喀斯特峡谷区常见植物叶片δ13C值与环境因子的关系研究

通过对贵州花江峡谷喀斯特石漠化区4种典型石漠化植物群落中11种常见植物种叶片的δ¹³C值测定，研究了各植物种对影响植物碳同位素分馏的主要环境因子（土壤储水量、大气相对湿度、光照强度、土壤厚度）的响应，分析了石漠化梯度中不同土层土壤储水量、大气相对湿度、土壤有机质、年均气温、光照强度等环境因子梯度变化与植物叶片δ¹³C值的关系.结果表明，大部分物种的δ¹³C值对环境因子的变化趋势表现为随环境水分好转呈下降趋势，即水分利用效率下降；也有部分物种呈稳定不变或逆势上升趋势.相关性分析表明，清香木（Pistacia weinmannifolia）、石岩枫（Mallotus repandus）、红背山麻杆（Alchornea trewioides）的主导因子是土层储水量；肾蕨（Nephrolepis cordifolia）、野桐（Mallotus japonicus var.floccosus）的主导因子是土壤厚度；肾蕨、八角枫（Alangium chinense）、构树（Broussonetia papyrifera）的主导因子是光照强度；而广西密花树（Rapanea kwangsiensis）、圆叶乌桕（Sapium rotundifolium）和灰毛浆果楝（Cipadessa cinerascens）则分辨不出主导因子，即环境影响因素更为综合.总体而言，叶片高δ¹³C值是对低水分、高光、低资源环境的适应.

Integration Pollution Index (IPI) Method for Evaluation of Polychlorinated Biphenyls (PCBs) Pollution in Soil

An integration pollutant index (IPI) evaluation method with proportional addition of toxicity pollution sub-index (TPI), persistence pollution sub-index (PPI), and bio-accumulation pollution sub-indexes (BPI) for polychlorinated biphenyls (PCBs) pollution in soil was set up for the first time by referring to the conception of IPI and introducing the standard value series of total PCBs employed by national guideline and standards office, Canada. The relevant expressions for pollution indexes were defined; three transformation coefficients for PCBs toxicity (T_i), persistence (P_i), and bio-accumulation (B_i) pollution were apportioned, too. Then, by the application of the evaluation method, the IPIs for PCBs pollution evaluations in 22 soil sample stations in the Yellow River Delta and a background sample were accomplished successfully, the quantification results were in range of 1.1-531.7, the qualification result was that the Yellow River Delta was slightly polluted by PCBs. This integrated evaluation model considered the characteristic differences between PCBs congeners and was more scientifical and comprehensive than current method, and should be employed in evaluations of persistent organic pollutants (POPs).