泉州市大气降尘中稀土元素地球化学特征及来源解析

Geochemical Characteristics and Source Apportionment of Rare Earth Elements in the Dustfall of Quanzhou City

稀土元素因其特殊的地球化学特性,具有一定的示踪性质.为了研究泉州市大气降尘中稀土元素地球化学特征及其来源,在泉州市不同功能区以及潜在源区共采集降尘样品34份,对REE组成特征、配分模式、特征参数进行了分析并结合三角图和特征参数关系图解揭示了其来源.结果表明,泉州市大气降尘的ΣREE空间分布差异较大,由高到低顺序为工业区>交通繁忙区>商业区>居住区>农业区.居住区、交通繁忙区、商业区的ΣREE变异系数均较小,显示其来源的一致性.降尘和潜在源样品中稀土元素的配分曲线均为右倾,轻稀土相对重稀土富集,具有明显的Eu负异常,表明研究区大气降尘具有较明显的陆源属性.各功能区降尘与潜在源的部分REE特征参数平均值较接近,未能揭示空间差异的成因.LaCeV三角图解表明居住区、交通繁忙区、商业区降尘中REE主要受交通源和土壤尘的影响,其次为燃煤源.δEu-ΣREE和HREEN/MREEN-LaN关系图解进一步说明汽车尾气排放是交通繁忙区和商业区降尘中REE的主要来源.所有功能区的稀土元素受钢铁厂排放物和水泥尘的影响较小,且农业区和工业区的稀土来源与其他功能区存在差异.

Rare earth elements（ REE） have certain properties as tracing elements which result in their special geochemical characteristics. In order to study the geochemical characteristics of REE in the dustfall and their sources,34 dustfall samples were collected in five functional areas and potential source areas of Quanzhou City,then REE compositions,distribution patterns and characteristic parameters were analyzed together with ternary diagrams and characteristic parameter diagrams,for investigating the main provenance. The results showed that Σ REE in the dustfall presented significant spatial difference with the sequence of industrial area heavy traffic area commercial area residential area agricultural area. The lower coefficient variation of Σ REE in residential,heavy traffic,commercial areas indicated homogeneous sources of REE. The chondrite-normalized REE patterns were all of the rightward inclined type with the enrichment of LREE relative to HREE and showed obvious negative Eu anomalies which indicated that the dustfall in study area had obvious terrigenous property. Some REE characteristic parameters in each functional area were close to the average in potential source areas,failed to reveal the causes for spatial differences. The results of LaCeV diagram demonstrated that REE in the dustfall of residential area,heavy traffic area and commercial area were mainly derived from traffic source and soil dust,followed by coal combustion,δEu vs. Σ REEs diagram and HREEN/ MREENvs. LaNdiagram further explained that vehicle emission was the main anthropogenic source of REE in the dustfall of heavy traffic area and commercial area. The REE in the dustfall of Quanzhou City was less affected by steelworks emissions and cement plant dust and there were additional REE sources in the dustfall of industrial and agricultural area different from other functional areas.