The occurrence of selected organic pollutants in the soils of the Songnen Plain, China

Purpose

To protect and improve the soil environment of the Songnen Plain, detailed identification of organic pollutant contamination features in the soil and the degree of contamination is required. The primary goals of this research are to measure the levels of organic pollutants detected in the soil of the Songnen Plain, to correlate the levels of organic pollutants with different land use practices, and to assess the environmental quality of the soil using various pollution indicators.

Material and methods

Contaminated soil was collected in three types of areas: residential (n = 26), agricultural (n = 22), and industrial (n = 12) in the Songnen Plain of Jilin Province, at 0–20 cm and 20–40 cm depths. The concentrations of dichlorodiphenyltrichloroethane, benzene hexachloride, toluene, ethylbenzene, xylene, benzo (a) pyrene (BaP), trichloromethane, tetrachloromethane, hexachlorobenzene, and atrazine in the soil samples were determined using gas chromatography (GC), gas chromatograph-mass spectrometer-mass spectrometer (GC-MS-MS), and high-performance liquid chromatography (HPLC).

Results and discussion

Soil BaP had the highest concentration with a mean value of 20.59 ng/kg, followed by atrazine, hexachlorobenzene, benzene hexachloride, dichlorodiphenyltrichloroethane (DDT), trichloromethane, toluene, ethylbenzene, xylene, and tetrachloromethane with mean concentrations of 0.46, 0.44, 0.34, 0.28, 0.21, 0.14, 0.06, 0.03, and 0.02 ng/kg, respectively. Soil organic pollutants at all sampling sites did not exceed the secondary environmental quality standard values. The most serious soil contamination was found in landfill sites, followed by urban areas, industrial areas, and farmland areas.

Conclusions

Soil contamination is more severe in locations where human activity is more prevalent. The subsoil can better reflect the characteristics of soil pollution in the area compared to the upper layer of soil. Although contamination is low in the research region, the presence of these pollutants must be taken seriously in order to maintain the quality and safety of agricultural products and human health.