Phytoplankton Structure biochemical Stoichiometry and elemantal comnosition in Lake Nasser Egypt

The relationship between environmental variables and elemental, biochemical composition of phytoplankton species in Lake Nasser were studied. In the lake 130 phytoplankton species were recorded, the lake is dominated mainly by Cyclotella glomerata (Bacillariophyceae), Planktolyngbya limnetica, Eucapsis minuta (Cyanophyceae). Phytoplankton organic carbon content at the lake was 32%. The elevation of NO3 (365 μg/l) and CO3 (21 mg/l) at the east of the lake was concurrently with the highest proportion of inorganic C, N and algal protein content. C/N ratio decreased thus Redfield ratio indicating a high growth rate of phytoplankton with increasing protein content. C/H and O/C ratio for natural phytoplankton samples were less than one, which means unsaturated aliphatic compounds at metabolites categories of phytoplankton. RDA analysis cleared that, Cyclotella glomerata (dominant at the north area) was sensitive to flushing, tolerant to nutrient deficiency and had higher protein content. Planktolyngbya limnetica (dominant at the middle) was more sensitive to pH, phosphorus is non-limiting factor and characterized by elevation in lipid content. Eucapsis minuta (dominant at the south) was tolerant to mild light deficiency and contains a maximum value of carbohydrates and Chlorophyll a

Phytoplankton response to changes of physicochemical variables in Lake Nasser, Egypt

Seasonal and spatial changes of phytoplankton in relation to environmental variables affecting the water quality were investigated along the main channel of Lake Nasser throughout 2013. In total, 104 phytoplankton species, belonging to 7 classes, were identified. Phytoplankton assemblages were dominated by Bacillariophyceae, Cyanophyceae and Chlorophyceae, whereas Dinophyceae, Euglenophyceae, Chrysophyceae and Cryptophyceae were infrequent. Cyclotella glomerata, C. ocellata and Aulacoseira granulata represented the most abundant species among Bacillariophyceae. Cyanophyceae was dominated by Planktolyngbya limnetica and Eucapsis minuta, and Chlorophyceae by Ankistrodesmus fusiformis and Staurastrum paradoxum. The water column was thermally stratified during summer, while being mixed throughout winter. Phytoplankton features and physicochemical variables were analyzed with the principal component analysis. Electrical conductivity and water temperature were the most common factors negatively controlling phytoplankton density. Phytoplankton density was positively associated with NO3, whereas it was negatively correlated with PO4 and HCO3. Cyanophyceae were strongly adapted to the environmental variables and NO2 was limiting their growth. Chlorophyceae were more dependent on PO4 than NO3. The vertical distribution of Chl a was associated with the summer thermal stratification and its concentration increased southwards. Chl a was affected by NO2 and linked to Chlorophyceae. The regional variations of phytoplankton reflected its response to varying environmental conditions. The annual average of the trophic state index indicated eutrophic waters of Lake Nasser

The isotherm and kinetic studies of the biosorption of heavy metals by non-living cells of Chlorella vulgaris

In general, the biosorption of heavy metals by various types of non-living organisms appears to be a very effective, low-cost and innovative method for their removal from aquatic environments. The aim of this study was to determine the applicability of adsorption isotherms and kinetic models during the biosorbent activity of non-living Chlorella to the removal of Cd, Cu and Pb. Dead cells of Chlorella vulgaris were used to remove these heavy metals from aqueous solution in experimental conditions, i.e. under various condition of pH, biosorbent dosage and contact time. Afterwards, the Langmuir and Freundlich adsorption isotherm models and the sorption kinetic (pseudo-first and pseudo-second order models, and intraparticle diffusion) were applied to the experimental data to check the effectiveness of the removal process. The removal of heavy metals on C. vulgaris following the order of Pb+2 > Cu+2 > Cd+2 was confirmed by the maximum biosorption capacities (qmax), the Langmuir constant (b), separation factor (RL) and Freundlich intensity parameter (1/n) values. The equilibrium data were well fitted with the Langmuir and Freundlich isotherm models. The adsorption process followed the pseudo-second-order model and it suggested that such kinetics is the most effective. The present results confirmed highly efficient biosorbent activity of C. vulgaris in the removal of heavy metals, especially Cd, Cu and Pb, from aqueous solution. The environmentally friendly origin indicates that non-living cells of C. vulgaris could find many broad-scale, cost-effective and alternative applications

The isotherm and kinetic studies of the biosorption of heavy metals by non-living cells of Chlorella vulgaris

In general, the biosorption of heavy metals by various types of non-living organisms appears to be a very effective, low-cost and innovative method for their removal from aquatic environments. The aim of this study was to determine the applicability of adsorption isotherms and kinetic models during the biosorbent activity of non-living Chlorella to the removal of Cd, Cu and Pb. Dead cells of Chlorella vulgaris were used to remove these heavy metals from aqueous solution in experimental conditions, i.e. under various condition of pH, biosorbent dosage and contact time. Afterwards, the Langmuir and Freundlich adsorption isotherm models and the sorption kinetic (pseudo-first and pseudo-second order models, and intraparticle diffusion) were applied to the experimental data to check the effectiveness of the removal process. The removal of heavy metals on C. vulgaris following the order of Pb+2 > Cu+2 > Cd+2 was confirmed by the maximum biosorption capacities (qmax), the Langmuir constant (b), separation factor (RL) and Freundlich intensity parameter (1/n) values. The equilibrium data were well fitted with the Langmuir and Freundlich isotherm models. The adsorption process followed the pseudo-second-order model and it suggested that such kinetics is the most effective. The present results confirmed highly efficient biosorbent activity of C. vulgaris in the removal of heavy metals, especially Cd, Cu and Pb, from aqueous solution. The environmentally friendly origin indicates that non-living cells of C. vulgaris could find many broad-scale, cost-effective and alternative applications

Ecosystems of artificial saline lakes. A case of Lake Magic in Wadi El-Rayan depression (Egypt)

The Wadi El-Rayan is a depression in the Fayoum oasis collecting agricultural drainage water from the Fayoum. Since 1973, this drainage water formed two man-made lakes. Twenty years ago, a third lake, called Lake Magic was formed. Since this newly formed lake was not yet studied, in January of 2019 we conducted research related to its physico-chemical (ion composition, nutrients, heavy metals, etc.) and biological (phyto-, bacterio- and zooplankton) characteristics. The depth of the lake ranged from 1.5 to 9.0 m, water transparency was up to 4.0 m, and the water temperature was 13.6 °C. The average salinity was 29.1 g/l, and the salinity of drainage waters from agricultural fields was 2.9 g/l. A total of 28 phytoplankton species was identified belonging to Bacillariophyceae (eight species), Dinophyceae (three species), Cyanobacteria (seven species), Chlorophyceae (nine species) and Conjugatophyceae (one species). Chlorophyll a content varied from 14.3 to 24.2 μg/l. In zooplankton, there were three species of Ciliophora, five of Rotifera, and two Copepoda as well as Nematoda and Cirripedia larvae. Salinity in Lake Magic was much higher than in drainage waters coming in the lake. This is a result of a strong salinity increase in Lake Magic after its creation due to climate aridity, and salinity may markedly increase during the next 20 years along with the sharp changes of the lake's ecosystem