Porcellio scaber Latr. and Lumbricus terrestris L.—PAHs Content and Remediation of Long-Term Aging Soil Contamination with Petroleum Products during a Single- and Two-Species Experiment

Abstract

The presence of earthworms in soil contaminated with petroleum products (PPs) increase the rate of decomposition. The use of more than one animal species simultaneously in soil remediation could accelerate the process. However, the effects may be different when long-term aging soil contamination exists during which toxic by-products can be formed. This study evaluated the effect of soil contamination with PPs (petrol, diesel fuel, and used engine oil) carried out 12 and 24 months earlier on the life parameters of Lumbricus terrestris L. during single- and dual-species breeding with Porcellio scaber Latr. The changes in the content of total petroleum hydrocarbons (TPH) in the soil were also measured, as were the levels of polycyclic aromatic hydrocarbon (PAH) accumulation in the bodies of the test animals. Survival of earthworms cultivated separately (single-species experiment) in soil contaminated with diesel fuel 12 months earlier significantly decreased, while body mass gain was not significantly changed under the influence of tested PPs. Breeding of L. terrestris together with P. scaber contributed to significant mortality of earthworms regardless of treatments, while woodlice showed much greater resistance to PPs. Occurrence of both animals in soil contaminated with engine oil 24 months earlier resulted in a significant reduction in TPH after 4 weeks (by 29% compared to the initial soil). The content of PAHs in the tissues of L. terrestris was higher than in P. scaber, and the highest amounts of PAHs were found when earthworms were exposed to engine oil. Use of L. terrestris together with P. scaber can be considered a promising scenario for increasing the effectiveness of remediation of soils contaminated with petroleum products, however, further research is needed to establish conditions preventing excessive mortality of earthworms in such a layout.