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Nigeria, Kaduna State, Kaduna

Adverse effects of waste dumps on groundwater quality in Kaduna and environs

The study area lies between latitudes 100 26' to 100 40'N and longitudes 70 19' to 70 33'E with a total surface area of 630km2. The major town in the study area is Kaduna, which is the capital of Kaduna State.\r\n\r\nThe area is underlain by the Nigerian Basement Complex. The dominant rock types are the migmatite-gneiss complex and the Older Granites, which intruded the host gneissic rocks. Prolonged in-situ weathering of the crystalline Basement Complex rocks under tropical conditions has produced a sequence of unconsolidated material (laterites) whose thickness and lateral extent vary extensively. \r\n\r\nThere are three major aquifers in the study area namely weathered overburden aquifer, fractured bedrock aquifer and the stream alluvial deposits aquifer. The three aquifers are interconnected and form one hydraulic system with unconfined water table. \r\n\r\nEighty-eight (88) hand-dug wells, with depths ranging from 0.2 to 11.6m, were studied and thirty-four (34) representative water samples were analyzed in the laboratory. The results were compared with WHO (2006) and NAFDAC standards for drinking water. \r\n\r\nResults of physical parameters showed pH ranged from 4.83 to 7.80, electrical conductivity from 20-980µS/cm and TDS from 10-490mg/l. Results of the cations showed Na+ varied from 1.66-221.20mg/l, Ca2+ from 0.23-92.00mg/l, Mg2+ from 0.12-154.00mg/l, K+ from 0.72-71.48mg/l, Fe2+ from 0.02mg/-0.22mg/l and Pb2+ from 0.18-0.95 mg/l. Results of the anions showed Cl- ranged from 2.67-176.94 mg/l, SO42- from 1.00-250 mg/l, NO3-from 0.05-55.00mg/l ,CO32- from 4.80-50.40mg/l and HCO3- from 2.40-62.00mg/l. Result of the microbial analysis showed Cfu/ml varied from 80-240. The concentration values of the cations and anions (except Fe2+ and SO42-) exceeded the WHO (2006) and NAFDAC recommended limits for drinking water in some places. The dominant cation and anion in the groundwater are magnesium and chloride respectively. The water types are Mg-Cl, Ca-Mg-SO4 and Na- K waters. \r\nThe high concentration of sodium and chloride in the water samples from some places in the study area could be from contamination by saline effluents or leachates from waste dumps. The relative high concentration of nitrate in the study area could be as a result of pollution from septic tanks. \r\nWaste dumps of serious environmental concern were observed at Fire Brigade, Tudun Nupewa, Tudun Wada, Hayin Banki, Ungwan Dossa, and Kawo. Kaduna River around the factories at Kakuri and downstream of River Kaduna are polluted with industrial waste. \r\nIt is recommended that the factories located in Kaduna South should process their industrial wastes before discharging them into the river. In addition, the water from hand-dug wells in the area should be treated before drinking.\r\n

Inserted in the reports are the following maps (1:50,000): Geological map, Depth to Water Table map, Water Table Elevation Contour map.