Enhanced Phytoremediation Technology for Chromium contaminated Soils using Biological Amendments

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Author(s) Sunitha, R | S. Mahimairaja | A. Bharani | P. Gayathri
Pages 153-162
Volume 3
Issue 3
Date March, 2014
Keywords Contaminated soil, Chromium, Organic amendments, Zea mays and Immobilization.
Abstract

The chromium contamination in soil is an environmental concern because, the accumulated metals may have adverse affects on soil ecology, agricultural production, animal and human health as well as groundwater quality. Phytostabilization involves the reduction of the mobility of heavy metals in soil. Immobilization of metals can be accomplished by decreasing wind-blown dust, minimizing soil erosion, and reducing contaminant solubility or bioavailability to the food chain. The addition of soil amendments, such as organic matter, phosphates, alkalizing agents, and biosolids can decrease solubility of metals in soil and minimize leaching to groundwater. The mobility of contaminants is reduced by the accumulation of contaminants by plant roots, absorption onto roots, or precipitation within the root zone. In some instances, hydraulic control to prevent leachate migration can be achieved because of the large quantity of water transpired by plants. Within these new approaches, in-situ immobilization and phytoremediation are becoming increasingly attractive remediation options. Thus a bioremediation technology was developed by integrating organic amendments and microbial strains. The effectiveness and feasibility of the bioremediation technology was evaluated by conducting field experiment in the ‘Hot-spots’ of Cr contaminated area in Vellore district. This study examined the effects of two organic soil amendments; poultry manure and vermicompost and microbial cultures on Cr accumulation in maize (Zea mays L.) in soil contaminated with tannery wastes. The Cr content of the maize plants were harvested and determined with Atomic Adsorption Spectrophotometer (AAS). It was found that total Chromium uptake by maize decreased with the application of organic amendment towards contaminated soil samples. The results demonstrated that the bioremediation of Cr contaminated soil has resulted in significant improvement in yield of maize. The yield increase over control was about 53.6 to 118 percent in maize, due to the application of poultry manure and vermicompost, with or without microbial strains. The addition of poultry manure or vermicompost with or without microbial strains significantly (60 %) reduced the Cr content and uptake by maize due to manure-induced Cr immobilization in soil. This is explained in terms of in-situ immobilization of the metals, due mainly to the phosphorus content of the organic matter that was provided for the soil from the amendments.

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