Distribution pattern of trace metals in selected surface soils of Palakkad district, South India.

This study focussed on the extent of contamination caused by metals (Cd, Co, Pb, Cu, Zn, Mn, and Mg) in selected sites of Palakkad district, a major agrarian zone in Kerala, India. Soils sampled during summer and monsoon were processed for metal analysis using standard protocol and AAS. The metal data was compared with the threshold values proposed by the European Commission (EC), Indian Standard (IS), Lindsay Standard (LS) and the United States Environmental Protection Agency (USEPA). The extent of pollution caused by these metal contaminants was deduced using enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo) and pollution load index (PLI). Details regarding sources and their interaction with soil parameters were effectively deduced by Pearson's correlation and principal component analysis (PCA). The intensity and extend of monsoon play a prominent role in the distribution of trace metals in the study area which is evident from the distribution pattern during summer and monsoon. Even though most metals were found within the threshold limit, Cd (range: 0.25 to 3.00 mg Kg−1), and Co (range: ND to 22.56 mg Kg−1) was above the permissible limit. Spatial adsorption pattern along with the anthropogenic sources, specifically, agrochemicals, metals leaching and emitting from geological matrix and automobiles prevailing in these zones play a prominent role in regulating the levels of contamination caused by trace metals. [ABSTRACT FROM AUTHOR]