U. Tomza

Mass‐particle size distributions of atmospheric dust and the dry deposition of dust to the remote ocean

Size-separated mineral aerosol samples were collected and analyzed to investigate the relationships between the mass-particle size distributions (MSDs) of dust particles and the dust loadings in the atmosphere. The data also were used to assess the changes in the MSDs of dust in relation to transport processes and especially the associated effects on dry deposition. Atmospheric dust concentrations, as indicated by aluminum or scandium, in samples collected from three sites in the remote North Atlantic were higher than those in samples collected during a cruise in the North Pacific on board the R/V Moana Wave. However, the mass median diameters (MMDs) for the North Pacific samples were both larger on average (∼3 μm versus ∼2 μm aerodynamic equivalent diameter) and more variable than those from the North Atlantic; this difference was attributed to wet conditions and particle aggregation over the North Pacific. In addition, for the ensemble of all samples the geometric standard deviations of the mass-particle size distributions, which are analogous to the sorting values used to characterize sedimentary materials, tended to vary inversely and nonlinearly with the mass median diameters. Model-derived dry deposition velocities for the samples were at most weakly related to either the dust concentrations or the MMDs. However, the dry deposition velocities for two subsets of samples were correlated with the geometric standard deviations of the distributions; this is further evidence that the mass flux of dust via dry deposition can be controlled by a relatively small fraction of aerodynamically large particles.

Long-range transport of trace elements to Ny Ålesund, Spitsbergen

Abstract Atmospheric concentrations of ten trace elements (i.e. As, Cd, Cr, Mn, Ni, Pb, Sb, Se, V and Zn) were measured at Ny Alesund, Spitsbergen, during March–April 1983, and compared with those calculated using a simple receptor-oriented Lagrangian transport model and estimated emissions of the elements from various source regions inside the U.S.S.R. Very good agreement between the measured and calculated concentrations was obtained for Sb, suggesting that its emissions are accurately assessed. Fair agreement was observed for cadmium and manganese, but the atmospheric concentrations of the other elements are not fully accounted for. The major reasons for the differences between measurements and estimates are the following: incomplete emission inventory, improperly assumed dry deposition velocities, disregard of wet deposition processes, improperly assumed local deposition values, inaccuracies in the analytical procedures, uncertainties in mixing depth, and inaccuracies in trajectory calculations. In future work, seasonal variations between winter and summer concentrations should be investigated, as the differences in meteorological conditions will affect the long-range transport of pollutants.

Comparisons of trace constituents from ground stations and the DC‐8 aircraft during PEM‐West B

Chemical data from ground stations in Asia and the North Pacific are compared with data from the DC-8 aircraft collected during the Pacific Exploratory Measurements in the Western Pacific Ocean (PEM-West B) mission. Ground station sampling took place on Hong Kong, Taiwan, Okinawa, and Cheju; and at three Pacific islands, Shemya, Midway, and Oahu. Aircraft samples were collected during 19 flights, most over the western North Pacific. Aluminum was used as an indicator of mineral aerosol, and even though the aircraft did sample Asian dust, strong dust storms were not encountered. The frequency distribution for non-sea-salt sulfate (nss SO4=) in the aircraft samples was bimodal: the higher concentration mode (∼1 μg m−3) evidently originated from pollution or, less likely, from volcanic sources, while the lower mode, with a peak at 0.040 μg m−3, probably was a product of biogenic emissions. In addition, the concentrations of aerosol sulfate varied strongly in the vertical: arithmetic mean SO4= concentrations above 5000 m ( x- = 0.21±0.69 μg m−3) were substantially lower than those below ( x- = 1.07±0.87 μg m−3), suggesting the predominance of the surface sources. Several samples collected in the stratosphere exhibited elevated SO4=, however, probably as a result of emissions from Mount Pinatubo. During some boundary layer legs on the DC-8, the concentrations of CO and O3 were comparable to those of clean marine air, but during other legs, several chemically distinct air masses were sampled, including polluted air in which O3 was photochemically produced. In general, the continental outflow sampled from the aircraft was substantially diluted with respect to what was observed at the ground stations. Higher concentrations of aerosol species, O3, and CO at the Hong Kong ground station relative to the aircraft suggest that much of the continental outflow from southeastern Asia occurs in the lower troposphere, and extensive long-range transport out of this part of Asia is not expected. In comparison, materials emitted farther to the north apparently are more susceptible to long-range transport.

Color-related differences in the chemical composition of aerosol-laden filters

We examined color-related differences in the chemical composition of ∼6000 aerosol filters collected from 1989 to 1997 at three sampling sites in the North Atlantic Ocean (Barbados, Bermuda, and Izana) operated for the Atmosphere/Ocean Chemistry Experiment (AEROCE). The concentrations of the trace elements (Al, Br, Ca, Cl, Fe, Na, Sb, Sc, Se, V) and two ions, NO3− and SO42−; the activities of 210Pb and 7Be; and the mixing ratios of ozone were compared and contrasted for groups of samples and data matched to the three basic colors of aerosol filters (brown, gray or white). Chemical composition is related to filter color, that is, the brown and gray samples correspond to mineral dust and absorbing aerosol from various pollution sources, respectively, although these substances often are mixed in varying proportions. The white filters are best regarded as indicating the absence or low concentrations of dust or other absorbing aerosols, and they are often indicative of clean marine air. Relationships among atmospheric substances differ significantly in the color-stratified data subsets, and grouping the samples by color provides unique insight into the relationships among mineral dust, pollution aerosol, and other substances over the North Atlantic.

Trace elements in head hair of hemodialysis patients

Instrumental neutron activation analysis /INAA/ was applied to measure trace elements in head hair of 19 patients with impaired renal function /14 males and 5 females/ and of 40 normal individuals /20 males and 20 females/. It was the aim to use head hair as a possible indicator of total body trace elements status and to investigate whether significant changes occur as a result of chronic hemodialysis. The elemental concentrations of 20 elements /i.e. Na, Mg, Al, Cl, K, Ca, V, Mn, Fe, Co, Cu, Zn, As, Se, Br, Ag, Cd, Sb, I and Au/ are presented and compared with published data. The present study revealed that the hair of the dialysis patients contained about ten times more iodine than that of the control group. No significant differences were observed for the other elements measured, except for sodium and antimony.