| With a staggering e-waste being produced rapidly in the word,the pollution caused by e-waste dismantling cannot be ignore.As the largest e-waste production country and the largest e-waste import country in the past,the persistent organic pollutants(POPs)pollution in China stand out particularly.Taizhou,a coastal city located in Zhejiang Province of China,has been involved in dismantling and recycling e-waste produced globally for over 25 years and is assumed as one of the most developed e-waste dismantling area in China,so our study about POPs pollution in Taizhou dismantling area can dynamically reflect the current e-waste pollution in China,which is of great practical significance.Samples of soil,air,and locally grown crops from around an old e-waste dismantling area(Fengjiang)and a new e-waste dismantling area(Binhai)in Taizhou were collected and analyzed to determine 19 kinds of polychlorinated biphenyls(PCBs),12 kinds of polybrominated biphenyl ethers(PBDEs),2 kinds of dechlorane plus(DPs)and 7 kinds of novel brominated flame retardants(NBFRs)concentrations by GC-MS and GC-MS/MS.The concentration,congeners distribution,historical trend and source of these POPs in soil and air were discussed by comparing historical literatures and statistical analysis.Furthermore,the crop samples were divided into several parts and POPs in each part was analyzed separately.Combined with the POPs distribution in soil,rhizosphere soil and air,the migration rule of POPs in the soil-crop-atmosphere system was preliminarily explored.The results show that:The concentrations of PCBs,PBDEs,DPs and NBFRs in soil from e-waste diamantling area in Taizhou were 0.349-3.56×103 ng g-1 dw,6.18-2.50×103 ng g-1 dw,0.787-1.91×103 ng g-1dw and N.D.-1.56×103 ng g-1 dw,respectively.PCBs and PBDEs were the most prominent halogenated organic pollutants in soil from Fengjiang diamantling area,while PBDEs and DPs were the most prominent halogenated organic pollutants in soil from Binhai diamantling area.Compared with other e-waste dismantling areas at home and abroad,the level of PCBs and NBFRs in soil from e-waste diamantling area in Taizhou were relatively high,and PBDEs and DPs concentrations in soil were at a medium level.Furthermore,these traditional pollutants(such as PCBs and PBDEs)did not decrease significantly in the soil when compared to the historical reasearches in Taizhou.The results of principal component analysis showed PCB congeners in soil were related to PCB commercial products(Aroclor-1254、KC-500 和 KC-1000),so dismantling the imported e-waste caused PCBs pollution in soil at Taizhou.The composition of PBDEs in soil samples is similar to that in PBDE commercial products(Octa-BDEs and Deca-BDEs).Due to the prohibition for Octa-BDEs and Deca-BDEs currently,PBDEs emission in the process of electronic waste treatment in the past and now may be the main source of PBDEs in the soil of this study area.In addition,DPs and NBFRs in soil also showed the significant correlation with e-waste dismantling activity.The concentrations of PCBs,PBDEs,DPs and NBFRs in air from e-waste diamantling area in Taizhou were 156-8.00×103 pg m-3.26.2-3.24×103 pg m-3,2.90-589 pgm-3 and 3.69-1.25×103 pg m-3,respectively.PCBs and PBDEs were the most prominent halogenated organic pollutants in air from Fengjiang and Binhai diamantling area.The level of PCBs in air was equal to that in other polluted heavily areas,while the level of PBDEs and NBFRs were much higher than that of foreign reseaches.which were close to the level of domestic polluted areas.The concentration of DPs in the air was higher than that in the air of most cities and suburbs in China,but far lower than that in the air near the heavily polluted areas such as e-waste dismantling area and DPs production.Remarkably,these traditional pollutants(such as PCBs and PBDEs)did not decrease significantly in the air when compared to the historical reasearches in Taizhou.The frugacity model showed the heavily polluted soil around from e-waste dismantling areas in Taizhou would be a potential"secondary source".The pollutants(PCBs,Tri to Penta-BDEs,PBT,PBBz,PBEB and HBB)tend to volatilize from soil to atmosphere in Taizhou,while other pollutants(BDE-209,syn-DP and anti-DP)tend to deposit from atmosphere to soilPCBs and PBDEs were the most prominent halogenated organic pollutants in crop samples from Fengjiang and Binhai diamantling area,which was consistent with POPs contribution in soil and air.The concentration gradient of POPs in these crops showed the highest concentrations were in roots and leaves and the lowest were in stems,suggesting that POPs entered the crops through a combination of pathways,including root uptake and aerial uptake.For these crops with fleshy root and thick cuticles,PCBs,PBDEs,DPs and NBFRs were preferentially retained in the peel and that only small amounts were transferred from rhizosphere soil into the root flesh.POPs with higher octanol water partition coefficient are more difficult to be absorbed by the roots of crops.Some POPs(log Kow<8)in high-contaminated soil can be availably transported to the root of crop by the passive transport pathway,but these POPs with higher the octanol water partition coefficient(log Kow>8)were difficult to be absorbed by the roots of crops.In addition.the selectivity of plants and the physical-chemical properties of halogenated organic pollutants will affect their distribution in the crop system.Less-chlorinated PCBs(mainly including Tri-PCBs)can enter crops by root uptake and were translocated to the aerial tissues,and more-chlorinated PCBs(including Penta-PCBs and Hexa-PCBs)at high concentrations in soil can enter underground crop tissues through passive transport.More-chlorinated PCBs in underground tissues cannot be transferred to aboveground tissues of tall crops but may be transferred to aboveground tissues of short crops through the root-to-stem pathway and through soil dust being transferred to aboveground external surfaces.Compared with the higher brominated BDEs,the lower brominated BDEs in rhizosphere soil were more easily absorbed by crop roots,and were transferred to other aboveground parts by stem.The uptake selectivity and degradation selectivity of root results in the difference of PBDEs composition in roots.DPs entered the crops through a combination of pathways,the uptake selectivity results in the difference of DPs composition in crops.Compared with HBB,PBT and PBBz were easily absorbed by the roots of crops and transferred to the stems,which may be related to the smaller molecular weight,it caused they were more likely to migrate with transpiration. |
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