Haorongbam Nandakumar Singh1, Rout Jayashree
Keywords: Heavy metals, Tea garden, Agroecosystem, Southern Assam, Toxicity.
Heavy metal occurrence in agricultural soil is a widespread concern primarily due to their toxicity, perseverance and non-biodegradability. Soil contaminated with various heavy metals pose risks to environment and in turn health of living organism including human. The developmental activities associated with industrialization and intensive agricultural practice cause accumulation of heavy metals to toxic level in the soil. There exists hardly any account on the occurrence of heavy metals in tea garden soil from Assam. Studies related to occurrence and distribution of heavy metals in soil of three tea gardens of southern Assam is the main objective of the present paper. Soil samples from three different tea agroecosystem were air dried and digested using hydrogen peroxide and analysed by atomic absorption spectroscopy. Heavy metal occurrence in tea garden soil were found to be in the concentration order: Fe > Cr > Mn > Zn > Cu > Ni > Pb > As > Cd. The concentration level of these metals in all the tea garden soil were found to lie within the maximum permissible limit. The soil pH was found to be moderately acidic in all the sites. Variation in concentration of metals in relation to topsoil, subsoil (I) and subsoil (II) were observed. The concentration of the non-essential elements Ni, Cd, Pb and As decreased with soil depth pointing that these elements mainly originated from anthropogenic sources. It is noteworthy that the Cu and Zn concentration level registered a substantial hike at the end of third year while those of the other metals did not vary appreciably.
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*Corresponding author: Ecology & Environmental Science Department, Assam University, Silchar-788011, Assam, India. Email: email@example.com