我国典型电子废弃物拆解地农田土壤中的多溴联苯醚

选择我国主要电子垃圾拆解地清远龙塘-石角地区作为研究区,以14种多溴联苯醚(Polybrominated Diphenyl Ethers,PBDEs)化合物为研究对象,探讨了PBDEs化合物在龙塘-石角地区农田土壤中的含量、同系物组成及空间分布状况,分析了土壤TOC、土地利用方式(水旱轮作)等对农田土壤PBDEs含量特征的影响.结果表明,清远龙塘-石角地区农田土壤中14种PBDEs化合物的总量平均为(19.0±20.1)ng·g-1(以干重计),明显低于来自路边、拆解中心、居民区等表土中的PBDEs含量.研究区农田土壤中PBDEs的空间分布与土壤TOC呈现出一致性特征,当去除TOC的影响后,作为点源的电子垃圾拆解地成为土壤PBDEs分布的关键控制因素.水旱轮作的土地利用方式下,在一个轮作周期内,当轮作为水稻且土壤处于淹水状态时土壤中的PBDEs含量最低.总体来看,农田土壤中的PBDEs动态受土壤水含量、作物种植情况、土壤水旱状态等多因素的综合影响,表现出不确定的变化特征.本文的研究成果对土壤-作物系统PBDEs的行为研究进行了补充,并可为完善现有的土地质量评估体系提供基础资料.

PBDEs dynamic in farmland soils from an E-waste dismantling area in China

A detailed investigation was conducted to understand the concentration, profile, distribution and influencing factors of PBDEs in farmland soils from Longtang-Shijiao town, one of the main E-waste dismantling area in South China. Significant but different levels of PBDEs were widely detected in the local air, soil, water, and even in the human hair and blood. The averaged concentration of total PBDEs in the farmland soil was averaged (19.0±20.1) ng·g^-1 dry weight, which was much lower than that in roadside soil and in topsoil near E-waste dismantling sites. Spatial distribution of total concentration of farmland soil PBDEs in the study area showed consistent pattern with that of soil TOC, but when concentrations were standardized by TOC value, the influence of E-waste location became a key influencing factor on the spatial distribution of soil PBDEs. Under the water-dry land rotation system, the temporal concentration of PBDEs in the farmland soil was the lowest when the crop rotated to paddy and the soil was submerged by water. It was concluded that the dynamics of PBDEs in the farmland soil is influenced by multiple and interacting factors such as soil water content and soil water-dry condition, exhibiting uncertain variation characteristics. The results provided important supplement on PBDEs behavior in soil-crop ecosystem, and supplied basic data for establishing and improving the index system of land quality evaluation.