[Source Apportionment and Health Risk Assessment of Heavy Metals in Dust Around Bus Stops in Kaifeng City Based on APCS-MLR Model].

In order to reveal the influence of urban transportation systems on the quality of urban ecological environment, this study selected surface dust from bus stops, which is strongly disturbed by transportation, as the research object. The contents of eight heavy metals (V, Cr, Co, Ni, Cu, Zn, Cd, and Pb) in the dust were determined through inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-ASE). The spatial distribution characteristics and pollution levels of the eight heavy metals in the dust were analyzed using the geo-accumulation index method. A combined qualitative (correlation analysis and principal component analysis) and quantitative (absolute principal component scores-multiple linear regression model (APCS-MLR)) method was used to explore the sources of heavy metals in surface dust near bus stops. The spatial distribution characteristics of heavy metals from different sources were elucidated using the Kriging interpolation method. The health risk assessment model proposed by the United States Environmental Protection Agency was used to evaluate the human health risks. The results showed that the average values of ω(V), ω(Cr), ω(Co), ω(Ni), ω(Cu), ω(Zn), ω(Cd), ω(Pb), and ω(As) in the bus stop surface dust were 68.36, 59.73, 5.81, 19.34, 40.10, 208.32, 1.01, and 49.46 mg·kg-1, respectively. The concentrations of heavy metals (Cd, Zn, Pb, Cu, and Cr) in the dust were all higher than the background values in the surrounding dust, exceeding them by 3.37, 2.70, 2.01, 1.95, and 1.28 times, respectively. The order of the geo-accumulation index for the eight heavy metals was Cd > Zn > Pb > Cu > Cr > V > Ni > Co, with Cd, Zn, Cu, and Pb in the dust indicating mild pollution levels and the others showing no pollution. The source analysis results showed that Cr, Co, and Ni were natural sources, whereas Cu, Zn, Pb, and Cd were traffic sources, and V was derived from a combination of industrial and natural sources. The APCS-MLR results indicated that the average contribution rates of the four sources were as follows:natural source (34.17 %), traffic source (29.84 %), industrial-natural mixed source (14.64 %), and unknown source (21.35 %). The spatial distribution map of the contribution rate of the traffic source was consistent with the trends of traffic volume and bus route density distribution. According to the health risk assessment, the cancer risk and non-cancer risk for children were both higher than those for adults. Cr was the main non-cancer factor, and Cd was the main cancer-causing factor. Natural and traffic sources contributed the most to non-cancer risk and cancer risk, respectively.

[Soil Heavy Metal Contamination, Sources, and Health Risk of Typical Drinking Water Sources in the Suspended Reach of the Lower Yellow River].

With the implementation of ecological protection and a high-quality development strategy in the Yellow River Basin, the environmental conditions around the Yellow River have attracted wide attention from scholars. In this study, the soil of drinking water sources(Heichi and Liuchi) in the typical suspended reach of the lower reaches of the Yellow River was selected as the research object. The geo-accumulation index and pollution load index were used to analyze the pollution characteristics of seven heavy metals(Cr, Ni, Cu, Zn, Cd, Pb, and As), and correlation analysis, principal component analysis, and absolute factor score-multiple linear regression(APCS-MLR) were employed to reveal the sources of soil heavy metals from both qualitative and quantitative perspectives. The health risk assessment model recommended by the United States Environmental Protection Agency(USEPA) was used to analyze the impact of soil heavy metals on human health, and the contribution rate of pollution sources to health risks was analyzed by combining the APCS-MLR model. The results showed that the average values of ω(Cr), ω(Ni), ω(Cu), ω(Zn), ω(Cd), ω(Pb), and ω(As) in the soil around the water source were 60.27, 30.00, 35.14, 77.75, 0.38, 21.74, and 9.70 mg·kg-1, respectively. Except for As, the contents of Cr, Ni, Cu, Zn, Cd, and Pb were higher than the background values of soil elements in the fluvo-aquic soil area of the lower Yellow River, whereas the contents of Cu and Zn in the soil around Liuchi were significantly higher than those in Heichi. Both the geo-accumulation index and the single-factor index showed that the black pond and the willow pond were slightly polluted by heavy metals, and Cd was the main pollution factor. The pollution load index model showed that the number of non-polluted and mildly polluted samples in the study area accounted for 5% and 95% of the total samples, respectively, indicating that the study area was at a mild pollution level. The source apportionment showed that Cr, Ni, Cu, and As were mainly affected by parent materials. The analysis results of the APCS-MLR model showed that the soil pollutants in the study area were mainly from natural sources, traffic sources, agricultural sources, and unknown sources, and their contribution rates were 42.95%, 23.39%, 16.95%, and 16.71%, respectively. The health risk assessment showed that As was the main non-carcinogenic factor, and Ni was the main carcinogenic factor. The non-carcinogenic risk of heavy metals to adults and children was negligible, and there was a tolerable carcinogenic risk to the human body. For both adults and children, the non-carcinogenic and carcinogenic risk contribution rates of the four pollution sources were:natural sources>unknown sources>traffic sources>agricultural sources, among which natural sources contributed the most to non-carcinogenic and carcinogenic risks. Therefore, it is of great significance to study the characteristics, sources, and effects of soil pollution on human health around the water source area of the suspended reach of the lower reaches of the Yellow River, which is of great significance for the protection of water sources and provides theoretical support for the high-quality development of the ecological environment along the Yellow River.

[Pollution Characteristics and Source Analysis of Heavy Metals in Soils in Yellow River Cultural Park Based on APCS-MLR and PMF Receptor Model].

With open spaces and good ecological environments, urban parks have become the first choice for the leisure and entertainment of many people. Therefore, the quality of park soil environments has gradually attracted the extensive attention of scholars. In this study, we take the Yellow River Cultural Park, a typical human disturbance area in the lower reaches of the Yellow River, as the research area to discuss the characteristics and sources of heavy metal pollution in the soil. Thirty-three soil surface samples were collected from the Yellow River Cultural Park, and the contents of seven heavy metals (Cr, Ni, Cu, Zn, Cd, Pb, and As) were determined using an inductively coupled plasma emission spectrometer (ICP-AES) and an inductively coupled plasma mass spectrometer (ICP-MS). The geo-accumulation index and geo-statistics method were used. Meanwhile, the absolute factor analysis-multiple linear regression (APCS-MLR) receptor model and positive matrix factorization (PMF) analysis model were employed to reveal the sources of soil heavy metals. The results showed that the average contents of heavy metals (Cd, Zn, Cu, Pb, and As) in the surface soil of the study area were 4.62, 1.78, 1.41, 1.08, and 1.03 times higher than the background values of soil elements in the tidal soil area of the lower reaches of the Yellow River, respectively. Except for Zn, the contents of other elements were lower than the corresponding values of soil elements in different regions along the Yellow River Basin. Among the seven heavy metal elements, the coefficients of variation of Cd and As were greater than 50%, showing obvious spatial variability. The decreasing trend of the accumulation index of the seven elements was Cd>Zn>Cu>Ni>Pb>As=Cr, and the element Cd belonged to the middle pollution category, which was obviously accumulated in the surface soil. The spatial distribution of heavy metals in the soil differed:the high contents of Cr, Cu, and Ni were distributed in the southwest and northeast, and the high-value areas of Cd and Pb were consistent with the areas of human activity intensity. The high-value areas of Zn and As were located in the center of lacustrine sediments. The combined results of the APCS-MLR and PMF models suggested that the first pollution source of soil heavy metal elements in the Yellow River Cultural Park could have been a natural source, the second pollution source may have been a transportation source, and the third source of pollution was judged as a mixed source. Human activities such as transportation sources and mixed sources were the main sources of heavy metal soil pollution, and Cr, Cu, and Ni were affected by natural factors. The contribution rates of APCS-MLR were 46.67%, 24.11%, 16.12%, and 13.10%, respectively, and the contribution rates of PMF were 35.50%, 35.48%, and 29.02%, respectively. This research can provide a basis for improving the ecological environment quality of the park and improving the health level of the population and can also provide support for the ecological environment risk management and comprehensive management along the Yellow River.