Evaluating Polyaromatic Hydrocarbons (PAHs) Toxicity in Terrestrial Ecosystems Using Enzymatic Biomarkers in Achatina Fulica

Polyaromatic hydrocarbons (PAHs) have been linked to various human activities such as cooking, domestic heating, and the use of fuel for operating automobiles, resulting in common background levels of PAHs in soils. Although much has been revealed about the effects of PAHs on aquatic organisms, comparatively little is known about their impact on terrestrial organisms. This study investigates response of the model antioxidant, phase II and carbohydrate enzymes to stress induced by benzo(a)pyrene + pyrene and PAH associated pollution using the land snail Achatina fulica. The snails were exposed in triplicates to soil spiked with benzo(a)pyrene+pyrene and naturally polluted soil for a maximum of 21 days, with sampling conducted on days 1, 11, and 21 of exposure. Specific activities were significantly elevated with increase in exposure as revealed by RM Two-way ANOVA at 95% confidence level with the Giesser-Greenhouse correlation for superoxide dismutase (P<0.0001), catalase (P<0.0001), glutathione-S-transferase (P<0.0001), and lactate dehydrogenase [time of exposure (P < 0.0111) and between samples (P = 0.0001)]. In contrast, succinate dehydrogenase activity [time of exposure (P < 0.0017) and between samples (P = 0.0027)] was notably suppressed during the same time points. These results demonstrate significant stress induction by PAH-associated pollutants. Thus, enzyme activity in A. fulica proves to be a promising and practical biomarker for monitoring terrestrial pollution by polycyclic aromatic hydrocarbon.