Quantifying spatio-temporal variations in heavy metal enormity of groundwaters from Ankaleshwar area: GIS-based Normalized Difference Dispersal Index mapping

Heavy metal dispersion in groundwaters of Ankaleshwar Industrial Estate, south Gujarat displays colossal temporal variability in both degree and space. In order to facilitate the quantitative measure for site-specific variations, Normalized Difference Dispersal Index (NDDI) maps for five environmentally sensitive heavy metals (Ni, Zn, Cu, Mn and Pb) were generated by clutching geochemical analyses and GIS-based raster images. Median NDDI value for Ni (0.92) illustrates utmost accretion, whereas that for Zn (-0.58) shows absolute dilution. Widespread enrichment is exhibited by Cu (0.87) and Mn (0.84), while Pb (-0.01) shows inconsequential accretion or attrition. Areas of high inconsistencies were linked to surface-polluting sources by overlaying spatial data on these maps. NDDI mapping is functional for evaluation and comparative assessment of spatio-temporal variations in polymetallic determinants. Frequency distribution and inter-element correlation analyses of the dataset display coherence with the procedure.