title: Expressing lead isotopic compositions by fractional abundances for environmental source apportionment.
abstract: Lead (Pb) isotope has been extensively used to identify sources of Pb and apportion their contributions in the environment. Conventionally, isotope ratios are used to express Pb isotopic composition. However, the linear combination of Pb isotope ratios is not consistent with mass balance. Moreover, the graphical presentations based on Pb isotope ratios are always inconsistent when different Pb isotope ratios are used. In this study, we proposed to use fractional abundance to express Pb isotopic composition to achieve more accurate and reliable source apportionment. A new method (rotation-projection method) based on fractional abundance was developed in this research. The new method compared favorably to the isotopic ratio-based method and to another fractional abundance based method using default204Pb value (0) (Walraven's method). It allows to present four-dimensional (4-D) Pb isotope fractional abundance data in a 3-D plot. In the meantime, due to the low variation of the fractional abundance of204Pb in the terrestrial ecosystem, the terrestrial Pb isotope fractional abundance data fell nearly on a plane, which further allows to plot the Pb isotope fractional abundance data on a two-dimensional diagram. Proper presentation of the isotopic composition data helps to achieve more accurate and reliable source identification and apportionment.
authors.affiliation: Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural and Environment, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Yuyou
authors.initials: Y
authors.lastname: Zhi
authors.affiliation: Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural and Environment, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Guo
authors.affiliation: Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural and Environment, Zhejiang University, Hangzhou, 310058, China. Electronic address: jcshi@zju.edu.cn.
authors.forename: Jiachun
authors.initials: J
authors.lastname: Shi
authors.affiliation: Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural and Environment, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Lingzao
authors.initials: L
authors.lastname: Zeng
authors.affiliation: Department of Environmental Sciences, University of California, Riverside, CA 92521, USA.
authors.forename: Laosheng
authors.initials: L
authors.lastname: Wu
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D007554:Isotopes / Q000032:analysis; D007854:Lead / Q000032:analysis*; D008962:Models, Theoretical
chemical_list: D004785:Environmental Pollutants; D007554:Isotopes; D007854:Lead
keywords: Isotope fractional abundances; Isotope ratios; Isotopic compositions; Lead (Pb); Source apportionment