Journal of Hazardous Materials, Vol.183, No.1-3, 125-131, 2010
Temporal changes and depth wise variations in pit pond hydrochemistry contaminated with industrial effluents with special emphasis on metal distribution in water-sediment system
The investigation showed pronounced temporal and vertical variations of pit lake-water chemistry contaminated with industrial effluents. An intermixing layer of few meters at a depth of 5-8 m usually separates an upper oxic epilimnion with alkaline pH from deeper sub-oxic/anoxic zone with relatively lower pH. Metal concentrations were in higher magnitude at anoxic zone in comparison to surface layer. Most of the parameters including metals showed higher concentrations during summer, while least concentrations were observed during monsoon. In shallow sediments, metals were mainly in insoluble-residual form, while redox metals were fractionated as oxihydroxide-reducible form. Geoaccumulation of metals in bottom sediments were Fe > Cr > Pb > Cu > Cd > Mn > Zn. Toxicity assessment showed that pit pond water is highly contaminated (C-d = 7.52) and moderate pollution load (PLI = 2.272) in shallow sediments, with metal evaluation index (HEI) value of 11.08 and 15.91 respectively. (C) 2010 Elsevier B.V. All rights reserved.
Keywords:Temporal changes;Vertical variation;Hydrochemistry;Industrial wastewater;Metal contamination;Pollution load index