HYDROGEOCHEMICAL CHARACTERIZATION OF SURFACE WATER AROUND CANAL AND LAGOON IN PARTS OF LAGOS, SOUTHWESTERN, NIGERIA

Abstract

A hydrogeochemicals study of water from the drainage canal in industrial and residential parts of Ikeja and lagoon of southeastern suburbs of Lagos was carried out. The physico-chemical parameters of the water including TDS, EC, pH, Salinity Ca, Mg, Na, K, HCO3, CO3, Cl, SO4, NO3 and heavy metals were determined for characterization of the water. The water samples were processed and analyzed using atomic absorption spectrophotometry and inductively coupled plasmamass spectrometry respectively. The results shows that canal water are slightly acidic-neutral with pH range of (6.48-7.14), while the lagoon water are alkaline with pH range of (7.83-8.25). The lagoon water are brackish-marine with salinity range between (11-32) % while the canal water are fresh waters with salinity values generally less (<1) %. The lagoon water have constant TDS value of (2000 ppm) and EC value of (3999 ms/cm), whereas the canal water have low TDS value ranging from (77-460 ppm ) and EC range of (151-917 ms/cm). Based on the Geoaccumulation indices, both water from the canal and lagoon are considered to be unpolluted with respect to Zn, Cu, As, Ni, Co, Cr, Cd, Pb, and Fe. Hg is the only pollutant in both canal and lagoon water. While the lagoon water is moderately contaminated with respect to Hg, the canal water is very highly polluted. The canal water is Ca-Mg-HC03 water type, while the lagoon water is Ca-Mg-Na-SO4- Cl water type. Possible contamination sources are industrial and anthropogenic. These need to be monitored and controlled effectively.