不同营养湖泊沉积物中^(210)Pb_(ex)和营养盐垂向分布特征及相关性分析

Vertical Distribution and Relationship Between ^(210)Pb_(ex) Activities and Nutrients in Sediment Cores of Two Different Eutrophication Level Lakes

对比分析了两个不同营养湖泊抚仙湖和滇池湖中心部位沉积物柱芯放射性核素210Pbex和营养盐(TOC、TN和TP)的垂向分布特征,探讨了两个湖泊不同湖区沉积物柱芯中210Pbex与营养盐(TOC、TN和TP)之间的相关关系.结果表明,两个湖泊沉积物柱芯中210Pbex和营养盐各个指标的垂向分布存在差异,总体上滇池沉积物柱芯中210Pbex的波动变化幅度略高于抚仙湖.滇池表层沉积物中210Pbex较为紊乱的分布特征与人类活动影响下的沉积物中Pb的物理化学迁移有关.沉积物中营养盐各个指标的变化则与特定历史时期不同强度的自然演化和人类活动双重因素影响密切相关.放射性核素210Pbex和营养盐各个指标之间的相关关系与两个湖泊或同一湖泊不同湖区的营养水平高低有关,其变化关系为富营养化湖泊滇池>贫营养湖泊抚仙湖,抚仙湖北岸>南岸.就单个营养盐指标与210Pbex之间的相关关系而言,TOC最强,TP次之,TN最弱.

The ^210Pbex activities and nutrient（ TOC,TN and TP） contents in sediment cores of Fuxian Lake and Dianchi Lake were measured by traditional methods,as well as their vertical distribution and relationship were also comparatively analyzed in this paper.The study results indicated that the vertical distributions of ^210Pbex and nutrients were significantly different between Fuxian Lake and Dianchi Lake. The variation amplitude of ^210Pbex activities in Dianchi Lake was higher than that in Fuxian Lake. The disordered distribution characteristics of ^210Pbex in Dianchi Lake surface sediments were closely related to physicochemical migration of lead caused by human activities. The variation trends of nutrients in sediment cores were corresponded to local natural evolution and human activities in different historical periods. Relationship between ^210Pbex activities and nutrients were mainly affected by the nutrition level of lakes. The greater the lake eutrophication level was,the stronger the correlation was found. To the individual nutrient indicators,similar characteristics were shown in the two lakes,and the order was TOC TP TN.