某生活垃圾焚烧发电厂周边农田土壤中PAHs生态安全评价

Ecological Safety Evaluation of the Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Soil of Farmland around a Municipal Solid Waste Incineration Power Plant

    摘要
  • 摘要: 为了解淮北平原某生活垃圾焚烧发电厂周边农田土壤中PAHs（polycyclic aromatic hydrocarbons，多环芳烃）的污染状况及生态风险，按照点源扇形布点原则，在运行1 a的该生活垃圾焚烧发电厂周边不同风向2 km范围内布点，在距离电厂10 km以上的常年主导风向的上风向设置对照点，参照HJ/T 166-2004《土壤环境监测技术规范》共采集21个农田土壤样品.采用HPLC法测定样品中15种PAHs的含量，分析PAHs的空间分布特征和组分特征，在根据荷兰土壤环境质量标准评价土壤PAHs污染程度的同时，将其与国内其他相似污染源周边农田土壤中PAHs比对，进行生态安全评价.结果表明：该生活垃圾焚烧发电厂周边农田土壤中w（BaP）平均值为9.40 μg/kg（0.663~96.2 μg/kg），∑15PAHs（15种PAHs的质量分数）平均值为174 μg/kg（37.5~1 382 μg/kg），TEQ（BaP）15（15种PAHs的毒性当量）平均值为14.6 μg/kg（1.92~135 μg/kg），三者明显高于对照区的0.795 μg/kg（0.412~1.57 μg/kg）、52.6 μg/kg（27.2~68.8 μg/kg）和1.96 μg/kg（1.05~2.84 μg/kg）；下风向w（BaP）、∑15PAHs和TEQ（BaP）15基本均高于上风向和对照区，最大值均位于距电厂1 km处.该生活垃圾焚烧发电厂周边农田土壤中高环PAHs组分含量为52.5%，高于对照区的35.3%；7种致癌性PAHs在∑15PAHs中的贡献率达43.0%，远高于对照区的22.2%.运行1 a的该生活垃圾焚烧发电厂周边农田土壤中个别采样点PAHs处于严重污染水平，w（BaP）、∑15PAHs和TEQ（BaP）15均高于国内相似污染源且增长迅猛，存在不容忽视的生态安全风险.研究显示，该生活垃圾焚烧发电厂周边农田土壤中的PAHs累积速度快，高环PAHs特别是BaP明显高于对照区，建议加强对生活垃圾焚烧发电厂PAHs排放及周边环境影响的监控，在环境影响评价时充分考虑PAHs污染.

     

    Abstract: In order to understand and evaluate the pollution status and ecological safety of PAHs in soil of farmland around a municipal solid waste (MSW) incineration power plant, per the sector placement principle sample points were placed in the range of 2 km around the MSW incineration power plant that was operated for a year. The comparison points were set at 10 km from upwind of the perennial dominant wind direction. A total of 21 samples were collected according to Technical Specification of Soil Environmental Monitoring (HJ/T 166-2004). Treated sample was extracted and concentrated by acetonitrile ultrasound, and the content of 15 PAHs was determined by HPLC method. Finally, we analyzed the spatial distribution and component characteristics of measurement. The results showed that the mean level of BaP in the soil around the plant was 9.40 μg/kg (range:0.663-96.2 μg/kg), the level of total PAHs and TEQ(BaP)15 was 174 μg/kg (range:37.5-1382 μg/kg) and 14.6 μg/kg (1.92-135 μg/kg) respectively, which was significantly higher than those in the control area. In the downwind of dominant wind direction throughout the year, the levels of BaP, total PAHs and TEQ (BaP) were higher than those in the upwind direction and in control area. The maximum value was observed at a distance of 1 km on the downwind of dominant wind direction away from the plant. The proportion of PAHs with four or more aromatic rings was 52.5% in the samples around the plant, which was higher than that (35.3%) in the control area. The proportion of carcinogenic PAHs was 43.0% in the farmland around the plant, which was much higher than that (22.2%) in control area. There were sites with highly polluted PAHs around the plant. The levels of w(BaP), ∑15PAHs and TEQ(BaP)15 were higher and increased more rapidly than those reported around the thermal power plant. All these suggested that compared with the control area, there was a rapidly increase in the contents of PAHs, especially the contents of PAHs with four or more aromatic rings, in the surface soil of farmland around a MSW incineration power plant. Therefore, we should strength the monitoring of the PAHs emissions and the environmental impact of MSW incineration power plant. Meanwhile, the risk of PAHs emissions should be fully considered in the environmental impact assessment.

     

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