The Effcet Of Sand-dust Weather On Air Quality

In recent years, the disastrous influence of sand-dust weather on national economy, ecologyand social life has become a hot issue in China, even in the whole world. With an increasing numberof attentions to sand-dust weather and gradual increment of monitoring ways, the sand-dust weatherresearch has been made in order to prevent the disastrous. At the same time, the classification of thelevel of sand-dust weather and the air quality quantitative researches could clearly andquantitatively not only describe each effect of sand-dust weather processes on air quality, but alsoprovide effective and scientific supports for environmental protection workers who take reasonableand effective mitigation and prevention measures and for the scientific researches on effect,warning and assessment of sand-dust weather on air quality.The establishment of the sand-dust weather environmental grade index system can furtherstrengthen and perfect research of the effects, warning and assessment of environmental quality.Based on the composite index system of the effect of the sand-dust weather on environmentalquality grades division, which includes four grades: the Heavy Dust-covered Pollution, theMarginal Medium Pollution, the Long-Distance Light Pollution and the Long-Distance NoPollution, we analyzed one hundred and thirty-six sand-dust weather processes from2001to2009.The research results showed that the most contribution of effects of the sand-dust weather onambient environmental quality was in November and December, which was mainly a HeavyDust-covered Pollution. The main dust transport path that influenced Beijing was the northwestroute （fifty-nine times）, of which the effect of sand-dust weather on environmental quality （API=170） was divided into the Long-Distance No Pollution. Sand-dust weather processes usually lasttwo days,37.5%of which （API=83） was also divided into the Long-Distance No PollutionDefined the sand-dust quantitative indicators of environmental quality （contribution rates andcontribution）, and with the quantitative indicators, we analyzed the sand-dust contribution to thedust source area and the affected zone of the typical cities. The results showed that the maxcontribution index of the effect of sand-dust weather on the dust source area（Hohhot） and the affectzone（Beijing, Tianjin and Jinan） was in early spring（March）, which was19.21%in Hohhot,15.02%in Beijing,9.41%in Tianjin, and8.69%in Ji’nan. During the spring of2000²009, the effect ofsand-dust weather processes in2009on the Beijing air quality was the most, the average contribution of (PM₁₀) was47μg/m³which accounted for150μg/m³the National Air QualityStandard（Ⅱ）31%. In every March during the year of2000²009, sand-dust contribution to the airquality in2001was the most, which the average contribution concentration was80g/m³. In thespring（March, April, May） during the year of2000²009, the max average contribution of (PM₁₀)was83g/m³in April,2006, which accounted for166%of50μg/m³the National Air QualityStandard（Ⅰ）’s,55%of150μg/m³the National Air Quality Standard（Ⅱ）’s, and33%of250μg/m³the National Air Quality Standard（Ⅲ）’s. The least contribution of the sand-dust weather processesto air quality was in May. The average contribution of (PM₁₀) was47g/m³in May,2001. Also, itwas dominated for the contributions of sand-dust weather to the concentration of particulate matterboth in urban and suburban in Beijing by the factors of weather systems, the transmission paths andnear the source area or affected zone underlying surface etc. In this study, according to theSand-Dust Weather Almanac, in2009sand-dust weather processes occurred ten times in China.(PM₁₀) and （PM2.5） in the spring of2009in Beijing, Tianjin, Baoding, Xianghe and Yangfangwere observed and analyzed on the basis of sand-dust weather process above. And we studied thereasons and effects of the sand-dust weather processes on the air quality. Also, we studied the (PM₁₀),（PM2.5）, and the (PM_2.5(PM₁₀) when the sand-dust weather occurred in Beijing in2009. The results showed that in2009there were ten times sand-dust weather processes in China.Among the ten times sand-dust weather processes, there were seven times sand-dust weatherprocesses in spring this year with the less occurring times and lower intensity than in other years;in the seven-time sand-dust weather processes, Beijing and other cities surrounding Beijing wereinfluenced with less effect on air quality. There were16days while the daily average (PM₁₀) ismuch higher than250g/m³the National Air Quality Standards （Ⅲ）. And there were three quartersdays in2009, while the daily average (PM₁₀) is much more lower than150g/m³the National AirQuality Standards （Ⅱ）. However, in some sand-dust weather processes, the daily average (PM₁₀)is lower than50μg/m³, which made the air quality good; In2009, there were only three sand-dustdays occurring in Beijing,. At the same time, because of the less effect of sand-dust weather onBeijing air quality, the concentrations of dust particle is0.034times than that of PM₁₀in2009. And0.115times in2000,0.127times in2001,0.054times in2004and0.042times in2005. But in2003,it is0.07times.