A full-scale bioremediation study of diesel fuel-contaminated soil: the effect of plant species and soil amendments

Abstract

This article presents a comprehensive on-site bioremediation of an excavated diesel fuel-contaminated soil aided by various soil amendments and plant species. In the first 125 days, the excavated soil was placed in a land treatment unit, mixed with compost, and seeded with white clover (Trifolium repens). In the next 155 days, the land treatment unit was re-established and divided into four experimental plots. Experimental plots 2 and 3 were seeded with a mixture of plant seeds (Trifolium alexandrinum, Fagopyrum esculentum Moench, Trifolium incarnatum, Phacelia tanacetifolia, Sinapis alba, Trifolium repens), while experimental plots 1 and 4 were left without seeded vegetation. Moreover, a zeolite and an Ascophyllum nodosum-based biostimulant were added to experimental plots 3 and 4. The objectives were to select the most beneficial plant species for the plant-based bioremediation process, to evaluate applicability of different soil amendments for an enhanced hydrocarbon biodegradation, and to study their effects on the microbial community in soil. Our results showed an overall reduction in hydrocarbon pollution by more than 95% within 280 days. The rates of hydrocarbon degradation and changes in the microbial population were not affected by the presence of the zeolite and the biostimulant. In addition, the use of different plant species did not have a statistically significant effect on hydrocarbon degradation but affected microbial population dynamics, confirming stabile and diverse indigenous hydrocarbon-degrading microbial community in the native soil.