Laying Hens Feathers as a Bio-indicator for Monitoring Heavy Metals (Pb, Ni and Cd) Pollution in industrialized Regions of Wasit Governorate, Iraq

الملخص

The widespread and increasing industrial and anthropogenic activities bring an enormous pollution risk of heavy elements into the environment, which has negative consequences for both the environment and human health. As a result, the bioaccumulative and bioarchival nature of the keratin matrix of the feather makes these structures excellent non-destructive bioindicators for the detection of environmental contamination, especially from laying hens. In the present study, the samples from the chickens  named feather ( breast and wings) were collected from 30 hens  in every one of the five poultry farms of different  anthropogenic influence levels, such as the one as a control and four other sites with different anthropogenic impacts due to petroleum emissions, thermal power plant effluents, brick kiln particulates, and highway traffic exhaust. The samples were analyzed by Inductively Coupled Plasma Optical Emission Spectrometry  (ICP-OES) with two different subsample types: washed and unwashed, to distinguish between external depostion and internal bioaccumulation. The results showed that the levels of heavy metals were in the following order, washed and unwashed feathers, lead (Pb)> nickel (Ni)> cadmium (Cd), at all sites. The highest contamination by Pb was found in unwashed feathers at site 5 (6.00 mg/kg dry weight, mainly due to vehicular emissions and fossil fuel combustion) and site 3 (5.01 mg/kg dry weight, mainly  due to fossil fuel combustion). In contrast, Site 3 accumulated the highest  levels of Ni (5.40 mg/kg) and Cd (0.50 mg/kg). The statistical analysis showed highly significant differences between the sites (P < 0.001). In addition , washed and unwashed feathers showed a high degree of correlation for both Pb (r= 0.812) and Ni (r= 0.845). The result of the study demonstrate that laying hen feathers are an effective, sensitive, and reliable bioindicator of elemental deposition in the atmosphere and local ecosystem  health.