中文摘要：

苯并[a]芘（benzo[a]pyrene,B[a]P）是多环芳烃类有机污染物,在土壤中逐步累积,对土壤环境造成潜在的威胁。一次污染条件下,B[a]P进入土壤的过程与低剂量逐步累积的过程有一定差异,在一定程度上会高估B[a]P的环境风险。本试验采用多次叠加污染的方法,模拟B[a]P在土壤中逐步累积的过程,研究土壤B[a]P叠加污染的有效性特征及其在蚯蚓（Eisenia foetida）体内的富集规律,分析蚯蚓体腔细胞的毒性效应。结果表明：随着B[a]P在土壤中培养时间的增加,土壤B[a]P有效含量、蚯蚓体内B[a]P富集量和蚯蚓体腔细胞MDA含量均呈前期（1～28 d）下降速率较快,后期（29～56 d）下降速率逐渐减缓的趋势,且蚯蚓体内B[a]P富集量与土壤B[a]P有效含量（Tenax-TA提取量）之间呈极显著正相关（P〈0.01）,相关系数（R2）为0.893 2。叠加污染条件下,0～20 cm和20～40 cm土壤中B[a]P平均有效含量比一次污染低23.38%（P〈0.05,14和28 d的20～40 cm叠加污染土壤除外）;在1、7、14、28和56 d所取土样培养的蚯蚓,其体内B[a]P富集量是一次污染的22.42%～77.42%,蚯蚓体腔细胞MDA含量在14 d时分别比一次污染低13.76%和41.38%,这表明土壤B[a]P多次叠加污染对蚯蚓体腔细胞的毒性效应低于一次污染,叠加污染更能客观反映污染物的真实毒性效应。

英文摘要：

Benzo[a]pyrene（B[a]P） is one of typical polycyclic aromatic hydrocarbons（PAHs） formed by the incomplete combustion of organic materials. As a ubiquitous persistent organic pollutant found in the environment,it poses a serious threat to soil quality. Overestimating environmental risks has frequently been observed in the traditional approach because the desired level of B[a]P was achieved in soil by one-time addition. If a high dose of B[a]P was added into soil at a time,B[a]P did not have enough time to diffuse or move to remote sites of soil matrix,and thus the majority of B[a]P was present in the aqueous phase due to the short soil-B[a]P contact time. Therefore,in this study we proposed a new multiple-time addition（pollution） method,aiming to simulate the process of B[a]P entering soil reliably. In the multiple-time addition,B[a]P was added into soil step by step for 12 times,with the final concentration 1 200 μg·kg-1. In the one-time addition experiment,all the B[a]P was added into soil at a time. The soil samples prepared by multiple-time and one-time addition were allowed for aging for 1,7,14,28 and 56 d at 25 ℃ under the sterile condition,and the earthworms were incubated in the aged soils for a period of 7 days. The effects of multiple-time and one-time addition of B[a]P on its availability in soil and bioaccumulation in earthworms as well as malon dialdehyde（MDA） content in earthworms（Eisenia foetida） coelomocytes were investigated. Results showed that the available（Tenax-TA extractable） B[a]P contents in soil rapidly decreased at the initial aging stage（1-28 d）,and afterwards slowed down（29-56 d）. B[a]P accumulated in earthworms and MDA contents in earthworms declined as B[a]P aged in soil. The highly significant positive correlation（R2= 0. 893 2,P〈0. 01） was found between the available contents of B[a]P in soil and the quantities of B[a]P accumulated in earthworms. Moreover,the MDA content in earthworm coelomocytes were positively correlated with the available B[