Stable (Cu, Zn) and radiogenic (Pb) isotope geochemistry of airborne particulate matter
Author(s)
Dong, Shuofei
Type
Thesis
Abstract
The aim of the thesis was to test the isotope systematics of Cu, Zn and Pb in
atmospheric particulate matter and potential source material in order to critically
discuss its implications and applications to studies of global biogeochemical cycles
and anthropogenic impact.
Four specific objectives were addressed: First, we tailored existing analytical
methods to enable for the first time accurate and precise Cu and Zn isotope ratio
measurements in dust and aerosol samples with low element content. Second, we
studied the Pb, Cu and Zn isotope composition in aerosols collected in London to test
their potential to trace anthropogenic sources in the urban atmosphere. Third, we
characterized the Cu and Zn isotope systematics of major Asian and African dust
sources and constrained possible controls and implications on the marine isotope
signature. Finally, we investigated the isotope fractionation of Zn during dissolution
experiments with acidic solution of natural dust to test the possible effect of
atmospheric processing on the isotope signature of deposited Zn.
The conclusions from this work are: First, stable isotopes confirm that brake and
tyre emissions are the likely dominant sources of Zn and Cu in urban aerosols and that
recycled Pb deposited originally from leaded gasoline still contributes significantly to
the burden of atmospheric Pb in London. Second, we show that the Cu and Zn isotope
signatures vary significantly between the major Asian and African dust sources and
we find a significant correlation between Cu isotope ratio and illite content. Mass
balance calculation suggest that bulk samples record faithfully the isotope signature of
the <4 μm fraction. Third, significant isotope fractionation of Zn is observed during
dust dissolution suggesting that the isotope signature of Zn deposited in the surface
ocean is not only controlled by source mixing but also by atmospheric processing
during long range transportation.
The work clearly supports the initial hypothesis that metal isotopes are powerful
sources to study global and regional biogeochemical cycles.
atmospheric particulate matter and potential source material in order to critically
discuss its implications and applications to studies of global biogeochemical cycles
and anthropogenic impact.
Four specific objectives were addressed: First, we tailored existing analytical
methods to enable for the first time accurate and precise Cu and Zn isotope ratio
measurements in dust and aerosol samples with low element content. Second, we
studied the Pb, Cu and Zn isotope composition in aerosols collected in London to test
their potential to trace anthropogenic sources in the urban atmosphere. Third, we
characterized the Cu and Zn isotope systematics of major Asian and African dust
sources and constrained possible controls and implications on the marine isotope
signature. Finally, we investigated the isotope fractionation of Zn during dissolution
experiments with acidic solution of natural dust to test the possible effect of
atmospheric processing on the isotope signature of deposited Zn.
The conclusions from this work are: First, stable isotopes confirm that brake and
tyre emissions are the likely dominant sources of Zn and Cu in urban aerosols and that
recycled Pb deposited originally from leaded gasoline still contributes significantly to
the burden of atmospheric Pb in London. Second, we show that the Cu and Zn isotope
signatures vary significantly between the major Asian and African dust sources and
we find a significant correlation between Cu isotope ratio and illite content. Mass
balance calculation suggest that bulk samples record faithfully the isotope signature of
the <4 μm fraction. Third, significant isotope fractionation of Zn is observed during
dust dissolution suggesting that the isotope signature of Zn deposited in the surface
ocean is not only controlled by source mixing but also by atmospheric processing
during long range transportation.
The work clearly supports the initial hypothesis that metal isotopes are powerful
sources to study global and regional biogeochemical cycles.
Date Issued
2012
Date Awarded
2013-01
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Weiss, Dominik
Spiro, Baruch Felix
Sponsor
UK-China Scholarships for Excellence.
Publisher Department
Earth Science and Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)