Different Emergency Response Strategies to Oil Spills in Rivers Lead to Divergent Contamination Compositions and Microbial Community Response Characteristics

Abstract

Oil spills in inland rivers pose a significant threat to the surrounding environment, and the emergency response differs greatly from that in ocean or coastal areas. In this study, we focused on several commonly used emergency water treatment strategies in China's inland oil spills, as well as the spilled washing oil in a serious accident case. We investigated the changes in oil-related chemical components before and after water treatment using GCxGC-TOF MS (Comprehensive Two-dimensional Gas Chromatography Time of Flight Mass Spectrometer). We tracked the shifts of microbial communities in the microcosms incubated with clean river water, simulated oil-contaminated water, and the treatment effluent. The results revealed that typical components, especially nitrogen-containing heterocyclic compounds, had different removal efficiencies among treatments. The diversity, composition, and potential functions of microbial communities responded differently to the treatments, and could be related to various substances, including PAHs (polycyclic aromatic hydrocarbons) and heterocyclic compounds. A few genera, such as SC-I-84, exhibited a high correlation with washing oil-related components and could serve as an indicator in such an oil spill emergency response. Our findings indicated that simply using petroleum oil or PAHs to evaluate oil spills was likely to underestimate the ecological impact, especially when the spilled substances were coal chemical products widely used in China. This will provide an important scientific basis for decision-making and strategy evaluation in emergency responses to inland oil spills.

Keywords: emergency response; microbial community; oil spill; river sediment; washing oil.

Figure 1

The composition of washing oil-related semi-volatile organic compounds before and after water treatment. (a) heatmap showing the compounds with an average relative abundance of over 0.15%. (b) PCA giving an overview of organic chemical composition of each sample.

Figure 2

Variation in microbial alpha diversity in each microcosm incubated with sediment and simulated contaminated water with/without treatment.

Figure 3

PCoA of microbial community structure based on weighed UniFrac distance, focusing on (a) treatment, and (b) temporal variation. Treatments ADT, AET COT and DCT refer to adsorption, aeration, coagulation and demulsification–coagulation, respectively. While treatment POL refers to untreated simulated oil-contaminated water, and BLK refers to blank control.

Figure 4

Heatmap of dominant microbial groups during incubation and among treatments at (a) phylum level, and (b) genus level. Treatments ADT, AET COT and DCT refer to adsorption, aeration, coagulation and demulsification–coagulation, respectively. While treatment POL refers to untreated simulated oil-contaminated water, and BLK refers to blank control.

Figure 5

Shift of xenobiotic degradation function in each sample compared with the blank control. Treatments ADT, AET COT and DCT refer to adsorption, aeration, coagulation and demulsification–coagulation, respectively. Treatment POL refers to microcosm with untreated simulated oil-contaminated water, and BLK refers to blank.

Figure 6

The levels of PAHs and naphthalene composition and corresponding predicted function abundance on day 3. Treatments ADT, AET COT and DCT refer to adsorption, aeration, coagulation and demulsification–coagulation, respectively. Treatment POL refers to microcosm with untreated simulated oil-contaminated water, and BLK refers to blank.