Physico-Chemical Parameters and Heavy Metal Contents of Water from the Mangrove Swamps of Lagos Lagoon, Lagos, Nigeria

A study was conducted on physico-chemical parameters and heavy metal contents of water from the mangrove swamps of Lagos lagoon, Nigeria. The study was aimed at assessing its suitability for fish production and as well as its safety for drinking purpose in man. In all eleven (11) physical and chemical parameters and six (6) heavy metals were investigated for water quality assessment of the lagoon between January and December 2001. Data on temperature and pH were obtained from the field using mercury-in-glass thermometer and pH metre. Salinity, dissolved oxygen and carbon dioxide, total alkalinity and acidity, total suspended and dissolved solids were determined in the laboratory by titrimetric method. The concentrations of Fe, Zn, Mn, Cd, Cr and Pb in water were determined by Atomic Absorption Spectrophotometer (AAS). Air temperature varied between 26-31.75 (28.34±0.17°C); water temperature, 20.0-30.50 (28.07±0.18°C); pH, 1.89-8.50 (6.97±0.06); salinity, 0.2-16.75 (8.995±0.01%o); dissolved oxygen, 0.58-10 (9.97±0.03 mg L ); dissolved carbon 1 dioxide, 9-29-25.97 (17.40±0.04 mg L ); total alkalinity, 20.5-90.0 (43.33±18.67 mg L ); total acidity, 11.0-22.5 1 1 (16.26±0.27 mg L ) and rainfall, 2.4-460.9 (149.53±37.39 mm). The concentrations of heavy metals were above 1 the maximum contaminant level (MCL) recommendations of USEPA. The water parameters favoured the production of brackish water fish. However, it is highly contaminated and therefore not suitable for drinking purpose in man. In conclusion, this study is baseline data toward future ecological study, conservation and management of the resources of this economically important wetland in Nigeria.