Influence of new humic preparation on remediation of oil-contaminated soil

Abstract

A humic preparation obtained through alkaline extraction of humic-containing raw materials at the All-Russian Research Institute of Reclaimed Lands (branch of the V. V. Dokuchaev Soil Science Institute) is presented. The aim of the work is to study the effect of the humic preparation – named BoGum – on the remediation of oil-contaminated podzols. In a model experiment for soil remediation, artificially contaminated with oil in an amount of 5%, BoGum was used in 3 doses: as a stimulant of aboriginal microflora (300 l/ha), as a fertiliser (3000 l/ha), and as a sorbent (30000 l/ha). BoGum was found to be more effective as a stimulator of aboriginal microflora, whose maximum was observed one month following application, while the degree of destruction of oil over the two months of the experiment was 40.1%. Over the course of the experiment, it was determined that humic substances of the preparation were a more affordable source of nutrition for the soil microflora when BoGum was used as a sorbent; the breakdown of oil was the lowest when petroleum hydrocarbons were inaccessible to microorganisms due to sorption. The maximum degree of breakdown (44.9%) occurred with the combined use of the microbial preparation MicroBak (development of the Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences) and the humic preparation BoGum at a dosage of 300 l/ha. The preparation demonstrated a synergistic effect, which affected the active development of both hydrocarbon-oxidising microorganisms and aboriginal microflora. The percentage of the hydrocarbon-oxidising microorganisms from the total number of heterotrophs in all experimental variants was maximum in two weeks; this was reduced at different intensities. Calculated multiple regression equations were used to estimate the physiological influence of the groups of microorganisms on the degree of degradation being investigated.