Trace elements in the atmosphere over the North Atlantic

Abstract

The concentrations of trace elements in aerosol particles from the atmosphere over the North Atlantic Ocean were determined as part of a program designed to characterize the chemical climatology of the region. For these studies, which were part of the Atmosphere‐Ocean Chemistry Experiment (AEROCE), 2 years of samples were collected at Tudor Hill, Bermuda (BTT), and at Ragged Point, Barbados (BAT); and 1 year of samples was collected at Mace Head, Ireland (MHT) and at the Izaña Observatory, Tenerife, Canary Islands (IZT). One major component of the aerosol was atmospheric dust, and the ranking for the median mineral dust concentrations as represented by aluminum was BAT > IZT > BTT > MHT. The Al concentrations at BAT, IZT, and BTT ranged over 4 orders of magnitude, i.e., from 0.001 to 10 μg m−3. At MHT the maximum dust concentrations were about a factor of 10 lower than at the other sites, but the lower end of the range in dust concentrations was similar at all sites. The mineral dust concentrations generally were highest in summer, and the flux of atmospheric dust was dominated by sources in North Africa. The elements showing clear enrichments over the concentrations expected from sea salt or crustal sources were I, Sb, Se, V, and Zn. At Izaña, which is in the free troposphere (elevation ∼2360 m), the concentrations of Se and I were much lower than at the boundary layer sites; this difference between sites most likely results from the marine emissions of these elements. The impact of pollution sources on trace element concentrations was evident at all sites but varied with season and location. The concentrations of elements originating from pollution sources generally were low at Barbados. Analyses of trace element ratios indicate that there are large‐scale differences in the pollution emissions from North America versus those from Europe and Africa. Emissions from pyrometallurgical industries, steel and iron manufacturing, and possibly biomass burning are more evident in the atmospheric samples influenced by transport from Europe and Africa.

Long-range transport of mineral dust in the global atmosphere: Impact of African dust on the environment of the southeastern United States

“…Concurrent mineral dust measurements at Miami show that there was a strong influx of North African dust at the same time. High concentrations of African dust are also routinely observed on Bermuda during the summer (45)(46).…”

Columnar aerosol single‐scattering albedo and phase function retrieved from sky radiance over the ocean: Measurements of Saharan dust

“…Isentropic trajectories of 96 hours were calculated at 1800 UTC for 500, 1000, and 3000 m. The air parcels over the Dry Tortugas during the measurement period consistently arrived from the easterly or southeasterly sectors (Figure 4), a common characteristic of winds over south Florida in the summer [Henry et al, 1994] and in accord with winds associated with high dust concentrations observed every year in Bermuda, Barbados, and Miami [Arimoto et al, 1995;Prospero, 1999].…”

Urban aerosol number size distributions

“…Even if nucleation mode particles do not transport, the spatial scale of nucleation mode particles can still be thousands of kilometers (Mäkelä et al, 1998). The coarse fraction of PM 10 do not normally travel more than a few tens of kilometers except for some special cases like Sahara dust episodes (Arimoto et al, 1995). In practice, LRT is affected by mesoscale meteorology.…”