季节变化对贵阳市不同功能区地表灰尘重金属的影响

为揭示季节变化对城市不同功能区地表灰尘重金属含量的影响,分别于2010年7月和2011年2月在贵阳市城区采集对应灰尘样品,从整个城区和不同功能区两个尺度分析季节变化对地表灰尘重金属分布的影响.结果表明,季节变化对贵阳市地表灰尘重金属含量影响最大的元素是Pb和As;冬季灰尘中的As和Pb含量显著高于夏季,元素更易在细粒级灰尘中富集;受季节变化影响较大的功能区是城市广场和校园,其次是住宅区.夏-冬两季地表灰尘重金属粒级效应差异最大的元素是As和Pb,差异较大的功能区是城市广场、校园,最小的是商贸区.铅同位素比值分析表明贵阳市地表灰尘Pb与柴油尾气尘、油漆碎片和土壤有关.夏季降雨、冬季燃煤和夏冬两季温差等因素可能对贵阳市地表灰尘As和Pb含量季节变化有一定影响.

Influence of Season Change on the Level of Heavy Metals in Outdoor Settled Dusts in Different Functional Areas of Guiyang City

To study the influence of season change on the level of heavy metal in outdoor settled dusts at both city and functional area scale, dust samples were collected in July 2010 and February 2011 from different functional areas in the Guiyang City. The results showed that among all heavy metal elements involved, Pb and As were most significantly affected by season change, with a significantly higher amount in winter than in summer, mostly accumulated in smaller particles of dust. Functional areas where heavy metal concentrations were most significantly affected by seasons were city square and school area, and followed by residential area. Elements that showed the greatest difference in distribution pattern in different fractions between summer and winter were As and Pb, while the functional areas that were most severely influenced were city square and school area,followed by residential area. The isotopic ratio analysis showed that the Pb in the outdoor settled dust in Guiyang was partly contributed by Diesel exhaust dust, paint chip and soil. Summer precipitation, coal-burning in winter and temperature difference between summer and winter may contribute to the seasonal change of the level of Pb and As in the dusts.