上海市不同类型道路灰尘铂族元素（PGEs）空间分布特征

车辆行驶特征对PGEs排放影响很大,而不同类型道路,其车辆行驶特征会有很大差别。基于此,对上海市5条不同类型的道路进行灰尘PGEs空间分布规律的探讨。灰尘样品用王水消解制样,ICP-MS测定。结果表明：道路灰尘Rh、Pd、Pt的平均含量在主干道为24.50、96.40、29.04 ng·g-1,次干道为23.18、76.92、37.21 ng·g-1,快速路为41.73、188.05、57.21 ng·g-1,郊区高速公路为13.35、63.34、18.01 ng·g-1,郊区公路为7.49、22.76、0.97 ng·g-1,除次干道Pt含量高于主干道外,5种类型道路的PGEs含量均表现为：快速路﹥主干道﹥次干道﹥郊区高速公路﹥郊区公路,郊区高速公路及郊区公路虽然车流量大,但PGEs含量并不高,车流中许多车辆因未安装VECs而不排放PGEs是主要原因。如以1.5-1.6 km道路（两端为路口）为长度单位,主干道、次干道及快速路灰尘PGEs的分布呈波浪型;郊区公路灰尘PGEs的分布呈半圆弧型;郊区高速公路（仅有一端为收费口）灰尘PGEs分布呈先高后低再趋于平稳的折线型,车辆行驶特征的差异是造成不同类型道路灰尘PGEs分布模式差异的主要原因。郊区高速公路及郊区公路的路口（或收费口）,PGEs含量往往很高;而主干道、次干道及快速路的路口,PGEs含量不一定很高,频繁的怠速和加减速使得上述三种道路远离路口的地方也常出现怠速是主要原因。

Distribution characteristics of PGEs in dust from different type roads

In order to study distribution characteristics of PGEs in dusts from different type roads,samples of road dusts were collected from five roads in Shanghai and analyzed by ICP-MS following aqua regia digestion.The results show that average concentrations of Rh,Pd and Pt were 24.50,96.40,29.04 ng·g-1 in trunk road,23.18,76.92,37.21 ng·g-1 in secondary road,41.73,188.05,57.21 ng·g-1 in elevated road,13.35,63.34,18.01 ng·g-1 in expressway and 7.49,22.76,0.97 ng·g-1 in suburban road,respectively.Except Pt of secondary road was higher than that in trunk road,the rank of PGEs levels in different type roads demonstrated that elevated Road﹥Trunk Road﹥Secondary road﹥Expressway﹥Suburban road,implementation of the automobile emission standard only in central city of Shanghai were the main reason that PGEs concentrations in expressway and suburban road didn＇t accord with their traffic volume.If we took 1.5~1.6 km as length unit（both sides were intersection）,the distribution model of PGEs in trunk road,secondary road and elevated road showed wavy type,suburb road showed semi-circle type,elevated road showed polygonal line type.The distribution model of PGEs had difference because of dissimilarity of vehicles.The contents of PGEs in intersection of trunk road,secondary road and elevated road were not possible high,the main reason was the vehicles shut down,accelerate and decelerate frequently at the place away from the junction.