A Study on PAHs in the surface soil of the region around Qinghai Lake in the Tibet plateau: evaluation of distribution characteristics, sources and ecological risks

Abstract

In order to evaluate the pollution and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in the soil around the Qinghai Lake, 89 surface soil samples were collected in May 2019. After ultrasonic extraction and purification of silica gel-alumina-anhydrous Na2SO4 chromatographic column, GC-MS was used to test and analyze 16 kinds of monomer PAHs under priority control of USEPA in the samples, so as to study the distribution characteristics, sources and ecological risks. The results are shown as follows: (1) The total amount of 16 kinds of PAHs in the soil of the study area was 169.00 ∼ 638.94 μg·kg−1 , with an average of 318.37 μg·kg−1. The PAHs are dominated by dicyclic and tricyclic aromatic hydrocarbons, accounting for 40.89%∼70.73% of the mass fraction of PAHs, with an average of 49.22%, and phenanthrene accounts for the highest mass fraction. (2) The percentage of sampling points that exceeded the standard (200 μg·kg−1, which represents the upper limit of ‘no pollution’) was 87.6%, dominated by mild pollution(200 ∼ 600 μg·kg−1). The soil pollution in the west and south of the Qinghai Lake is relatively lighter than the north of the Qinghai Lake. (3) The toxicity equivalent concentration of TEQBaP for pyrene ranged from 8.19 to 42.35 μg·kg−1, with an average of 18.82 μg·kg−1. The ecological risk assessment results based on toxicity equivalent concentration and risk quality standard method showed that there was a low risk of PAHs in soil in this study area, and only a few areas exceeding the target reference value, mainly concentrated in the northern area of Qinghai Lake. (4) The results of source analysis by ratio method and principal component analysis method show that PAHs in the surface soil of the region around the Qinghai Lake come mainly from the combustion of oil and biomass.

Spatial occurrence and sources of PAHs in sediments drive the ecological and health risk of Taihu Lake in China

“…2 ). Many studies compared the concentration of ∑ 16 PAHs in the surface sediments in China 12 , 35 – 37 . Only the average concentrations of ∑ 16 PAHs in Chaohu Lake, China 38 and Tecocomulco Lake, Mexico 39 were greater than 10,000 ng g −1 , which could induce aquatic metabolism disorders and promote unpredictable effects on humans’ health.…”

Distribution and Relationships of Polycyclic Aromatic Hydrocarbons (PAHs) in Soils and Plants near Major Lakes in Eastern China

“…On the other hand, medium to low volatility atmospheric PAHs are more prone to wet and dry deposition [ 37 ], so Phe with lower volatility is more likely to enter soil and plants than Nap. For PAHs in soil, Phe is also dominant in rural soils in China [ 38 ] and in soils near Qinghai Lake [ 39 ]. In urban soils in China [ 31 ], soils of the Yangtze River Delta [ 40 ] and soils of the Yinma River Basin [ 41 ], the content of Phe is not the highest, but it still ranks in the forefront.…”