Application of whole-cell bioreporters for ecological risk assessment and bioremediation potential evaluation after a benzene exceedance accident in groundwater in Lanzhou, China.

Oil spill events challenge human health and ecosystem safety, which are priority concerned issues for sustainable development. There is then an increasing demand of tools for ecological risks assessment at contaminated sites. In this study, we introduced two whole-cell bioreporters, ADPWH_alk and ADPWH_recA, to measure the available n-alkanes and the genotoxicities of total petroleum hydrocarbons in soils and groundwater which were contaminated by the Benzene Exceedance Accident in Lanzhou, China. Comparing to traditional chemical analysis methods, the whole-cell bioreporter method could provide risk assessment on cell level within a shorter time and a less cost, which is economical and environment friendly. The highest contents of available alkanes in soil and groundwater were 18,737 mg/kg and 308.4 mg/L, respectively. In addition, the available n-alkanes significantly (p < 0.01) correlated to chemical analysis of total n-alkanes. The highest genotoxicity level was found in soil and groundwater samples with lower TPHs concentration (4338.0 mg/kg and 1.4 mg/L Mitomycin C equivalent), suggesting the significant impacts of geochemical variables and alkane availability on the ecological risks of petroleum contamination. Combining chemical analysis and whole-cell bioreporter results, bioremediation strategies were suggested for groundwater and soils with higher n-alkane availability and lower ecological risks, whereas chemical oxidation were suggested for other contaminated sites. For the first time, we mapped the distribution of available n-alkanes and petroleum toxicities in a large scale soil-groundwater system using whole-cell bioreporters, showing their huge potential for rapid contaminant detection and fast risk assessment.