珠江口海域气溶胶中重金属含量的时间变化特征及入海通量初步估算

采用2009～2011年珠江口海域获取的代表春、夏、秋、冬4个季节的240个气溶胶样品，分析重金属（Cu、Pb、Zn、ca）质量浓度和大气干沉降通量的年、季变化特征．结果表明：气溶胶中zn的质量浓度最高，其次是Pb和Cu，Cd的质量浓度最低，年平均质量浓度依次为69，2、31．2、12．6和0．58ng／m3．Cu、Pb和Zn的年平均质量浓度和入海通量表现为2009年〉2011年〉2010年．Cd的年平均质量浓度和入海通量呈现逐年递减的变化趋势．各金属质量浓度及大气干沉降通量均为秋季最高，冬春季次之，夏季最低，这种季节性差异主要与季风和雨水冲刷作用有关．气溶胶中Cu、Ph、Cd和Zn平均质量浓度的较低值出现在2010年夏季．Pb在4个季节的平均质量浓度低值均出现在2010年，平均质量浓度依次为18．9、3．8、56．7、20．2ng／m3，表明加强人为污染物排放的控制，可有效地降低气溶胶中重金属的含量，提高环境空气质量．通过评估金属元素分别从大气和河流进入珠江口海域的输入量，该海域金属物质输送入海仍以河流输入为主，但大气中Pb对该海域的输入具有重要作用．

Characteristics of heavy metal concentration and estimation of fluxes to sea in aerosol of the Pearl River Estuary

From 2009 to 2011,240 aerosol samples in the Pearl River Estuary are collected which represented seasons of spring, summer, autumn and winter. Based on the data, the variation of the metal concentration and the airsea fluxes via dry deposition in year and season was analyzed. The results showed that the highest concentrations in aerosols is Zn, followed by Pb and Cu and the minimum Cd. The annual average concentrations in turn were 69.2, 31.2,12.6 and 0.58 ng/m3. The average annual metal concentration and fluxes to sea for Pb and Zn were in consequence of 2009 〉 2011 〉 2010. Average annual metal concentration and fluxes to sea for Cd showed decrease yearly. The metal concentration and the air-sea fluxes in autumn were the highest and summer were the lowest. This seasonal difference were mainly associated with monsoon and rain wash. In aerosols, the lower average concentration of Cu, Pb, Cd and Zn occurred in summer of 2010. The lower average concentration of Pb appeared in all seasons of 2010 when average concentrations were 18.9,3.8,56.7 and 20.2 ng/m3 , respectively. It shows that strengthening control of man-made emissions of pollutants can effectively reduce the content of heavy metals in aerosol and improve the air quality. The assessment of metal elements from the atmosphere and the rivers shows that the river is an important source of metal material transportation to the sea. However, atmospheric Pb deposition fluxes to sea still plays important role in the area input.