南京城郊道路两侧稻田土壤多环芳烃污染特征及风险评价

Pollution Characteristics and Risk Assessment of PAHs in Roadside Paddy Soil in Suburban Nanjing

    摘要
  • 摘要:
    目的 探讨城郊道路两侧稻田土壤中多环芳烃（PAHs）污染特征，为道路沿线农田土壤中 PAHs 的污染风险调控提供依据，保障农田土壤环境质量和农产品安全。
    方法 采集南京市江宁区周岗镇中心道路网两侧及道路垂向分布的水稻田表层土样（0 ~ 10 cm），采用气相色谱质谱法测定并分析16种优控PAHs的含量、组成及来源，并进行致癌风险评价。
    结果 土壤中16种PAHs均被检出，Σ16PAHs含量范围为265.75 ~ 1390.93 μg kg−1，平均值为551.52 μg kg−1，土壤中PAHs含量在道路垂向的分布情况表现为在离道路10 m处出现峰值，50 m后随距离增大而减小，高环PAHs与总PAHs趋势相同，而低环PAHs在距离变化上差距不明显。基于特征比值法的源解析结果表明样点土壤的PAHs主要来自于燃烧源，在离道路较近处以石油燃烧为主的交通排放占稻田土壤中PAHs来源的主要部分，超过一定距离则交通源的影响减少，受与木材、煤炭燃烧相关的居民区活动等其他因素影响更大。风险评估表明，土壤中PAHs的总毒性当量均未超过生态风险限值。
    结论 南京城郊道路两侧稻田土壤PAHs污染水平较区域农田总体偏高，且在道路源的影响下其与距离道路远近存在一定相关性。

     

    Abstract:
    Objective The aims were to explore the pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in paddy soil on both sides of suburban roads, so as to provide a basis for the risk control of PAHs pollution in farmland soil along the road, so as to ensure the environmental quality of farmland soil and the safety of agricultural products.
    Methods The surface soil samples (0 ~ 10 cm) of paddy fields on both sides of the road network and the vertical distribution of roads were collected in Zhougang Town, Jiangning District, Nanjing. The contents, composition and sources of 16 kinds of optimal control PAHs were determined and analyzed by gas chromatography and mass spectrometry, and the carcinogenic risk was evaluated.
    Results All 16 kinds of PAHs were detected in the soil, Σ16PAHs contents ranged from 265.75 to 1390.93 μg kg−1, with an average value of 551.52 μg kg−1. The distribution of PAHs in the soil in the vertical direction of the road showed that the peak appeared at 10 m away from the road. After 50 m, it decreased with the increase of distance. The trend of high ring PAHs and total PAHs was the same, while the difference of low ring PAHs in distance change was not obvious. The results of source analysis based on the characteristic ratio method showed that the PAHs in the soil of the sample was mainly from the combustion source, and the traffic emission mainly from petroleum combustion accounted for the main part of the PAHs source in the soil of the paddy field when it was close to the road. The influence of the traffic source was reduced after a certain distance, and the other factors such as residential activities related to wood and coal combustion were more significant. The risk assessment showed that the total toxicity equivalent of PAHs in soil did not exceed the ecological risk limit.
    Conclusion The level of PAHs pollution in the roadside rice field in suburban Nanjing is higher than that in the regional farmland, and it has a certain correlation with the distance from the road under the influence of the road source.

     

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