Accumulation Of Hydrophobic Organic Compounds By Earthworms In Soils

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.