TY - JOUR
T1 - Cadmium isotope fractionation during sorption to soil minerals
T2 - Lab evidence and field implication
AU - Wang, Liuwei
AU - Guo, Jiameng
AU - Tsang, Daniel C.W.
AU - Hou, Deyi
N1 - Funding Information:
This work was supported by the National Key Research and Development Program of China (Grant No. 2020YFC1808000), and the National Natural Science Foundation of China (Grant No. 42225703, 42077118). The authors thank the technical staff from Institute of Geochemistry, Chinese Academy of Sciences for isotope analysis.
Funding Information:
This work was supported by the National Key Research and Development Program of China (Grant No . 2020YFC1808000 ), and the National Natural Science Foundation of China (Grant No. 42225703 , 42077118 ). The authors thank the technical staff from Institute of Geochemistry, Chinese Academy of Sciences for isotope analysis.
Publisher Copyright:
© 2023 Elsevier B.V.
PY - 2023/9/20
Y1 - 2023/9/20
N2 - Stable isotope is a potent geochemical tracer unveiling the dynamic sources of cadmium (Cd) in the environment. However, the sorption process of aqueous Cd onto solid surfaces (e.g., soil) fractionates isotopic signatures, which makes it difficult to interpret its sources and migration processes. Understanding how Cd fractionates during sorption to soil minerals, therefore, provides necessary data to open the isotope fractionation black box of liquid-solid phase partition of Cd. In this study, we explored isotopic fractionation characteristics during Cd sorption to typical soil minerals. Distinct Cd isotope fractionation was observed during sorption, including goethite (∆114/110Cdsolid−solution=−0.51∼−0.47‰), montmorillonite (−0.34∼−0.32‰), quartz (−0.34∼−0.30‰), gibbsite (−0.29∼−0.25‰), and kaolinite (−0.09∼−0.07‰), where lighter isotopes tended to be preferentially sorbed to the solid phase in a reversible manner. We've also conducted a field survey in a historical flooding-affected region to explore Cd isotopic compositions of soil samples adjacent to a polluted creek. Distinct isotopic signatures for surficial soils and deep soils were observed, which was depicted by a binary mixing mode. Leaching of Cd from mine tailings to the creek, as well as its re-adsorption to soil during historical flooding events both led to preferential enrichment of light isotopes in the solid phase, which was consistent with findings from lab sorption experiments. Mineralogical analyses including EPMA, TOF-SIMS, Mössbauer spectra, XRD, and chemical extraction tests, were applied to unveil how Cd was bound to soil minerals at field. Possible linkage between lab and field data were discussed on the basis of these findings. Results from this study are encouraging for future application of Cd isotopes for source tracing.
AB - Stable isotope is a potent geochemical tracer unveiling the dynamic sources of cadmium (Cd) in the environment. However, the sorption process of aqueous Cd onto solid surfaces (e.g., soil) fractionates isotopic signatures, which makes it difficult to interpret its sources and migration processes. Understanding how Cd fractionates during sorption to soil minerals, therefore, provides necessary data to open the isotope fractionation black box of liquid-solid phase partition of Cd. In this study, we explored isotopic fractionation characteristics during Cd sorption to typical soil minerals. Distinct Cd isotope fractionation was observed during sorption, including goethite (∆114/110Cdsolid−solution=−0.51∼−0.47‰), montmorillonite (−0.34∼−0.32‰), quartz (−0.34∼−0.30‰), gibbsite (−0.29∼−0.25‰), and kaolinite (−0.09∼−0.07‰), where lighter isotopes tended to be preferentially sorbed to the solid phase in a reversible manner. We've also conducted a field survey in a historical flooding-affected region to explore Cd isotopic compositions of soil samples adjacent to a polluted creek. Distinct isotopic signatures for surficial soils and deep soils were observed, which was depicted by a binary mixing mode. Leaching of Cd from mine tailings to the creek, as well as its re-adsorption to soil during historical flooding events both led to preferential enrichment of light isotopes in the solid phase, which was consistent with findings from lab sorption experiments. Mineralogical analyses including EPMA, TOF-SIMS, Mössbauer spectra, XRD, and chemical extraction tests, were applied to unveil how Cd was bound to soil minerals at field. Possible linkage between lab and field data were discussed on the basis of these findings. Results from this study are encouraging for future application of Cd isotopes for source tracing.
KW - Adsorption
KW - Field
KW - Flooding
KW - Fractionation
KW - Source identification
KW - Stable isotope
UR - http://www.scopus.com/inward/record.url?scp=85162931543&partnerID=8YFLogxK
U2 - 10.1016/j.chemgeo.2023.121607
DO - 10.1016/j.chemgeo.2023.121607
M3 - Journal article
AN - SCOPUS:85162931543
SN - 0009-2541
VL - 634
JO - Chemical Geology
JF - Chemical Geology
M1 - 121607
ER -