Spatial distribution and seasonal variation of heavy metal contaminants and pollution indices in a coastal landmass of Kerala, peninsular India

Abstract

ABSTRACT Heavy metal contamination in groundwater is a global health concern and its gravity is higher in India, as more than 80% of the rural and 50% of the urban population rely on it for drinking purposes. The present study comprehensively analysed the source, distribution pattern, and seasonal flux of heavy metals in the groundwater sources of Malappuram district, a coastal landmass in peninsular India, using multivariate statistics, pollution indices, and interpolation models in GIS. In three seasons, higher incidences of Pb, Ni and Cd and lower persistence of Zn and Cu were observed during the study period. Heavy metal Pollution Index (HPI) was highest during the pre-monsoon season as 57.57% of the samples were above the critical value. The Metal Index (MI) was higher in coastal areas and is linked to fluvial deposits. More than 77% of the samples were noted to be acidic in all the seasons due to geogenic influxes that accelerated the dissolution of toxic metals upon contact. The HPI interpolation model reveals less heavy metal contamination in the coastal plains, compared to midland and highland urban centres, indicating the least influence of terrain characteristics in the translocation of heavy metals in the groundwater sources.