Assessment of Water Quality of Lotic and LenticEcosystems in Agbede Wetlands using a Multimetric Approach

Abstract

In this study, an index method was adopted to grade the water quality of Agbede Wetlands for a period of 18 months (December, 2012 and May, 2014). On monthly basis, water samples were obtained from seven designated stations within the wetlands and analyzedfor the classical parameters adopting standard methods. These parameters which included Water temperature, pH, electrical conductivity, turbidity , total dissolved solids, total suspended solids, dissolved oxygen, biological oxygen demand, chemical oxygendemand, chloride, sulphate, phosphate, nitrate, total hydrocarbon content,sodium, potassium, magnesium, calcium, copper, cadmium, iron, lead, chromium, zinc, nickel and manganese contributed invariably to water quality of Agbede Wetlands when keyed into Water Quality Index (WQI). The mean WQI values at stations 1, 2 and 3 werein all cases <30.00, for station 5 and 6, 30< WQI <50 while for stations 4 and 7, 50< WQI <100. Thus based on the parameters characterized in this study while adopting Federal Ministry of Environment standard for surface water, the water quality at stations 1,2,3,5 and 6 were said to be excellent while those of stations 4 and 7 were good. An attempt to x-ray the contribution of individual parameter towards the WQI values showed that the principal parameters were pH, turbidity, dissolved oxygen and heavy metals which include copper, lead, zinc, cadmium and nickel. There is need to ascertain the level of microbial agents, pesticides and herbicides oncentrations in Agbede Wetland as the activities witnessed at the watershed are likely to influence them.