Sara P B Kamaludeen

Publications (3)5.75 Total impact

• Chapter: Chromium-Microorganism Interactions in Soils: Remediation Implications

  Sara P.B. Kamaludeen, Mallavarapu Megharaj, Albert L. Juhasz, Nabrattil Sethunathan, Ravi Naidu
  05/2006: pages 93-164;
• Article: Microbial activity and phospholipid fatty acid pattern in long-term tannery waste-contaminated soil.

  Sara P B Kamaludeen, M Megharaj, R Naidu, I Singleton, A L Juhasz, B G Hawke, N Sethunathan
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  ABSTRACT: We investigated the phospholipid fatty acid (PLFA) pattern and dehydrogenase activity (DHA) in soil samples from three sites (designated as low, medium, and high based on the level of chromium) in a long-term (25 years after last waste input) tannery waste-contaminated area rich in Cr. Soil samples, collected from different soil depths (0-100 cm), at each site were used in this study. In general, soil samples from all three contaminated sites had elevated pH, electrical conductivity, organic carbon (OC), total Cr, and hexavalent Cr [Cr(VI)]. The maximum total Cr concentration in surface soils (0-10 cm) at the highly contaminated site was 102 gkg(-1), with 4.6 mgkg(-1) present as the bioavailable water-soluble Cr. More than 50% of soluble Cr was in the form of Cr(VI) (2.7 mgkg(-1)). DHA (normalized to OC) was inhibited to a greater extent in soil samples from the highly contaminated site than in low- and medium-contaminated soil samples. PLFA analyses of surface soils indicated that there was a shift in PLFA patterns. PLFAs specific for bacteria (i15:0, a15:0, 15:0, i16:0, a17:0, and cy17:0) decreased significantly (P<0.01) with an increase in Cr contamination. Among the bacterial PLFAs, 15:0, i16:0 and a17:0 had a significant negative correlation with contamination including bioavailable Cr(VI) in soil solution. To our knowledge, this is the first report of alterations in the PLFA profile in soils due to long-term tannery waste pollution.
  Ecotoxicology and Environmental Safety 10/2003; 56(2):302-10. · 2.29 Impact Factor
• Article: Chromium-microorganism interactions in soils: remediation implications.

  Sara P B Kamaludeen, Mallavarapu Megharaj, Albert L Juhasz, Nabrattil Sethunathan, Ravi Naidu
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  ABSTRACT: Discharge of Cr waste from many industrial applications such as leather tanning, textile production, electroplating, metallurgy, and petroleum refinery has led to large-scale contamination of land and water. Generally, Cr exists in two stable states: Cr(III) and Cr(VI). Cr(III) is not very soluble and is immobilized by precipitation as hydroxides. Cr(VI) is toxic, soluble, and easily transported to water resources. Cr(VI) undergoes rapid reduction to Cr(III), in the presence of organic sources or other reducing compounds as electron donors, to become precipitated as hydroxides. Cr(VI)-reducing microorganisms are ubiquitous in soil and water. A wide range of microorganisms, including bacteria, yeasts; and algae, with exceptional ability to reduce Cr(VI) to Cr(III) anaerobically and/or aerobically, have been isolated from Cr-contaminated and noncontaminated soils and water. Bioremediation approaches using the Cr(VI)-reducing ability of introduced (in bioreactors) or indigenous (augmented by supplements with organic amendments) microorganisms has been more successful for remediation of Cr-contaminated water than soils. Apart from enzymatic reduction, nonenzymatic reduction of Cr(VI) can also be common and widespread in the environment. For instance, biotic-abiotic coupling reactions involving the microbially formed products, H2S (the end product of sulfate reduction), Fe(II) [formed by Fe(III) reduction], and sulfite (formed during oxidation of elemental sulfur), can mediate the dissimilatory reduction of Cr(VI). Despite the dominant occurrence of enzymatic and nonenzymatic reduction of Cr(VI), natural attenuation of Cr(VI) is not taking place at a long-term contaminated site in South Australia, even 225 years after the last disposal of tannery waste. Evidence suggests that excess moisture conditions leading to saturation or flooded conditions promote the complete removal of Cr(VI) in soil samples from this contaminated site; but Cr(VI) reappears, probably because of oxidation of the Cr(III) by Mn oxides, with a subsequent shift to drying conditions in the soil. In such environments with low natural attenuation capacity resulting from reversible oxidation of Cr(III), bioeremediation of Cr(VI) can be a challenging task.
  Reviews of environmental contamination and toxicology 02/2003; 178:93-164. · 3.45 Impact Factor