天气因素对道路灰尘铂族元素累积的影响

以新疆昌吉市为研究区,探讨了天气因素对道路灰尘铂族元素(PGEs)累积的影响及其作用机制.样品经王水消解后由ICP-MS测定.结果表明,径流冲刷与风力是道路灰尘中PGEs迁移转化的主要外力,而降水量与气温是城市道路形成径流的主要影响因素,干旱区降水稀少,更利于灰尘PGEs的累积.各类天气因素对道路灰尘PGEs含量的影响具体表现为:降水量小(12h降水量5mm),且气温高于0℃以上时的降雪(包含雨夹雪)后PGEs含量下降;气温低于0℃时,无论降雪量大小,雪后PGEs含量下降.单场次小雨(12h降雨量5mm)后PGEs含量下降;连续性小雨(12h降雨量<5mm)后PGEs含量上升,其累积达到上限,若继续降小雨,其含量不再升高反而呈缓慢下降趋势.4级以上大风天气后PGEs含量明显下降.

Influences of weather on PGEs accumulation in road dust

In order to study the characteristics and its mechanism of PGEs acculation in road dusts from different types weather, Changji city was elccted as an example, and samples of road dust were collected and determined by ICP-MS after aqua regia digestion. The results showed that runoff souring and wind strength were the primary external forces, which affected PGEs transport and transfer, while the rainfall and temperature primarily affected the formation of runoff in urban city, poor rainfall in arid area was more beneficial for accumulation of PGEs. Influences of various weather situations on PGEs content in road dust were as follows: the PGEs content increased after small rainfall (12hours rainfall5mm); but always decreased after snowfall, no matter how big, when the temperature was lower than 0℃. After single small rain, single moderate and bigger rain(12hours rainfall>5mm), and continuous small rain, the PGEs contents increased, decreased, and increased respectively, however, when the accumulation achieved top limit, there was no increasing but slow and steady decreasing tendency in continuous small rain. After a wind force 4, the PGEs content decreased significantly.