Bioaccessibility And Health Risk Of Heavy Metals In Atmospheric Particulate Matters From Residential And Industrial Areas In Shanghai,China

With the development of the industrialization,vechile exhaust,construction activity,and natural engery utilization release a lot of particles into the air.These atmospheric particulate matters cause a getting serious pollution.Especially in recent years,the heavy haze has frequently happened in some major cities in China,which raises the great concen of the Chinese govement and people.In this study,the atmospheric particulate matters were collected from residential and industrial areas in Shanghai between November and December in 2014.The bioaccessibility and human health risks of heavy metals in the atmospheric particulate matters were evaluated using the typical simulated respiratory Gamble method,simulated digestive PBET method and human health risk models.The main results were obtained as follows:?1?The concentration of atmospheric particulate matters in the two functional areas during sampling period continued to increase.The average daily concentrations were higher than the first class standard of the"National Ambient Air Quality Standard"?GB3095-2012?,but below the second standard limits.The average daily concentration of atmospheric particulate matters in the residential area was slightly lower than the average of Shanghai over the sampling period,while the significantly higher results were observed in the industrial area,due to t large-scale coal-fired emissions,which is considered as the main source of atmospheric particulate matters in this area.The average concentration ratio?R?of PM_2.5 to PM₁₀ in Shanghai was in the range of 0.44-0.88,with the average value of 0.64.The average R-value in the residential area was 0.63,with the range of 0.41-0.92,while range of R-value in the industrial area was 0.47-091,with the average value of 0.62.The results indicated the particle size distribution has a high relation with the functional areas due to the different particle emission sources.?2?The mean contents of 7 important heavy metals in both PM₁₀ and PM_2.5 followed the order of Zn>Pb>Cu>Mn>Ni?Cr>Cd.Cu,Ni,Pb,Zn,and Cr were more accumulated in PM_2.5 than that in PM₁₀.There were no significant differences about the enrichments of Mn and Cd in different diameter atmospheric particulate matters.On different functional areas in terms of distribution of heavy metals,in addition to Mn,the contents of heavy metals in industrial area were less than residential area.The order of the mean concentrations of heavy metals in both PM₁₀and PM_2.5 particulates is similar with that of the mean values of contents.However,the concentrations of heavy metals in PM₁₀ was higher than in PM_2.5,since there contained more PM₁₀ than PM_2.5 in atmosphere.The concentrations of Cu,Mn,Ni,Pb and Zn in the residential area were higher than those in the industrial area,which may due to the emissions from coal-fired industrial area was higher than car emissions from residential area.?3?The results of the typical simulated respiratory bioaccessibility extraction test of the studied metals varied among elements,with Cd,Mn and Zn showing the higher bioaccessibility?>40%?,followed by Ni,Cu and Pb?5%-25%?,Cr is lowest?<5%?.Bioaccessibility of Mn and Cd in PM_2.5 was higher than in PM₁₀,other heavy metals showed no significant differences.The results of Mn and Pb showed the higher bioaccessibility in residential area than that in industrial area.However,the mean bioaccessible Cu and Ni in the residential PM was significantly lower than that in the industrial samples,s?ggesting that chemical speciation of heavy metals with different sources plays an important role in bioaccessible diversity.?4?In simulated gastric phase,the strong acidity?pH².0?induced high dissolution of heavy metals from atmospheric particulate matters,which resulted in the high bioaccessibility of the studied metals.Cd,Mn and Zn showed the highest bioavailability level?>60%?,followed by Ni,Cu and Pb?15%-45%?,while Cr bioavailability was the lowest?<10%?.In the simulated intestinal phase,the bioaccessibility of heavy metals was significantly reduced,resulting from low acidic condition?pH⁷.0?and addition of trypsin and bile salts.Bioaccessibility of heavy metals in the different diameter atmospheric particles were found no significant difference.Different functional areas of data comparison showed that the mean bioaccessible Cu in the residential PM was significantly lower than that in the industrial samples.However,the results of Mn and Pb showed the higher bioaccessibility in residential area than that in industrial area.?5?Carcinogenic average daily intake of heavy metals in both PM₁₀and PM_2.5 follows the order of Ni>Cd>Cr,and the non-carcinogenic average daily intake follows the decreasing order of Pb,Cd,Zn and Cr,Cu,Mn,Ni.Carcinogenic average daily intake of adult was higher than that of children;while the opposite trend was observed for the non-carcinogenic average daily in take.Since the concentrations of heavy metals in PM₁₀higher than PM_2.5,the average daily intake of heavy metals in PM_2.5?both carcinogenic and non-carcinogenic?was lower.As the concentrations and bioaccessibility of heavy metals were different,the average daily intake of Cu,Mn,Ni and Zn in industrial area was more than that in a residential area,while the opposite exposure dose was evaluated for Pb average daily exposure were less than residential,Cr and Cd in two functions areas resulting similar exposure dose.?6?Carcinogenic risk of the heavy metals for adult via inhalation exposure was higher than that to children.Among them,the carcinogenic risk of Cr and Cd was low and that of Ni can be ignored;Hazard quotients for all 7 heavy metals were lower in adult than those in children.,but the health risks of all 7 heavy metals in both PM₁₀ and PM_2.5 v were within the acceptable level.However,the adequate attention must be paid to Pb and Cd since they had a relatively higher hazard quotient.