An Investigation of Chromium Toxicity in the Wild Population of Black-Headed Oriole Oriolus brachyrhynchus (Swainson, 1837) Using Atomic Absorption Spectrometry (AAS)

Chromium is commonly present in the surroundings as a result of its natural occurrence, human activities from industries and agriculture [1]. Most industrial processes produce metals as byproduct in the ecosystem, and these may end-up in tissues of bird species existing in such natural ecosystems [2]. In most cases, the concentration may be higher than the permissible limit in avian species. Chromium (Cr) is a trace element that seems to be an essential micronutrient in animal diet. It occurs in two oxidation states such as trivalent (Cr3+) and hexavalent (Cr6+). However both are biologically active, but some differences in their metabolism are known. Cr6+ is more readily absorbed than Cr3+, but Cr6+ toxicity is higher [3] in the environment. It occurs in rock strata rich in Cr3+ bearing minerals, in particular chromites are universally found in sedimentary rocks. Analysis of fertilizers marketed in Nigeria indicated that N15P15K15, N20 P10 K10 and N27P 13 K13 and phosphate fertilizers contained significant and varying amounts of chromium [4] as contaminants thereby, making it a potential source of agro-contamination. Birds have been recognized as good indictors of environmental contamination because of their abundance, wide distribution, feeding at different trophic levels, and their long life span [1,5,6]. Several studies have shown that chromium in phosphate fertilizers can subsequently accumulate in soil and become readily available to plants and wild birds [7,8] that forage on such plants. Black headed oriole is a farmland dependent bird with a conservation status of least concern but with global changes, it is imperative to study a particular species living in a sensitive habitat such as agricultural ecosystem [6]. According to [9] chromium accumulation in soil does not depend on levels of phosphate fertilizer but on the levels of impurities in the phosphate rock used for the fertilizer production. In the study Volume 2 Issue 5 2017