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English :
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Soil microorganisms and specific biochemical activities under lead and cadmium contamination
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Arabic :
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ميكروبات التربة و بعض الأنشطة الآنزيمية الحيويةتحت ظروف التلوث بعنصري الرصاص و الكادميوم
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| Abstract |
Two separate laboratory experiments were carried out to achieve the main objective of this research. The first was to estimate the relative lead or cadmium tolerance of some soil microorganism, under different concentrations strengths (10, 50, 100, 250, 500 and 1000 ppm of Pb+2 or Cd+2 strength) compared with the control (0 level), which introduce in the appropriate media recommended for the enumeration of total bacteria, actinomycetes, fungi, Azotobacter sp. and Azospirillum sp. Population densities of these groups which could tolerate different concentrations of either metal salts were determined.
Results should that the multiplication of all microorganisms studied was adversely affected by the presence of Pb+2 or Cd+2 salts in the media, also, the remarkable deleterious effect began at concentration starting from 250 ppm Pb+2 or 100 ppm Cd+2 and higher concentration of either metal was accompanied by a corresponding increased suppression rates further more, cadmium proved to be more toxic than lead, as well as fungi was more relatively resistant and Azospirillum sp. was lower relatively resist than other microorganisms.
The second experiment was conducted to study the effect of pollution with lead or cadmium, that could be introduced to soil through the application of contaminated sewage sludge, on multiplication rates of some microorganisms and specific biochemical activities in soil. The fertile clay loam soil uncontaminated with heavy metals was amended with 0, 2.5 and 5 % sewage sludge together with 0, 50, 100 and 250 ppm Pb+2 or Cd+2 as lead acetate and cadmium chloride. The counts of the aforementioned microbial groups as in the first experiment, as well as dehydrogenase , phosphatase and nitrogenase activities were determined periodically.
Generally, results indicated that the counts of total bacteria, actinomycetes, fungi, Azotobacter sp. and Azospirillum sp. as well as dehydrogenase and phosphatase activities increased, with increasing the application rates of sewage sludge and incubation periods compared with S1 (without sludge), particularly 2.5 % sludge at 21 days under different levels of both Pb+2 or Cd+2 was more effective, opposite trend with nitrogenase activity was observed particularly with 5 % sludge, cadmium was more toxic than lead. It is also note that fungi were more resistant while Azospirillum sp were more sensitive compared with the other microorganisms
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| Publication year |
2006
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| Pages |
325-341
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| Availability location |
The Egyptian Society of Applied Sciences(معهد بحوث الاراضى والمياه والبيئة)
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| Availability number |
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| Organization Name |
Soil, Water and Environment Research Institute (SWERI)
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| City |
Zagazig
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| serial title |
Egyptian Journal of Applied Sciences
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| ISSN |
1110-1571
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| Department |
Agricultural Microbiology Research
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| Author(s) from ARC |
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| Agris Categories |
Soil biology
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AGROVOC
TERMS |
Biological control.
Cadmium.
Lead.
Pollution.
Pollution control.
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| Publication Type |
Journal
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