Environmental footprints of brick kiln bottom ashes: Geostatistical approach for assessment of metal toxicity

Coal fired brick kiln factories generate significant of brick kiln bottom ash (BKBA) that contaminate soil and water environments of areas near the dumping sites through leaching of toxic metals (Pb, Cr, Cd, Zn, Mn, and Cu). However, characteristics and environmental effects of BKBAs are ye l unknown. We collected BKBA samples from 32 strategic locations of two rapidly developing Stales (West Bengal and Assam) of India. Scanning electron microscope images indicated spherical and granular structures of BKBAs produced in West Bengal (WBKBA) and Assam (ABKBA) respectively; while energy dispersive spectroscopy and analytical assessments confirmed substantial occurrence of total organic C and nutrient elements (N, P, K, Ca, Mg, and S) in both the BKBAs. FUR analysis revealed greater predominance of organic mailer in ABKBAs than WBKBAs. Occurrence of toxic metals (Cd, Pb, Zn, Mn, and Cu) was higher in ABKBAs Lhan in WBKBAs; while organic and residual fractions of metals were highly predominant in most of the BKBAs. Principal component analysis showed that metal contents and pH were the major distinguishing characteristics of the BKBAs generated in the two different environmental locations. Human health risk associated with BKBAs generated in Assam is of significant concern. Finally, geostatistical tools enabled to predict the spatial distribution patterns of toxic metals contributed by the BKBAs in Assam and West Bengal respectively. Assessment of contamination index, geo-accumulation index, and ecological risk index revealed sonic BKBAs to be more toxic than others. (C) 2017 Published by Elsevier B.V.