Assessment of the exposure of two fish species to metals pollution in the Ogun river catchments, Ketu, Lagos, Nigeria

Abstract

The concentrations of metals (Ca, Cd, Fe, Mn, Pb and Zn) were determined by flame atomic absorption spectrophotometry in water, sediments and fish samples in the Ogun river catchments, Ketu, Lagos, which is an important bird nesting, fishing and drinking water source. The results show that the southern tip bothering the Lagos lagoon is where the highest metal concentrations are found in the fish species (Tilapia sp. and Chrysichthys sp.), whereas the Agboyi creek segment near the lagoon with higher surrounding human population density recorded higher levels of metals in sediments and water samples. The two fish species accumulated different amounts of metals. However, the differences were not statistically different at p < 0.05. There is a significant correlation (p < 0.05) for Cd concentration in water. The concentrations of Pb in sampling points 3 and 4 as well as Cd, Mn and Fe in all six sampling points exceeds the World Health Organization (WHO) limits for drinking water. Levels of metals obtained for sediments are within the range reported for Nigeria's river sediments. Based on this study, the human risks for heavy metals in the harvested fish species from the Ogun river catchments, Ketu, are low for now as the concentrations were below the recommended Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg/Kg), Cd (0.5 mg/Kg), and Zn (30 mg/Kg) in fish.

Heavy Metals in Paddy Soils of Brunei Darussalam and Their Relationship with Selected Soil Properties

“…It is relevant with our results that extremely strong acidic conditions (pH value-3 to 4.6) in the Brunei Soils increased metal availability (Table 5). Similar results reported by [66,2]; nearly all the metals in higher soil acidic conditions are activated which promote metal uptake of the plant. High organic matter (OM) content is favorable for the sorption of HMs in soils.…”

Copper, Lead and Zinc Concentration in Water, Sediments and Catfish (Clarias macrocephalus Gunther) from Butuanon River, Metro Cebu, Philippines

“…The BSAF values for Cu and Zn obtained in this study follow in the same order with another carnivorous fish, S. thumbergi [37]. However, the BSAF values are relatively smaller compared to other studies implying that the degree of accumulation in the C. macrocephalus is not that high as compared to other polluted aquatic ecosystems [37,38]. In a previous study [43,8], Pb and Zn had a BSAF value of 1.72 and 4.96 respectively for Chrysichthys sp.…”

“…and 2.59 and 7.48 respectively for Tilapia sp. BSAF value for Cu could also reach as high as 11.2 [37]. Measured BSAFs above or below 1 to 2 are entirely reasonable for fish [39] as there are solid mechanistic reasons why fish should not be in equilibrium with their sediments.…”

Growth, biochemical variables, and zinc bioaccumulation in Nile tilapia, Oreochromis niloticus (L.) as affected by water-born zinc toxicity and exposure period

“…In addition to being a source of protein to humans, they play important roles as bioindicators of trace element pollution (Rashed 2001). For this reason, the utility of fish for assessing environmental conditions in aquatic ecosystems has gained prominence in recent years (Yilmaz 2003;Budambula and Mwachiro 2006;Adeniyi et al 2008;Palaniappan et al 2010). Due to the deleterious effects of Zn on aquatic ecosystems, it is necessary to monitor its potential impact on fish performance and health.…”