2+and Cu2+are>1,consistent with the results found in previous experimental studies.Although the substitution for Ca2+is likely the main uptake process of these metals into calcite,depending on their ionic radius and charge,trace elements may also be incorporated by adsorption or physical entrapment.Our study shows that unlike laboratory experiments performed under specific conditions,the partitioning of metals between two phases in the natural travertine system could be controlled by several,even multiple,environmental factors(e.g.,carbonate deposition rate,temperature,and pH),which should be taken into account when using trace metals(and their isotopes)in carbonate archives as a paleoclimate proxy.展开更多
基金financially supported by the National Key Research and Development Program of China (2019YFC1804400)the National Natural Science Foundation of China (U1612442, 41961144028, 41625012, 41830647)"Ten Thousand Talent" project of Ministry of Science and Technology of the People’s Republic of China。
文摘Trace elements(and their isotopes)in carbonates are commonly used to reconstruct paleoenvironment and paleoclimate.Understanding the processes and mechanisms of element incorporation into carbonates is thus crucial for using such geochemical parameters as paleoclimate proxies.In contrast to laboratory-based experimental results,the partitioning of trace metals between solid and solution phases in natural carbonate precipitation systems has rarely been reported.In this study,we investigated the partition coefficients of metal ions between solid and solution in the channel of the natural Baishuitai travertine system,Yunnan,China.Our results show that the partition coefficients of Li+,Na+,Mg2+,Sr2+and Ba2+are<1,that of Ni2+is approximately 1,and those of Co2+,Mn2+,Zn2+and Cu2+are>1,consistent with the results found in previous experimental studies.Although the substitution for Ca2+is likely the main uptake process of these metals into calcite,depending on their ionic radius and charge,trace elements may also be incorporated by adsorption or physical entrapment.Our study shows that unlike laboratory experiments performed under specific conditions,the partitioning of metals between two phases in the natural travertine system could be controlled by several,even multiple,environmental factors(e.g.,carbonate deposition rate,temperature,and pH),which should be taken into account when using trace metals(and their isotopes)in carbonate archives as a paleoclimate proxy.