| Abstract: |
The aim of the present investigation was mainly intended to characterise the water quality of Bahr Moues and Bahr Hados - economically important water habitats in El- Sharkia Governorate, Egypt. Physical and chemical properties of water and their relation(1) Generally, the physico-chemical properties of water which will be mentioned below as (mg.l-1) showed remarkable local and seasonal variations:Water temperature (17.5 - 31.5oC), pH (7 - 8), chlorides (17.5 - 53.1), Dissolved oxygen (3.35 - 11.1), BOD5 (7.6 - 85.6), COD (3.25 -109.4), CO2 (1.1 - 2), nitrate-N (0.03 - 1.2), ammonia-N (0.03 - 3.76), TSIN (0.17 - 4.4), TKN (1.25 - 6.12), TON (0.44 -(2) 40 algal taxa were recorded and identified. Chlorophyta formed about 38 % of total phytoplankton (15 taxa), Bacillariophyta was about 30 % (12 taxa) and Cyanophyta was about 25 % (10 taxa), while only two taxa of Euglenophytes were recorded and just o(3) In Bahr-Moues, the most dominant genera were Scenedesmus, Chlorella, Pediastrum, Synerda, Melosira, Merismopedia, Microcystis and Oscillatoria. Meanwhile Euglena was always the dominant taxa at downstream (Bahr-Hados) which, organically rich effluent.(4) The qualitative and quantitative growth and distribution of each algal division display great local and seasonal variations. Diatoms were the predominant algal group followed by green and then blue-green algae. On the other hand, Euglenophytes and Din(5) The upstream stations tended to support higher standing crop than the downstream ones. This may reflect the relatively higher nutritional capacity (nutrients availability) and/or lower water toxicity with the upstream water.(6) Chlorophyll ”a” concentration ranged between 3.25 and 9.23 µg.l-1.(7) Regarding the biological assessment of water quality, the saprobic, diversity, species richness, trophic state and palmer indices revealed the presence of ß- mesosaprobic forms of algae and different degree of pollution.(8) The results of the production and distribution of phytoplankton reflected more or less the physico-chemical characteristic of water, so using algae, as biological indicators were accurate, applicable and effective.(9) The results of the algal growth potential (AGPT) using Selenastrum capricornutum as a test organism revealed that:a- Phosphorus was the primary growth factor (increase the algal growth 3 to 4 folds) while nitrogen was the secondary one and then followed by metals toxicity.b- The test alga were able to utilize organic nitrogen under sever nitrogen limitation. Combination of phosphorus, nitrogen and Na2-EDTA together gave highly obvious effect on the algal growth especially at summer.c- Na2-EDTA supplementation with phosphorus and/or nitrogen increased the algal growth values, so this revealed its role to the metals toxicity removal or increasing the bioavailability of nutrients. Moreover, the calculated percentage of inhibition (% I1d- The relation between chemical analysed and bioavalable concentrations revealed the limitation of bioavailable nitrogen and bioavailable phosphorus in the used natural water.(9) At another laboratory experiment, three green algae were grown in both immobilized and free states to evaluate their efficiencies for pollutants removal from Bahr- Hados, which contain a heavy load of pollution. The results can be summarized at the foa- Immobilization techniques of the three different algal taxa using alginate beads increased their efficiencies of removal of different pollutants where the results of immobilized algae grown for 6 days were more or less similar to those grown freely forb- Chlorella vulgaris had a maximum efficiency of metals removal, where the maximum removal efficiency for metals by Chlorella vulgaris after 6 days more or less higher than the efficiency of the other two algae at 8 days incubation periods.c- Chlorella ellipsoida showed a higher efficiency for reducing BOD5, NO3, NH3, phosphorus and consequently T.N. while, Scenedesmus quadricauda showed a good efficiency for COD and T.N. removal.d- On the other hand, at free state, the smaller alga has the highest efficiencyfor pollutants removal so, Chlorella vulgaris showed the most potent for removal of all different pollutants when compared with the other two algae.e- Scenedesmus quadricauda at either free or immobilized forms was the lowest alga regarding the reduction rate of heavy metals compared with the corresponding data obtained by Chlorella spp.The study area received large amount of different wastes (industrial, agriculture and other human activities pollution) from surrounding urbanized area which exerted impressive negative effect on the water quality especially with downstream stations. Unle
|
|
|