广东东江流域多氯萘的大气沉降研究

为考察多氯萘(PCNs)通过大气沉降作用对东江流域的影响,利用通用型大气沉降采样器,在东江流域广东省境内代表性地段布设11个采样点,于2010年冬季(1、2月)和夏季(7、8月)分别采集和分析了沉降样品中PCNs的通量及组成.结果表明,东江流域总PCNs日均沉降通量为828 pg.(m2.d)-1,对应毒性当量(TEQ)为0.14 pg.(m2.d)-1,由此估算东江流域广东境内PCNs年沉降总量为8.5 kg,相应TEQ年沉降总量为1.3 g.地域上,广州和东莞地区沉降通量明显高于惠州,同时城镇采样点的沉降通量显著高于农村;季节上,各采样点总体呈现夏季高于冬季的特点;组成上,三氯萘(tri-CNs)是主要的污染物,占总量的50%以上,但广州、东莞的5～8氯萘含量比惠州高.来源分析表明,东江流域PCNs的大气沉降可能受燃烧源与非燃烧源的共同影响;东莞大气沉降中PCNs多来自燃烧源,广州点大气沉降的PCNs以非燃烧源为主.

Atmospheric Deposition of Polychlorinated Naphthalenes in Dongjiang River Basin of Guangdong Province

Atmospheric deposition of polychlorinated naphthalenes (PCNs) was investigated at 11 sites in Dongjiang River basin of Guangdong Province during the winter (January and February) and summer (July and August) of 2010 to assess the effect of PCNs on those areas. The average daily deposition fluxes of total PCNs was 828 pg x (m2 x d)(-1), and the corresponding TEQ was 0.14 pg x (m2 x d)(-1). Based on these values, the presumed average annual deposition value of sigma PCNs was 8.5 kg for Dongjiang River basin within Guangdong province, while the corresponding TEQ was 1.3 g. Spatially, the average daily deposition fluxes of PCNs in Guangzhou and Dongguan were much higher than that in Huizhou, and the fluxes were higher in urban areas than those in rural areas. Seasonally, the fluxes were generally higher in summer than those in winter. Tri-CNs dominated the deposition fluxes in all samples and contributed to more than 50% of total PCNs. In addition, higher contents of high chlorinated PCNs (penta-CNs to octa-CN) were found in Guangzhou and Dongguan in comparison with Huizhou. Combustion and other sources may both contribute to the PCNs emission in the Dongjiang River basin. Combustion related source may be the main contributor of PCNs in Dongguan; while non-combustion related source may dominate the contribution to the site of Guangzhou.