Xinwei Lu

Multivariate statistical analysis of heavy metals in street dust of Baoji, NW China

The concentrations of Pb, Cu, Zn, Mn, Ni, Co and Cr in street dust samples from Baoji in north-west China were measured by wavelength dispersive X-ray fluorescence spectrometry, while As and Hg in street dust samples were determined by atomic fluorescence spectrometry. Principal component analysis and cluster analysis, coupled with correlation coefficient analysis, were used to analyze the data and to identify possible sources of these heavy metals. The results indicate that street dust in Baoji has elevated heavy metal concentrations, especially Hg, Pb, Zn and Cu, which are 16-77, 7-92, 6-26 and 4-12 times the background levels in Shaanxi soil, respectively. The mean heavy metal concentrations in street dust divided by the corresponding background values of Shaanxi soil decrease in the order of Hg>Pb>Zn>Cu>Cr>As>Ni>Co>Mn>V. Three main sources of these heavy metals were identified. As, V, Pb and Co originated from nature and traffic. Cu, Zn, Hg and Mn, especially the former two, mainly derive from industry sources, as well as traffic. Cr and Ni mainly originate from soil.

Assessment of metals pollution and health risk in dust from nursery schools in Xi'an, China.

Concentrations, pollution and health risks of metals in dust from nursery schools in Xian, China were determined. In comparison with local soil, dust samples have elevated metals concentrations except for Mn. The results indicate no distinct pollution of Mn, Ni, As and Ba in the dust, while Cu, Co and Zn are moderate pollution, Pb is significant pollution, and Cr with large pollution range. Most samples presented moderately polluted by metals. The non-cancer risks of the studied metals are within the safe range, and the cancer risks of As, Co, Cr and Ni are also within the currently acceptable range.

Metal contamination in campus dust of Xi'an, China: a study based on multivariate statistics and spatial distribution.

The concentrations of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V and Zn in campus dust from kindergartens, elementary schools, middle schools and universities of Xian, China were determined by X-ray fluorescence spectrometry. Correlation coefficient analysis, principal component analysis (PCA) and cluster analysis (CA) were used to analyze the data and to identify possible sources of these metals in the dust. The spatial distributions of metals in urban dust of Xian were analyzed based on the metal concentrations in campus dusts using the geostatistics method. The results indicate that dust samples from campuses have elevated metal concentrations, especially for Pb, Zn, Co, Cu, Cr and Ba, with the mean values of 7.1, 5.6, 3.7, 2.9, 2.5 and 1.9 times the background values for Shaanxi soil, respectively. The enrichment factor results indicate that Mn, Ni, V, As and Ba in the campus dust were deficiently to minimally enriched, mainly affected by nature and partly by anthropogenic sources, while Co, Cr, Cu, Pb and Zn in the campus dust and especially Pb and Zn were mostly affected by human activities. As and Cu, Mn and Ni, Ba and V, and Pb and Zn had similar distribution patterns. The southwest high-tech industrial area and south commercial and residential areas have relatively high levels of most metals. Three main sources were identified based on correlation coefficient analysis, PCA, CA, as well as spatial distribution characteristics. As, Ni, Cu, Mn, Pb, Zn and Cr have mixed sources - nature, traffic, as well as fossil fuel combustion and weathering of materials. Ba and V are mainly derived from nature, but partly also from industrial emissions, as well as construction sources, while Co principally originates from construction.

Heavy metal contamination in dust from kindergartens and elementary schools in Xi’an, China

Concentrations of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in campus dust from kindergartens and elementary schools in Xi’an, China, were analyzed using X-ray fluorescence spectrometry and heavy metal contamination levels were assessed based on the geoaccumulation index (Igeo), enrichment factor (EF) and numero synthesis pollution index (NSPI). The results indicate that, in comparison with Shaanxi soil, dust samples have elevated metal concentrations as a whole, except for V, Mn, Ni, and As. The assessment results of Igeo and EF indicate that V, Mn, Ni, and As in campus dust are uncontaminated, while Ba and Cr are uncontaminated to moderately contaminated, and Co, Cu, Pb, and Zn are moderately to strongly contaminated. The NSPI results show that most dust samples presented heavily contaminated by heavy metals. More attention should be paid to heavy metal contamination of campus dust from kindergartens and elementary schools of Xi’an.

A comprehensive analysis of heavy metals in urban road dust of Xi'an, China: Contamination, source apportionment and spatial distribution

A detailed investigation was conducted to study heavy metal contamination in road dust from four regions of Xian, Northwest China. The concentrations of eight heavy metals Co, Cr, Cu, Mn, Ni, Pb, Zn and V were determined by X-Ray Fluorescence. The mean concentrations of these elements were: 30.9mgkg-1 Co, 145.0mgkg-1 Cr, 54.7mgkg-1 Cu, 510.5mgkg-1 Mn, 30.8mgkg-1 Ni, 124.5mgkg-1 Pb, 69.6mgkg-1 V and 268.6mgkg-1 Zn. There was significant enrichment of Pb, Zn, Co, Cu and Cr based on geo-accumulation index value. Multivariate statistical analysis showed that levels of Cu, Pb, Zn, Co and Cr were controlled by anthropogenic activities, while levels of Mn, Ni and V were associated with natural sources. Principle component analysis and multiple linear regression were applied to determine the source apportionment. The results showed that traffic was the main source with a percent contribution of 53.4%. Natural sources contributed 26.5%, and other anthropogenic pollution sources contributed 20.1%. Clear heavy metal pollution hotspots were identified by GIS mapping. The location of point pollution sources and prevailing wind direction were found to be important factors in the spatial distribution of heavy metals.

Spatial distribution and contamination assessment of heavy metals in urban topsoil from inside the Xi’an second ringroad, NW China

The paper reports the spatial distribution and contamination level of heavy metals (Co, Cr, Cu, Mn, Ni, Pb, Zn and V) in urban topsoil from the interior area of the second ringroad of Xi’an city, China, based on X-ray fluorescence spectroscopy measurements. Geostatistical analysis shows that Co, Cu, and Pb have similar spatial distribution patterns. Heavy traffic density mainly contributed to the high concentrations of Co, Cu and Pb. The spatial distribution of Cr coincides with the industrial activity, whereas the spatial distribution of Zn differs from other heavy metals. The high concentrations of Zn coincide with heavy traffic and high population density. For Mn, Ni and V, natural factors are important in controlling their distribution. The calculated geoaccumulation indices indicate that urban topsoil inside the Xi’an second ringroad was uncontaminated by Cr, V, Mn and Ni, while Pb, Cu, Co and Zn are classified as uncontaminated to moderately contaminated with means of 0.64, 0.46, 0.26 and 0.21, respectively. The Nemero synthesis pollution index of these heavy metals revealed that the topsoil inside Xi’an second ringroad has been heavily contaminated due to anthropogenic activity.

Level and Contamination Assessment of Environmentally Sensitive Elements in Smaller than 100 μm Street Dust Particles from Xining, China

Concentrations of the environmentally sensitive elements (ESEs) As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining were measured using X-ray fluorescence spectrometry and their contamination levels were assessed based on enrichment factor (EF), geoaccumulation index (Igeo) and pollution load index (PLI). The concentrations of As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining are 0.1–0.8, 2.7–10.9, 0.7–5.2, 0.3–1.1, 0.6–2.5, 1.2–11.1, 0.7–1.3 and 0.4–2.9 times the background values of Qinghai soil, respectively. The calculated EF and Igeo values reveal the order Co > Pb > Cu > Zn > V > Ni > Mn > As. The EF and Igeo values of Co, Cu, Pb and Zn are higher indicating that there is considerable pollution by these elements in smaller than 100 μm street dust particles, especially for Co. The EF and Igeo of Mn, Ni and V are lower and the assessment results indicate an absence of distinct Mn, Ni and V pollution in the studied samples. The mean value of PLIsite is 1.14, indicating a slightly pollution in the whole city of Xining. The order of PLIarea for the five tested districts is Center District (CD) > East District (ED) > West District (WD) > North District (ND) > South District (SD), showing that ESEs pollution in the South District is the lightest while it is the highest in the Central District.

Radiological hazards of coal and ash samples collected from Xi’an coal-fired power plants of China

The natural radiological characteristics and their respective annual effective dose (AED) rates, produced by 226Ra, 232Th and 40K in coal, fly ash and bottom ash from two large coal-fired power plants (CFPPs) of Xi’an were determined by means of γ-ray spectrometry. The average activity concentrations of 226Ra, 232Th and 40K in all ash samples (fly ash and bottom ash samples) from the two CFPPs were 67.6, 74.3 and 225.3xa0Bqxa0kg−1, respectively. The results are compared with data from other locations. To evaluate the radiological hazards of the natural radioactivity, the radium equivalent activity (Raeq), air absorbed dose rate (D), AED and external hazard index (Hex) are compared with internationally accepted values. Raeq and Hex of all samples except three fly ash samples were less than the limits of 370xa0Bqxa0kg−1 and unity, respectively. The average D and AED for ash samples were 86.8xa0nGyxa0h−1 and 0.11xa0mSvxa0y−1, respectively, which exceed the world average and Xi’an average values.

Measurement of natural radioactivity and assessment of associated radiation hazards in soil around Baoji second coal-fired thermal power plant, China

Activity concentrations of natural radionuclides (226)Ra, (232)Th and (40)K in soil around Baoji Second coal-fired thermal power plant of China were determined using gamma ray spectrometry. The mean activity concentrations of (226)Ra, (232)Th and (40)K in soil were found to be 40.3 ± 3.5, 59.6 ± 3.1 and 751.2 ± 12.4 Bq kg(-1), respectively, which are all higher than the corresponding average values in Shaanxi, Chinese and world soil. The radium equivalent activity (Ra(eq)), the air absorbed dose rate (D), the annual effective dose (E), the external hazard index (H(ex)) and internal hazard index (H(in)) were evaluated and compared with the internationally reported or reference values. All the soil samples have Ra(eq) lower than the limit of 370 Bq kg(-1) and H(ex) and H(in) less than unity. The overall mean outdoor terrestrial gamma air absorbed dose rate is ∼86.6 ± 3.4 nGy h(-1) and the corresponding outdoor annual effective dose is 0.106 ± 0.004 mSv, which is higher than the worldwide average (0.07 mSv y(-1)) for outdoors annual effective dose.

Content, speciation and pollution assessment of Cu, Pb and Zn in soil around the lead–zinc smelting plant of Baoji, NW China

The concentration and speciation of Cu, Pb and Zn in soil samples collected around the lead–zinc smelting plant of Baoji, NW China, were determined using X-ray fluorescence spectrometry and the modified European Community Bureau of Reference sequential extraction procedure. The single pollution index (PI) and the integrated pollution index (IPI) were calculated to evaluate the contamination levels of Cu, Pb and Zn in the soil. The mean concentrations of Cu, Pb and Zn in the topsoil samples are 31.8, 41.3 and 102.6xa0mgxa0kg−1, respectively, higher than their concentrations in the control sample. The concentrations of Cu, Pb and Zn decreased significantly with depth from 0 to 35xa0cm, while they were relatively constant for depths between 35 and 100xa0cm. The concentrations of Cu, Pb and Zn in topsoil north of the lead–zinc smelting plant decreased exponentially with distance from the plant. Cu and Zn in the soil are mainly associated with the residual fraction, while Pb is dominated by the reducible and residual forms. The mobile fractions of Cu, Pb and Zn in topsoil are Pb (60.1xa0%)xa0>xa0Cu (20.1xa0%)xa0≈xa0Zn (20.6xa0%). The PI for Cu, Pb and Zn varies from 1.1 to 1.4, 1.0 to 2.5 and 1.1 to 2.0, with means of 1.2, 1.4 and 1.4, respectively, indicating that Cu, Pb and Zn are all moderately polluted in the topsoil around the lead–zinc smelting plant. IPI values range from 1.1 to 2.0 with an average of 1.3, showing that the topsoil samples are moderately contaminated by Cu, Pb and Zn.