土壤冻融对溶解性有机质与菲结合的影响

以沈阳市公园土壤和道路边土壤中的溶解性有机质(DOM)为研究对象,利用荧光淬灭法测定DOM与菲的结合常数(K),考察了冷冻温度、融化温度、冷冻时间和冻融次数对其光谱学特性及其与菲的结合常数(K)的影响,并结合相关性矩阵分析K与其他参数的关系.结果表明:冻融处理条件下,K值与溶解性有机碳含量(DOC)显著负相关(p0.01),与254 nm处的紫外吸光系数(a_(254))和单位浓度DOC的254 nm的紫外吸光值(SUVA)显著正相关(p0.01).城市公园土壤DOM和城市道路边土壤DOM的K值都是3.5×10~4L·kg~(-1),经过冷冻温度、冷冻时间和冻融次数相同的冻融处理后,城市公园土壤DOM的K值始终高于城市道路边土壤DOM,这是由于冻融导致城市土壤DOM的芳香性高于城市道路边土壤DOM,而分子量小于城市道路边土壤DOM.经过冻融作用二者的K值变化范围分别为1.6×10~5～8.4×10~5L·kg~(-1)和1.5×10~5～3.7×10~5L·kg~(-1),冻融作用使二者的K值都增大一个数量级.这一方面会增强固相土壤中多环芳烃的溶出和迁移,另一方面也会降低多环芳烃的生物可利用性.

Effects of soil freezing and thawing on the binding of phenanthrene to dissolved organic matter in soils

The effects of freezing-thawing treatments with different freezing temperature, thawing temperature, freezing time and the times of freezing-thawing cycles on the binding coeffcients (K) of phenanthrene to two kinds of dissolved organic matters (DOMs) in soils were examined. In addition, the relationship between K and spectra parameters was studied by the correlation method. The two kinds of DOM were extracted from park soil (PS) and roadside soil (RS) in Shenyang, respectively. K values were measured by the method named fluorescence quenching. The results showed that K values were significantly negatively correlated with dissolved organic carbon (DOC), and were significantly positively correlated with specific ultraviolet light absorbance (SUVA). The K values of both original DOM were 3.5×10⁴ L·kg^-1. The K value of PS was always higher than that of RS after freezing-thawing treatments with the same freezing temperature, same freezing time and same times of freezing-thawing cycles,because the aromaticity of PS was stronger than RS while the molecular weight of PS was smaller than RS after those freezing and thawing treatments. The K values for PS and RS ranged from 1.6×10⁵ to 8.4×10⁵ L·kg^-1and from 1.5×10⁵ to 3.7×10⁵ L·kg^-1, respectively, after freezing-thawing treatments. K values for both DOM increased by about one order of magnitude as a result of freezing-thawing treatments. The increased K values would increase the dissolution and migration of PAHs in solid-phase soils. On the other hand, it would reduce the bioavailability of PAHs.