Fingerprint analysis reveals sources of petroleum hydrocarbons in soils of different geographical oilfields of China and its ecological assessment.

The distribution and characteristics of petroleum in three different geographic oilfields in China: Shengli Oilfield (SL), Nanyang Oilfield (NY), and Yanchang Oilfield (YC) were investigated. The average concentration of the total petroleum hydrocarbons (TPHs) conformed to be in the following law: SL Oilfield > NY Oilfield > YC Oilfield. Fingerprint analysis on the petroleum contamination level and source was conducted by the geochemical indices of n-alkanes and PAHs, such as low to high molecular weight (LMW/HMW) hydrocarbons, n-alkanes/pristine or phytane (C17/ Pr, C18/Ph), and ratio of anthracene/ (anthracene + phenanthrene) [Ant/(Ant + Phe)]. Soils adjacent to working well oils indicated new petroleum input with higher ratio of low to high molecular weight (LMW/HMW) hydrocarbons. The oil contamination occurred in the grassland soils might result of rainfall runoff. Petroleum source, petroleum combustion source, and biomass combustion were dominant PAHs origination of soils collected from oil exploitation area, petrochemical-related sites, farmland and grassland, respectively. The suggestive petroleum control strategies were proposed in each oilfield soils. Ecological potential risk of PAHs was assessed according to the toxic equivalent quantity (TEQ) of seven carcinogenic PAHs. The results showed that high, medium, and low ecological risk presented in petro-related area, grassland soils, and farmland soils, respectively. High ecological risk was persistent in abandoned oil well areas over abandoned time of 15 years, and basically stable after 5 years. This study can provide a critical insight to ecological risk management and source control of the petroleum contamination.

Ball-milled biochar can act as a preferable biocompatibility material to enhance phenanthrene degradation by stimulating bacterial metabolism.

The aim of this study was to evaluate the impact of different concentrations of ball-milled biochar pyrolyzed at 300-700 °C on the lethality, growth, metabolism, and degradability of gram-negative petroleum-degrading bacteria. BM-biochar was not toxic to Acinetobacter venetianus, only slowing the growth rate and extending the logarithmic phase. The ability of A. venetianus to produce extracellular polymeric substances (EPS) and biosurfactants was positive with ROS level. The highest degradation efficiency of phenanthrene (PHE) was 2.84-fold that of the control. Mechanism analysis revealed that increased EPS stimulated the adsorption of PHE and biosurfactant enhanced PHE solubility. The improved PHE biodegradability of A. venetianus through phthalic acid pathway is mainly owing to the intensify of PHE bioavailability and accessibility. These findings provide new insights into effects of BM-biochar on cellular responses and indicate that BM-biochar can act as a biocompatible material to enhance the degradation of organic pollutants.