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  • 1 Department of Botany, University of Calcutta 35 Ballygunge Circular Road, Kolkata 700019, India
  • 2 Department of Botany, University of Calcutta 35 Ballygunge Circular Road, Kolkata 700019, India
  • 3 Radiochemistry Division, Bhabha Atomic Research Centre Mumbai 400085, India
  • 4 Chemical Sciences Division, Saha Institute of Nuclear Physics 1/AF Bidhannagar, Kolkata 700 064, India
  • 5 Chemical Sciences Division, Saha Institute of Nuclear Physics 1/AF Bidhannagar, Kolkata 700 064, India
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Summary  

The bioaccumulation of gold in trace concentration by Nitzschia obtusa and Navicula minima, two members of bacillariophyceae, has been studied. It has been observed that Nitzschia obtusa showed better accumulation of gold in acidic pH in comparison to neutral and basic pH. Maximum accumulation was observed with 1 mg . kg-1 or less   gold concentration. However, the accumulation by the living cells was reduced when the matrix concentration was higher. Navicula minima, on the other hand, found to be a better accumulator of gold in wide ranges of pH and substrate concentration of the media. It was also inferred that the gold accumulation by diatom was mainly due to adsorption by biosilica (siliceous frustules of dead diatom cells). Accumulated gold was recovered with conc. HNO3.