Assessment of the contamination of rice husk ash of Izzi CP, Ikwo CP and Izzi R8 rice species of South-Eastern Nigeria

Abstract

In a previous study by the authors (Ogbuefi et al., 2020), the concentrations of heavy metals in Izzi CP, Ikwo CP and Izzi R8 were reported to be quite high. As an extension of the previous work, in the present work, pollution of rice husk ash (RHA) of Izzi CP, Ikwo CP and Izzi R8 rice species due to heavy metal contamination was assessed using various pollution indices. The results of the study showed that all the samples indicated ultra-high contamination level due to the heavy metals as indicated by the modified contamination degree (mCd) values. Also, the results showed that in the Izzi CP, the order of contamination factor is Cu<Zn<Cr<Ni<As, Cr<Zn<Cu<Ni<As for Ikwo CP and Cr<Cu<Zn<Ni<As for Izzi R8. For all the samples Cr and As showed the lowest and highest enrichment respectively of all the metals. The values of the geoaccumulation index, Igeo, for Ni and As suggested extremely polluted conditions for all the samples and the highest ecological risk is from Arsenic (As). Furthermore, it was observed that Izzi CP is the most contaminated of all the samples and that the major contributor to this contamination is Arsenic (As).