ABSTRACT
Background Air pollutants PM2.5 and its adsorbed metal elements are important factors affecting public health. Objective To explore the distribution characteristics and sources of metal elements in atmospheric PM2.5 in Lanzhou from 2019 to 2020, and to assess the health risks of metal elements to different groups of residents through inhalation. Methods From January 2019 to December 2020 in two districts of Lanzhou City (Chengguan District and Xigu District), regular PM2.5 and metal elements [antimony (Sb), aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), manganese (Mn), nickel (Ni), selenium (Se), and thallium (Tl)] were regularly monitored, and their concentrations were described by the median (M) and 25th and 75th percentiles (P25, P75) as not following a normal distribution (because the detection rates of the five elements Be, Cr, Hg, Ni, and Se were less than 70%, the five elements were not included in subsequent analysis), and then compared with the secondary concentration limits in the Ambient Air Quality Standards (GB 3095-2012). The differences between the medians of the two groups were compared by the Mann-Whitney U rank sum test, and the differences among the medians of multiple groups were compared by the Kruskal-Wallis H rank sum test; the enrichment factor (EF) method and principal component analysis were used to evaluate the pollution degree of the metals and their sources; the health risks of five non-carcinogenic metals (Sb, Al, Pb, Mn, and Tl) and two carcinogenic metals (As and Cd) in PM2.5 were evaluated by hazard index (HI) and hazard quotient (HQ) using the incremental lifetime cancer risk (LCR) model and the non-carcinogenic risk assessment model, respectively. Results The PM2.5 concentrations [M (P25, P75)] in Lanzhou City were 38.50 (26.00, 65.00) and 41.00 (29.00, 63.10) μg·m−3 in 2019 and 2020, respectively, and the difference was not statistically significant (Z=−0.989, P > 0.05). The average levels of the metal elements from high to low were: Al > Pb > Mn > As > Cd > Sb > Tl, and the annual average concentration of each metal element in 2019 was higher than that in 2020 (P<0.05). The M ( P25, P75) of PM2.5 concentrations in Chengguan and Xigu districts were 52.98 (17.00, 61.00) and 55.40 (17.00, 67.00) μg·m−3, respectively, with no statistically significant differences (P<0.05); the concentrations of Sb and Al in Chengguan District were lower than those in Xigu District (P<0.05), and the concentrations of other metal elements were not different between the two areas (P>0.05). There were seasonal differences in the concentrations of PM2.5 and seven metal elements in Lanzhou City (except PAl=0.007, the other Ps < 0.001). The results of the enrichment factor method showed that the EF values of the six metals (Sb, Al, As, Cd, Pb and Tl) were all greater than 1. Among them, except As, the EF values of other metal elements were all greater than 10, and the EF values of Al and Cd were both greater than 100. The results of principal component analysis showed that the variance contributions of the three principal components were 45.61%, 24.22%, and 14.42%, and the cumulative contribution reached 84.25%. The principal component 1 included Pb, As, Cd, and Sb, the principal component 2 included Al and Mn, and the principal component 3 contained Tl. The non-carcinogenic risks of the five metals were, in descending order, Al > Mn > Pb > Tl > Sb, among which the HQ values of the remaining four metals were less than 1 for adults and children, except the HQ value of Al for adults, which was greater than 1. The ILC values of carcinogenic metal As for adult males, adult females, and children were 2.68×10−5, 2.51×10−5, and 1.45×10−5, respectively; the ILC values of carcinogenic metal Cd for adult males, adult females, and children were 1.53×10−6, 1.43×10−6, and 8.26×10−7, respectively. Conclusion There is pollution of atmospheric PM2.5 and its adsorbed metal elements in Lanzhou. As and Cd elements may pose potential carcinogenic risks to the residents.
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The present investigation deals with the accumulation of heavy metals in fields contaminated with fly ash from a thermal power plant and subsequent uptake in different parts of naturally grown plants. Results revealed that in the contaminated site, the mean level of all the metals (Cd, Zn, Cr, Pb, Cu, Ni, Mn and Fe) in soil and different parts (root and shoots) of plant species were found to be significantly (p<0.01) higher than the uncontaminated site. The enrichment factor (EF) of these metals in contaminated soil was found to be in the sequence of Cd (2.33) > Fe (1.88) > Ni (1.58) > Pb (1.42) > Zn (1.31) > Mn (1.27) > Cr (1.11) > Cu (1.10). Whereas, enrichment factor of metals in root and shoot parts, were found to be in the order of Cd (7.56) > Fe (4.75) > Zn (2.79) > Ni (2.22) > Cu (1.69) > Mn (1.53) > Pb (1.31) > Cr (1.02) and Cd (6.06) ~ Fe (6.06) > Zn (2.65) > Ni (2.57) > Mn (2.19) > Cu (1.58) > Pb (1.37) > Cr (1.01) respectively. In contaminated site, translocation factor (TF) of metals from root to shoot was found to be in the order of Mn (1.38) > Fe (1.27) > Pb (1.03) > Ni (0.94) > Zn (0.85) > Cd (0.82) > Cr (0.73) and that of the metals Cd with Cr, Cu, Mn, Fe; Cr with Pb, Mn, Fe and Pb with Fe were found to be significantly correlated. The present findings provide us a clue for the selection of plant species, which show natural resistance against toxic metals and are efficient metal accumulators.
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Monthly, the distribution and enrichment of heavy metals (Fe, Mn, Cu, Pb and Zn) in surface waters were examined at eight sampling sites, in Tapacurá river (Pernambuco State, Brazil), from March 1997 to December 1998 and from June 2005 to March 2006. On average, metal levels ranged from 0.30 to 4.22 for Fe; 0.02 to 1.09 for Mn; 0.001 to 0.014 for Cu; ï£ 0.006 to 0.029 for Pb and 0.003 to 0.020 for Zn, all in mg L-1. Heavy metals presented a great heterogeneous horizontal distribution, with hotspots in municipal and agricultural areas. The enrichment factor (EF) and the potential contamination index (Cp) indicated moderate to severe contamination by Cu and Zn. The results pointed the potential pathways of trace metals via the transport of soil for the river basin, mainly from agricultural areas, and inefficient sewage treatment at the cities. The first step to apply a remedial measure is the inspection of the agricultural areas, the controlled use of fertilizers and herbicides, as well as the development of an efficient sewage treatment to urban areas.
Níveis de metais pesados em águas superficiais de um rio tropical, Estado de Pernambuco, Brasil
Subject(s)
Environmental Pollution , Metals, Heavy , Water QualityABSTRACT
Objective To study the chemical composition and the sources of indoor PM10 in some residential houses in Beijing. Methods PM10 samples were collected using cascade impactors in smoker's and non-smoker's homes in winter. The mass concentrations and enrichment characteristics of nineteen elements, such as Al, Si, and S in airborne particles were analyzed by proton induced X-ray emission (PIXE) and enrichment factor. Results The concentrations of 19 elements were higher in smoker's homes than those in non-smoker's homes in winter, especially K and S concentrations were 2-4 times of those in non-smoker's homes. Al, Si, S, K, Ca and Fe made greater contribution to concentrations of elements in PM10, of which K and S accounted for 72% of total elements in smoker's homes while Al, Si and Ca amounted to 57% of total elements in non-smoker's homes. Conclusion Al, Si, Ca, Ti and Fe come from natural sources while S, Zn, Pb, Cr, Cu, As, Cl and P originated from anthropogenic sources such as smoking, coal combustion and oil combustion.