| With the rapid economic development,the lifespan of electrical and electronic products has become shorter.The environmental issues on the production and recycling of electrical and electronic devices have been attained attention.In the present study,two typical manufacturing center of electrical and electronic devices and e-waste recycling zone,i.e.,Dongguang and Qingyuan in Guangdong Province,China,were selected as sampling sites.Heavy metals and hydrophobic organic chemicals were target compounds.The present study was conducted to?1?evaluate the potential health risk for residents inhalation exposure to particle-bound heavy metals in the e-waste recycling zone;?2?determine the characterization of hydrophobic organic chemicals in sediments collected in Dongjiang River around Dongguang.The total concentrations of 15 particle-bound heavy metals ranged from 670 to 5200 ng m-3.Comparatively,there was no significant difference in the concentrations of the target metals among the different sampling heights?t-test;p > 0.05?.Enrichment factors were used to identify the source of heavy metals.Fe,Co,and Ti were mainly of natural origin,which were mainly enriched in coarse particles?Dp > 1.8 ?m?.In contrast,Cu,Zn,Se,Pb,Sb,and Cd were contributed mainly from anthropogenic sources,which were predominantly enriched in fine particles?Dp < 1.8 ?m?except for Cu;in addition,the other elements were mixture sources?including natural origin and anthropogenic source?,which were uniform spread in fine and coarse particles.Simplified equations from the International Commission on Radiological Protection model were used to calculate deposition fractions and flux of size-fractionated particle matters in the human respiratory tract.The deposition fluxes of heavy metals in the alveolar region were smaller than those in the head airway,but significantly higher than those in the tracheobronchial region.The relative contribution of particle-bound heavy metals deposition fluxes were size and sources dependent.For example,coarse particles of crustal elements were the major contributor?64%-94%?to the deposition fluxes in the head airway;whereas fine particles contained the majority?55%-94%?of anthropogenic elements in the alveolar region.The chronic daily inhalation intake values of airborne particle-bound heavy metals for adults and children based on the deposition concentrations were 530 ng kg-1(range: 130-1000 ng kg-1)and 3700 ng kg-1(range: 890-7000 ng kg-1),respectively.The total hazard quotient of particle bound heavy metals for adults and children were 2.7?95% confidence interval?CI?: 1.0-5.5?and 8.0?95% CI: 3.0-17?;the total ILCR of five carcinogenic metals?Cr,Co,Ni,As,Cd?for adults and children were 2.3 × 10-4(95% CI: 9.7 × 10-5-4.4 × 10-4)and 6.9 × 10-4(95% CI: 2.9 × 10-4-1.3 × 10-3),both were substantially higher than the acceptable cancer risk threshold of 10-6 set forth by the United States Environmental Protection Agency.The results demonstrated that the health risk for residents in the e-waste recycling zone through inhalation exposure of airborne heavy metal was high,especially for children.Twenty-three surface sediment samples and two sediment cores were collected from Dongjiang River and analyzed for 28 polycyclic aromatic hydrocarbons?PAHs?,24 polybrominated diphenyl ethers?PBDEs?and seven novel halogenated flame retardants?NHFRs?.The results show that the concentrations of BTBPE(ND-890 ng g-1),DBDPE(ND-640 ng g-1),and BDE-209(3.5-12000 ng g-1)were significantly higher than those in sediments collected in other regions in China.The concentrations of 28 PAHs in two sediment cores varied between 450-2300 ng g-1 and 1400-2500 ng g-1,whereas the levels of 16 PAHs were in the ranges of 260-1000 ng g-1 and 690-1300 ng g-1.The trends of concentration profiles of PAHs were different in these two sediment cores.On the other hand,the sediment concentrations of BDE-209 and NHFRs both decreased with increasing sediment depth,indicating that new halogenated flame retardants in replace of PBDEs have been widely used.In addition,the freely dissolved concentrations of PAHs,PBDEs,and NHFRs in sediment porewater were also assessed by the multi-section passive sampler.The concentrations of PAHs in sediment porewater were 93-153 and 360-570 ng L-1.Only BDE-47,-99 and-209 were detected in sediment porewater,and the levels of BDE-47 and BDE-99 in two sampling sites were in the ranges of ND-1.3 × 10-1,1.2 × 10-3-7.4 × 10-2 and 2.0 × 10-2-3.4 × 10-2,8.9 × 10-4-1.1 × 10-2 ng L-1.Also,only BTBPE and DBDPE were detected in sediment porewater,suggesting that those usage amounts were greater than those of other NHFRs. |
PDF Full Text Request