Sources of aerosols over the South Atlantic Ocean
File(s)
Author(s)
Khondoker, Roulin
Type
Thesis
Abstract
The atmosphere is an important pathway of particulate matter and their associated trace elements to the
ocean and can play vital roles in marine bio-geochemical cycles. Factors that control trace element inputs
from the atmosphere (e.g. solubility, sources) are not well understood, in particular for the South Atlantic
Ocean.
In this thesis, select major, trace and rare earth elements and the isotopes of two of the elements,
lead (Pb) and neodymium (Nd), were investigated in potential sources of aerosols, and aerosol samples,
from over the South Atlantic Ocean. Chapter 2 of this thesis presents new element concentration and
isotopic compositions of potential source areas from South America and southern Africa, combined with
previously published data to represent an up-to-date characterisation of natural and anthropogenic aerosol
source areas in South America and southern Africa. Chapters 3 and 4 of this thesis present new element
concentration and isotopic compositions of aerosol samples from across the 40°S transect of the South
Atlantic Ocean (from the UK GEOTRACES GA10 transect). The results provide the first constraints on the
elemental and isotopic composition of total and soluble fraction of aerosol samples across a zonal transect
of the South Atlantic Ocean. By comparing the element and isotopic compositions of the aerosol samples to
the potential source areas from South America we demonstrate that natural and anthropogenic sources from
South America and southern Africa are major sources of atmospheric particulates, but of varied
contribution, across the South Atlantic. Elemental and isotopic compositions of the aerosols suggest there is
a strong impact of anthropogenic sources from South America on atmospheric particles delivered to the
western South Atlantic and a strong influence of natural sources from South America on atmospheric
particles delivered to the middle of the South Atlantic. We further demonstrate that there is an importance
of anthropogenic southern African sources on aerosol composition over eastern South Atlantic as well as
South American source inputs. In Chapter 4 we reveal that large ranges in trace element solubility (between
<5 and >95%, generally above 40% across the ocean) in aerosols carried to the South Atlantic may be
available for seawater dissolution and may have implications on marine biogeochemical cycles.
Overall the present thesis underlines the important role that anthropogenic source areas can play on
atmospheric composition, and provide for the first time measurements of major, trace and rare earth
element availability to the surface ocean of the South Atlantic. The thesis also highlights the key role that
multi-element concentrations and Pb and Nd isotopic compositions can play in deciphering the provenance
of aerosols and element seawater supply.
ocean and can play vital roles in marine bio-geochemical cycles. Factors that control trace element inputs
from the atmosphere (e.g. solubility, sources) are not well understood, in particular for the South Atlantic
Ocean.
In this thesis, select major, trace and rare earth elements and the isotopes of two of the elements,
lead (Pb) and neodymium (Nd), were investigated in potential sources of aerosols, and aerosol samples,
from over the South Atlantic Ocean. Chapter 2 of this thesis presents new element concentration and
isotopic compositions of potential source areas from South America and southern Africa, combined with
previously published data to represent an up-to-date characterisation of natural and anthropogenic aerosol
source areas in South America and southern Africa. Chapters 3 and 4 of this thesis present new element
concentration and isotopic compositions of aerosol samples from across the 40°S transect of the South
Atlantic Ocean (from the UK GEOTRACES GA10 transect). The results provide the first constraints on the
elemental and isotopic composition of total and soluble fraction of aerosol samples across a zonal transect
of the South Atlantic Ocean. By comparing the element and isotopic compositions of the aerosol samples to
the potential source areas from South America we demonstrate that natural and anthropogenic sources from
South America and southern Africa are major sources of atmospheric particulates, but of varied
contribution, across the South Atlantic. Elemental and isotopic compositions of the aerosols suggest there is
a strong impact of anthropogenic sources from South America on atmospheric particles delivered to the
western South Atlantic and a strong influence of natural sources from South America on atmospheric
particles delivered to the middle of the South Atlantic. We further demonstrate that there is an importance
of anthropogenic southern African sources on aerosol composition over eastern South Atlantic as well as
South American source inputs. In Chapter 4 we reveal that large ranges in trace element solubility (between
<5 and >95%, generally above 40% across the ocean) in aerosols carried to the South Atlantic may be
available for seawater dissolution and may have implications on marine biogeochemical cycles.
Overall the present thesis underlines the important role that anthropogenic source areas can play on
atmospheric composition, and provide for the first time measurements of major, trace and rare earth
element availability to the surface ocean of the South Atlantic. The thesis also highlights the key role that
multi-element concentrations and Pb and Nd isotopic compositions can play in deciphering the provenance
of aerosols and element seawater supply.
Version
Open Access
Date Issued
2014-08
Date Awarded
2015-07
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Weiss, Dominik
van de Flierdt, Tina
Rehkamper, Mark
Sponsor
Natural Environment Research Council (Great Britain)
Publisher Department
Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)