Size distributions of atmospheric trace elements at Dye 3, Greenland, II : sources and transport

Airborne concentrations and size distributions of 15 elements over the Greenland Ice Sheet have been measured during a one-month period in March 1989. The concentrations are relatively uniform, varying by less than a factor of three for virtually all of the elements. Notable exceptions are Na and Cl which vary by more than an order of magnitude; these differences can probably be accounted for by the link with transport from the oceans surrounding Greenland, although a significant fraction of the Na is of crustal origin in some samples. The size distributions show strong peaks in the accumulation mode(0.4-1.0 mu m) or the coarse particle mode (1.0-2.5 mu m); some species show bimodal distributions with the presence of both modes. The aerosol chemistry and size distribution data are consistent with back trajectories and local weather conditions. For example, relatively high concentrations of Pb, Zn, Ni, Fe, and Mn in the accumulation mode during one of the runs are associated with trajectories from industrial regions of the Soviet Arctic. The elements Si, Al, Fe, K, Ca, Mn, and Ti in the coarse mode are believed to be dominated by crustal sources. However, some runs show the presence of an accumulation mode for most of these elements (with the exception of Al), suggestive of combustion sources. Overall, the results show that use of an impactor with several submicron size cuts combined with a suitable data inversion program can provide insights into the sources and transport of aerosols at remote locations such as the Greenland Ice Sheet

Seasonal variation of PM10 main constituents in two valleys of the French Alps, I : EC/OC fractions

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Size-fractionated aerosol composition during an intensive 1997 summer field campaign in northern Finland

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Identification des sources d’émission des polluants organiques persistants dans les vallées alpines par l’utilisation de nouveau traceurs

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Detailed mass size distributions of particulate trace elements at Summit, Greenland

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Concentrations and mass size distributions of paniculate trace elements at Summit, Greenland : impact of boreal forest fires

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Size distributions of atmospheric trace elements at Dye 3, Greenland, I : distribution characteristics and dry deposition velocities

Cascade impactor samples were collected at Dye 3 on the south-central Greenland Ice Sheet during March 1989. The impactor was calibrated in the laboratory, and the resulting collection efficiency curves were used to derive the impactor response for use in a data inversion procedure. The impactor samples were chemically analysed by proton-induced X-ray emission (PIXE), and the chemical concentration data were used with the inversion procedure to generate smooth size distributions for 15 elements. Results show three distinct size distribution categories. The first category includes elements that mainly originate from gas to particle conversion, with a substantial fraction-from anthropogenic combustion (S, Pb, Zn, Br and Ni). These elements exhibit a unimodal size distribution with geometric mean aerodynamic diameter close to 0.6 mu m, although S and in shaw a weak second mode centered at about 2 mu m. Elements in the second category (Ti, Si, Fe, Mn, Ca, K) exhibit bimodal size distributions, with geometric mean diameters for the two modes of 0.6 and 2 mu m, respectively. These elements result from a variety of sources, including crustal erosion as well as combustion from natural and anthropopenic sources. For elements in the third category (Al, Cl, Na, Mg), most of the mass occurs in particle sizes above 1 mu m. Their size distribution is generally unimodal, with the geometric mean aerodynamic diameter around 2 mu m. These elements are most likely to be of crustal and/or marine origin. The best-fit size distributions were used with curves of dry deposition velocity vs aerodynamic particle diameter to estimate the overall dry deposition velocity expected from the entire distribution. The deposition velocities for S, Pb, Zn, Br and Ni are all very low, with values less than about 0.02 cm s(-1) if hygroscopic growth in the humid layer is neglected. For those other elements, deposition velocities are in the range 0.2-0.7 cm s(-1). For those distributions that are bimodal, the upper mode generally dominates deposition even when most of he airborne mass is associated with the lower modes, as in the case of S and Zn