PLANT-MICROBIAL INTERACTIONS IN DIESEL SPILLED WETLAND SITE AT OYONBRU-JESSE, ETHIOPE WEST LOCAL GOVERNMENT AREA, DELTA STATE, NIGERIA

Abstract

Wetlands among its numerous definitions are transitional areas between terrestrial and aquatic systems in which the water table is usually at or near the surface or the land is covered by shallow water. They support a wide variety of organisms ranging from aquatic, sub-aquatic species to deep rooted plants. In the geographical zone (Niger Delta), where this study was conducted, hydrocarbon spills are a frequent occurrence. Following the diesel spill which occurred at Oyonbru, Jesse, Ethiope West local Government Area of Delta state, Nigeria, a study of the possible effects of the pollutant on the plants and fauna was carried out. Sand, loam, silt and clay were the predominant soil types at the study site. Soil particle size was between 0.05mm - 0.40mm. Water Holding Capacity was between 38% and 55% for sand and clay respectively. The four plants studied had moderate growth rate of 12.70% for Azolla pinnata, 13.00% for Phragmatis sp and 16.10% for Pennisetum purpureum. The four plants studied recorded declining diesel concentration in their rhizospheres. Microbial load were higher within the plant rhizospheres than between the plant rhizospheres. Total viable plate count (TVPC) for soil from diesel-impacted wetland ranged from 2.32 × 10-3 ? 0.40cfu/g to 3.56 × 10-3 ? 0.83cfu/g; while TVPC for unpolluted soil which served as control ranged from 2.85 × 10-3 ? 0.69cfu/g to 4.6 × 10-3 ? 0.67cfu/g. As there was steady increase in plant biomass, there was a corresponding decline in the hydrocarbon concentration from January to August. Among the biological diversity encountered were: bacteria-Arthrobacter sp, Bacillus sp, Nitrosomonas sp, Pseudomonas sp; Moulds-Aspergillus sp, Mucor, Saccharomyces sp, Geotrichum sp; Algae-Chlorella sp, Chlorobium sp, Spirogyra sp, Chlamydomonas sp. The study confirmed an interactive relationship between plants and microorganisms in the remediation of the diesel pollutant. The four plants studied can therefore be said to have potentials for hydrocarbon remediation.