Distribution of Arsenic (As) in Water, Sediment and Fish from a Shallow Tropical Reservoir (Aiba Reservoir, Iwo, Nigeria)

摘要

The status of arsenic in Aiba Reservoir, Iwo, Nigeria was assessed todetermine its levels and distribution in water, sediment and tissues of fish. Total arsenic wasestimated by atomic absorption spectrophotometry. The mean levels detected for reservoirwater (1.50 ± 0.22ppb) and sediment (2.00 ± 0.17ppb) were below the World HealthOrganization recommended limit of 0.01mg/L (10ppb) for drinking water. Arsenic insediments significantly followed (r = 0.588, p = 0.002, n = 24) the level of contamination ofwater. The distribution of arsenic in reservoir water shows significant spatial and temporalheterogeneity; while that for sediment shows temporal homogeneity. Mean As levels for fishkidney (15.72 ± 4.14ppb) and liver (12.04 ± 2.73ppb) were significantly higher than levels forfish gills (2.03 ± 0.34ppb) and muscle (1.46 ± 0.13ppb). The first and second CanonicalVariate showed 49.82% and 34.75% between-species variation respectively. This reportsuggests that fish at the lower level of the food web have higher levels of As compared tothose at a higher trophic status. The current low levels of arsenic in the abiotic component ofthe reservoir suggest that contamination is mainly from anthropogenic rather than fromnatural sources. This report suggests seasonal, municipal and agricultural sources of arseniccontamination of Aiba Reservoir.