| Abstract: |
The present work aims to assess the environmental geochemistry of the Red Sea coast of Egypt from Abu Darag on the Gulf of Suez due north to Berenice due south. The study involves description of the shore line nature, giving complete systematic classificaV.1. Nature of shore line:According to the type of shore materials, the shoreline could be classified into the following types:V.1.1. Reefal beaches:These beaches are composed of hard, massive algal coralline limestone of the youngest Pleistocene coral reef, along the Red Sea Coast. Most of the tourist villages and resorts were built above this unit. Reefal beaches are found in two forms:(1) The first form consists of walls facing the sea, 0.5-9m height, clean from sediments and sea water reaches during high tide. They are vertical or strongly sloped (60?-90?) and represent a suitable substrate to some invertebrate dwellers that tolerate V.1.2. Gravelly beaches:Beaches formed of non-consolidated pebbles to cobbles of different origins (rhyolite, basalt, porphyritic dacite or even of sedimentary). These clasts are transported to the shore from the hinterland “mountains”. Such clasts act as a suitable substrate foV.1.3. Sandy beaches:These beaches are mostly present along the entrances of large wadies. They formed of friable sandy and locally gravelly sediments as well as shell fragments of molluscs, algae, corals, and foraminifera, which drifted by storms and high tide above these beV.1.4. Mangrove beaches:Mangrove beaches are found in many stations on the Red Sea Coast. They become more frequent and extensive towards the south. The roots are nurseries and provide nests for several species of fish, shrimps, algae, bivalves and other crustaceans. The trees fV.1.5. Man-made beaches:These are locally landfill beaches formed of moderate to huge concrete masses, rock fragments, mining products and sands. They present around main cities as wave breaks to protect cities from high storms. Also they are used to make artificial lagoons and V.2. Sea-Shell Taxonomy:Sixty-four living species have been described, illustrated and identified. These species are covering the main invertebrate shells of the Red Sea coast. These identified species belong to forty seven genera and thirty six families. They include one AmphinV.3. Rocky-shore dwellers:The studied invertebrate rocky shore dwellers are classified into the following four major groups:V.3.1. Incrusters:Incrusters are those sessile epibenthos which are permanently attached to the substrate by cementation, and cement themselves by calcification. This group includes the following taxa: Barnacles (Balanus perforatus and giant barnacle Tetracelita squamosa),V.3.2. Clingers:Clingers are very slow vagile epibenthos, and clinging tightly to rocks in shallow water or in littoral (or exposed to splash) zone. They are represented by limpets (Patella (P.) vulgata, Nerita albicilla, N. longii and N. textilies) and chitons (Chiton pThey adhere themselves firmly by a strong and large muscular foot and use well developed radula for grazing on algae. They tolerate the same environmental stresses mentioned in the incrusters. Representatives of this group confined their foraging activitiV.3.3. Crawlers:Crawlers are those epibenthos that and have long-spired turreted shells move slowly with their bodies close to the ground. They are here represented by four gastropod species: Planaxis sulcatus, Cerithium caeruleum, C. nodulosum and Rhinoclavis (Proclava)V.3.4. Byssate:Many bivalves secrete threads of the protein collagen, with which they attach themselves to the sea floor. This group is represented in this study by two bivalve species: Modiolus (M.) auriculatus and Tridacna squamosa. Both species live entirely covered V.4. Geochemistry of Sea shells:In the present study, two gastropod species are selected for monitoring toxicity by trace metals, namely; Nerita albicilla (Linnaeus) and Canarium (Gibberulus) gibbosus (R?ding). These two species have a wide geographical distribution along the Red Sea coThe relationships among the analyzed elements are determined by correlation matrix and factor analysis. Moreover, they display very serious differences in abundance of elements, where Nerita can be considered as a geochemical marker for a sizeable group oThis is possibly due to differences in their incorporation of the elements within the crystal lattice of carbonates composing the shells or to the mode of life. According to the nature and habitat of life, Nerita lives vegetarian commonly in the intertidaThe second species (Canarium) is, in contrast, not able to live outside sea water. It is herbivorous and has serrated edge, which the animal uses for lunging movements in shallow sea-grass beds where the sediments are quite fine and the soft sediments areOn basis of their geochemical behavior, the studied elements can be divided into three groups, namely; (1) Major elements group including Fe, Ca, Mg, Na, K and S. In both Nerita and Canarium there are good similarities among all these elements, except forAccording to the chemical analysis data of the two species, the investigated area can be divided into three zones, the first one is the almost pristine zone which covers the stations: 12km north Mersa Alam, 43km south Mersa Alam and 43km north Berenice, wThe second zone represents the moderately polluted area of Hamrawein and the area from 40km north Mersa Alam to Mersa Alam. This zone shows relative enrichment of Th and sometimes Mo or U. Indeed, there is no straightforward explanation of such sporadic pThe sorption affinity of Ismailia canal bottom sediments to134Cs, 89Sr, 60Co and (152+154)Eu is affected by contact time, pH of the aqueous phase, competing ion concentration, metal ion concentration and humic acid concentration.The uptake percent increases with time, till it attains a constant value depending on the type of the radioelement, nature of the sediment sample and the chemical composition of the aqueous phase. The equilibrium time between the different sediment sampleThe uptake percent of the investigated radionuclides is very small or negligible in strongly acidic solutions. As the pH increases the sorption gradually increases till reaching a maximum value around pH 7.5, 7.0, 6.5 and 6 for 134Cs, 89Sr, 60Co and (152+Sorption of the investigated radioisotopes on the sediment samples was affected by low or moderate electrolyte concentrations, which was attributed to the competition in ion exchange. It is shown that the presence of K+, Ca2+, Mg2+and Fe3+ ions decrease tThe uptake percent of the investigated radionuclides showed a significant decrease with increasing the metal ion concentration of these elements. The sequence of decreasing the uptake of different radioisotopes as related to the nature of the sediment samHumic acid concentration has no effect on sorption of 134Cs by Ismailia canal bottom sediment samples. This result was interpreted as showing that the humic acid has no tendency to form complex with cesium ions. The sorption of 89Sr and 60Co by Ismailia cThe desorption of the studied radionuclides from loaded sediment samples is relatively low. It was discussed in the light of the formation of chemical bonds. This desorption was interpreted to the presence of K+, Na+, Ca2+, Mg2+,… ions in Ismailia canal wThe integral method used to analyze the data obtained from sorption of 134Cs, 89Sr, 60Co and (152+154)Eu by Ismailia canal bottom sediments illustrates that the sorption reaction is first-order reaction.Chapter four: Modeling of Radionuclides Transport in Surface WaterThis chapter includes the suggested mathematical computer model for radionuclide transport in Ismailia canal. The data obtained shows that the concentration of the studied radionuclides decreased as the distance increased from the point of the discharge. It should be stated here that the investigations carried out in this work enabled us to collect preliminary data on some of the physicochemical characteristics of the Ismailia canal environment. Also, it gave information about the possible interactions be
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