Recent observations on some hydrographic and chemical aspects of lake Edku waters, Egypt

Lake Edku which is a shallow brackish water receives huge amounts of drainage and industrial waters, carrying great amount ef pollutants. The study pertains to investigate precisely the changes which took place on the hydrography and chemistry of the waters of lake Edku as a result of pollutants disposal. To achieve this goal; a very comprehensive study was made du- fing 1990. The present paper deals with the results of some hydrogaphic and chemical parameters; namely; temperature, Unity, hydrogen ion concentration, dissolved oxygen, oxidizable organic matter, hydrogen sulphide, chlorophyll-a, am onia, nitrite, nitrate and phosphate. The levels of which are in the ranges: [14.99-30.1.0C], [1.16-26.527], [8.08-9.83], [1.15-11.5 ml/U], [0.24-11.64 mg O[2]/L], [0.15-1.1-4 mg/L], [0.69-2.76 mg/m[3]], [Zero-9.53 ug at./I], [Zero-12.37 ug .it./P]. [Zero-57.79 ug at./I] and [Zero-6.60 ug at./I]. The present paper ascertained that the discharge industrial wastes, farm effluents enriched with chemical fertilizers in addition to drainage waters affected greatly the hydrography and chemistry of tlie waters of lake Edku as manifested by the high amounts of organic matter [5.5 mg O[2]/L], high hydrogen sulphide/ ammonia ratio [1.55] and relatively low percentage of dissolved oxygen that present after complete oxidation of organic matter [47%]. The polluted water disposal elevated the nutrients concentrations to levels which caused some levels of eutrophication at some stations. The N/P ratio suggests that phosphorus is the most limiting factor for the growth of algae in lake Edku

Environmental condition of the western harbour of Alexandria: I-physico-chemical characteristics

A study was carried out in order to evaluate the recent environmental condition of the Western harbour of Alexandria during the period from August 1988 to June 1989. The levels of temperature, salinity, hydrogen ion concentration [pH], dissolved oxygen, hydrogen sulphide, chlorophy11-a, ammonia, nitrite, nitrate and inorganic phosphate are scattered in the ranges [17.00-30.50C], [24.92-39.09%], [7.70-9.25], [0.00-8.35 nl/D], [0.22-13.60 mg 0/1], [1.61-4.30 mg/1], [0.02-7.22 mg/m], [0.72-26.98/ug it/I], [0.07-2.84/ug at.1].[0.036-24,69/ig at./I] and [0.003-3.98 > ug at./I]. Hydrogen sulphide-ammonia showed an obvious relationship. The calculated ratio of H[2]S/NH[3]- was 0.49 which is much lower than the theoretical value of anoxic water. The calculated amount of dissolved oxygen present after complete oxidation of organic matter [54-55%] was comparable to that recorded in the Eastern harbour and El-Mex Bay during 1988. The mean annual ratio of N/P [14:1] suggests that phosphorus is the most limiting factor for the growth of algae in the harbour

Trace elements concentrations in the fish samples from Alexandria region

Fish samples representing 10 different species of fish were collected from Abou-Qir Bay; namely, Mullus surmuletus, Marone laprax, Anguilla spp., Mugil cephalus, Dentex dentex, Sardinella spp., Sphyraena spp., Epinephelus alexandrinus, Pagrus, Trichiurus lepturus in addition to Tilapia galliae from Lake Edku in order to evaluate the concentration levels of Zn, Mn, Fe, Ni, Cu, Co, Cd, Cr and Pb in their tissues. A composite sample for each of the different species was digested in decomposition vessels and measured by means of an atomic absorption spectrophotometer. The data presented in this paper indicated that the concentrations of the different trace elements did not only vary between the tissues of different fish species but also varied in the same specimen, depending on the season. The mean concentration revealed that there was no high trace elements concentration in the tissues of the different fish species that could endanger consumer

Major cations and alkalinity in the western harbour waters of Alexandria

The concentrations of major cations, total alkalinity and chlorinity have been determined in seawater samples collected monthly from eight hydrographic stations in the Western Harbor of Alexandria during 1989-1990. Although the concentrations of major cations and alkalinity are nearly the same in surface and bottom waters, the surface waters of the western harbor exhibited higher levels of specific alkalinity and major cations to chlorinity ratios compared with the bottom waters. On contrary, also to the proper sea waters, broad seasonal and regional variations of chlorinity, total alkalinity, major cations as well as their ratios to chlorinity have been observed in the harbor waters. On the result of polluted water disposal, no definite correlations could be found between alkalinity and chlorinity or major cations and chlorinity in the investigated area. The specific alkalinity is higher in the harbor waters than that of the normal seawater. The harbor waters exhibited also higher ratios of calcium and potassium than normal sea water and the reverse is true for magnesium and sodium

Iron, manganese, nickel, lead and cadmium in fish and crustacea from the eastern harbour and El-Mex bay of Alexandria

Fish and crustacean samples [Siganus rivulatus, Xyrichthys mavacula, Thalassom pavo, Scorus creiensis, Pagrus pagrus, Monacanthus procellus, Lithognathus mormyrus, Chrysophris aurata, Diplodus cervinus, Sphyranea sphyranea, Diplodus vulgaris, Scomber japonieus and Portunus spp.] were collected from the Eastern Harbor and Al-Max Bay during 1988. All samples were analyzed for Fe, Mn, Ni, Pb and Cd by flame atomic absorption spectrophotometer. The results of the metal concentrations in fish and crustacea varied, i. e. Fe: 0.82-5.03 ppm, Mn: 0.01-0.22 ppm, Ni: 0.06-2.66 ppm, Cd: 0.008-0.13 ppm and Pb: 0.28-0.14 ppm. The concentrations of trace elements examined in fish and crustacea varied from one species to another. Interspecies variations in the concentration of trace metals were found, indicating the importance of monitoring program for different fish species. The concentrations of heavy metals in fish and crustacea did not reflect any contamination signs and the levels found in the investigated area were much lower than the recommended values. The concentration factors estimated from the levels of trace metals in fish and water in the area of investigation were in the order: Pb > Ni > Fe > Cd. These factors were found to be higher in the Eastern Harbor in comparison with Al-Max Bay

Effect of pollution by hydrogen sulphide on certain aquatic organisms

The toxicity of hydrogen sulphide toward some marine aquatic organisms; namely; Tilapia gallilae; Nauplii larvae; of Artemia salina, Ocenebra erinacea and Idotea baltica have been studied. The results of the present study indicated that both Nauplii larvae and Ocenebra erinacea are very resistant to the effect of hydrogen sulphide even at very high concentrations of hydrogen sulphide [30 mg/1 and 42 mg/1 respectively] during the period of investigation. The hydrogen sulphide affected the survival of Tilapia gallilae to a degree of 21.5%; while the time factor contributed by only 3.47. It was difficult to get a 50% mortality with Tilapia gallilae after 7 days and at a maximuir concentration of hydrogen sulphide [16 mg/1]. The survival rate of Idotea baltica was affected to a degree of 65.5% after 9 days and at a concentration level of 10 mg/1. The time factor played a role by only l5.8%. The LC[50] was achieved at a concentration level of 6.6 mg/1 of hydrogen sulphide