The collaborative monitored natural attenuation (CMNA) of soil and groundwater pollution in large petrochemical enterprises: A case study

A large in-service petrochemical enterprises in Northeast China was taken as the research object, and the Collaborative Monitored Natural Attenuation (CMNA) for soil and groundwater pollution was carried out to remedy combined pollution and reduce environmental risks. The pollutants distributions were obtained based on detailed regional investigation (Mar. 2019), and feature pollutants in soil and groundwater were then screened. The spatiotemporal variations of feature pollutants and relative microbial responses were explored during the CMNA process. Furthermore, the CMNA efficiency of the contaminated site at initial stage was evaluated by calculation of natural attenuation rate constant. The results showed that the feature pollutants in soil were 2,2 ',5,5 '-tetrachlorobiphenyl (2,2 ',5,5 '-TCB) and petroleum hydrocarbons (C10-C40), and the feature pollutant in groundwater was 1,2-dichloroethane (1,2-DCA). The concentrations of all feature pollutants decreased continuously during four years of monitoring. Feature pollutants played a dominant role in the variability of microbial species both in soil and groundwater, increasing the relative abundance of petroleum tolerant/ biodegradation bacteria, such as Actinobacteria, Proteobacteria and Acidobacteriota. The average natural attenuation rate constant of 2,2 ',5,5 '-TCB and C10-C40 in soil was 0.0012 d-1 and 0.0010 d-1, respectively, meeting the screening value after four years' attenuation. The average natural attenuation rate constant of 1,2-DCA was 0.0004 d-1, which need strengthening measures to improve the attenuation efficiency.

Automated summary

A study was conducted on a large in-service petrochemical enterprise in Northeast China to carry out Collaborative Monitored Natural Attenuation (CMNA) for soil and groundwater pollution in order to reduce environmental risks. The distribution of pollutants was determined through regional investigation in March 2019, and feature pollutants in soil and groundwater were identified. The study explored the spatiotemporal variations of feature pollutants and their impact on microbial responses during the CMNA process. The efficiency of CMNA at the contaminated site was evaluated by calculating the natural attenuation rate constant, showing a decrease in feature pollutants over four years of monitoring.