الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Alexandria is the second largest city in Egypt, it occupIes a narrow stretch along the sea, extending for about 40 km, from Abu-Qir at the east to EI-Agamy at the west between the Mediterranean sea and lake Mariut. The problem of marine pollution by heavy metals is of great concern in the last three decades due to the harmful effect on the marine environment and consequently on the human health. Oceans and open seas sustain a large number of heavy metals in different centrations. Coastal areas which are subjected to a direct discharge of erent types and amounts of land-based effluents; domestic, agricultural and lustrial wastes contain several heavy metals. An additional amount of heavy :tals originates from marine paints and atmospheric fallout. EI-Mex, Eastern Harbour, Kayet Bay and Abu-Qir areas are considered as points of pollution along Alexandria beach. Umum drain receives different unts of industrial effluents originating from several plants in addition to ’cultural drainage water from Alexandria and Bohiera Provinces and an ’eased amounts of domestic wastes. EI-Mex Bay is directly subjected to urn drain and receives also dumped wastes from the ship traffic running to &om Western Harbour. The Eastern Harbour water is mainly subjected to central part of Alexandria through the Kayet-Bay Iines. Abu-Qir area receives effluents from different sources; El- Tabia the highest regional average 3.15mg 02/1 recorded for Kayet-Bay water reflects ,1 ~ quality of the discharged wastes in this area. Biochemical oxygen demand , , troD) values were fluctuated between 0.04-15.26 mg/l with a mean value of 1 , i,j) mg/I. It was noticed that the western part of the beach is characterized by high values, while lower levels were detected in the eastern one. Kayet-Bay .. water recorded the highest average 5 mg/l affected by the discharged domestic illtes. , With respect to nutrient salts levels, the western part of the beach was characterized by high values of nutrient salts. Land-based effluents are the main sources of nutrient in the studied area, EI-Mex water recorded the highest 1~ional nitrite 2.95 J.lM, nitrate 11.93 J.lM and silicate 38.79 J.lM, while Kayet ~y area recorded the highest phosphate 3.54 J.lM and ammonia 57.81 J.lM. The highest seasonal averages of Ca and Mg were reported during autumn ~ing 431 and 1502mg/l respectively, while the lowest average for Ca was letected during winter and for Mg during spring being 391, 1317 mg/l ~respectively. EL-Mex area recorded the lowest regional averages of Ca and Mg maicating the dilution effect on seawater quality, particularly in (July) where the 18Jues of both Ca and Mg decreased to be 269, 718 mg/l respect~vely. With o:espect to total suspended matter, Kayet-Bay and Stanly waters reflected the , ~maximum and miriimum concentrations, respectively. Concerning the studied heavy metals concentration in Alexandria water, i~ese ranges a..TJ.d averages in dissolved forms were as foJIows; Cu (0.26-15.83; 1 mean3.04~g/I), Zn (0.33-40.62; mean 6.9IJ.Lg/I), Pb (ND-28.63; mean 4.03J.Lg/I), (d (ND-2.16; mean 0.52J.Lg/I), Co (ND-9.II; mean 1. 88J.Lg/l), Ni (ND-I3.07; mean 3.98~g/l) and Cr (ND-5.09; mean 0.83J.Lg/I). The dissolved heavy metals reflected temporal as well as spatial variations. Abu-Qir water and to a less Ixtent Kayet-Bay area are characterized by high averages of dissolved Cu, Zn, ~o and Cr, EI-Agamy water sustained the highest levels of Cd, Co and Cr. Kayet- Bay water represents the highest Ni average. Low seasonal averages of Issential metals Cu and Zn in addition to Cd and Ni recorded during spring can ’~explained by phytoplankton bloom and subsequent scavenging of these metals. A significant direct correlation (FO.52) was computed between the IDssolved forms of Zn and Cd. Cobalt (dissolved form) shows, on the other hand, reversible correlations with each of Cu (- 0.33), Ni (-0.40) and Zn (-0.39). The wncentration of dis~olved metals in Alexandria beach water could be arranged as follows: Zn > Pb > Ni > Cu > Co > Cr > Cd. The particulate fonn either ranges or averages could be reported as follows; Cu (ND-I2.39; mean 1.78J.Lg/I, Zn (ND-79.64; mean 6.96J.Lg/I), Pb (ND-l1.62; mean 3.31 J.Lg/I), Cd (ND-2.08; mean 0.45J.Lg/I), Co (ND-0.62; mean . . ~.l3~g/l), Ni (ND-20.27; mean 3.11 J.Lg/l), Cr (ND-20.05; mean 0.86J.Lg/l). Kayet-Bay water in the western part of the beach sustained the highest levels ofparticulate tu, Zn and to a less extent Co, Ni and Cr. EI-Agamy water contained the highest levels of both dissolved and particulate Cd. Contrary to the :ase of dissolved fonn, spring and to a less extent summer achieved the highest wncentration of particulate Zn, Cd and Ni. Concerning the distribution of heavy metals in the particulate fonn it follows the order: Zn >Pb >Ni>Cu>Cr >Cd >Co. It is clear that only the first four elements in both orders (dissolved and ~miculate) occupy sImilar pattern. The results displayed that dissolved fonns of Umost studied metals are higher in concentration than particulate ones.