交通源大气和土壤中多环芳烃赋存及生态风险

Occurrence Characteristics and Ecological Risks of PAHs in Atmospheric Particles and Soil from Traffic Sources

为探讨交通源对道路沿线大气及土壤中多环芳烃(PAHs)的影响,作者采集了道路沿线0、20、50、100、200 m不同距离梯度大气颗粒物(TSP)和土壤样品,分析两者PAHs的含量、组成和空间分布特征,通过构建PAHs的RQ-TEQ模型和土壤环境归趋模型估算多环芳烃累积生态风险影响。结果表明,200m范围内TSP中∑16PAHs的浓度范围为2.66~16.31ng/m^(3),平均值(8.17±3.51)ng/m^(3),随着与道路的距离增加,PAHs浓度呈现秋季先降低后升高再降低、春季先升高后降低的趋势,0~50 m范围内变化较大。土壤中∑16PAHs的含量为0.05~2.43 mg/kg,平均值(0.70±0.57)mg/kg,空间变化趋势与秋季TSP中PAHs基本一致,20 m处土壤中PAHs含量最低,这与行道树的遮蔽效应有关。苯并[b]荧蒽、苯并[k]荧蒽、茚苯[1,2,3-cd]芘和苯并[ghi]苝等高环PAHs含量在TSP中占比较高,土壤中则以荧蒽、芘、苯并[b]荧蒽、苯并[k]芘等中高环PAHs为主,均呈现出交通源指示特征。道路沿线200 m范围内土壤中PAHs生态风险可以忽略。不同距离处土壤中PAHs的增量随时间累积由大到小依次为50m>0m≈20m>100m>200m,10年后土壤中PAHs增加0.11~0.15mg/kg,RQ值增加10%,土壤中PAHs的累积作用使土壤生态风险增加,应引起关注。

To explore the impact of traffic sources on polycyclic aromatic hydrocarbons(PAHs)in the atmosphere and soil along roads,atmospheric particulate matter(TSP)and soil samples were collected at different distance gradients of 0/20/50/100/200 m along the road.The content,composition and spatial distribution characteristics of PAHs in TSP and soil were analyzed.Ecological risk impact of PAHs in soil was estimated using RQ-TEQ model and soil phase fate model.The results showed that the concentration ofΣ16PAHs in TSP ranged from 2.66 to 16.31 ng/m^(3),with an average value of(8.17±3.51)ng/m^(3).With distance increase,the concentration of PAHs was decreased,then increased and then decreased in autumn,in spring it was increased and then decreased,both with significant changes within the range of 0~50 m.The content ofΣ16PAHs in soil ranged from 0.05 to 2.43 mg/kg,with an average value of(0.70±0.57)mg/kg.The spatial variation trend is basically consistent with the PAHs in autumn TSP.The PAHs content in soil is the lowest at 20 meters,which is related to the shading effect of roadside trees.High-ring PAHs such as benzo[b]fluoranthene,benzo[k]fluoranthene,indene benzene[1,2,3-cd]pyrene and benzo[ghi]perylene were dominant components in TSP,while medium and high ring PAHs such as fluoranthene,pyrene,benzo[b]fluoranthene,benzo[k]pyrene were dominant in soil.The ecological risk of PAHs in the soil within 200 m along road can be ignored.The cumulative increment of PAHs in soil at different distances over time was 50 m>0 m≈20 m>100 mben>200 m,and 10 years later,PAHs in soil increases by 0.11~0.15 mg/kg,and RQ increases by 10%.The cumulative effect of PAHs in soil increases soil ecological risk.