Abstract
The stable isotope compositions of Cu and Zn in major geochemical reservoirs are increasingly studied with the aim to develop these isotope systems as tools to investigate the global biogeochemical cycles of these trace metals. The objectives of the present study were (i) to expand the range of Cu, Zn, and Pb isotope compositions of mineral dust by analyzing samples from major mineral dust sources in Asia and Africa (Chinese Loess Plateau, Chinese deserts, Thar desert, Sahel region) and (ii) to assess the potential impact of human activities on the isotope composition of aerosols by synthesizing published Cu and Zn isotope compositions in aerosols and natural and anthropogenic sources. For the newly analyzed mineral dust areas in Asia and Africa, δ^{65}Cu_{NIST-976} values range from −0.54 to +0.52‰, δ^{66}Zn_{JMC-Lyon} values from −0.07 to +0.57‰, and {206}^Pb/{204}^Pb values from 18.522 to 19.696. We find a significant geographic control with samples from the Thar Desert having the heaviest isotopic compositions (δ^{65}Cu_{NIST-976} = +0.48 ± 0.06‰, δ^{66}ZN_{JMC-Lyon} = +0.49 ± 0.11‰) and samples from the Sahel and the Badain Jaran desert having the lightest Zn isotope composition (δ^{66}ZN_{JMC-Lyon} = +0.19 ± 0.15‰ and +0.07 ± 0.07‰, respectively). We find important variations in the isotope signatures between particle size fractions with heavier isotopic compositions in the smallest and largest particle size fractions and lighter isotopic compositions in the mid particle size fractions. Associations with the mineralogical composition are less clear. Newly analyzed aerosol samples for Beijing and Xi'an show δ^{65}Cu_{NIST-976} values of +0.29 ± 0.19‰ and +0.16 ± 0.04‰, δ^{66}Zn_{JMC-Lyon} values of −0.36 ± 0.04‰ and +0.02 ± 0.06‰, and {206}^PB/{204}Pb values of 18.129 ± 0.003 and 18.031 ± 0.003, respectively. Based on a synthesis of published and novel data, we suggest improved ranges and mean values for the isotopic composition of mineral dust from selected locations in Asia and Africa and of anthropogenic sources such as non-exhaust traffic emissions, combustion, electroplating and galvanization. This should serve as a valuable reference for future studies using these isotope systems. This paper demonstrates univocally that human activity introduces a wide range of Zn isotope compositions into the atmospheric environment and, thus, impacts the biogeochemical cycle of Zn.
Highlights
Earth system processes and human activity influence the global biogeochemical cycles of copper (Cu) and zinc (Zn) in a variety of ways
Based on a synthesis of published and novel data, we suggest improved ranges and mean values for the isotopic composition of mineral dust from selected locations in Asia and Africa and of anthropogenic sources such as non-exhaust traffic emissions, combustion, electroplating and galvanization
The present study examines associations between observed isotopic compositions in urban aerosols and source reservoirs including mineral dust and anthropogenic materials
Summary
Earth system processes and human activity influence the global biogeochemical cycles of copper (Cu) and zinc (Zn) in a variety of ways. Atmospheric long-range transport and deposition of mineral dust and particulate matter delivers these micronutrients to remote marine and terrestrial regions, controlling ecosystem development, and influencing the global carbon cycle (Mahowald et al, 2005). Both metals are toxic at higher concentrations for oceanic microorganisms or when inhaled by humans, they induce adverse health effects. Copper causes damage to molecules such as proteins and lipids (Brewer, 2010) Both Cu and Zn in urban atmospheric particles (Beijing) are present to a high percentage in leachable fractions and may be environmentally mobile and bioavailable (Schleicher et al, 2011). Identifying their sources in atmospheric aerosols remains critical for controlling emissions and improving air quality in urban environments (Moffet et al, 2008)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
