Isotope fractionation (δ13C, δ15N) and microbial community response in degradation of petroleum hydrocarbons by biostimulation in contaminated soil

This study investigated the isotope effects of delta C-13 and delta N-15 and microbial response during biodegradation of hydrocarbons by biostimulation with nitrate or compost in the petroleum-contaminated soil. Compost and KNO3 amendments promoted the total petroleum hydrocarbon (TPH) removal accompanied by a significant increase of Actinobacteria and Firmicutes phyla. Soil alpha diversity decreased after 90 days of biostimulation. An inverse significant carbon isotope effect (epsilon(c) = 16.6 +/- 0.8 parts per thousand) and strong significant nitrogen isotope effect (epsilon(N) = -24.20 +/- 9.54 parts per thousand) were shown by the KNO3 supplementation. For compost amendment, significant carbon and nitrogen isotope effect were epsilon(c) = 38.8 +/- 1.1 parts per thousand and epsilon(N) = -79.49 +/- 16.41 parts per thousand, respectively. A clear difference of the carbon and nitrogen stable isotope fractionation was evident by KNO3 or compost amendment, which indicated that the mechanisms of petroleum degradation by adding compost or KNO3 may be different.

Automated summary

This study investigated the isotope effects of delta C-13 and delta N-15 during biodegradation of hydrocarbons with biostimulation of nitrate or compost in petroleum-contaminated soil. The results showed that KNO3 supplementation had a significant carbon isotope effect and strong nitrogen isotope effect, while compost amendment had significant carbon and nitrogen isotope effects. The findings indicate that the mechanisms of petroleum degradation may vary when using compost or KNO3 as biostimulants.