Evaluating the Impact of Nutrient Doses on Biostimulation of Petroleum Hydrocarbon Biodegradation in Cold Region Soils

Abstract

Biostimulation by addition of nitrogen (N) and phosphorus (P) for enhancement of biodegradation of petroleum hydrocarbons in contaminated soils is a common practice in sub-Arctic (cold) regions. Based on the data reported in 58 peer-reviewed papers on hydrocarbon degradation in northern region soils, there was no identifiable optimal nutrient dose, although applied doses ranged over 3 orders of magnitude. Microcosm slurry biodegradation experiments conducted over a range of N (41 to 1350 mg/kg) and P (46 and 115 mg/kg) doses, using a northern site soil spiked with Arctic diesel, also showed comparable results. While addition of nutrients improved degradation extents, the degradation extents were not dependent on N and P doses. Biodegradation rate constants for C10–C16 and C16–C24 hydrocarbon fractions, however, showed the highest enhancements for the lowest N dose. Microbial community composition analysis based on 16S rRNA sequencing of DNA extracted from microcosms amended with only diesel, only nutrients, and both diesel and nutrients revealed that diesel enriched hydrocarbon degraders such as Pseudomonadaceae and Burkholderiaceae. Overall, our results and analyses show limited benefits of biostimulation of hydrocarbon degradation with high nutrient doses, and low nutrient doses are generally more or equally effective.