TY - GEN AU - Mohamed Nasr Leithy AU - Hoda Ali Sadek , AU - Nahla Abd El Fattah Elkady , AU - Sanaa Abd El Kareem Helmy , TI - effect of heavy metals on microbial activity insome ecosystems / PY - 2006/// CY - Cairo : PB - Mohamed Nasr Leithy , KW - Heavymetals KW - Organic motter KW - soil pollution N1 - Thesis (PH.D.) - Cairo University - Faculty Of Agriculture - Department Of Microbiology; Issued also as CD N2 - The effect of four metal concentrations , as well as , six Gamma - irradiation doses on the activity of cellulase , urease and dehydrogenase was determinedApplication of heavy metals at any rate caused noticeable reduction in their activity depending upon the metal type and concentrationEven at the low concentration , Cr6+followed by Hg2+had the most harmful effect on the enzymatic activities , while Pb2+showed the least toxicitySoil exposure to Gamma - irradiation differently affected the enzymatic activitiesThis varied from stimulating effect on urease to suppressive one on dehydrogenaseGenerally , the high doses of - rays inhibited the activity of the three enzymes and dehydrogenase proved to be the most susceptible enzyme toward radiation UR - http://172.23.153.220/th.pdf ER -