Implications of Soil Pollution with Diesel Oil and BP Petroleum with ACTIVE Technology for Soil Health

Abstract

Grass Elymus elongatus has a potential in phytoremediation and was used in this study in a potted experiment, which was performed to determine the effect of polluting soil (Eutric Cambisol) with diesel oil (DO) and unleaded petroleum (P) on the diversity of soil microorganisms, activity of soil enzymes, physicochemical properties of soil, and on the resistance of Elymus elongatus to DO and P, which altogether allowed evaluating soil health. Both petroleum products were administered in doses of 0 and 7 cm³ kg^-1 soil d.m. Vegetation of Elymus elongatus spanned for 105 days. Grasses were harvested three times, i.e., on day 45, 75, and 105 of the experiment. The study results demonstrated a stronger toxic effect of DO than of P on the growth and development of Elymus elongatus. Diesel oil caused greater changes in soil microbiome compared to unleaded petroleum. This hypothesis was additionally confirmed by Shannon and Simpson indices computed based on operational taxonomic unit (OTU) abundance, whose values were the lowest in the DO-polluted soil. Soil pollution with DO reduced the counts of all bacterial taxa and stimulated the activity of soil enzymes, whereas soil pollution with P diminished the diversity of bacteria only at the phylum, class, order, and family levels, but significantly suppressed the enzymatic activity. More polycyclic aromatic hydrocarbons (PAHs) were degraded in the soil polluted with P compared to DO, which may be attributed to the stimulating effect of Elymus elongatus on this process, as it grew better in the soil polluted with P than in that polluted with DO.

Keywords: PAHs degradation; bacteria metagenomics; enzymatic activity; grass resistance.

Figure 1

Microbiological properties of uncontaminated soil (C), soil contaminated with diesel oil (DO) and unleaded petroleum (P); (a) count of soil microorganism presented by the Principal Component Analysis (PCA) method; (b) physiological diversity index of microorganisms (EP); (c) colony development index (CD). Homogeneous groups denoted with letters (a, b, c) were calculated separately for each of microorganism. Org—organotrophic bacteria, Act—Actinobacteria, Fun—fungi.

Figure 2

The relative abundance of dominant phylum of bacteria in the soil with the difference between proportions ≥1%. C—uncontaminated soil, DO—soil contaminated with diesel oil, P—soil contaminated with unleaded petroleum.

Figure 2

The relative abundance of dominant phylum of bacteria in the soil with the difference between proportions ≥1%. C—uncontaminated soil, DO—soil contaminated with diesel oil, P—soil contaminated with unleaded petroleum.

Figure 3

The relative abundance of dominant classes of bacteria in the soil with difference between proportions ≥1%. C—uncontaminated soil, DO—soil contaminated with diesel oil, P—soil contaminated with unleaded petroleum.

Figure 4

The relative abundance of dominant orders of bacteria in the soil with difference between proportions ≥1%. C—uncontaminated soil, DO—soil contaminated with diesel oil, P—soil contaminated with unleaded petroleum.

Figure 5

Abundance of bacterial communities at the family level (a) and genus level (b) in uncontaminated soil (C), soil contaminated with diesel oil (DO) and soil contaminated with unleaded petroleum (P). Abundances <1% are gathered into the category “other”.

Figure 6

Abundance of bacterial communities at the species level (a) in uncontaminated soil (C), soil contaminated with diesel oil (DO) and soil contaminated with unleaded petroleum (P). Abundances <1% are gathered into the category “other”; (b) diagram of common OTU readings in uncontaminated soil (C), soil contaminated with diesel oil (DO) and soil contaminated with unleaded petroleum (P).

Figure 7

Activity of soil enzymes (a) presented with the PCA method; (b) enzyme resistance indices (RS) to soil contamination with diesel oil (DO) and unleaded petroleum (P). Deh—dehydrogenases; Cat—catalase, Ure—urease; Pac—acid phosphatase; Pal—alkaline phosphatase; Glu—β-glucosidase; Aryl—arylsulfatase. Homogeneous groups denoted with letters (a,b) were calculated separately for each of enzyme.

Figure 8

Yields of Elymus elongatus in cuts number 1, 2 and 3 (g DM pot⁻¹). Homogeneous groups denoted with letters (a–h) were calculated for yield.