الفهرس 
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Abstract
520. التبصرة الخاصة بالت... 3# a) The present study aimed to investigate the effect of some heavy metals on algae. It is divided into three parts. The first part deals with heavy metals toxicity from an ecological stand point, the second part deals with heavy metals toxicity from a physiological stand point, and the third part deals with interaction of some environmental factors in attenuation the toxicity of heavy metals from a chemical equilibrium stand point.
The ecological part demonstrated the toxic effect of cobalt, copper and zinc on Nile water phytoplankton at various concentrations (10-9, 10-8, 10-7 and lO-6M). The following conclusions were reached:-
1. The lower doses of the tested metals (Cobalt, copper and zinc) enhanced the growth of Nile phytoplankton, which is represented by increase in species number and pigment content,a trend that was more pronunced in cobalt teatment . The moderate and higher concentrations of these metals markedly inhibited the growth of Nile phytoplankton.
2. Regarding to species composition, total disappearance of some species with metal treatments was observed, whill the number of other species increased. In case of disappearance a direct toxic effect indicating a sensitivity of some species to the used metals, however in case of increase, there are metal resistant or tolerant species.
3. For metal toxicity Chlorophyceae was the most resistant algal groups, and finally Bacillariophyceae followed by Cyanophyceae.
1. The lower doses of cobalt, copper and zinc had stimulatory effect in biomass yield of ChIarella vulgaris, whereas the higher doses were inhibitory depending on the type of the metal.
4. The species-dependent metal sensitivity and the ecosystem-dependent metal availabilities might influence the composition of phytoplankton communities.
5. Copper was more toxic to phytoplankton growth than the other two metals,. The arrangement of these three metals in respect to increasing toxicity yields the following sequence: Cu2+ > C02+ > Zn2+.
The physiological part demonstrated the toxic effect of the three tested metals mentioned above on the metabolism of the green alga ChIarella vulgaris isolated from the Nile water at various concentrations (10-9, 10-8, 1007 and 10-6M). The following conclusions were reached:-
2. The inhibitory effect of copper to the growth parameters of ChIarella vulgaris was more pronounced than the other two tested metals.
3. The total protein content of the tested green alga ChIarella vulgaris gradually decreased in a manner dependent on the metal concentration in the medium.
4. Total carbohydrate content of ChIarella vulgaris also declined in a manner dependent on the metal concentration in the medium, but the inhibitory effect of the three tested metals were not as pronounced as on protein content. However the high concentrations of the three tested metals did not reduce the total amount of carbohydrates.