Swindell A L, Reid B J
School of Environmental Sciences, University of East Anglia, Norwich, UK.
Chemosphere. 2007 Jan;66(2):332-9. doi: 10.1016/j.chemosphere.2006.04.069.
This study was carried out to assess the influence of diesel, applied over a log concentration range, on the loss and extractability of phenanthrene (measured as putative 14C-phenanthrene residues) in two different soils. The influence of diesel on the ability of a cyclodextrin based extraction method to predict the microbial bioavailability of 14C-residues was also assessed. An increase in loss of 14C-residues with increasing diesel concentration from 0 to 2000 mg kg-1 was generally observed with time in both soils. It is suggested that this trend is attributable to competitive sorption for soil sorption sites and to a lesser extent to displacement of 14C-residues from soil sorption sites by diesel resulting in greater compound availability and therefore greater loss by degradation via the actions of indigenous microorganisms. However, in the 20000 mg kg-1 diesel treatments of both soils, results indicated a delayed loss. It is suggested that this retarded loss was due to the formation of a discrete NAPL-phase into which 14C-phenanthrene residues partitioned, thereby decreasing their availability and as a consequence their degradation. Furthermore, it is suggested that nutrient limitation may have slowed down degradation rates as diesel concentrations increased. Comparison between cyclodextrin-extractability and microbial mineralisation supported the use of cyclodextrin to assess microbial bioavailability of 14C-residues after 50 d or more ageing up to diesel concentrations of 2000 mg kg-1. However, results suggested that at high diesel concentrations (specifically 20000 mg kg-1) co-extraction of 14C-phenanthrene residues may have occurred as a result of the combined solvation powers of both the cyclodextrin and the diesel. Furthermore, mineralisation of 14C-phenanthrene residues may have been affected by extreme nutrient limitation in this treatment.
本研究旨在评估在两种不同土壤中，施加不同浓度柴油对菲（以假定的14C - 菲残留量衡量）的损失和可萃取性的影响。同时评估了柴油对基于环糊精的萃取方法预测14C - 残留微生物生物可利用性能力的影响。随着时间推移，在两种土壤中，通常观察到随着柴油浓度从0增加到2000 mg kg-1，14C - 残留量损失增加。这一趋势被认为归因于对土壤吸附位点的竞争吸附，在较小程度上也归因于柴油将14C - 残留从土壤吸附位点置换出来，从而使化合物的可利用性增加，进而因本地微生物作用导致更大的降解损失。然而，在两种土壤的20000 mg kg-1柴油处理中，结果显示损失延迟。这一延迟损失被认为是由于形成了离散的非水相液体（NAPL）相，14C - 菲残留分配到其中，从而降低了它们的可利用性，进而降低了它们的降解。此外，随着柴油浓度增加，营养限制可能减缓了降解速率。环糊精可萃取性与微生物矿化之间的比较支持使用环糊精评估老化50天或更长时间后直至柴油浓度为2000 mg kg-1时14C - 残留的微生物生物可利用性。然而，结果表明，在高柴油浓度（特别是20000 mg kg-1）下，由于环糊精和柴油的综合溶剂化能力，可能发生了14C - 菲残留的共萃取。此外，该处理中极端的营养限制可能影响了14C - 菲残留的矿化。
