某垃圾焚烧厂投产前后周边土壤二噁英类化合物的分布

Distribution of PCDD/Fs in Soil before and after Operation of Municipal Solid Waste Incinerator

为研究垃圾焚烧厂运行对周边土壤二噁英类化合物(PCDD/Fs)含量的影响,采集了珠三角地区某垃圾焚烧厂投产前和投产后周边土壤样品,分析研究了该垃圾焚烧厂运行对周边土壤中PCDD/Fs含量和组分的变化.结果表明:①2012年(投产前)珠三角地区某垃圾焚烧厂周边土壤PCDD/Fs含量较低,范围为163~591 ng/kg (毒性当量范围为0.198~0.863 ng I-TEQ/kg,I-TEQ为国际毒性当量因子折算的毒性当量值);2017—2019年(投产后)周边土壤PCDD/Fs含量范围为151~1.75×10^3ng/kg(毒性当量范围为0.812~3.88 ng I-TEQ/kg),与其他研究相比处于较低的水平.②投产后,距该垃圾焚烧厂较近(1.5 km)的采样点(S1)土壤PCDD/Fs含量逐年增长,在较远(5.2 km)但人口较密集的采样点(S3)土壤PCDD/Fs含量整体较高,但呈逐年下降趋势.③投产后,土壤中的17种PCDD/Fs单体组分中,毒性当量贡献率最高的单体为八氯二苯并二噁英(OCDD)和2,3,4,7,8-五氯二苯并呋喃(2,3,4,7,8-PeCDF),二者毒性当量贡献率范围为15.7%~45.4%.④在同一采样点土壤PCDD/Fs单体组分年间差异不明显,但同一年份不同采样点差异明显.研究显示,目前该垃圾焚烧厂周边土壤PCDD/Fs含量较低,但仍需要长期监测其可能带来的风险.

In order to investigate the concentrations and congener profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the vicinity of a municipal solid waste incinerator (MSWI) before and after its operation,soil samples were collected around a MSWI in the Pearl River Delta. The results showed that: (1) Before the MSWI operation,PCDD/Fs concentrations ranged from163 to 591 ng/kg (0. 198-0. 863 ng I-TEQ/kg) in 2012. After its operation,PCDD/Fs concentrations in all soil samples from 2017 and 2019 were in the range of 151-1. 75×10^3 ng/kg (0. 812-3. 88 ng I-TEQ /kg) and the concentrations were lower than those reported in other previous studies. (2) Since the MSWI operation,the PCDD/Fs concentrations in the sample closest to the MSWI (sample S1 within 1. 5 km) increased year by year. And the PCDD/Fs concentrations in sample S3 (5. 2 km from MSWI) located in a densely populated area was higher and decreased slightly. (3) After the operation of MSWI,the main contributors in congener profiles in the TEQ values of PCDD/Fs were OCDD and 2,3,4,7,8-PeCDF with contributions ranging from 15. 7% to 45. 4%. (4) The present study showed that there was little difference in the congener profiles of PCDD/Fs from the same site in different years. But there was huge difference in the congener profiles of PCDD/Fs from different sites in the same year. In conclusion,the PCDD/Fs in the soils near the MSWI was low at present,but PCDD/Fs concentration monitoring should be maintained to determine possible risks.