临安本底站2010～2015年PM_(10)污染特征及影响因素分析

Variation characteristics of PM_(10) and its influencing factors at Lin'an regional background station in Yangtze River Delta region during 2010～2015

利用长江三角洲区域代表性站点临安区域大气本底站2010~2015年的PM_(10)质量浓度和各气象要素资料,分析了PM_(10)质量浓度的变化特征及其影响因素.结果表明:与《环境空气质量标准》(GB3096-2012)二级标准相比,2010~2015年PM_(10)质量浓度达标率为96.17%;日变化中峰值出现在09:00和20:00,低值出现在06:00和13:00,并表现出周末比平时高的"周末效应";月份和季度的变化为7月最低、1月最高,夏季最低、冬季最高,与能见度呈明显负相关关系;年均值从2010年的79μg/m^3到2015年的56μg/m^3,总体呈下降趋势,并在全国范围内处于中间水平.相对湿度、日降水量和气压与PM_(10)质量浓度有更好的相关性,风速越大对PM_(10)质量浓度影响越大.气团后向轨迹聚类分析和潜在源贡献解析结果表明,临安本底站在2010~2015年不同季节中,春季、秋季和冬季的气团大部分来自西北和北方,夏季更多的是来自东部海洋和沿海地带,而不同年份里,每年的气团轨迹均以北方居多,其次是南方和东部海洋.总体分析得出,2010~2015年临安本底站的气团主要来自安徽、浙江、江苏、广东、福建和北方地区,并且PM_(10)高值主要来源于安徽、江苏、上海和浙江等长三角附近区域.

PM10mass concentration variations in the Yangtze River Delta Region and the causes were investigated,using measurement of PM10mass concentration and meteorology during2010~2015at the regional representative Lin’an Regional Atmosphere Background Station.The results show that PM10mass concentration met the Grade2Standard specified in the Ambient Air Quality Standards(GB3096-2012)for96.17%during2010~2015.Diurnal PM10mass concentration showed the maximum value at09:00and20:00,minimum at06:00and13:00,and it also presented a“weekend effect”with higher value on weekend than on weekdays.Monthly variation showed the lowest PM10mass concentration in July in summer and the highest in January,which negatively correlated with visibility.Annual average of PM10mass concentration at Lin’an decreased from79μg/m3to56μg/m3from2010to2015,which is a moderate concentration level in China.PM10mass concentration correlated well with relative humidity,daily precipitation and local air pressure.Stronger wind also had greater impact on PM10mass concentration.Back-trajectories and cluster analysis reveal that prevailing air masses were from the northwest and the north in spring,autumn,and winter,and from the sea and the coastal areas in the east in summer.Throughout the years,the dominant air masses were from the north,followed by southerly and east marine air masses.It is concluded that the majority air mass at Lin’an arrived from Anhui,Zhejiang,Jiangsu,Guangdong,Fujian and the north region.Potential source contribution function(PSCF)results suggest that PM10pollution may mainly originate from the areas around the Yangtze River Delta region,including Shanghai,Anhui,Jiangsu and Zhejiang Provinces.