Hydrology and heterogeneneous distribution of water quality characteristics in the complex Porto-Novo Lagoon ecosystem

Abstract

A study was carried out on the hydrology and heterogeneous distribution of water quality characteristics in the Lagoon of Porto-Novo between July 2014 and June 2015. The water body was stratified into 12 strata for sampling. Data and samples were collected based on season and stations. The results were analyzed in the laboratory and interpreted using ANOVA.Water parameters and annual range was obtained . Temperature (25.81 oC – 31.03 oC), dissolved oxygen (4.85 mg/L- 7.74mg/L), salinity (0.10%o,- 8.34a%o), electrical conductivity (8.12 μS/cm-37.68 μS/cm), pH (6.74 – 7.0), transparency (0.18- 0.77 m),total dissolved solids (4.09 mg/L-26.18 mg/L), total hardness (39.92 mg/L-7624.47 mg/L), biological oxygen demand (9.76 mg/L - 4.83 mg/L), and chemical oxygen demand (18.32 mg/L - 11.59 mg/L).Temperature, salinity, electrical conductivity, total dissolved solids, total hardness, biological oxygen demand, chemical oxygen demand were significant at probality level of 5% while dissolved oxygen and pH were not significant at p<0.05 by using Duncan Post Hoc tests for the homogeneous subset respectively. The results attested that the water quality characteristics from Porto-Novo Lagoon were influenced by hydrological cycle and highly polluted and the annual range obtained are above the international legislation limits. It is therefore recommended that the activities of reparian on Porto-Novo Lagoon should be curtailed for adequate revamping.Keywords: Physico-chemical parameters, hydrology, heterogeneous, Porto-Novo