| Urban surface dust is a multi-component,complex source of particle mixture.The research of heavy metals in dust has become one of the important contents in the study of urban surface dust.Campus,as the most important learning place for children,children stay on campus for a long time and the micro environment of the campus is of vital importance to children's physical and mental growth.The levels,sources and potential risks of heavy metals in surface dust of the different activities in campus should be paid attention.Selecting Huainan city,the typical coal industry city in Anhui province,samples of dust were collected from the different active areas of 40 elementary schools including TJA,PJ,XJJ,DT,BGS.On the one hand,the heavy metals of the full size dust and fine particle dust from the different campus activities?corridor-CD,playground-PG,school gate-SG?were investigated by ICP-OES.The research scope of urban dust and heavy metal pollution in campus environment were expanded,and the research on the mechanism and distribution of heavy metal pollution on campus dust were strengthened.On the other hand,PBET?Physiologically Based Extraction Test?method was conducted to determine the bioaccessibility of heavy metal?Cd,Co,Cr,Cu,Ni,Pb,V,Zn?in dust of the different elementary school active areas.Morether,the sources an influencing factors of heavy metals were analyzed by IBM SPSS Statistics 20.This study can be more accurate and objective to assess the heavy metals of campus dust on the microscopic scale to harm children,and to ensure the healthy growth of children.The main conclusions are obtained as follows.?1?The distribution of heavy metal in five areas of Huainan primary school were the follow rules.Cd: PJ(1.56 mg·kg-1)> XJJ(1.52 mg·kg-1)> TJA(1.18 mg·kg-1)> DT(0.60 mg·kg-1)>BGS(0.58 mg·kg-1).The content of Cd in the five districts was larger than that in Huainan city with the exceeding standard rate being 100 %.What's more,the content in PJ and XJJ areas were more serious than the background value of soil environment,exceeded 25.55 times and 24.88 times respectively.Co:PJ(11.41 mg·kg-1)> DT(11.00 mg·kg-1)> TJA(10.73 mg·kg-1)> XJJ(10.04 mg·kg-1)> BGS(10.00 mg·kg-1).Ni :BGS(24.89 mg·kg-1)> TJA(24.47 mg·kg-1)> PJ(21.42 mg·kg-1)> XJJ(21.05 mg·kg-1)> DT(19.77 mg·kg-1).V:PJ(63.21 mg·kg-1)> DT(58.66 mg·kg-1)> XJJ(56.43 mg·kg-1)> BGS(55.64 mg·kg-1)> TJA(54.42 mg·kg-1).The spatial variability of Co,Ni,V was not obvious in the five regions,which was lower than or similar to the soil background value.Cr :BGS(121.47 mg·kg-1)> TJA(103.37 mg·kg-1)> XJJ(95.06 mg·kg-1)> DT(65.04 mg·kg-1)> PJ(48.29 mg·kg-1).Cu:TJA(74.88 mg·kg-1)>BGS(57.00 mg·kg-1)> XJJ(54.21 mg·kg-1)> PJ(41.65 mg·kg-1)> DT(28.29 mg·kg-1).Pb:TJA(119.25 mg·kg-1)> XJJ(115.14 mg·kg-1)> BGS(76.38 mg·kg-1)> PJ(62.05 mg·kg-1)> DT(40.25 mg·kg-1).Zn:XJJ(321.53 mg·kg-1)> TJA(291.09 mg·kg-1)> BGS(253.91 mg·kg-1)> PJ(199.17 mg·kg-1)> DT(129.15 mg·kg-1).?2?The average contents of Cd,Co,Cr,Cu,Ni,Pb,V,and Zn in SG were 0.97,9.59,78.08,61.72,22.90,72.09,59.91 and 164.04 mg·kg-1.The contents of Cd,Cu,Pb and Zn were more than 15.91,2.55,2.37 and 2.03 times of the background value of soil environment in Huainan City.The results showed that the heavy metal concentration in SG have different levels of enrichment,which especially the concentration enrichment of Cd was the highest.PG: 1.02,11.09,80.15,42.55,23.99,97.21,57.16,273.21 mg·kg-1.The coefficient of variation were large,which indicated that the spatial heterogeneity is strong duing to the influence of human activities.CD: 1.69,11.46,102.29,67.54,21.08,114.03,54.87,335.29 mg·kg-1.Comparing the spatial distribution of heavy metals from different places,Cd,Co,Cr,Pb,Zn were in order of: CD > PG > SG.Cu: CD > SG > PG.Ni and V in the three active areas were not obvious and didn't have statistically significant differences.The contents of heavy metals Co,Cr,Cu,Ni,Pb,V,Zn in the surface soil of Huainan primary school were 14.73,59.09,40.27,34.38,44.27,88.98,125.12 mg · kg-1.The contents of Cr,Cu,Pb and Zn in soil were much lower than those in dust.Compared with the average content of Zn in dust,the Zn from soil decreased by 2.68 times,followed by Pb,a decline of 2.58 times,Cr decline of times,the lowest decline of Cu was about 1.68 times.?3?The average contents of Cd,Co,Cr,Cu,Ni,Pb,V,Zn of the fine particle size in SG showed 1.15,11.31,84.87,76.47,28.50,81.11,66.0,206.17 mg·kg-1.The Cd concentration was 18.87 times higher than the background and the enrichment level was the highest.PG: 1.38,12.12,94.92,60.10,28.94,117.10,63.97,305.96 mg · kg-1.The average contents of Cd,Cu,Pb,and Zn were 22.69,2.49,3.84 and 3.79 times higher than those of Huainan soil.CD: 1.99,14.07,117.25,93.65,30.69,134.25,60.04,370.12 mg · kg-1.The results showed that Cd,Co,Cr,Ni,Pb and Zn were in the order of CD > PG > SG.Cu showed: CD > SG > PG.?4?The distribution of heavy metals in five regions is as follows.Cd: PJ(2.09 mg·kg-1)> XJJ(1.99 mg·kg-1)> TJA(1.31 mg·kg-1)> DT(0.70 mg·kg-1)> BGS(0.64 mg·kg-1).Co: XJJ(15.73mg·kg-1)> PJ(13.18 mg·kg-1)> TJA(11.18 mg·kg-1)> DT(11.05 mg·kg-1)> BGS(10.73 mg·kg-1).Ni: 29.34 mg·kg-1,20.22 mg·kg-1,34.97 mg·kg-1,29.21 mg·kg-1,28.02 mg·kg-1.V: 57.59 mg·kg-1,59.56 mg·kg-1,71.00 mg·kg-1,58.80 mg·kg-1,67.87 mg·kg-1.Cr: 137.20 mg·kg-1,65.89 mg·kg-1,75.69 mg·kg-1,110.27 mg·kg-1,104.97 mg·kg-1.Cu: XJJ(88.12 mg·kg-1)> TJA(86.85 mg·kg-1)> PJ(74.61 mg·kg-1)> BGS(57.65mg·kg-1)> DT(32.65 mg·kg-1).Pb:XJJ(150.64mg·kg-1)> TJA(121.80 mg·kg-1)PJ(95.14 mg·kg-1)> BGS(80.18 mg·kg-1)> DT(45.47 mg·kg-1).Zn: XJJ(366.13 mg·kg-1)> TJA(322.29 mg·kg-1)> BGS(296.53 mg·kg-1)> PJ(248.91 mg·kg-1)> DT(136.98 mg·kg-1).?5?In gastric stage,the bioaccessible content of Cd,Co,Cu,Cr,Ni,Pb,V,Zn in SG was 0.22,1.32,2.74,5.96,1.46,6.18,6.39,74.41 mg·kg-1.In intestinal stage: 0.08,0.88,3.27,8.71,1.50,3.49,5.27,6.57 mg · kg-1.In PG,the gastric stage: 0.24,1.59,4.26,5.48,3.32,20.79,9.30,94.84 mg · kg-1.In intestinal stage: 0.12,2.42,4.15,10.12,3.84,13.68,9.21,4.12 mg · kg-1.In CD,the gastric stage: 0.54,2.68,11.36,27.27,9.17,27.74,12.09,106.03 mg · kg-1.In intestinal stage: 0.21,2.06,8.44,16.01,4.64,7.41,10.40,16.72 mg · kg-1.The bioaccessible contents of Cd,Pb,V,Zn in the gastric stage at the three active areas were higher than those in the intestinal stage.Except for Pb and Zn,the other six heavy metals showed as corridor dust > playground dust > school gate dust.?6?In gastric stage,the bioaccessible content of Cd,Co,Cr,Cu,Ni,Pb,V,Zn of the fine particle size in SG showed 0.29,3.40,5.93,9.941.02,27.42,11.92,81.41 mg·kg-1.In intestinal stage: 0.15,2.37,4.22,13.13,5.40,6.80,6.18,8.20 mg·kg-1.In PG,the gastric stage: 0.39,4.29,9.62,10.14,4.33,31.68,15.26,117.37 mg·kg-1.In intestinal stage: 0.24,2.78,6.40,24.04,8.78,17.35,14.74,11.14 mg·kg-1.In CD,the gastric stage: 0.60,4.65,14.95,19.68,5.42,56.38,18.08,150.78 mg·kg-1.In intestinal stage: 0.37,2.61,10.07,38.06,13.77,24.71,15.58,16.98 mg·kg-1.Compared with the bioaccessible content in the three activity areas,the content showed: CD > PG > SG.The bioaccessibility of heavy metals was different in different sites,except for Cr and Zn,the bioaccessibility of the other six heavy metals were: CD > PG > SG.These were consistent with the distribution of heavy metal bioavailability in full size dust,which were mainly related to the total amount of fine-grained heavy metals and the bioaccessible content.Except for Zn,the bioavailability was the lowest at SG and the bioavailability of Cr in the three sites was the lowest,which were the same as the bioavailability of Cr in the full grain size.?7?There was a great difference in heavy metals of fine size dust in different regions.In the gastric stage,the bioaccessible content of heavy metals in the same area was different.The bioaccessible content of Zn was the highest and the bioaccessible content of Co and Cd was the lowest,which was mainly related to the total content of fine dust on campus in different areas.In the intestine stage,the bioaccessibility of heavy metals in the fine dust of different areas in Huainan City was different,and the average bioaccessibility of Cu in DT,TJA,XJJ and PJ were the highest.The distribution of bioaccessibility of heavy metals in fine-grained dust were also different in different areas.In general,the bioaccessibility of heavy metals in fine-grained dust in primary schools in TJA,XJJ and PJ was significantly higher than other districts.Which was consistent with the bioaccessibility distribution of heavy metal.The bioaccessibility of Cd,Co,Cu,Pb and Zn increased significantly,which was significantly higher than that of the whole grain size,indicating that the bioaccessibility of fine-particle heavy metals was higher and the potential risk to human body was higher. |
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