Heavy metal contamination in “chemicalized’ green revolution banana fields in southern India

Abstract

The present report is a general assessment of the level of nutrient and toxic heavy metals as an impact of "chemicalized" cultivation practices for decades in banana fields in the three south Indian states, Kerala, Karnataka, and Tamilnadu. The major objective was to critically analyze the status of metallic content in green revolution fields, where chemical fertilizers or plant protective chemicals remain the major source of heavy metal contaminants. Since soil series being a soil taxonomic category that includes slightly variant soils of similar origin and common parent materials, the 286 field samples of the broad south Indian region were further grouped into composite samples representing 47 different soil series for limiting the sample analysis. The quantitative assessment of ten metals done in these soils using the Atomic Absorption Spectrophotometer included Ca, Mg, Mn, Zn, Fe, Cu, Pb, Ni, Cr, and Co. The amount of Cu observed in many fields was higher than all the previous reports of the same in the "chemicalized" fields. Similarly, the amount of Co observed in 25 fields was above its threshold levels expected for normal soils. The amount of Pb observed in all the soils appeared quite normal. The amount of Ni observed in 14 soil series was higher than its threshold levels for normal soils, except in 4 soil series, where its amount exceeded the upper limit of contamination. Cr was detected in all the samples, but found higher than its threshold level in 31 soil series. Significant positive correlations were observed between the amounts of different metals in the study. PCA results indicated that variables were correlated to four principal components, and 74.36% of the total variance was justified.