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蚯蚓对土壤中疏水性有机污染物的动态积累
Accumulation of Hydrophobic Organic Compounds by Earthworms in Soils
【作者】 徐雷;
【作者基本信息】 浙江工业大学 , 环境工程, 2010, 硕士
【摘要】 本文建立了土壤和蚯蚓中菲和3-PCB的提取、纯化、分析检测方法。在10天和30天两个时间段内,研究了4种土壤中赤子爱胜蚓(Eisenia fetida)对菲和3-PCB的动态累积过程,并与分配理论的预测值进行比较。上述研究为土壤环境生态安全评价提供了基础数据。用100ml丙酮/正己烷(1:3,v/v)索氏提取土壤中的菲和3-PCB,100ml正己烷/二氯甲烷(1:1,v/v)索氏提取蚯蚓中的菲和3-PCB;然后以100~200目的三氧化二铝和无水硫酸钠为填料,用层析柱来净化样品,最后用气相色谱质谱联用仪检测分析样品中的菲和3-PCB。测得土壤中菲和3-PCB的回收率分别为99.1%,98.6%,蚯蚓中菲和3-PCB的回收率分别为98.0%,95.1%。通过4种土壤和干蚯蚓对水中菲和3-PCB的吸附实验,证实了吸附过程由分配作用控制。菲和3-PCB在土壤有机质的平均分配系数对数值(log Koc)分别是3.92和4.08,干蚯蚓吸附经脂质含量标化后对菲和3-PCB的分配系数对数值(log Klipd)分别为4.63和4.96。由以上数据计算得到菲和3-PCB的平衡BSAF(biota-soil accumulation factors)值分别是5.18和7.41。本文还考察了在10天和30天两个时间段内,蚯蚓在4种土壤中对菲和3-PCB的动态累积量,并分别计算了其实验BSAF值。将实验BSAF值与平衡BSAF值比较,发现经10天积累,菲和3-PCB在土壤有机碳和蚯蚓类脂(lipid)之间的分配远未达到平衡,而经30天积累后,分配接近或基本达到平衡状态。蚯蚓对菲比对3-PCB有更高的利用性。
【Abstract】 This thesis first established the methods of extracting phenanthrene and 3-polychlorinated biphenyl (3-PCB) from soils and earthworm, sample purification and analyses. The 10-day and 30-day accumulations of the two hydrophobic compounds in earthworm (Eisenia fetida) from four soils were determined. The obtained accumulations were compared to those predicted based on the partition theory. The results provide valuable information for evaluation of soil environmental quality and ecological safety.Phenanthrene and 3-PCB were extracted by Soxhlet from soils using 100 ml of acetone/hexane (1:3, v/v) and from earthworm using 100 ml of methylene dichloride/hexane (1:1, v/v). The extracts were purified by eluting the samples through a column packed with 6 g of alumina (100-200 meshes) and anhydrous sodium sulfate using 25 ml of methylene dichloride/hexane (1:1, v/v). Phenanthrene and 3-PCB were then analyzed by GC-MS. The recoveries of phenanthrene and 3-PCB were 98.0% and 95.1% in earthworm and 99.1% and 98.6% in soils, respectively.Sorption of phenanthrene and 3-PCB to earthworm and four soils occurred by a partitioning process. The logarithmic partition coefficients of phenanthrene and 3-PCB in soils normalized to soil organic matter (log Koc) were 3.91 and 4.06, respectively, and those in earthworm normalized to earthworm lipids (log Klipid) were 4.63 and 4.96 for phenanthrene and 3-PCB. From these partition coefficients, the calculated biota-soil accumulation factors, i.e., equilibrium BSAF values, of phenanthrene and 3-PCB were 17.6 and 12.8, respectively.The accumulations of phenanthrene and 3-PCB in earthworm from four soils for 10 and 30 days were determined. The concentrations of both compounds in soils and earthworm were analyzed and used to calculate the BSAF at given exposure times. Compared to the respective equilibrium values, the BSAF of phenanthrene and 3-PCB after a 10-d accumulation were much smaller, whereas those following a 30-d exposure approached the equilibrium values. The availability of phenanthrene to earthworm relative to 3-PCB appeared higher, due presumably to a higher structural comparability of the former compound to earthworm lipids.
【Key words】 BSAF; accumulation; partition; hydrophobic organic compounds; earthworm;