Search

The Tibetan Plateau (TP) serves as the background for persistent organic pollutants around the world. In addition to outside sources, local sources greatly contribute to the environment of the TP in recent decades. Mining activity could serve as an emerging source of polycyclic aromatic hydrocarbons (PAHs), although this issue has been neglected in the TP until now. To investigate the distributions and contributions of PAHs transported from mining activity, forty-one surface soil samples along six sampling directions were collected at a regular distance from the Jiama mining area (JMA) of the TP at altitudes between 3726 and 4863 m. The total concentration of 16 PAHs was 52.34 ± 22.58 ng/g. The result of the source identification suggested that mining activity represented the primary source for heavy molecular weight (HMW) PAHs in soils, while light molecular weight (LMW) and middle molecular weight (MMW) PAHs were contributed by multiple sources. For HMW PAHs, the concentrations and proportions decreased logarithmically with transport distance from the JMA. Furthermore, the transport distance of HMW PAHs was found to be affected by the prevailing wind direction. In addition to transport from the source area, the distributions of LMW and MMW PAHs were also influenced by the altitude. In the impact area of Jiama mining activity, the soil mass inventory was estimated to be 6.4 ± 0.8 tons for HMW PAHs. In future decades, HMW PAHs emitted from Jiama mining activity are projected to exceed 5% of the annual local emission in the TP. Our study evidenced that Tibetan mining activity serves as an important emerging source of PAHs, which would be transported within the TP and threaten the fragile ecosystem of the TP. [ABSTRACT FROM AUTHOR]

The characteristic distribution patterns of hydrocarbons have been used for fingerprinting to identify their sources. The historical air depositions of hydrocarbons recorded in natural media help to understand the evolution of the air environment. Travertine is a natural acceptor of air deposition that settles on the ground layer by layer. To reconstruct the historical air environment of hydrocarbons in the North Tibetan Plateau (NTP), a unique background region, twenty-seven travertine samples were collected systematically from a travertine column according to its precipitated year. For each sample, the precipitated year was dated while n -alkanes and polycyclic aromatic hydrocarbons (PAHs) were determined. Based on source identification, the air environment of hydrocarbons in the past century was studied for the region of NTP. Before World War II, the anthropogenic sources of hydrocarbons showed little influence on the air environment. During World War II and China's War of Liberation, hydrocarbons increased significantly, mainly from the use of fossil fuels. Between 1954 and 1963, hydrocarbons in the air decreased significantly because the sources of petroleum combustion decreased. From the mid-1960s through the end of the 1990s, air hydrocarbons, which mainly originated from biomass burning, increased gradually because agriculture and animal husbandry were developing steadily in Tibet and China. From the late 1990s, hydrocarbons in the atmosphere increased rapidly due to the rapid increase of tourism activities, which might increase hydrocarbon emissions from traffic. The reconstruction of the historical air hydrocarbons in NTP clearly reflects the evolution of the region and global development. [ABSTRACT FROM AUTHOR]

Abstract: In order to assess the health risk of persistent organic pollutants (POPs) in the topsoil of a typical urban renewal area, a comprehensive study was conducted to determine their spatial distribution, possible sources and potential carcinogenic risk. Topsoil samples were collected from former chemical industrial areas in south-east Beijing and tested for concentrations of POPs, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The concentration of PAHs ranged from 126.68 to 365926.17ng/g, OCPs ranged from 2.38 to 933.12ng/g, and PCBs ranged from 47.04 to 3883.77ng/g. The spatial distribution of POPs was mapped using a geographic information system (GIS) to identify hotspots. Although PAHs, OCPs and PCBs varied in terms of their concentration and spatial distribution, the sources of each type of POPs were identified using multivariate statistical analysis and the diagnostic ratios method. Total lifetime carcinogenic risk (TLCR) for PAHs, OCPs and PCBs exposure was evaluated quantitatively for each sampling site using the Risk Assessment Guidance for Superfund (RAGS) methodology, and a risk distribution map was created. The TLCR values of 76% sites for the PAHs were higher than the target level for individual excess lifetime cancer risk (10−6) and with 12% sites were higher than the acceptable levels (10−4) for residential cancer risk. There are 28% sites that have TLCR above 10−6 for recreational exposure to PAHs. [Copyright &y& Elsevier]

A total of 370 samples of agricultural soils were collected from the Pinggu district of Beijing to distinguish the natural and anthropogenic sources of potentially hazardous elements (PHEs) and to investigate the relationships between the PHEs and soil properties. The concentrations of potentially hazardous elements were detected in soil, and their median values (mg/kg) followed a decreasing order: V (81.4) > Zn (75.5) > Cr (68.4) > Ni (27.7) > Cu (27.1) > Co (12.6) > Cd (0.240) > Hg (0.096). The methods of multivariate statistical analysis were applied for source identification. It was determined that Co, Ni, Cr and V were primarily originated from the parent material of the soils, and that Cd, Cu, Zn and Hg were added primarily from agricultural cultivation. These results were confirmed by the method of spatial variability. Furthermore, the results of a linear model of redundancy analysis suggested that Co, Ni, Cr and V were closely associated with Fe 2 O 3 and Al 2 O 3 , while Cd, Cu, Zn, Hg were associated with P, N and organic matter. In addition, the ecological risks were assessed for the evaluated elements in the soil of the study area. Our research provides comprehensive approaches to better understand the potential sources and the fate of contaminants in agricultural soils. [ABSTRACT FROM AUTHOR]

Thirty-one topsoil samples were collected from the area of the Yanshan petrochemical industries to comprehensively determine the spatial distribution, the possible sources and the potential risks of legacy Persistent Organic Pollutants (POPs) in a typical petrochemical industrial area. The total concentration of 16 PAHs, predominantly originated from the local emission from fuel combustion, ranged from 35.29 to 6120.22 ng/g with a mean value of 906.11 ng/g. Organochlorine Pesticides (OCPs) originated mainly from the recent inputs and their total concentrations varied from 4.13 to 7215.24 ng/g with a mean of 336.13 ng/g. Polychlorinated Biphenyls (PCBs) were associated with the usage of commercial products and the total concentrations of 125 congeners ranged from 2.21 to 4008.47 ng/g with a mean of 486.12 ng/g. Residential Total Lifetime Carcinogenic Risk (TLCR) value, higher than the target excess individual lifetime risk (1 × 10 − 6 ), was calculated to be of 22.6% for PAHs, 16.1% for OCPs and 6. 5% for PCBs respectively. Occupational TLCR, higher than the target excess individual lifetime risk was of 9.7% for PAHs, 6.5% for OCPs and 0% for PCBs respectively. In all sampling sites, non-carcinogenic risks expressed as Total Hazard Quotient (THQ) for PAHs, OCPs and PCBs were always below 1. As a consequence, the carcinogenic and non-carcinogenic risks due to exposure to POPs in soil were very low even in such a typical petrochemical industrial area. In the study, the management and the risk assessment of POPs in a petrochemical industrial area close to a metropolis, were evaluated comprehensively. [ABSTRACT FROM AUTHOR]

• Most V, Cr, Ni and As were endogenous, while Cd, Zn, Pb and Hg were anthropogenic and exogenous. • Urban emission was identified as a major source for 8 PTEs in suburban soils. • Relative contributions of three sources to 8 PTEs were estimated by PMF. The risk assessment and source identification for potentially toxic elements (PTEs) in soils, particularly agricultural soils from megacities, are significant for environmental protection and pollution control. In this study, an intensive sampling (4127 topsoil samples and 994 subsoil samples) was conducted in the Shunyi District, Beijing, which is a suburban area with extensive cropland cover and has been impacted by the megacity over several decades. Concentrations and distributions of 8 PTEs, including V, Cr, Ni, As, Cd, Zn, Pb and Hg, were determined, and their possible sources were quantitatively assessed by principal component analysis (PCA), redundancy analysis (RDA), positive matrix factorization (PMF) analysis, and anthropogenic contribution ratio method. Among 8 PTEs, Zn, V and Cr exhibited significantly high concentrations in soils, with means of 68.29, 68.19 and 52.13 mg/kg, respectively, followed by Pb (23.84 mg/kg), Ni (22.91 mg/kg), As (8.30 mg/kg), Cd (0.15 mg/kg) and Hg (0.05 mg/kg). RDA and PCA demonstrated that the rock weathering was a significant source of V, Cr, Ni and As, and the local emissions and atmospheric deposition respectively contributed most of Cd, Zn and Pb, and of Hg in soils. This source category was confirmed the spatial variations of anthropogenic contribution ratios to individual PTEs. PMF results showed that the local emissions contributed 96.3% of Cd, 44.4% of Zn and 32.0% of Pb in soils, and the atmospheric source carrying urban pollutants amounted to 78.7–80.2% of Hg. In this case, several effective analysis methods have been successfully applied to quantify the impact of a megacity to PTEs in suburban soils. These results improve understanding of the contamination status of PTEs in suburban soils from Beijing megacity, and provide basis for policymaker regarding environmental protection and pollution control. [ABSTRACT FROM AUTHOR]