不同降雨条件下城市路尘中稀土元素流失特征

通过对包头市路尘中14种稀土元素(rare earth elements,REEs)含量的测定分析以及小型人工降雨冲刷模拟,对稀土元素在路尘中的赋存特征及在其降雨径流中的流失特征进行了分析和探讨。结果表明,(1)路尘中的稀土元素随降雨过程发生迁移并在径流产生"流失浓缩"效应,浓缩强度随雨强增加而增强;相同雨强下,水泥下垫面的聚集效应高于沥青混凝土下垫面。(2)径流中水相稀土元素含量随降雨时间下降。(3)径流流失过程中,固相颗粒态中稀土元素的配分模式与路尘样品基本一致,呈现轻稀土富集的特征,轻重稀土之间的分馏程度较高;而水相中稀土元素的配分模式与原始路尘样品中有一定差异,轻重稀土之间的分馏程度降低。

Loss Characteristics of Rare Earth Elements in Urban Surface Road Dust under Different Rainfall Conditions

Based on the determination and analysis of 14 rare earth elements(REEs)in road dust in Baotou city and the simulation of small artificial rainfall scour,the characteristics of REEs in road dust and rainfall runoff were analyzed and discussed.The results showed:(1)REEs in road dust migrated with the process of rainfall scour,and the REEs contents enhanced in runoff,the concentration intensity increased with rainfall intensity;under the same rain intensity,the aggregation effect on cement underlying surface was higher than that on asphalt concrete underlying surface.(2)The REEs concentration in water phase of runoff decreased with rainfall time.(3)In the process of runoff,the distribution patterns of REEs in particulate matter of solid phase were basically the same as those in road dust samples,showing LREE enrichment,and the fractionation degree between LREE and HREE was higher.However,REEs distribution patterns in water phase were different from those in the original road dust,and the fractionation degree between LREE and HREE reduced.