Summertime aerosol chemical components in the marine boundary layer of the Arctic Ocean

Abstract

[1] Samples of aerosols from the marine boundary layer of the Arctic Ocean were collected aboard the R/V Xuelong during summer on the Second Chinese Arctic Research Expedition (July-September 2003). Synchrotron radiation X-ray fluorescence (SR-XRF) was used to determine chemical compositions of aerosol particles. Multivariate analysis of the SR-XRF data resolved a number of components (factors), which, on the basis of their chemical compositions and from their affiliation with specific meteorological flow patterns, were assigned physical meanings. Five factors explaining 94.7% of the total variance were identified. Ship emissions accounted for 35.3% of the variance (factor 1 (F1)) and are loaded significantly with S, Fe, V, and Ni. The total Fe emitted from ships globally was estimated at 8.60 Â 10 6 kg yr À1 . Heavy-metal-rich factors included 34.0% of the variance (F2 and F3) and were interpreted to be pollution carried into the Arctic Ocean by long-range transport. Anthropogenic contributions from industrial regions to the Arctic Ocean during the summer vary and depend on the source locations. Air mass backward trajectories indicate that the metals including Hg, Pb, Cu, and Zn come mainly from northern Russia. The third source controlling the chemical compositions of aerosols was sea salt (F4, 12.8%). The role of sea salt decreased from the open sea to areas near pack ice. On the basis of the factor scores of aerosol samples, we infer that chlorine volatilization from sea salt may occur, enhanced by nitrogen and sulfur contamination emitted from ships. Because the global inventories of nitrogen and sulfur for ship exhausts are large, and halogens could have important consequences in possible tropospheric ozone destruction, the role of ships in influencing halogen depression in sea salt should be further investigated. Finally, we also identified a crustal factor (F5, 12.6%) and suggest that crustal elements (e.g., Ca) contaminating sea ice may become reinjected into the atmosphere as windblown aerosols.

Summertime carbonaceous aerosols collected in the marine boundary layer of the Arctic Ocean

“…are EPR silent. The relative levels of iron in each sample, which were obtained by synchrotron radiation X‐ray fluorescence [ Xie et al , 2006], are also listed in Table 1. The narrow sharp singlet line (shown with an arrow on Figure 6) corresponds to the BC.…”

“…The other nine samples have relatively higher intensities with a maximum value at 762. The relation between the extent of impact of ship emissions (represented by the F1 factor score determined from inorganic chemical analyses of the filters by Xie et al, 2006) and the level of BC is shown in Figure 7. This result clearly suggests that the occurrence of BC is significantly correlated with ship emissions except for one outlier and the six samples that are below detection limits.…”

“…This result clearly suggests that the occurrence of BC is significantly correlated with ship emissions except for one outlier and the six samples that are below detection limits. In a previous report [ Xie et al , 2006], we documented the wind directions and speeds during each of the sampling periods and evaluated the relationship between the frequency of relative wind directions and potential contamination by emission directly from the Xuelong research vessel. The lack of correlation between the F1 factor (derived from ship emissions) and the frequency of relative wind directions [ Xie et al , 2006] suggested that there was no significant contamination from the research vessel and that instead the F1 chemical constituents and the BC were derived from the regional effect of ship emissions.…”

“…Other recent studies have also measured PAHs and/or soot in airborne particulate matter using cellulose filters [ Crimmins et al , 2004; Ochsenkuhn‐Petropoulou et al , 2003]. The same samples selected for SR‐XRF measurement [ Xie et al , 2006] were also selected for analysis in this study; the sample locations are shown in Figure 1. One snow sample collected near Barrow, Alaska, in March 2005 was used for a comparative analysis.…”

Arctic Air Pollution: Origins and Impacts

“…For example, increased areas of open ocean could lead to increases in natural dimethyl sulfide emissions and production of sulfate aerosols (51), whereas emissions of halogens and NO x from the ice and snow could be reduced. There is evidence that ship traffic is already affecting the summertime Arctic atmosphere, with strong signatures seen in marine aerosols (52). Increased deposition of soot from increased shipping after the reduction of summertime sea ice could further accelerate sea-ice melting.…”