Spatial Distribution of PBDEs in Topsoils from Electronic Waste Dismantling Sites and the Surrounding Areas in Guiyu, Guangdong Province

Since 2005, research on contamination of polybrominated diphenyl ethers (PBDEs) at Guiyu, the largest electronic waste disposal and recycling area in Guangdong Province of South China, have mainly focused on the dismantling sites, hardly representing the pollution status of PBDEs in surrounding areas on a large scale. In order to investigate the PBDE contamination status in different types of lands from Guiyu and surrounding areas, in this paper topsoil samples were collected in a gridded area of 72 square kilometers covering Guiyu and the surrounding area were analyzed for the geographical distribution patterns of eight PBDEs congeners by using soxhlet extraction, complex silica gel-alumina chromatographic column and Gas Chromatography-Mass Spectrometry. The results show that PBDE contamination in soils of the studied areas has not been improved in comparison with the published data in 2005. The PBDE contamination in rice field was reduced. PBDE 209 is the dominant congener (dry weight: 0.4-720.9 ng/g). The concentration of PBDE 209 was ten times higher than non-209 PBDE congeners which were at levels of nd-83 ng/g (dry weight). PBDE 209 was distributed mainly around Guiyu downtown dismantling sites and the nearby area. The differences in geophysical distribution patterns of PBDE congeners were related with the distribution of the dismantling sites and the molecular weight of the compounds. The congeners with similar molecular weight showed close geographical distributions, suggesting the influences from the physico-chemical properties such as vapor pressure and water solubility. PBDEs with larger molecular weight were distributed mainly around the Guiyu downtown and nearby villages' dismantling sites. The distribution of congeners with medium molecular weight was related with to particular sites. The low molecular weight congeners displayed a diffusion pattern starting from Guiyu downtown. The composition of PBDE compounds showed that fractionation may have occurred during the diffusion process from the source sites to clean areas. It was found that PBDE 209 is the dominant congener and its distribution patterns and compound composition are discussed.