北京东南郊再生水灌区土壤PAHs污染特征

采用Eijkelkamp土壤采样器对北京东南郊再生水灌区进行了3个钻孔剖面采样，同时采集了灌溉用水及地下水样品，并采用气相色谱-质谱联用仪对16种多环芳烃（PAHs）进行定量分析。结果表明，表层土壤中有14种PAHs检出，浓度在0.4-53.1 μg·kg-1之间，∑PAHs平均含量为206.7 μg·kg-1，达到了土壤污染临界值；表层以下PAHs的检出种类和含量显著减少，以中、低环的萘、菲、芴、荧蒽、芘为主，∑PAHs仅占表层的3.8%-12.0%，从剖面PAHs含量变化可以判断，低环PAHs较易迁移，迁移性强弱顺序为萘、芴〉菲〉芘、荧蒽；污灌区表土中PAHs组成与大气降尘接近，但与再生灌区有明显差异，这种差异主要由于灌溉用水不同所造成；再生水灌区表土以下土壤剖面检出的PAHs与再生水中的PAHs一致，说明再生水灌溉是导致土壤剖面PAHs污染的主要原因，同时地下水中检出的PAHs种类也与土壤剖面基本一致，但含量较高，可能是早期污水灌溉所造成。

Distribution Characteristics of Soil PAHs in Reclaimed Water Irrigation Area in the Southeastern Suburb of Beijing

Samples of soils, groundwater and reclaimed water were collected from the reclaimed water irrigation area in the southeastern area of Beijing. The soil samples were collected from three borehole profiles by Eijkelkamp soil sampler. The results of GC-MS analyses showed that 14 PAHs were detected in the topsoils and their concentration was in a range of 0.4 to 53.1 μg·kg^-1. The average total content of PAHs in the topsoil was 206.7μg·kg^-1, which is very close to the contamination threshold of soil proposed by Maliszewska-Kordybach. Below the topsoil, both species and contents of detected PAHs drop very fast. Only 2 to d-ring PAHs （i.e., naphthalene, fluorene, phenanthrene, fluoranthene and pyrene） were detected and the total content PAHs was only 3.8%-12.0% of that in the topsoil. The content distribution of PAHs in the soil profiles indicated that PAHs with less tings were easier to migrate than the PAHs with more rings. The sequence of the migration ca- pabilities from strong to weak was naphthalene, fluorene〉phenanthrene〉fluoranthene, pyrene. The detected PAHs components in topsoils in waste water irrigation area were quite same to those of the dust fall, but different from those in the topsoil of the reclaimed water irrigation area. The difference was mainly caused by the difference of the irrigation waters. However, the detected PAHs compositions in subsoils were consistent to those of the reclaimed waters. This meaned that the contamination of soil profiles was mainly caused by reclaimed water irriga- tion. The detected PAHs in groundwater were also very close to those of the soil profiles, but the contents were slightly higher than those of the reclaimed water, which was probably resulted from the waste water irrigation quite long ago.