『Abstract
Saharan dust is persistently transported and deposited in ecosystems
of the western Atlantic Ocean. This dust is an aggregate of clay
and quartz particles cemented with Fe oxides. Samples collected
and analyzed from Mali (central Africa), the Azores, the Caribbean
and the Eastern United States document the levels of minor and
trace metals in the dust. Metal loadings, particularly the toxic
elements−Hg and As, are significantly higher than average crustal
rocks. Over the past decade, the focus has been to understand
the cycling of Hg in south Florida, but As has received very little
attention. Arsenic in the sediment deposited in the past decade
in south Florida averages 14 mg/kg and appears to be correlated
with Al, a proxy for dust. The largest available aerosol data
set containing As is the IMPROVE (Inter-agency Monitoring of Protected
Visual Environments) data set. The average concentrations in aerosols
collected during this program range from 17 mg/kg in the Virgin
Islands to 79 mg/kg at Chassahowitzka, Florida. At Chassahowitzka,
most of the As appears to be associated with organic C. If it
is assumed that the concentrations in Mali dust and in the aerosols
in the Virgin Islands are indicative of soil dust, then the higher
values at Chassahowitzka may be derived from local or regional
sources. A simple calculation indicates that African dust supplies
about 25％ of the As deposited from aerosols in the southeastern
United States. Comparison of the average yearly As concentrations
measured in the Virgin Islands and Everglades shows a negative
relationship with the North Atlantic Oscillation (NAO). This relationship
demonstrates the influence of climate on the transport and deposition
of aerosols to the southeastern United States.』
1. Introduction
2. Geography
3. Previous studies on the composition, transport and effects
of dust
4. Trace metal distribution in the Central Atlantic aerosols
4.1. Aerosol database
4.2. Aluminum proxy and iron content
4.2.1. Aluminum
4.2.2. Iron
4.2.3. Arsenic
5. Analysis
5.1. Average distribution
5.2. Correlation coefficients
5.3. Dendrograms
6. Seasonal air flow
6.1. Method of assessing origin of airflow
7. Discussion and conclusion
Acknowledgements
References