Investigation into the spatial occurrence of wet season phytoplankton and zooplankton in Lagos lagoon, Nigeria was carried out in October, 2008 in 12 stations. A total of 36 species of phytoplankton from 21 genera, 20 zooplankton species from 17 genera and 10 juvenile forms were recorded for the study. The results showed that freshwater conditions within the lagoon were due to high freshwater inflow from adjoining waterways and reduced tidal incursion from the sea. The wet season spectrum of the lagoon was dominated by diatoms for the phytoplankton and copepods for the zooplankton. The presence and array of juvenile forms in the wet season suggest that the lagoon remain a sanctuary, nursery and breeding grounds for aquatic species Crustaceans dominated the spectrum of the juvenile forms.
The levels of PCBs in sediments, water, leachate and aquatic fauna (Tilapia guineensis, Callinectes amnicola and Cardiosoma armatum) found in and around e-waste dumpsites in Lagos and Osun States, South-West, Nigeria were analyzed using Gas Chromatography Electron Capture Detector (GC ECD) Agilent 7820A. All the 28 PCBs congeners studied were detected with the ∑hexa-PCBs dominating in Lagos (21%) while the ∑tetra-PCBs (24%) enriched the samples from Osun State. The concentrations of ∑-PCBs in decreasing order were Lagos: sediment ˃ fish gill ˃ fish muscles ˃ water ˃ crab ˃ leachate and Osun: fish gill ˃ fish muscle ˃ sediment ˃ crab ˃ water ˃ leachate. The concentrations of total indicator PCBs ( ∑7PCBs) in the sediment from Lagos (4.19 µg/kg) and Osun (8.58 µg/kg) exceeded the Canadian Sediment Quality standard threshold effect level (CSQ TEL) (0.03 µg/kg) and the National Oceanic Atmospheric Administration threshold effect level (NOAA TEL) for fresh and marine sediments.. The calculated toxic equivalent quotient (TEQ) for fish from Lagos and Osun (3.7 and 4.4) respectively further suggests a likely occurrence of adverse effects to humans who consume the fish. This study reveals the high health and ecological risks associated with e-waste pollution in the aquatic environment.
Investigations were carried out on spatial and seasonal composition and distributions of phytoplankton in some parts of the Lagos Lagoon. Phytoplankton samples were collected from twelve stations during the wet (July, 2008) and dry (March, 2009) seasons. A typical freshwater condition prevailed in the study area during wet season with salinity of 0 parts per thousand (o / oo) at every station, whereas during the dry season, relatively high salinity levels were recorded from all the stations with decreasing trend toward the river mouth. The two seasons had the diatoms (Bacillariophytes) of the Orders Centrales and Pennales as the dominant phytoplankton taxa. A total of 2896 phytoplankton belonging to twenty-seven species, eight orders and four classes were recorded during wet season while the dry season had a total of 1550 phytoplankton, which cut across sixteen species, three orders and two classes. Wet and dry seasons respectively had Aulacoseira granulata and Coscinodiscus sps. as the dominant phytoplankton taxa. Higher dominance (0.33) and Margalef diversity (3.26) but lower Shanon-Wiener diversity (1.94) and evenness of distribution (0.26) indices were recorded during the wet than dry seasons. The findings show the influence of seasonality on phytoplankton composition and distributions in the Lagos Lagoon and suggest relatively stress-free environmental conditions within the study area.
Some physico-chemical parameters of Badagry Creek and Ologe Lagoon in the Barrier Lagoon Complex of western Nigerian coastal zone were measured on quarterly basis from June 2011 to May 2012. Water samples were collected and analyzed using standard methods at five stations in each of the two water bodies. A brackish condition was observed in Badagry Creek with salinity range of 2.00 ± 3.8 ‰ to 3.85 ± 4.48 ‰ while entirely freshwater condition was recorded in Ologe Lagoon. Surface water temperature, pH, alkalinity, nitrate and phosphate at every station in the two water bodies were within the normal ranges considered suitable for tropical aquatic life. However, high levels of biochemical oxygen demand (BOD) were recorded at a station in Badagry Creek (8.15 ± 1.66 mg/l) and two stations in Ologe Lagoon (16.9 ± 10.46 and 9.40 ± 7.56 mg/l), where untreated municipal wastes are being discharged into the water bodies. These stations also had relatively low dissolved oxygen (DO) levels (3.30 ± 0.22, 1.08 ± 0.96 and 3.68 ± 3.2 mg/l respectively). Relatively high levels of lead were also recorded at these stations (0.50 ± 0.42, 0.85 ± 0.07 and 0.35 ± 0.35 mg/l respectively). The implications of the physico-chemical conditions on bio-communities as well as the imperativeness of regulating the discharge of untreated wastes into the water bodies for their sustainable management and conservation are discussed.
The contamination of the aquatic ecosystem with heavy metals arising from the discharge of electronic waste (e-waste) or seepage of leachate from open waste dumpsites is on the increase. The impact of e-waste leachate on the micronucleus (MN) of Tilapia guineensis and the levels of heavy metals (Pb, Cd, Cr, As, Hg, Al and Ba) in the sediments, water, leachate and aquatic fauna (Tilapia guineensis, Callinectes amnicola and Cardiosoma armatum) found in and around e-waste dumpsites in Lagos and Osun States was studied. The levels of heavy metals were determined using PyeUnicam model 969 Atomic Absorption Spectrophotometry and Inductive Coupling Plasma Atomic Absorption Spectrophotometry (ICP-AAS).The heavy metal concentrations decreased in the order: Pb ˃ Cd ˃ Cr ˃ Hg ˃ Al ˃Ba ˃As in the samples. The level of Cd in fish muscle from Lagos (1.4mg/kg) exceeded the Environment Canada threshold effect level (EC TEL, 2006) recommended for sea food (1.0mg/kg). The calculated bioconcentration factor (BCF) for fish gills (1.4 and1.0) and fish muscles. (3.6 and 1.2) from Lagos and Osun States respectively as well as the bioaccumulation factor (BAF) for crabs (1.78 and 1.36) are strong indications of the ability of the organisms to bioaccumulate the heavy metals. The MN assay showed an initial increase in the frequency of mionccronuclei on the 7 th day which gradually decreased on the 14 th and 21 st day. The result of this study reveals the toxic impacts of e-waste contamination on ecological and human health in a developing economy.
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