Gerald L. Hoffman

ATMOSPHERIC TRACE METALS AT REMOTE NORTHERN AND SOUTHERN HEMISPHERE SITES: POLLUTION OR NATURAL?

The chemical composition of atmospheric particles collected near sea level over the North Atlantic indicates that Al, Sc, Mn, Fe, Co, Cr, Na, Mg, Ca, K, and Sr are derived from either crustal weathering or the ocean. The elements V, Zn, Cu, Cd, Pb, Sb, and Se are present in concentrations higher than expected from these sources. Although the V is probably derived from pollution sources on the North American continent, a comparison of enrichment factors relative to average crustal material for the remainder of these elements over the North Atlantic with enrichment factors for similar samples collected at the geographic South Pole suggests that the anomalously high enrichment factors may be due to natural rather than anthropogenic sources. A vapor phase for these metals may be involved at their source.

Atmospheric vanadium transport to the ocean

Abstract The distribution of atmospheric vanadium in urban and remote marine areas is evaluated. It appears that most of the vanadium present in the northern hemisphere westerlies over the Atlantic and Pacific Oceans is from anthropogenic sources. Several crude models are utilized to calculate the flux of vanadium from the atmosphere to the oceans and it is concluded that approx. 10% of the anthropogenic atmospheric vanadium produced in continental areas is deposited in open ocean regions. Vanadium may serve as a valuable tracer in theoretical and experimental models designed to evaluate transport of atmospheric pollutants to the open ocean areas.

The influence of organic matter and atmospheric deposition on the particulate trace metal concentration of northwest Atlantic surface seawater

Abstract Particulate trace metals (PTM), organic carbon (POC), and organic nitrogen (PON) were measured in a series of surface bucket samples collected between the New England coast of the United States and Bermuda. PTM concentrations were lower or equivalent to the lowest PTM concentrations reported in the literature. Examination of the relative variations in PTM with respect to particulate aluminum and carbon led to the conclusion that organic matter was the probable regulator of PTM abundance in open-ocean surface waters and was important in this respect for continental shelf and slope waters as well. Enrichment factors of trace metals relative to their crustal abundances were found to be similar in the atmosphere sampled in Bermuda and in Sargasso Sea surface water particulate matter. A simplistic vertical flux model was constructed which showed atmospheric input of trace metals to the Sargasso Sea to be of the same approximate magnitude as the rate of removal of PTM from the mixed layer by sinking in association with POC. Essentially all of the particulate Al, Fe, and Mn in the Sargasso Sea mixed layer was attributed to aeolian sources. The fate of other atmospherically derived trace metals in the Sargasso Sea mixed layer was suggested to be a function of their solubility in seawater.

A note on the contamination of atmospheric particulate samples collected from ships

Abstract Collection of atmospheric particulate samples from ships is subject to severe contamination problems. This contamination can arise from direct stack effluents; dirt, paint, rust, etc. from the decks and superstructure carried by local wind eddies around the ship; sea salt from bow spray; and the pump and filter holder used for collection. A collection system for atmospheric particulates has been designed to avoid these contamination problems. Operation of the collector, which consists of a plastic filter holder and protective door mounted on an eight meter high bow tower, is controlled by relative wind direction. Condensation nucleus counts are also monitored at the top of the tower.