The effect of the bioremediation of soil contaminated with petroleum derivatives on the occurrence of epigeic and edaphic fauna

This field study investigated the colonization process of soil contaminated with different petroleum products (petrol, diesel fuel, spent engine oil; dose: 6000 mg of fuel·kg^?1 dry mass [d.m.] of soil) by epigeic and edaphic invertebrates during the progress of natural bioremediation and bioremediation enhanced using selected microorganisms (ZB-01 biopreparation). Epigeic fauna was captured using pitfall traps. Occurrence of edaphic fauna in soil samples as well as total petroleum hydrocarbon contents (TPH) were also investigated. Results showed that inoculation with ZB-01 biocenosis allowed the degradation of petroleum derivatives in the soil contaminated with diesel fuel and engine oil, with 82.3% and 75.4% efficiency, respectively. Applying bioremediation to all contaminated soils accelerated the process of recolonization by edaphic invertebrates. However, the 28-month period was too short to observe full population recovery in soils contaminated with diesel fuel and engine oil. Microbe-enhanced bioremediation accelerated recolonization by epigeic invertebrates on soil contaminated with diesel fuel, whereas it exerted inhibitory effect on recolonization of soil contaminated with engine oil (especially by Collembola). The observed discrepancies in the rates of recolonization for soils contaminated with petrol and diesel fuel that were still noted at the stage of no longer different TPH levels justify the idea to include the survey of edaphic faunal density as one of the parameters in the ecological risk assessment of various bioremediation techniques.