Oil spills in the Niger Delta could exert environmental pressures on the soil component. We investigated the impacts of oil spills and the effect of the Enhanced Natural Attenuation (ENA) remediation method on contaminated soil and resident microbial populations in the Odhiaje community in Rivers State, Nigeria. Soil samples for microbiological studies were collected weekly during a 17-week remediation period, while those for edaphic parameters were taken before and after remediation, all at 4 sampling points (SPs). Serial dilution of the oil-impacted soils for microbial density enumeration was carried out according to standard methods. Results revealed that mean concentrations of Total Petroleum Hydrocarbon Contents (THC) (Sig.value = 0.009), SO42- ions (Sig.value = 0.001), and sand compositions (Sig.value = 0.045) all differed markedly across the sampling points at p<0.05. Mean levels of EC (Sig.tvalue = 0.039) and ΣN (Sig.tvalue = 0.058) & K+ ions (Sig.tvalue = 0.004) differed significantly before and after the remediation exercise at the 95% confidence interval. Application of nutrients was rapidly accompanied by microbial population increases, leading to the consumption of oil contaminants in soils to levels comparable to control over the remediation period. Total Heterotrophic Bacteria counts correlated with pH (r = 0.501) and SO42- ions (r = 0.500) (p<0.05), and K+ ions (r = -0.800) (p<0.01); Total Heterotrophic Fungi correlated with pH (r = 0.520) (p<0.05), and Mg2+ ions (r = 0.820) (p<0.01); Hydrocarbon Utilizing Bacteria correlated with available P (r = 0.530) and silt composition (r = -0.504) (p<0.05), and K+ (r = 0.626) and Mg2+ ions (r = 0.733) (p<0.01); and Hydrocarbon Utilizing Fungi correlated with K+ (r = 0.500) & Mg2+ ions (r = 0.506) (p<0.05). Results indicate improvement in C/N ratios and effectiveness of the current cost-effective bioaugmentation technique in the restoration of arable soil productivity in the Odhiaje community.

Cadmium (Cd) is ubiquitous and an unessential trace element existing in the environment. Anthropogenic activities and applications of synthetic phosphate fertilizers greatly enhance the concentration of Cadmium in the environment, which proves to be carcinogenic. The long-term effects of heavy metals contamination on plants and animals have recently become a major public health concern. Thanks to the application of science and technology, new environmental initiatives can have a lower environmental impact significantly. The role of microbes is very well known and must be considered as potential pollutant removers. Microbial flora can remove heavy metals and oil from contaminated soil and water. In comparison to conventional techniques, bioremediation itself proved to be a more potent technique because the established mechanisms render it ineffective. Biotechnological advancements are inherently harmful to the environment because they have the potential to reduce metal pollution. Pollutants in the environment can be effectively removed using bioremediation. Both native and introduced species can thrive in a microorganism-friendly environment.