Aerosol and air pollution size distribution

The size distribution of aerosols was measured in a moderately industrial city, in a semi-arid zone on the Negev desert border. The aerosols in the city of Beer Sheva are from two sources: the dust coming from the desert and urban pollution. The size measurements were done with a cascade impactor. The elemental content of the aerosols was investigated by neutron activation analysis and X-ray fluorescence. The main elements of the dust are: Ca, Si, Fe, Na and the trace elements are: Sc, Se, La, Sm, Hf and others. The main elements of the urban pollution are S, Br, Pb, Cl, Hg and others. It was found that the elements belonging to each group can easily be classified by the size distribution. The analytical consideration of the aerosol size distribution of each group are discussed and two corresponding analytical expressions are suggested. It is shown that aerosols originating in the dust have a hump shape distribution around ~ 4μm, and those originating in urban pollution have a distribution decreasing with increasing aerosol diameter. Many examples are given to prove the conclusions.     

Planetary-wave behavior and Arctic air pollution

An attempt has been made to relate episodes of air pollution at Barrow, Alaska, containing vanadium, to the behavior of planetary waves in middle and high latitudes. A stationarity index for planetary waves is defined as the ratio between amplitudes computed from monthly mean maps and the mean amplitudes computed on a daily basis and averaged over the same month, irrespective of phase angle. Longitude-time sections of 500 mb height anomalies at various latitudes are related to vanadium pollution episodes at Barrow.     

Self-organized criticality of air pollution

In this work, we investigate the frequency-size distribution of three pollution indexes (PM₁₀, NO₂ and SO₂) in Shanghai. They are well approximated by power-law distributions, which suggest that air pollution might be a manifestation of self-organized criticality. We introduce a new numerical sandpile model with decay coefficient to reveal inherent dynamic mechanism of air pollution. Only changing the number value of decay coefficient of pollutants, this model gives a good simulation of three pollutants' statistical characteristic. This work shows that it is the self-organized criticality of the air pollutants that results in the temporal variation of air pollutant indexes and the minor air pollution sources can trigger the occurrence of large pollutant events by SOC behavior.     

空气污染暴露评价研究进展

介绍了暴露及暴露评价的基本概念、人体空气污染暴露评价的指示物及其特征,讨论暴露评价方法的类型,对各种方法的优、缺点进行了比较分析。根据综述和案例分析情况,对空气污染暴露评价研究的发展趋势进行了展望。     

Assessment of air pollution impact

Several essential steps of air quality assessment are described, including identification, prediction, and evaluation of critical variables and potential changes of air quality. A coal-reconversion power plant in New York was selected as an example to illustrate the assessment.     

Fast-response measurements of air pollution

Concentrations of sulphur and phosphorus compounds in the atmosphere were measured up to 50 times per second, with flame-photometric apparatus developed for the purpose, at distances of 4–4800 m from the source. Rates of change and autocorrelograms were determined, from which the distance of a point source can be estimated without knowledge of the source strength.     

Marble weathering and air pollution in Philadelphia

Maps of damage to marble tombstones in the urban region of Philadelphia demonstrate a close spatial correspondence with airborne pollutant concentrations. Mean recession rates on upper tombstone faces are an order of magnitude greater (3.5 mm (100a)⁻¹) in the center of the city than they are 20 km away in the suburbs and countryside (< 0.5 mm (100a)⁻¹). Not only are more pollutants emitted in the city, but they are also concentrated in the city center by centripetal air movement into the urban heat island. Gaseous SO₂ appears to be the most damaging pollutant, as is shown by the presence of gypsum in urban stones. Although rainfall is important in removing sulfate reaction products, anthropogenically-induced acid rain has only a minor role in marble deterioration. High urban SO₂ concentrations cause sufficient gypsum accumulation within the stones to exfoliate the durable surface layer. Old photos of tombstones in central Philadelphia cemeteries show that exfoliation greatly accelerated between 1930 and 1960, concurrent with increases in SO₂ levels. Recent improvements in air quality are likely to have slowed stone deterioration.