The effects of heavy metals on microbial biomass in sediments of Palestine Lake

Abstract

Effects of metal contamination on microbial biomass in sediment samples from three areas in Palestine Lake (one area highly polluted with chromium, cadmium and zinc) were determined . Adenosine triphosphate (ATP) concentrations, determined by the luciferin-luciferase bioluminescent technique, and microbial colony numbers on pour plates were used as biomass indicators .Plate counts showed a significant (P < 0 .01) site effect with the highly contaminated area having an order of magnitude lower microbial population than the control area . ATP concentrations also indicated lower microbial biomass in contaminated sediments . The metal concentrations of the most contaminated area averaged 17,840 µg Zn/g, 4380 µg Cr/g and 585 µg Cd/g based on dry weight of sediments. A suppression of organic decomposition was evident in the impacted area ; high metal levels and resultant low microbial biomass may have been causative .

Toxicity of Zinc to Heterotrophic Bacteria From a Tropical River Sediment

“…The effects of zinc on the microbial activity of water and sediment communities have been reported [22,23,32]. A suppression of organic decomposition was observed in the heavy metal contaminated sediment of Palestine Lake containing average zinc level of 17840 mg/kg sediment [22]. Likewise, Zn 2+ inhibited glucose uptake and mineralization by water and sediment microbial communities of a contaminated stream.…”

“…It could be that the concentration of zinc was not high enough to select for tolerant organisms in the sediment. The effects of zinc on the microbial activity of water and sediment communities have been reported [22,23,32]. A suppression of organic decomposition was observed in the heavy metal contaminated sediment of Palestine Lake containing average zinc level of 17840 mg/kg sediment [22].…”