Distribution and Source Identification of Heavy Metals in Agricultural Soil of District Amritsar, India: A Multivariate Statistical Analysis
Heavy metal contamination of agricultural soils is a serious cause of concern because heavy metals get accumulated in crop plants, thus affecting animals and humans through food chain. Wheat (Triticum aestivum L.) is the main food crop of Rabi season in northern India and heavy metal contamination of wheat can pose major health risks to the population consuming contaminated crop. Therefore, a spatial study was conducted by collecting 28 soil samples to analyze the variation in contents of four heavy metals viz. chromium, cadmium, cobalt and copper in wheat cultivated agricultural soils of Amritsar district of Punjab, India. The studied soil samples were alkaline in nature with pH ranging from 7.55 – 8.55 and Soil Organic Matter (SOM) ranging from 3.37 – 9.78 %. The contents of Cr, Cd, Co and Cu ranged from 6.8 – 37.6 mg/kg, 0.25 – 1.8 mg/kg, 1.8 – 8.9 mg/kg and 8.5 – 42.4 mg/kg, respectively, which were below maximum permissible limits. Among different metals studied, maximum variation was found for Cd having highest coefficient of variation (59.84 %). Significant positive correlations were found among the heavy metals studied indicating their similar sources. Spatial distribution maps showed that comparatively higher levels of metals were observed in inner urban parts of Amritsar, which may be due to higher industrial and vehicular activity in these areas. Principal Component Analysis showed that the main source of Cr and Co was parent rock materials and Cd and Cu came from anthropogenic activities such as agriculture and industrialization.
Keywords— Agricultural soil; Heavy metal; Spatial variation; Wheat.