Detection And Ecological Impact Evaluation Of Persistent Toxic Substances In Shantou- A Typical Area With E-waste Recycling

Electronic waste (E-waste) has become one of the most important environmental problemsin the world. Persistent toxic substances (PTS) from E-waste have resulted in heavy pollutionand pose hazard on ecological system and human health. The E-waste recycling operation atGuiyu, southeast China, is a typical case of the exportation of hazardous wastes from developedcountries to the developing countries. The long history, large scale and primitive treatmenttechnologies of the operation has severely harmed the ecological systems at Guiyu and thedownstream of Lianjiang River and its estuary Haimen Bay. Therefore, it is important toinvestigate and assess the contamination in Guiyu and downstream areas affected by pollutantsfrom E-waste.We surveyed three regions: Guiyu area, the downstream of Lianjiang River, and the HaimenBay. Forty four surface water stations, 30 sediment stations, 12 ground water stations, 16 soilsites and 19 vegetation sites were established. Corresponding background control sites were setup at the Han River, Nanao Island, Tongyu, Hongchang, and Leiling. Samples were collected inJuly 2005 (rainy season), October 2005 (regular river flow), and January 2006 (dry season). ThePTS investigated included heavy metals (Copper, Lead, Nickel, Cadmium, Mercury, andArsenic), Polycyclic Aromatic Hydrocarbons (PAHs), Phthalates (PAEs), and Organochlorinepesticides (OCPs). Samples were processed and analyzed based on standard methods. Heavymetals were determined by AAS and AFS, and organic compounds were analyzed by GC-MS.The results reveal that the environmental pollution from E-waste was severe and thepotential hazard to ecological system included four aspects: 1) heavy metal pollution was mostserious. The concentrations in surveyed regions were significantly higher than those in thecontrol (reference) sites. Cd in surface water, Cd, Ni in ground water, Cu, Ni, Cd in sediment, Cu,Pb, Cd, Hg in soil from Guiyu and Lianjiang River were above the maximum values of ChineseEnvironmental Quality Standards. Concentrations of Pb, Cd, Hg, Ni in the vegetation sites wereabove the standard for Chinese Agriculture Products or FAO/WHO standards. Cu, Ni, Cd insediment, Cu, Pb, Ni, Cd in soil had 6.25％-93.75％probability of very high pollution risk. Cd,Cu in marine sediment had 50％-83.3％probability of low pollution risk; 2) PAHs in the samplesof surveyed regions significantly exceeded those of the reference sites. BaP were detected in thewater and exceeded the Chinese Environmental Quality Standards. Seven PAHs were above theinternational standards in over 50％of the surface water samples and three PAHs were above theinternational standards in 7.1％of the seawater samples. Three carcinogenic PAHs were found in62.5％-100％of the sediment samples. The toxic parameter of carcinogenic PAHs was thehighest in Longgang (0.551) and decreased along the downstream gradient: Guiyu, LianjiangRiver and Haimen Bay. The high-ring carcinogenic PAHs from the burning of E-waste weremost hazardous to the environment; 3) Concentrations of DBP and DEHP in the surveyedregions were significantly higher than those in the reference sites, with 95.2％-97.9％and45.8％-61.9％of the water samples, respectively, having DBP and DEHP concentrations exceeded the quality standards; 4) Concentrations of OCPs in the water samples exceeded theUS EPA standards, with lower concentrations in Guiyu than in Lianjiang River. Among thesediment samples, 12.5％, 87.5％and 100％of the samples from Guiyu, Lianjiang River andHaimen Bay, respectively, were higher than ERM.The spatial and temporal distributions of PTS suggest that they mainly come from thepollutants generated by E-waste recycling. PTS from burning of plastics and dumping ofE-wastes was most harmful to the environment, spread from Guiyu downstream to LianjiangRiver and Haimen Bay via water and air. Joint toxic effects were found among heavy metals,PAils and PAEs, which may pose more hazardous effects on ecological system. There is asignificant correlation in PTS concentrations between water and sediment, suggesting that PTSfrom water was deposited and accumulated in the sediment. There is also significant correlationin PTS concentrations between soil and plant, suggesting that the pollutant can be transferredthrough food web and pose health hazard for human. In addition, PTS concentrations in theground water were also significantly correlated with those of surface water.Other investigations have also shown that the pollution from the E-waste in Guiyu hascaused not only substantial negative effects to the ecological environment, but also the health ofresidents. Although the treatment and control practices have somewhat controlled the pollutionfrom the E-waste at Guiyu, stronger actions are needed to reduce the E-waste recyclingpollution.