Abstract
The potential toxic element (PTEs) contamination levels, sources, and exposure risk assessment in road dust (RD) from a typical plateau city in southwest China (Kunming) were conducted in this study. The RD was analyzed to determine the PTEs concentrations using ICP-MS. The enrichment factor (EF), geo-accumulation index (Igeo), and multivariate statistical analysis were employed to assess the pollution levels and source identification of PTEs, respectively. In addition, the health risk model was used to assess human health risks. The results showed that the concentrations of PTEs in each functional area could be arranged as follows: CA>TA>IA>RA. The Igeo of Cu, Zn, and Cd were mostly 1–3, which illustrated moderately to heavily contaminate to these element contaminations in each functional (RA, TA, IA, and CA) based on the EF and PCA analysis that the main sources of heavy metals in RD from Kunming are anthropogenic source (61.8%) and natural source (13.4%). The health risk assessment indicates that chromium has a non-cancer risk for children in RA, whereas no cancer risk was found from the inhalation pathways in this study.
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Introduction
Numerous consistent studies suggest that the rapid population growth, rapid development of urbanization and industrialization lead to the urban environmental quality has deteriorated rapidly (Al-Dousari et al., 2017; Ghanavati et al. 2019; Qadeer et al. 2020; Jasrotia et al., 2021). Road dust (RD), the carrier of potential toxic elements (PTEs) and other toxic materials in urban environmental (Xiao et al. 2020), is a useful media to characterize quality of urban environmental (Wang et al. 2020a). RD resuspend into the atmosphere through the action of wind and disperse through different means of transportation, and then enter the human body via inhalation, ingestion, and dermal absorption, which will eventually cause harm to the health of people. It is estimated that more than 1.5 million people worldwide die prematurely every year from exposure to RD (Taiwo et al. 2020). Lead is a neurotoxic element that causes neurodegeneration, cognitive impairment (Mason et al. 2014), and premature delivery (Flora et al. 2011), in particular children, which can cause encephalopathy (Meng et al. 2016); Copper and zinc are essential nutrients, but beyond safety constraints, the former will have central nervous system stimulation, kidney disease, and liver disease, while the latter will have skin irritation, reproductive defects, anemia (Jahandari 2020); hexavalent chromium, cadmium, arsenic, and nickel are carcinogenic elements, while hexavalent chromium can cause damage to human DNA, associated with nasal and sinus cancers (Abreu et al. 2018; Rahman and Singh 2019); cadmium can induce cardiovascular disease, bone disease, and kidney disease, and even prostate and renal cancers (Larsson and Wolk 2016; Fagerberg et al. 2017; Rahman and Singh 2019); arsenic can lead to pigment precipitation, night blindness, abnormality of Mee’s lines (Moradi et al. 2020); nickel can cause immune and nervous system diseases, and even lung cancer (Genchi et al. 2020; Son 2020). As a result of the above negative health effects of PTEs exposed to RD, the ecological and public health concerns have been raised for environmental pollution by PTEs (Doronzo et al. 2016; Doabi et al. 2018; Roy et al. 2019; Pragg and Mohammed 2020; Men et al. 2021).
During the past 10 years, the economy of Kunming city has grown rapidly with the total GDP value, urban population, and the number of cars in 2018 is 2.8, 1.3, and 3.3 times that of 2009 (KMBS, 2010, 2019). These factors are may lead to higher levels of PTEs in urban RD. Our work was conducted (1) to assess PTEs concentrations in RD in different functional areas and (2) to evaluate health risk of PTE in RD from Kunming city. In view of the limited information on PTEs pollution levels and related ecological and health risks caused by RD in Kunming, this research work will help to improve the pollution related to traffic management and improve the environmental quality of Kunming city.
Methods and materials
Kunming (102° 10′-103° 40′ E, 24° 23′-26° 22′ N), located in the southwest of China, is a plateau city and the fourth largest city in western China, with an elevation of 1891 m, the mean annual temperature of 15 °C, and the city covers an area of 2.1013×104 km2. A total of 45 samples (3 sub-samples for each sampling site) of RD were collected during November 2020 from four different functional areas (Fig. 1): 15 from residential area (RA), 12 from traffic area (TA), 9 from commercial area (CA), and 9 from industrial area (IA). At each sampling site, a disposable nylon brush was used to lightly brush about 50.00g of RD in a 1-square-meter area of the ground and the collected samples were stored in sealable and numbered labels polyethylene bags, which were brought back to the laboratory. All samples were naturally air-dried in the laboratory, and then, RD with a diameter (d) of >75 μm was removed from the samples using a nylon sieve with a 200 mesh.
Detailed sample weighing and digestion methods are described in Wang et al. (2020b) report. Briefly, the samples were digested by acid digestion method (HNO3-HF), and the contents of Cu, Mn, Pb, Zn, Cd, Ni, Cr, were determined by ICP-MS (DRC-e, USA. PerkinElmer). We use standard material (GSS-4) for quality control during digestion and instrument analysis. One parallel sample and blank sample (including sample and reagent blanks) are added to every 10 samples. The measured values of elements in the reference material were all within the ranges of standard values, with a relative standard deviation (RSD) of each element is less than 5%.
In order to evaluate the sources, pollution levels and harm to human health of PTEs in RD from different functional areas, enrichment factor (EF), geoaccumulation index (Igeo), principal component analysis (PCA), and health risk assessment method were introduced in our research. Their calculation formulas and related parameter can be found in the supplementary material (Table S1, Table S2, Table S3, and Table S4).
Results and discussion
The total levels of PTEs (Cr, Cu, Zn, Pb, Ni, and Cd) in the RD samples summarized in the Fig. 2. Illustrated by Fig. 2 and Table 1, the mean concentrations of PTEs in the study area are arranged like this: Zn>Cu>Cr>Pb>Ni>Cd. Compared with other cities, Kunming has higher concentrations of PTEs in RD than other large cities in China (e.g., Chengdu and Beijing) (Li et al. 2017). In our study, the Zn (624.23 mg/kg) was found to be the most abundant element in RD, which was 6.96 times of the soil background value. The high concentrations of zinc may come from galvanized road equipment (e.g., lamp posts, road signs, and crash barriers), which is released from corrosion due to various conditions (Yuen et al. 2012; Huang et al. 2014). The average concentrations of Cr, Cu, Pb, and Ni were 2.21, 3.85, 2.92, and 0.94 times of the corresponding soil background values, respectively. Furthermore, although the mean concentration of Cd (3.35 mg/kg) was the lowest among all elements, it was 15.37 times the soil background value.
The concentration of PTEs in RD from different functional areas of Kunming was depicted in Table 1. Except for Ni elements in the RA and TA, the other element concentration exceeds the local soil background values in RA, TA, IA, and the CA, indicating that heavy metals in urban RD may come from natural and anthropogenic emissions. According to the total concentration of elements in each functional area, they can be arranged like this: CA>TA>IA>RA; this result is similar to that in Chengdu, China (Li et al. 2017), Zahedan, Iran (Kamani et al. 2015), and Villavicencio, Colombia (Manuel Trujillo-Gonzalez et al. 2016). In addition, different land use types will cause different changes in the concentration of PTEs. For example, zinc (779.03mg/kg) and lead (127.72mg/kg) are the highest in CA, copper (223.64mg/kg) and cadmium (5.85mg/kg) are the highest in TA, nickel (46.99mg/kg) is the highest in IA, and chromium (155.32mg/kg) is the highest in RA. Therefore, the unique artificial activities of each functional area can discharge different kinds of PTEs and then deposit on the road surface, which leads to the difference of metal level between different functional areas (Manuel Trujillo-Gonzalez et al. 2016).
Illustrated by Table 2, the mean EF were 1.81 for Cr, 3.17 for Cu, 5.54 for Zn, 2.37 for Pb, 0.75 for Ni, and 12.07 for Cd, and they could be classified as follows: Cd>Zn>Cu>Pb>Cr>Ni. The EF values of Cd in RA, TA, IA, and CA are in the range of 5–20, which is significant enrichment. The EF values of Cu and Pb in RA, TA, IA, and CA are in the range of 2–5, which is moderate enrichment. EF values for Ni in RA, TA, IA, and CA were lower than 1, illustrating that anthropogenic factors are not remarkable. The mean Igeo were 0.46 for Cr, 1.14 for Cu, 1.94 for Zn, 0.79 for Pb, −0.72 for Ni, and 2.92 for Cd, and they could be classified as follows: Cd>Zn>Cu>Pb>Cr>Ni. The Igeo data for Ni indicated was unpolluted level while uncontaminated to moderate levels for Cr and Pb; copper and Zn were moderately contaminated; The Igeo data for Cd is greater than 2 but less than 3, illustrating that there was moderately to heavily contaminated. In addition, the EF and Igeo of Cd in the RD from TA were higher than in other functional areas. Complicated anthropogenic sources give rise to the high Cd concentration in the TA area with a higher vehicle density. In fact, the number of motor vehicles in Kunming has been increasing continuously in recent years, reaching 2.5 million by 2019 (KMBS, 2020). Therefore, tires and car batteries are potential sources of Cd pollution.
In our study, principal component analysis (PCA) was used to determine the main sources and contributions of PTEs in RD from Kunming City. Table S5 shows that the first three factors (PC1, PC2, and PC3 were 39.1%, 22.7%, and 13.4%, respectively) explain 75.2% of the total variable. PC1 is vital and accounts for about 39.1% of the total variance. This factor may be related to vehicles, for example, Zn and Cd are used in the manufacture of car tires, zinc borate is used as an additive in polymers needed to make car glass, and lead, cadmium, and zinc are also known to be trace elements in traffic exhaust (Heidari et al. 2021; Vlasov et al. 2021). In addition, correlation analysis also showed that Pb-Zn, Cd-Zn, Cd-Cu, and Zn-Cu had strong positive correlations, which were 0.422, 0.517, 0.364, and 0.379, respectively (Table S6). PC2 was dominated mainly by Cr with a loading value of 0.7 and accounts for 22.7% of the entire variance. Generally, the Cr in urban dust is chiefly derived from traffic emissions, industrial activities, consumption residuals, and thermal power plants (Han and Lu 2017; Pan et al. 2017; Yu et al. 2021). In our research, the average concentration of Cr was 2.21 times of the background value of the soil. Combined with the geographical location of Kunming city and the power plant, it was concluded that the Cr in the RD studied was mainly dominated by emissions from coal-fired power plants. Contributions of PC3 to the total variance comprise 13.4%. This factor mainly comes from natural sources (e.g., local soil).
Taking into consideration the adverse influences of PTEs on human health, the values of HQing, HQinh, HQderm, and HI were calculated. For children, the HI value of Cr in RA is 1.01 (exceeding safety value of 1), illustrating that children have a non-carcinogenic risk (Fig. 3). For adults, the HI value of PTEs in RA, TA, IA, and CA is exceeded safe value of 1, illustrating that adults have no non-carcinogenic risk (Fig. 4). In addition, as shown in Fig. 3 and Fig. 4, the level of ingestion to HI was the highest in all four areas, among the exposure pathways. Therefore, ingestion is the main exposure pathway of PTEs in RD from Kunming. In our research, we use Cr, Ni, and Cd to assess carcinogenic risk. As shown in Fig. 5, Cr, Ni, and Cd were lower than the acceptable threshold value 1E-6 in all functional areas, illustrating that Ni, Cd, and Cr have no carcinogenic risk to RD exposure.
Conclusions
The PET levels in the RD from different functional areas of Kunming city in SW China were assessed. Furthermore, the human health risks caused by PTEs were investigated. The average level of Cr, Cu, Zn, Cd, Pb, and Ni was all higher than the corresponding soil background values in Yunnan Province. According to the total concentration of elements in each functional area, they can be arranged as like this: CA>TA>IA>RA. EF and Igeo studies show that the heavy metals have the same order as follows: Cd>Zn>Cu>Pb>Cr>Ni. Zinc, copper, and cadmium are the main pollutant elements in CA, TA, IA, and RA, and their Igeo values range from the level of moderately to heavily contaminated. PCA showed that the main sources of RD in Kunming city were traffic exhaust, tire wear, coal burning, and natural sources (e.g., local soil). The health risk assessment model showed that the HI children-RA value of Cr is higher than safety level, illustrating that children have non-cancer risk. The results also determine the carcinogenic risk thresholds for Cr, Ni, and Cd, which were all lower than 1E-6, and have no carcinogenic risk.
References
Abreu PL, Cunha-Oliveira T, Ferreira LMR, Urbano AM (2018) Hexavalent chromium, a lung carcinogen, confers resistance to thermal stress and interferes with heat shock protein expression in human bronchial epithelial cells. Biometals 31(4):477–487
Al-Dousari A, Doronzo D, Ahmed M (2017) Types, indications and impact evaluation of sand and dust storms trajectories in the Arabian Gulf. Sustainability 9(9):1526
CNEMC China National Environmental Monitoring Center (1990) The background values of elements in Chinese soils. Environ Sci Press of China Beijing (in Chinese)
Doabi SA, Karami M, Afyuni M, Yeganeh M (2018) Pollution and health risk assessment of heavy metals in agricultural soil, atmospheric dust and major food crops in Kermanshah province, Iran. Ecotox and Environmental Safety 163:153–164
Doronzo DM, Al-Dousari A, Folch A, Dagsson-Waldhauserova P (2016) Preface to the dust topical collection. Arab J of Geosci 9(6).
Fagerberg B, Borne Y, Barregard L, Sallsten G, Forsgard N, Hedblad B, Persson M, Engstrom G (2017) Cadmium exposure is associated with soluble urokinase plasminogen activator receptor, a circulating marker of inflammation and future cardiovascular disease. Environ Res 152:185–191
Flora SJS, Pachauri V, Saxena G (2011) Arsenic, cadmium and lead. Reproductive and Developmental Toxicology 415-438
Genchi G, Carocci A, Lauria G, Sinicropi MS, Catalano A (2020) Nickel: human health and environmental toxicology. Int J Env Res Pub He 17:679
Ghanavati N, Nazarpour A, Watts MJ (2019) Status, source, ecological and health risk assessment of toxic metals and polycyclic aromatic hydrocarbons (PAHs) in street dust of Abadan, Iran. Catena 177:246–259
Han X, Lu X (2017) Spatial distribution, environmental risk and source of heavy metals in street dust from an industrial city in semiarid area of China. Arch Environ Prot 43(2):10–19
Huang MJ, Wang W, Chan CY, Cheung KC, Man YB, Wang XM, Wong MH (2014) Contamination and risk assessment (based on bioaccessibility via ingestion and inhalation) of metal(loid)s in outdoor and indoor particles from urban centers of Guangzhou, China. Sci Total Environ 479:117–124
Jahandari A (2020) Pollution status and human health risk assessments of selected heavy metals in urban dust of 16 cities in Iran. Environ Sci Pollut R 27(18):23094–23107
Jasrotia R, Kumari N, Kumar R, Naushad M, Dhiman P, Sharma G (2021) Photocatalytic degradation of environmental pollutant using nickel and cerium ions substituted Co0.6Zn0.4Fe2O4 nanoferrites. Earth Systems and Environment 5(2):399–417
Kamani H, Ashrafi SD, Isazadeh S, Jaafari J, Hoseini M, Mostafapour FK, Bazrafshan E, Nazmara S. Mahvi AH (2015) Heavy metal contamination in street dusts with various land uses in Zahedan, Iran. B Environ Contam Tox 94(3): 382-386
KMBS (Kunming Municipal Bureau of Statistics) National Economic Accounting. Statistical Yearbook of Kunming (2010, 2019, 2020) (in Chinese)
Larsson SC, Wolk A (2016) Urinary cadmium and mortality from all causes, cancer and cardiovascular disease in the general population: systematic review and meta-analysis of cohort studies. Int J Epidemiol 45(3):782–791
Li HH, Chen LJ, Yu L, Guo ZB, Shan CQ, Lin JQ, Gu YG, Yang ZB, Yang YX, Shao JR, Zhu XM, Cheng Z (2017) Pollution characteristics and risk assessment of human exposure to oral bioaccessibility of heavy metals via urban street dusts from different functional areas in Chengdu, China. Sci Total Environ 586:1076–1084
Manuel Trujillo-Gonzalez J, Aurelio Torres-Mora M, Keesstra S, Brevik EC, Jimenez-Ballesta R (2016) Heavy metal accumulation related to population density in road dust samples taken from urban sites under different land uses. Sci Total Environ 553:636–642
Mason LH, Harp JP, Han DY (2014) pb neurotoxicity: neuropsychological effects of lead toxicity. Biomed Re Int 2014: 840547
Men C, Liu RM, Wang QR, Miao YX, Wang YF, Jiao LJ, Li L, Cao LP, Shen ZY, Li Y (2021) Spatial-temporal characteristics, source-specific variation and uncertainty analysis of health risks associated with heavy metals in road dust in Beijing, China. Environ Pollut 278.
Meng HT, Wang L, He JH, Wang ZF (2016) The protective effect of gangliosides on lead (Pb)-induced neurotoxicity is mediated by autophagic pathways. Int J Env Res Pub He 13(4):365
Moradi Q, Mirzaei R, Alipour M, Bay A, Ghaderpoori M, Asadi A, Fakhri Y, Sorooshian A, Mousavi Khaneghah A (2020) The concentration, characteristics, and probabilistic health risk assessment of potentially toxic elements (PTEs) in street dust: a case study of Kashan. Iran. Toxin Rev.:1–10. https://doi.org/10.1080/15569543.2020.1728336
Pan H, Lu X, Lei K (2017) A comprehensive analysis of heavy metals in urban road dust of Xi’an, China: contamination, source apportionment and spatial distribution. Sci Total Environ 609:1361–1369
Pragg C, Mohammed FK (2020) Distribution and health risk assessment of heavy metals in road dust from an industrial estate in Trinidad, West Indies. Int J Environ Heal R 30(3):336–343
Qadeer A, Saqib ZA, Ajmal Z, Xing C, Khalil SK, Usman M, Huang YP, Bashir S, Ahmad Z, Ahmed S, Thebo KH, Liu M (2020) Concentrations, pollution indices and health risk assessment of heavy metals in road dust from two urbanized cities of Pakistan: comparing two sampling methods for heavy metals concentration. Sustain Cities Soc 53:101959
Rahman Z, Singh VP (2019) The relative impact of toxic heavy metals (THMs) (arsenic (As), cadmium (Cd), chromium (Cr)(VI), mercury (Hg), and lead (Pb)) on the total environment: an overview. Environ Monit Assess 191:419
Roy S, Gupta SK, Prakash J, Habib G, Baudh K, Nasr M (2019) Ecological and human health risk assessment of heavy metal contamination in road dust in the National Capital Territory (NCT) of Delhi, India. Environ Sci Pollut R 26(29):30413–30425
Son YO (2020) Molecular mechanisms of nickel-induced carcinogenesis. Endocr Metab Immune 20(7):1015–1023
Taiwo AM, Michael JO, Gbadebo AM, Oladoyinbo FO (2020) Pollution and health risk assessment of road dust from Osogbo metropolis, Osun state, Southwestern Nigeria. Hum Ecol Risk Assess 26(5):1254–1269
Wang J, Huang Y, Li T, He M, Cheng X, Su T, Ni SJ, Zhang CJ (2020b) Contamination, morphological status and sources of atmospheric dust in different land-using areas of a steel-industry city, China. Atmos Pollut Res 11(2):283–289
Wang X, Liu E, Lin Q, Liu L, Yuan H, Li Z (2020a) Occurrence, sources and health risks of toxic metal(loid)s in road dust from a mega city (Nanjing) in China. Environ Pollut 263:114518
Xiao Q, Zong Y, Malik Z, Lu S (2020) Source identification and risk assessment of heavy metals in road dust of steel industrial city (Anshan), Liaoning, Northeast China. Hum Ecol Risk Assess 26(5):1359–1378
Yu B, Lu X, Fan X, Fan P, Zuo L, Yang Y, Wang LQ (2021) Analyzing environmental risk, source and spatial distribution of potentially toxic elements in dust of residential area in Xi'an urban area, China. Ecotox Environ Safe 208:111679
Yuen JQ, Olin PH, Lim HS, Benner SG, Sutherland RA, Ziegler AD (2012) Accumulation of potentially toxic elements in road deposited sediments in residential and light industrial neighborhoods of Singapore. J Environ Manage 101:151–163
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This work was supported by the Opening Fund of Provincial Key Lab of Applied Nuclear Techniques in Geosciences (No. gnzds202003).
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Bo, Q., Wang, J. Pollution levels and health risk assessment of potential toxic elements in road dust from different functional areas of Plateau city in SW China. Arab J Geosci 14, 1960 (2021). https://doi.org/10.1007/s12517-021-08346-y
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DOI: https://doi.org/10.1007/s12517-021-08346-y