新疆柴窝堡地区沉积物元素地球化学特征及其环境意义

通过对新疆柴窝堡地区湖泊沉积物和流域表层沉积物中元素含量的分析,研究了柴窝堡湖沉积物中元素的地球化学特征及其环境意义,并利用重金属潜在生态危害指数法对沉积物重金属的生态效应进行了简要评价。相关分析及主成分分析表明,柴窝堡流域Al、K、Na、Be、Ba、Ti、Ca、Mg、Sr等元素含量的变化主要受流域化学风化作用强度的影响,而Fe、Mn、Zn、Cu、Cr、Ni、Pb、Co等重金属元素与黏土含量之间相关性显著,反映了自然与人类活动的影响过程。1950年前,人类活动影响弱,湖泊沉积物重金属元素主要受控于流域水动力条件;1950年后,流域人类活动的加强使得湖泊沉积物中重金属含量显著增加。利用聚类方法进行了湖泊沉积物与流域表层沉积物元素组成的比较分析,结果显示不同湖泊沉积物元素的组合特征反映了流域人类活动和自然作用的影响。最后,通过重金属潜在生态危害指数法对柴窝堡湖泊沉积物中Cu、Cr、Zn、Pb等4种重金属的潜在危害程度进行初步评价,其中以沉积物中Pb和Cu危害程度较高,但潜在生态危害程度尚属轻微。

The Characteristics of Element Contents in Lacustrine Sediments and Surface Soils and Its Environmental Significances in Chaiwopu Region,Xinjiang, China

Based on the element analysis of lacustrine sediments and surface soils in Chaiwopu Lake watershed, Xinjiang, the geochemical characteristics and potential ecological effects of the heavy metals are discussed with the methods of mathematical statistics. Associated with the principal component analysis (PCA) and correlation analysis of element contents from Chaiwopu Lake sediment core, the change of element content including Al, K, Na, Be, Ba, Ti, Ca, Mg and Sr was controlled by the regional chemical weathering intensity. The correlations are significant positive between the heavy metals (Fe, Mn, Zn, Cu, Cr, Ni, Pb and Cr), the organic matter content and the content of clay fraction. Before 1950 with the background of weak human activity, the heavy metals are controlled by the watershed hydrodynamics. In the period of last 50 years with strong human activities, the anthropogenic sources resulted in high loadings of heavy metals. With the constrained incremental sum of squares cluster analysis (CONISS) and cluster analysis of element contents of surface soils and lacustrine sediments, the geochemical composition characteristics were analyzed, which showed that the element contents recorded the impacts of human activity and natural environmental change. Finally, the potential ecological risk assessment of heavy metals (Cu, Cr, Zn and Pb) was evaluated. The results showed Cu and Pb were the more harmful heavy metal species in the studied areas, but the potential ecological risk of the whole heavy metals was slight.