Runoff water samples were taken at the St. Rombout's Cathedral (Mechelen, Belgium), which was constructed with sandy limestones of Balegem and Gobertingen. Gypsum appeared to be the principal deterioration compound. The mean annual surface recession from the cathedral was calculated to be around 20 μm. Yearly several tons of stone material are flushed away from the cathedral with the rain water.
Aircraft sampling of atmospheric particulate matter often implies small mass collection for subsequent analysis, especially when free tropospheric samples are considered. We present here results of the use of an X-ray fluorescence instrument, specifically designed for small-mass samples, in the determination of free tropospheric and boundary layer elemental concentrations. Based on 1- to 2-h-long samples, ng m−3 ambient air concentrations of Ti, Cr, Mn, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, Mo, Cd and Pb may be determined with uncertainties of 5–15% in polluted and even some rural boundary layer samples. In free tropospheric and remote boundary layer samples, concentrations may be determined for many of these elements but with larger uncertainties.
The concentrations of two classes of chlorinated pesticides were measured in various locations within four homes. The prevalent compounds were chlorinated derivatives of cyclopentadiene which had been used as termiticides. These compounds were found in basement areas at higher concentrations than in upstairs areas of the homes. Another class of chlorinated pesticide was represented by chlorpyrifos; its spatial profile was consistent with its application in upstairs areas.
In order to examine possible natural as well as anthropogenic aerosol ionic components in the Arctic troposphere, we have measured the concentrations of 12 organic and inorganic ions in late winter Arctic aerosols at Barrow, Alaska, sampled as separated coarse and fine fractions. Inorganic ion concentrations are similar to previous data reported from the Arctic. The organic anion methanesulfonate (MSA), in total coarse + fine, averages 0.12 ± 0.02 nmol m−3. High levels of formate (Fo −) and acetate (Ac−) and traces of propionate (Pp−) and pyruvate (Py−) are found, which altogether account for 20% of the total aerosol mass. Total concentrations, as mean ± S.E. nmol m−3, are (Fo−) 5.3± 0.7, (Ac−) 12.4 ± 2.2, (Pp−) 0.3±0.1, and (Py−) 0.1 ± 0.04. Internal relationships among the carboxylic acid anions suggest emissions from natural vegetation. Lacking local sources during winter, these organic anions are likely to have come from lower latitudes as acid vapors that condensed with gaseous NH3 into aerosols in the cold Arctic.
Four aerosol types, evidenced by seven principal components in the coarse and fine aerosol fractions of 69 12-h samples, are found by absolute principal component analysis (APCA). The most prominent type is a contaminated sea salt, apparently transported to the Arctic after scavenging combustion products. The second contains carboxylic acid anions, such as could have resulted from co-condensation with NH3 of organic acid vapors from natural sources at lower latitudes. The third is a marine aerosol component containing most of the MSA, Br− and NO−3, as well as small amounts of carboxylic acid anions and some sea salt, and may be a collection of products from gas phase oxidation of precursors. Finally, a fine non-sea salt sulfate (nssSO2−4) component is found that may have come from SO2 conversion in air. Most components have good charge balance of the measured ions as indicated by anion/cation ratios near unity. The ratios reflect approximate acid-base neutralization in the components and indicate aged aerosol systems with long atmospheric residence times.
Viewing similar components in coarse and fine fractions together, about 10% of the carboxylic acid anions are associated with pollutants in aerosol type 1. Type 2 accounts for 80% of Fo−and 60% of Ac−. Type 3 accounts for 18% of Fo− and 10% of Ac−. Thus, the carboxylic acid anions appear to be mostly natural, with more than 90% of Fo− and 70% of Ac− in types 2 and 3. In coarse aerosols viewed separately, 67% of nssSO2−4 is in the contaminated sea salt. In fine aerosols, 52% of nssSO2−4 is in a separate SO2−4 component which may be forme
A numerical model is presented that considers the micro-physics and chemistry of cloud condensation nuclei (CCN) as the nuclei are transported vertically from the base of a cloud. The CCN are initially composed of mixtures of (NH4)2SO4, H2SO4 and H2O and are in equilibrium with gaseous SO2 and NH3 concentrations. The model incorporates liquid phase oxidation of S(IV) to S(VI) during adiabatic lifting of the CCN. Simultaneous absorption of SO2 and NH3 between the cloud droplets and gaseous dispersion medium is also considered. The model also evaluates whether the droplets are in chemical equilibrium with respect to gaseous SO2 and NH3 concentrations. Results from the model indicate that oxidation of S(IV) increases cloud droplet acidity during activation of the CCN. Large cloud droplets also exhibit gas phase mass transfer limitations with respect to SO2 and NH3. pH values of the resulting cloud droplet size distribution range over 3 pH units within the cloud at typical atmospheric conditions.
From late February to mid April 1985 pressurized air samples were collected 3 times per week on weathership M in the North Atlantic and in Ny-Ålesund on Svalbard. The samples were analyzed for individual light hydrocarbons C2-C6, and it was found that the average sum of C2-C6 hydrocarbons was about 35 ppbC in Ny-Ålesund and 31 ppbC on ship M, with the least reactive species ethane and propane as the most abundant ones.
Samples from three snowpits near Dye 3 in South Greenland have been used to study seasonal variations in contaminant transport from the atmosphere to the Ice Sheet. The snowpits cover the years 1982–1987. The samples have been dated by comparing δ18O values with meteorological data from Dye 3. Airborne concentrations of SO2−4 over the Ice Sheet have been estimated for the dates corresponding to each snowpit sample by statistically analyzing data from several air monitoring stations throughout the Arctic, and computing average values from the appropriate stations. Seasonal variations in concentrations in air, concentrations in snow, and mass-basis scavenging ratios (concentration in snow divided by concentration in air) have been identified. Results indicate that concentrations of SO2−4in the air show a strong peak in late February, resulting from long-range transport of mid-latitude anthropogenic emissions, while those in the snow show a broad peak in January, February and March with smaller seasonal variation overall. The smaller variation in the snow is attributed in part to the effect of riming, which results in more efficient scavenging during warm weather when airborne concentrations are low. The importance of riming is also supported by the annual cycle in scavenging ratio which peaks in mid-summer coincident with maximum temperatures. In agreement with previous estimates, dry deposition appears to account for 10–30% of the total SO2−4 in the snow. Concentrations of NO−3 in the snow show a strong peak in summer; natural material from the stratosphere as well as anthropogenic emissions transported from the mid-latitudes may be responsible. Concentrations of Cl− in the snow are maximum in January, with relatively high concentrations during October through March and a smaller peak in July. The winter peak is believed to reflect long-range transport (LRT) of marine aerosol from north Atlantic storms, while the summer peak is attributed to seaspray from nearby coastal Greenland. Riming also may influence the seasonal variations in NO−3 and Cl− in the snow.
Research on Arctic haze has provided an example when anticyclones may play a dominant role in carrying out low-level tropospheric long-range transport. This dominant role of anticyclones in transporting Arctic haze may be the result of the unique geographic and climatological situation existing during winter/spring in which both the huge Eurasian continent and the adjacent ice-covered Arctic Ocean tend to be regions where anticyclones form and exist over long periods of the winter and spring seasons. It is assumed that the seasonal variation of transport mechanisms provided by anticyclones is the primary cause for the seasonal variation of Arctic haze. Centers of anticyclones are the regions where air masses form and obtain their characteristics, both meteorological and chemical, due to the aerosols and gases released into the air. Transport within an air flow along the edges of quasi-stationary anticyclones will remain under stable atmospheric conditions, hence, dilution, lifting and removal of aerosols and gases will be less compared to a transport within the influence of a cyclonic pressure system. According to the concept of isentropic flow, anticyclones may dominate only low-level transport, whereas cyclones may be more important in controlling transport at upper tropospheric levels.
Pollution control generally is moving from the specific to the general, from the local to the international, from reactive measures to foresight management, from emission based to technology forced, and from single media managed to integrated. These are trends only, but there is a persistence behind these trends. This suggests that air pollution legislation and regulation will be driven more by international protocols and commitments than by national interests. Since enforcement will remain primarily a national responsibility because individual countries vary in their enthusiasm to meet externally imposed air pollution legislation, the weak link in the regulatory chain may well prove to be practical implementation of legislative intent.
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