Abstract:
Coastal lagoons provide many benefits or services; however, some of
these lagoons are under increasing threat of pollution from expanding
population and over-exploitation. This study assessed the quality of five coastal
lagoons in the Western and Central Regions of Ghana. Sediments and water
samples were collected and analyzed for physicochemical parameters and heavy
metal concentrations from Muni, Narkwa, Amisa, Fosu and Hwini lagoons from
August 2020 to February 2021 . Sediments and water quality were assessed
following analytical procedures outlined in the standard methods using water,
wastewater and various pollution index indicators. The mean range values for
water samples for all the lagoons investigated are; pH, 7.87 - 9.34; DO 2.08-
5.59 mg/L; TDS 23.34 - 32.58 gi L; Cond 36.47 - 50.91 mS/cm; Temp 28.29-
29.67 °C; Sal 36.69 - 58.09 PSU; Nitrate 6.77 - 14.81 mg/L; Phosphate, 3.62-
13.37 mg/L; Turbidity, 5.66 - 45.43 NTU; Fe, 0.81 - 3.1 0 mglL; Pb, 0.64 - 1.09
mg/L; Mn, 0.05 - 0.29 mglL; Cr, 0.05 - 0.39 mg/L; Cd, 0.05 - 0.31 mg/L; Ni,
0.08 - 0.25 mg/L; Zn, 0.18 - 0.40 mglL. The concentration ranges found for the
metals in the sediments were Fe 126.20 - 141.10 mg/kg; Pb 12.70 - 27.20
mg/kg; Mn 22.10-37.50 mg/kg; Cr 8.40-21.50 mg/kg; Ni 6.30- 19.80 mg/kg,
Zn 9.70 - 23.40 mg/kg. Cadmium (Cd) was below detection limit in all the
sediment samples. Significant spatial variations were observed within and
between the lagoons. The Nemerow's Pollution Index for all lagoon water were
greater than I . The quality of lagoon water for Hwini was fair and marginal for
Muni, Fosu, Narkwa and Amisa lagoons. The lagoon sediments were extremely
contaminated with regards to all sediment pollution indicators used. These
observations suggested anthropogenic pollution of the lagoon water and
sediments. There is the need for continuous monitoring of the lagoon ecology
by local authorities and institutions mandated to manage these water resources
to stop or minimize the deterioration of these lagoons in order to preserve them
to sustain the ecosystem.
