Combined pollution of heavy metals and polycyclic aromatic hydrocarbons in the soil in Shenfu Region, China: a case of three different cities.

It is a challenging issue to investigate the combined pollution of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in urban soils. The purpose of this study was to determine the concentrations of these two pollutants in soils in Shenyang, Fushun, and Fushun New District, to analyze their distribution, their interaction, and co-contamination levels. The concentrations of heavy metals were measured by inductively coupled plasma mass spectrometry (ICP-MS), while the concentrations of 21 kinds of PAH were analyzed by gas chromatography-mass spectrometry (GC-MS). Based on the analysis of pollution concentrations and distribution patterns, the intrinsic links between heavy metals and PAHs in three different cities were assessed using a variety of multivariate analysis methods. Compared to Shenfu New District, the concentration of pollutants in Shenyang and Fushun shows a higher level. Moreover, the results of redundancy analysis (RDA) of samples may quantify the possibility of combined pollution of different heavy metal elements and PAHs. This study also affirms the important role of multivariate analysis in being used to reveal the complex interactions and spatial distribution of different pollutants.

[Occurrence, Distribution, Source, and Health Risk Assessment of Polybrominated Diphenyl Ethers in Surface Soil from the Shen-Fu Region, Northeast China].

The Shen-Fu region is an important urban area in northeast China. We report on a study of the distribution of polybrominated diphenyl ethers (PBDEs) in representative topsoil from this region. In the summer of 2016, 72 soil samples from three cities (Shenyang, Fushun, and Shen-Fu New City) were collected, which covered four land use types:urban, rural residential, cultivated, and woodland. We report on the concentrations, compositions, and distributions of 14 PBDEs in soil and explore their sources, and additionally undertake human exposure analysis and health risk assessments. The results showed that the concentration of ∑14PBDEs in the topsoil ranged from 0.279-50.719 ng·g-1(dry weight), with a mean of (10.466±9.246) ng·g-1. The concentrations of PBDEs was ranked for the cities as:Fushun > Shenyang > Shen-Fu New City > background, and for different land use types as:urban land > rural residential land > cultivated land > forest. Deca-PBDE had the highest proportion of all congeners, accounting for 81.25%-89.23% of all PBDEs. Source analysis indicated that commercial Deca-PBDE was the main source, contributing 66.06% of the total Deca-PBDE according to principal component analysis/multiple linear regression (PCA-MLR). Among five different age groups assessed for exposure, children in Fushun had the highest exposure dose:(20.98±25.01) ng·(kg·d)-1. In terms of different land types, the highest exposure dose was for children living in urban areas:(18.54±20.27) ng·(kg·d)-1. The non-oncogenic health risks in the Shen-Fu region are of a relatively low level.

[Pollution Characteristic and Risk Assessment of Polycyclic Aromatic Hydrocarbons in the Groundwater of Shen-Fu New City in the Hunhe River Basin].

To protect the safety of water used by the residents in Shen-Fu New City, which is undergoing the process of urbanization, 49 groundwater samples were collected along the Hunhe River Basin and 16 US EPA priority control polycyclic aromatic hydrocarbons (PAHs) were analyzed. The occurrence, distribution characteristics, sources, and potential health risk of drinking the groundwater were also assessed in this study. The results show that PAHs were detected in all samples. The concentration of PAHs ranges from 4.38 to 2005.02 ng·L-1, with an average value of (414.64±526.13) ng·L-1. Based on the comparison of the concentration level with that of other regions, the results in this study indicate a higher pollution level. The 3-4 ring PAHs are dominant; the average value was (190.93±238.96) ng·L-1 and (140.01±234.69) ng·L-1, respectively, accounting for 80% of the total PAHs. The distribution of PAHs in the groundwater is affected by the land use types. The concentration of PAHs is higher when the land use type is cultivated land, while it is lower when it is forest land. The source of PAHs was identified using Principal Component Analysis-Multiple Linear Regression (PCA-MLR). It was revealed that 36.26% of the PAHs are due to incomplete combustion of petroleum and gas, 32.72% are due to coal combustion, 28.17% originate from petroleum spills, and 2.87% are due to traffic emissions. The cancer risk levels releated to drinking the groundwater range from 5.55×10-10 to 5.65×10-6 and 13.60% of the values is in the range of 10-6-10-4. The levels are higher than the baseline of the acceptable risk, indicating the potential cancer risk. More attention should be paid to the quality of the groundwater.

[Vertical Distribution Characteristics of PAHs in Soils with Different Land Use Types During Rapid Urbanization].

To study the vertical distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) in the soils from different land use types during urbanization, three land use types (urban land, cultivated land, and woodland) were selected in the eastern part of Shenyang, where urbanization is occurring rapidly. In each case, five soil samples were obtained from different depths (0-1 m). Change in the concentrations of PAHs, vertical migration factors, and the distribution and sources of PAHs were analyzed in the vertical soil profiles. Total concentrations of PAHs in the different soil type were ordered as follows:city 1 (513.19-12689.04 µg·kg-1); dry field (36.18-7196.10 µg·kg-1); paddy field (70.92-747.53 µg·kg-1); city 2 (19.39-636.47 µg·kg-1); and woodland (4.79-349.24 µg·kg-1). PAHs were mainly trapped in shallow soils in urban and forest land, but can migrate deeper into the soil profile in cultivated land. High-ring PAHs were abundant at depths of 0-30 cm, while low-ring PAHs were abundant deeper in the soil profiles. SOM had a significant effect on the vertical distribution of PAHs, and the physical and chemical properties of PAHs had a significant influence on their migration ability. However, combustion sources from industrial activities and transportation in the region are still considered the main sources of PAHs despite the fact that some low-ring PAHs derive from petroleum product inputs.

[Pollution Status and Risks of Dioxin-like Polychlorinated Biphenyls in the Soil of the Yellow River].

The concentration levels, toxic equivalency (TEQ) concentrations, and carcinogenic and non-carcinogenic risks of dioxin-like polychlorinated biphenyls in shore soil from the 40 national key monitoring sections along the entire Yellow River were comprehensively studied. The results showed that the concentrations of ΣDL-PCBs in the soil were between 0.37-7.17 ng·g-1 (dry weight), and the mean value was 0.38 ng·g-1 (dry weight). The TEQ concentrations of DL-PCBs in the soil were between 0.00-30.31 pg·g-1 (dry weight), and the mean value is 13.63 pg·g-1 (dry weight), posing no significant risk to the ecological environment and human health. The carcinogenic and non-carcinogenic risks of DL-PCBs in this study did not exceed the limits set by the USEPA, and there were no obvious health risks. The residents in the middle reaches of the Yellow River were more vulnerable to DL-PCBs.

[Sources and Risk Assessment of Polycyclic Aromatic Hydrocarbons from the Urbanization Process of Topsoil].

To study the effects of urbanization on concentration, sources, and health risks of polycyclic aromatic hydrocarbons (PAHs), 95 topsoil samples were collected from Liaoning Province. For this assessment, 21 PAHs were analyzed via gas chromatography-mass spectrometry and discussed. The results show the total concentrations of the 21 PAHs in background, Shen-Fu, Shen-Yang, and Fu-Shun were 1496.76 µg·kg-1, 3000.50 µg·kg-1, 8705.11 µg·kg-1, and 8178.90 µg·kg-1, respectively, which is positively correlated with the urbanization levels. Diagnostic ratios and PMF modal analysis indicate that the sources of the PAHs in soils were most likely coal combustion and traffic combustion (petroleum combustion). The main sources of PAHs in the four areas were petrochemical combustion (41.0%), coal combustion (64.4%), traffic combustion (67.5%), and traffic combustion (62.0%), that is, with the urbanization process, human activity (mainly traffic combustion) gradually become the major contributor of PAHs to the environment. Health risk assessment showed that the risk of cancer exposure through soil digestion and skin exposure was higher. There is a higher health risk from PAHs in urban soils, and the health risks associated with children and adolescents are greater than with other residents, requiring more attention.

[Concentration, Sources and Ecological Risks of PAHs of Different Land Use Types in Shenfu New City].

The concentration level of polycyclic aromatic hydrocarbon (PAHs) in topsoil from Shenfu New City in urbanization was studied. 54 topsoil samples were collected from Shenfu New City and 4 different land uses (urban land, rural land, forest land, cultivated land) were included. The concentration of PAHs in different land uses was analyzed, the sources of soil PAHs were analyzed by using diagnostic ratios and principal component analysis, and the ecological risks were calculated using toxic equivalency concentrations of BaP and the incremental lifetime cancer risk(ILCR)model. Results indicated that the concentrations of ∑PAHs in urban land, cultivated land, rural land and forest land were in the range of 184-18276, 230-14102, 151-3205, 303-2980 µg·kg-1, respectively. Four land uses had similar sources, the main sources were coal combustion and traffic emission. According to the calculation of ecological risks, there were potential health risks for residents in Shenfu New City, especially urban land, meanwhile, residents were easily exposed to soil PAHs through dermal contact.