泉州湾洛阳江河口潮间带柱状沉积物铅同位素组成的变化与来源

Composition variations and sources of Pb isotopes in the intertidal core sediment from Luoyang estuary of Quanzhou Bay

不同源区铅同位素的组成不同,可以利用铅同位素的这种"指纹"特征来示踪铅的不同来源.泉州湾洛阳江河口潮间带柱状沉积物中,从底层到表层其铅同位素组成呈现出一定的变化规律,其中207Pb/204Pb呈上升趋势,206Pb/207Pb和208Pb/(206Pb+207Pb)呈下降趋势.铅污染的来源主要与工业生产、污水排放和燃油尾气排放有关,受燃煤的影响很少,从底层到表层铅同位素组成的演化趋势为:由工业及污水排放逐渐向汽车尾气方向飘移.结合定年分析,推断出油铅的污染起源于20世纪80年代中期,其污染呈不断加重趋势;其中表层沉积物中铅的污染受汽车尾气排放的影响最为严重.对不同时期沉积物中铅污染的来源及其相对贡献率研究表明,1973年到1984年间,沉积物受燃油铅的影响较少,其污染来源主要以工业污染为主,其贡献率占70%以上;1984到1994年间汽车尾气铅的贡献率迅速上升,占到了50%;而1996年到2008年汽车尾气铅的贡献率逐渐增加,由50%上升到了66%.

Each source of lead has distinct isotope compositions.This fingerprint characteristic of lead isotope can be used to trace the sources of lead in the environment.207Pb/204Pb ratios increased while 206Pb/207Pb and 208Pb/（207Pb＋206Pb） ratios decreased from bottom to surface in the core sediment collected from Luoyang estuary of Quanzhou Bay.Lead pollutants in the sediment mainly came from industrial discharge,sewage and automobile exhaust,while seldom came from coal combustion.The lead isotope compositions showed an evolvement trend of industrial discharge and sewage to automobile exhaust from bottom to surface in the core sediment.Combining the dating analysis,we could draw the conclusion that the oil lead pollution originated in the mid 1980s and became worse and worse from then on,so the lead pollution in the surface sediment were most seriously affected by the automobile exhaust.The analysis of Pb pollution sources and the corresponding contributions in the sediments of different periods showed that,from 1973 to 1984,the sediment lead pollution was less from automobile exhaust but mainly from industrial pollution with the contribution rate of more than 70%;from 1984 to 1994,the contribution of automobile exhaust increased rapidly,accounting for 50%;from 1996 to 2008,the contribution of automobile exhaust increased from 50% to 66%.