Study On Acid Buffering Capacity Of PM₁₀ In Jinan City

The total emission of SO2 in North of China is higher than that in South, while acid rain pollution in North is lower. That's because the acid buffering capacity of atmospheric PM(particulate matter) has an important influence on PH value about precipitation. It may cause the formation of acid rain, as also as neutralize acidity of precipitation. Researches on the acid buffering capacity of atmospheric particulate matter have been carried out in some cities of China, but most of them are short-term study. As an important north city, Jinan has severe particles pollution, and the primary pollutant in environmental atmosphere is PM10, however,there is still no report about any research on acid buffering capacity of atmospheric particles in Jinan.With Jinan city as the research region, author collected.filter samples of PM10 in environmental atmosphere for every seven days at middle of the month (March 2009-Feb 2010) on top floor of Technological Building(30m) in ShanDong JianZhu University. In this article, acid buffering capacity of PM10(ΔCb) in Jinan was analyzed. Influence factors were determined mainly by ions chromatography(SO42-, NO3-, CL-, etc) atomic absorption method and spectrophotometric method(K+,Na+,Ca2+,Mg2+,NH4+, etc). Combining data of Jinan inhalable particles(PM10) in recent years and analysis on research data about acid buffering capacity of atmospheric particulate matter at home and abroad, we come to specific experiment conclusion as follows:(1)ΔCb determined at the observation point is not high, annual average acidity and acid-buffering capacity of PM10 are 0.041neq/m3 and -35.80neq/m3, which has seasonal features to some extent:PM10 acid buffering capacity in winter is the lowest (-97.25 neq/m3),then autumn(-33.98 neq/m3), summer(-9.88 neq/m3) and spring(-2.09 neq/m3) one by one; PM10 acidity is the highest in spring, then winter, summer and autumn one by one. Overall speaking, PM10 around the observation points can't neutralize the acid in the atmosphere. Conversely, it increases the acidity of precipitation.PM10 pollution in the air(2009.3-2010.2) is heavier in autumn and winter, while lighter in spring and summer. Mass concentration and acid buffering capacity of PM10 in spring and summer (March to August) had positive correlation, while they had negative correlation in autumn and winter (September to next February). It showed thatΔCb of PM10 related not only with PM mass concentration, but also with its own compounds.(2) By comparing the acid buffering capacity data of PM10 monitored synchronously at Shandong Jianzhu University and Jinan city center in July 2009, we found that concentrations and acid buffering capacity of PM10 were higher at Shandong Jianzhu University than in the city center, but the differences were subtle. PM acidity at Shandong Jianzhu University is 0.33 to 0.91 times as high as in the city center. Comparing with researches in other cities and regions at home and abroad, the annual average acid-buffering capacity of PM10 in Jinan is relatively low.(3) By analyzing interrelation between different influence factor, we hold that the main factors of acid buffering capacity were NH4+, SO42-, NO3-, Ca2+, Mg2+ and so on.As acid buffering capacity of PM10 changing, mass concentrations of SO42- changed as follow:spring construction dust (0.059 neq/m3)> soil dust (0.053neq/m3)> coal dust (0.036 neq/m3)> road dust (0.033neq/m3). Viewed from the angle of raising PM acid buffering capacity, while we control fugitive dust emission, the acid gas sulfur dioxide and nitric oxide shuold be controlled too, otherwise it will cause further deterioration of acidic pollution.By analyzing influence of different fators to buffering capacity, we conclused that the carrying capacity for acid gas of PM10 in Jinan is low at this stage. The conclusion can provide data and technical support for futher comprehensive research of acid buffering capacity of PM10 in Jinan city in the future.