Assessing Aquifer Vulnerability And Contaminant Plume At Artisanal Refining Sites In Parts Of Okrika And Ogu-Bolo Local Government Areas, Rivers State, Nigeria

This study aims at the assessment of aquifer vulnerability and contaminants plume where artisan refining of crude is taking place, which is a threat to availability of potable water. The ArcGIS version 10.3, ENVI version 4.7, Surfer 10, SPSS 22 and Microsoft Enterprise were used for the interpretation and the water and soil samples were analyzed in the laboratory using standard methods. A total number of sixteen (16) sampling points were selected using random sampling techniques for the water points and soil samples within Ogu Bolo and Okrika. The Digital Elevation Model was created from the elevation data obtained from SRTM (Short Radar Thematic Mapper) satellite image and contour extracted from the topographic map. The influence of the soil type, slope, flow accumulation, flow direction of the study area was used to delineate the level of contaminant plume. This was generated from the DEM using the ArcGIS 10.3 3-D analyst tool function. A water Quality index rating of 1 was measured in the study area which is an indication that the water is very bad. Also, the physiochemical analysis on soil and water revealed poor water and soil. Water analysis showed high concentration of Fe and Zn which made the water in the area unsuitable for drinking. Also, the soil samples recorded high levels of crude content from 1m, with concentration reducing with depth up to 3m. A general contamination map of Okrika/Ogu-bolo was modelled, indicating the contamination rating of the total land mass of the study area, with 23.59km (5.71%) rated very good, while 85.65km (20.71%) were rated good. Also, 140.37km (33.95%) had only showed moderate level of contamination while 112.56km (27.22%) recorded high level of contamination, with 51.29km (12.40%) of the total land mass having a very bad contamination record.