Abstract
PurposeThe present study envisaged the stoichiometry of microbial biomass in petroleum-contaminated soil, in order to study the influence of the petroleum-contaminated soil on the ecosystem stability.MethodsA typical oil well area in the Northern Shaanxi was considered the research object and the oil pollution status was assessed by studying the physical, chemical, and microbiological characteristics of the soil in the area.ResultsFrom the measurement and analysis of the petroleum pollutants in the soil samples, it was observed that the concentration of the petroleum pollutants around all the oil well areas was higher than the critical value of 500 mg/kg. Furthermore, the C to N ratio of 8 soil samples around the oil wells (0.8:1~13.3:1) was lower than that of the control soil samples in most cases and could not reach the nutrient proportion level required by soil microorganisms. It was observed that the oil organic carbon content at 0~10 m from the wellhead was obviously higher than that in other areas, and decreased with an increase in the distance from the well. Based on the determination of soil organic carbon, total nitrogen, total phosphorus, and the soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), and phosphorus content analysis, it was observed that only the soil organic carbon was significantly positively correlated to the oil pollutants in soil.ConclusionsImbalance in the C to N, SMBC, and SMBN ratio can lead to an acute shortage of the required nutrients than microorganisms, limit the soil microbial reproduction and growth, and thereby slow down the rate of indigenous microbial degradation of petroleum hydrocarbons, so as to reduce the impact of oil pollution on the stability of the entire ecosystem. Therefore, during the remediation of petroleum-contaminated soil in this study area, adequate nutrients need to be reasonably added to the soil.
Highlights
Northern Shaanxi is known to possess rich oil reservoirs, and the petroleum resources are distributed in Yanchang, Ansai, Wuqi, Zhidan, and other counties and towns
In the present study, the typical oil well areas with different mining years in the loess hilly region were selected as the research object, and each well site mouth was taken as the center point to expand to the surrounding area
The results showed that the minimum amount of petroleum hydrocarbons in these soils was 73 mg/kg at 30–50 cm in abandoned oil well area No 8, and the maximum amount was 1090 mg/kg at 10–30 m in it was concluded that the range of oil pollution in the soil around the oil well was about 73–1090 mg/kg, and most of them were higher than the critical value of soil oil pollution 500 mg/kg
Summary
Northern Shaanxi is known to possess rich oil reservoirs, and the petroleum resources are distributed in Yanchang, Ansai, Wuqi, Zhidan, and other counties and towns. Petroleum hydrocarbons pollute the soil by changing the surface properties of the soil particles, composition of soil nutrient, and air composition. It influences the soil microbial community structure leading to crop failures by soil particles adhesion (Mashalash et al 2007; Valeria et al 2007; Wang et al 2009), pore blockage, affecting the soil permeability, and hindering the crop root respiration, thereby causing root rot and killing the crop (Gong He et al 2020; Xu et al 2020; Liu Danqing 2020). Relevant studies have compared the effects of oil pollution on the soil properties and found that the soil with oil pollution has a higher total organic carbon content, C/N ratio, C/P ratio, and lower total nitrogen content, while the total phosphorus content and electrical conductivity exhibit no significant change (Mingyang et al 2020; Wang and Wang 2010)
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