Lead in roadway dusts from different functional areas in a typical valley city, NW China: contamination and exposure risk

Potentially toxic elements in surface fine dust of residence communities in valley industrial cities

A comprehensive analysis of content, pollution characteristics, health hazard, distribution, and source of some broadly concerned potentially toxic elements (PTEs, Pb, V, Mn, Cr, Ba, Zn, Ni, and Cu) in surface fine dust with particle size <63 μm (SFD63) from residence communities in Xi'an, a representative valley industrial city, was conducted in this research to analyze the quality of environment and influencing factors of valley industrial cities in China. The average contents of Ba (794.1 mg kg-1), Cu (61.3 mg kg-1), Pb (99.9 mg kg-1), Zn (408.1 mg kg-1), Cr (110.0 mg kg-1), and Ni (33.4 mg kg-1) in SFD63 of Xi'an residence communities surpassed their background contents of local soil. The high enrichment-value regions of PTEs were chiefly located in the regions with high traffic flow, high population density, and areas around industries. Zn and Pb had moderate enrichment, and the overall pollution level of PTEs was unpolluted-to-moderate and moderate pollution. Three source categories (including natural geogenic source, industrial anthropogenic source, and mixed anthropogenic source of transportation, residential activities, and construction) were identified as the predominant sources for the PTEs pollution in SFD63, with the contribution levels of 29.9%, 32.4%, and 37.7%, respectively. The assessment of health risks according to Monte Carlo simulation revealed that the 95% of the non-cancer risk of PTEs to residents (the elderly, working people, and children) was less than the threshold of 1, while the probability of cancer risk exceeding the acceptable threshold of 1E-6 was 93.76% for children, 68.61% for the elderly, and 67.54% for working people. Industrial source was determined as priority pollution source and Cr was determined as priority pollutant, which should be concerned.

Spatial distribution, pollution level, and health risk of Pb in the finer dust of residential areas: a case study of Xi'an, northwest China

The spatial distribution, pollution level, and exposure risk of Pb in the finer dust (particle size < 63 μm) of residential areas in Xi'an, northwest China were investigated in this study. Geographical information systems and geodetector methods were used to analyze the spatial variability of Pb content in the finer dust of Xi'an and its forming mechanism. The enrichment factor was used to assess the extent of Pb pollution, and the hazard index was used to evaluate the health risks to children and adults exposed to Pb. The results showed that the average content of Pb in the finer dust of residential areas in Xi'an was 99.9 mg kg^-1. In the Xi'an urban area, a higher Pb content was mainly found in the finer dust near the Second Ring Road of Xi'an City, and the Pb content in the old town of Xi'an City was relatively lower than that near the Second Ring Road. The results of geodetector analysis indicate that the spatial variability of Pb in the finer dust of the Xi'an urban area was primarily controlled by the interaction among vehicle emissions, daily behavior of residents, and industrial emissions. Pb in the finer dust from residential areas in all districts showed moderate enrichment. The non-cancer risks of Pb in the finer dust were within the safe range for both children and adults. However, the prolonged exposure risk of Pb in the finer dust of residential areas should be considered for children.

Risk and sources of heavy metals and metalloids in dust from university campuses: A case study of Xi'an, China

College students study and live at university for several years; however, the pollution levels, ecological health risks, and sources of heavy metals and metalloids (HMMs) in the dust found at university campuses are still unknown. In this study, dust samples from university campuses in Xi'an were collected and the Zn, Mn, As, Pb, V, Cr, Co, Cu, Ba, and Ni contents were measured using X-ray fluorescence spectrometry. The pollution levels and ecological health risks of these HMMs were evaluated using the geo-accumulation, pollution load, and potential ecological risk indices and a health risk assessment model while their sources were apportioned using positive matrix factorization. The mean HMM concentrations in the dust were higher than the corresponding background values in the topsoil of Shaanxi Province. The Mn, V, Co, As, and Ni concentrations in the dust samples analyzed were within the levels categorized as no pollution by the geo-accumulation index standard, whereas other HMMs caused pollution to different degrees. Assessment of the pollution load index indicated that the dust samples analyzed were moderate contamination with HMMs. Pb and Cu in the dust presented considerable and moderate ecological risks, respectively; the other HMMs presented low ecological risks. The combined ecological risk of the HMMs measured in the dust samples was considerable. The non-carcinogenic and carcinogenic risks to male and female college students were within the safe levels. This study found three main sources of the HMMs measured in the dust: traffic, natural, and mixed sources (the latter including automobile repair industry waste and paints and pigments), which accounted for 47.5%, 29.3%, and 23.2% of the total HMM concentration, respectively.

Analyzing environmental risk, source and spatial distribution of potentially toxic elements in dust of residential area in Xi'an urban area, China

A comprehensive study on concentration, spatial distribution, pollution, ecological-health risk and source of potentially toxic elements (PTEs) in dust of residential area in Xi'an, China were conducted to explore the environmental quality of residential area in urban district. The results show that the concentrations of V, Ni, and Mn in the dust were less than, while the contents of Cr, Zn, Pb, Cu, and Ba in the dust were obviously larger than, the soil background values of Shaanxi. The high-value area of PTEs primarily concentrated in densely populated areas, heavily trafficked areas and the surroundings of plants. Cr, Pb and Zn posed moderate enrichment and Pb possessed moderate ecological risk in the dust. The comprehensive pollution levels of PTEs in the dust were uncontaminated to moderately contaminated and their comprehensive ecological risk were moderate. The non-carcinogenic risks of the PTEs for adults and children were in the safe level and the carcinogenic risks of Ni and Cr were under the current acceptable value. Four major sources were discriminated on basis of the multivariate statistical analysis results and the content characteristics, enrichment degrees, and the spatial distribution features of the PTEs, viz. Mn, V, and Ni primarily came from natural source; Pb, Zn, and Cu mainly originated from traffic source; and Ba and Cr were respectively from construction source and coal-fired power plant source, which respectively contributed 22.8%, 28.3%, 47.3%, and 1.6% to the total content of PTEs determined in the dust.

Environmental Risk Evaluation and Source Identification of Heavy Metal(loid)s in Agricultural Soil of Shangdan Valley, Northwest China

To understand the environmental quality and heavy metal(loid) pollution of farmlands in Shangdan Valley, the contents of macroelements (Na, K, Si, Mg, Ca, Al, Fe, Ti, P, S, Cl, Br) and heavy metal(loid)s (Cu, Pb, Zn, Mn, Ni, V, Co, Cr, As) were surveyed by the X-ray fluorescence method. The pollution degree and ecological risk of the heavy metal(loid)s were judged by the Nemerow synthetic pollution index, geo-accumulation index, and potential ecological risk index, and their sources were identified by the multivariate statistic method. The mean contents of nine heavy metal(loid)s in Shangdan Valley farmland soil exceeded their corresponding reference values. Soils were not contaminated with As, Cr, Mn, and Ni but were slightly contaminated with Co, Cu, Pb, V, and Zn. Their comprehensive pollution levels were moderate to serious. The ecological risk index of single heavy metal(loid) decreased in the sequence As > Pb > Co > Cu > Ni > V > Zn > Cr > Mn. The source analysis results indicated that Cu, Pb, Zn, and As were highly affected by anthropogenic inputs, e.g., metal smelting and agricultural activities, while Mn, Ni, Cr, and V were principally derived from a natural source. As for Co, it was affected by a mixture source of nature, fossil fuel combustion, and fertilizer.

Lead smelting effects heavy metal concentrations in soils, wheat, and potentially humans

Cadmium, Cu, Pb and Zn concentrations and distribution in soil, wheat, and the potential for human heavy metal accumulation near a Pb smelting affected area were investigated. Farm land soil, wheat grain and scalp hair samples were collected from three villages (named QD, GF and BS) with increasing distance from a large Pb smelter in China. Soil Cd and Pb concentrations exceeded national standards 46-100% of the time, depending on location. Soil and wheat grain Cd, Cu, Pb and Zn concentrations increased as distance to the smelter decreased. Similarly, greater Cd, Cu and Pb concentrations were present in human scalp hair for those residents living closest to the smelter. Decreasing trends existed for hair-to-wheat grain ratios for Cd and Pb as distance to the smelter increased. Results suggest that as distance to the smelter decreases, human heavy metal absorption via the consumption of metal-contaminated food products (e.g., wheat) increases.

Using magnetic susceptibility to evaluate pollution status of the sediment for a typical reservoir in northwestern China

Intensive anthropogenic activities may add to pollution risks to lakes and rivers, which can be revealed by the magnetic characteristics of sediments. The present study aims to assess the pollution status of the sediment of a typical reservoir in northwestern China by application of magnetic susceptibility. The values of magnetic susceptibility exhibited significant positive correlations with trace metals (Co, Cu, Mn, Ni, and V) and natural radionuclides (²³²Th and ⁴⁰K). Multivariate statistical analysis indicated common sources and similar deposition characteristics of magnetic particles and trace metals. It was conformed that magnetic susceptibility could be used as an indicator to identify industrial sources of trace metals, but was not suitable to indicate the traffic or natural sources. Linear regression equations between the low-frequency magnetic susceptibility and the integrated pollution index as well as annual effective dose rate indicated a potential for using magnetic susceptibility in semi-quantitative assessment of trace metal pollution and radiological hazard in sediments. A three-step procedure is proposed for the use of magnetic susceptibility in pollution monitoring, which provides a fast and effective method for estimating the pollution extent and tracing the major sources of trace metals in the sediment of lakes and rivers.