Physicochemical and Heavy Metal Contents of Groundwater in Okrika Mainland, Rivers State

The study focused primarily on the assessment of physicochemical and heavy metals contents of ground water in Okrika mainland. Ground water samples were randomly collected from 10 sampling locations (2 hand-dug wells and 8 boreholes) in six different communities in Okrika mainland, Okrika Local Government Area of Rivers State. These communities include Abonrin-dendemie Ama, Daka Ama, Ekerekana Community, Okochiri Community, Oko Ama and Okoro Ama. Sampling was carried out in the month of June, 2015. Standard analytical techniques were employed in the investigation. Physicochemical parameters and heavy metal contents were measured in the water samples in order to determine the present status of the water quality since the study area is host to the Port Harcourt Refinery Company. The pH values for the boreholes and hand dug well samples ranged from 5.40-9.20 and 5.27-5.30 respectively. 70 % of the boreholes and hand dug wells studied had pH below the SON (2007) and WHO (2004) range of 6.5-8.5 considered acceptable and satisfactory for potable use. The remaining 30 % had values within the range of 8.6-9.2 thereby meeting the WHO maximum allowable range. The result showed that no borehole water going by the National SON Standard (2007), has acceptable, satisfactory water quality. It also showed that 70 % of boreholes and hand dug wells were acidic, unacceptable and below the national and international guideline limits while 30 % of the boreholes had pH above the guideline limit though within the maximum allowable limit of the World Health Organization. However, the physicochemical parameters were within the allowable limits though BH 1 borehole showed elevated concentrations in some parameters. Iron ranged from below <0.001-0.218 mg/l for boreholes and <0.001- 1.593 mg/l in the Hand-dug wells. In one privately owned borehole (BH 6 at 42 kings Road, Okochiri), Iron was approaching the guideline limit while in one hand dug well, iron was five times (1.5 mg/l) more than the standard allowable value of 0.3 mg/l. Other boreholes were free of iron content. Manganese is a metal to be watched as it was present in all boreholes except one (BH 3 at 78 Ekerekana, behind Okrika General Hospital) and exceeded the National SON limit in two boreholes (BH 6 & BH 7) and in the well water HW 1 at Oko ama (0.56 mg/l). There were traces of copper and zinc in the sampled waters though within the allowable limits of WHO and SON. Lead, Cadmium and Mercury were below detection levels in all the boreholes and hand-dug wells.