Mugudamani Innocent, Oke Saheed A, Gumede Thandi Patricia
Department of Life Sciences, Central University of Technology, Bloemfontein 9301, Free State, South Africa.
Department of Civil Engineering, Centre for Sustainable Smart Cities, Central University of Technology, Bloemfontein 9301, Free State, South Africa.
Toxics. 2022 May 17;10(5):253. doi: 10.3390/toxics10050253.
The study was aimed at assessing the influence of urban informal settlement on trace element accumulation in road dust from the Ekurhuleni Metropolitan Municipality, South Africa, and their possible health implications. The concentration of major and trace elements was determined using the wavelength dispersive XRF method. The major elements in descending order were SiO (72.76%), AlO (6.90%), FeO (3.88%), CaO (2.71%), KO (1.56%), NaO (0.99%), MgO (0.94%), MnO (0.57%), TiO (0.40%), and PO (0.16%), with SiO and PO at above-average shale values. The average mean concentrations of 17 trace elements in decreasing order were Cr (637.4), Ba (625.6), Zn (231.8), Zr (190.2), Sr (120.2), V (69), Rb (66), Cu (61), Ni (49), Pb (30.8), Co (17.4), Y (14.4), Nb (8.6), As (7.2), Sc (5.8), Th (4.58), and U (2.9) mg/kg. Trace elements such as Cr, Cu, Zn, Zr, Ba, and Pb surpassed their average shale values, and only Cr surpassed the South African soil screening values. The assessment of pollution through the geo-accumulation index (Igeo) revealed that road dust was moderately to heavily contaminated by Cr, whereas all other trace elements were categorized as being uncontaminated to moderately contaminated. The contamination factor (CF) exhibited road dust to be very highly contaminated by Cr, moderately contaminated by Zn, Pb, Cu, Zr, and Ba, and lowly contaminated by Co, U, Nb, Ni, As, Y, V, Rb, Sc, Sr, and Th. The pollution load index (PLI) also affirmed that the road dust in this study was very highly polluted by trace elements. Moreover, the results of the enrichment factor (EF) categorized Cr as having a significant degree of enrichment. Zn was elucidated as being minimally enriched, whereas all other trace elements were of natural origin. The results of the non-carcinogenic risk assessment revealed a possibility of non-carcinogenic risks to both children and adults. For the carcinogenic risk, the total CR values in children and adults were above the acceptable limit, signifying a likelihood of carcinogenic risk to the local inhabitants. From the findings of this study, it can be concluded that the levels of trace elements in the road dust of this informal settlement had the possibility to contribute to both non-carcinogenic and carcinogenic risks, and that children were at a higher risk than the adult population.
该研究旨在评估南非埃库鲁莱尼市都市自治市城市非正式住区对道路灰尘中微量元素积累的影响及其可能的健康影响。使用波长色散X射线荧光光谱法测定了主要元素和微量元素的浓度。主要元素按降序排列为SiO（72.76%）、AlO（6.90%）、FeO（3.88%）、CaO（2.71%）、KO（1.56%）、NaO（0.99%）、MgO（0.94%）、MnO（0.57%）、TiO（0.40%）和PO（0.16%），其中SiO和PO高于页岩平均含量。17种微量元素的平均浓度按降序排列为Cr（637.4）、Ba（625.6）、Zn（231.8）、Zr（190.2）、Sr（120.2）、V（69）、Rb（66）、Cu（61）、Ni（49）、Pb（30.8）、Co（17.4）、Y（14.4）、Nb（8.6）、As（7.2）、Sc（5.8）、Th（4.58）和U（2.9）mg/kg。Cr、Cu、Zn、Zr、Ba和Pb等微量元素超过了它们的页岩平均含量，只有Cr超过了南非土壤筛选值。通过地累积指数（Igeo）评估污染情况表明，道路灰尘受到Cr的中度至重度污染，而所有其他微量元素被归类为未受污染至中度污染。污染因子（CF）显示道路灰尘受到Cr的高度污染，受到Zn、Pb、Cu、Zr和Ba的中度污染，受到Co、U、Nb、Ni、As、Y、V、Rb、Sc、Sr和Th的轻度污染。污染负荷指数（PLI）也证实本研究中的道路灰尘受到微量元素的高度污染。此外，富集因子（EF）的结果将Cr归类为具有显著程度的富集。Zn被阐明为最低程度的富集，而所有其他微量元素均为自然来源。非致癌风险评估结果显示儿童和成人都有可能面临非致癌风险。对于致癌风险，儿童和成人的总CR值均高于可接受限值，这表明当地居民有可能面临致癌风险。从本研究的结果可以得出结论，这个非正式住区道路灰尘中的微量元素水平有可能导致非致癌和致癌风险，并且儿童比成人面临更高的风险。
