In order to evaluate the contamination of the Moroccan Mediterranean coasts by persistent organic pollutants we studied hydrocarbons and linear alkylbenzenes in bivalve tissues (cockles) collected seasonally from seve...In order to evaluate the contamination of the Moroccan Mediterranean coasts by persistent organic pollutants we studied hydrocarbons and linear alkylbenzenes in bivalve tissues (cockles) collected seasonally from several points along the western Moroccan coasts in the Mediterranean Sea. Two fractions corresponding to non aromatic and aromatic hydrocarbons were analyzed by GC/FID and GC/MS. Non aromatic hydrocarbon concentrations vary in the range of 24.1 - 2731 μg/g dry weight (dw) while total n-alkanes vary from 2.2 to 68.2 μg/g. Few exceptions were noted with values up to 243 μg/g (dw), which is high compared to other Mediterranean sites. The presence of an important unresolved complex mixture (UCM) indicated a significant petroleum contamination, confirmed by the identification of 17α(H), 21β(H) hopanes. Biogenic contributions were also detected within the n-alkane distribution (n-C17, n-C18, n-C27, n-C29, n-C17, /Pr, n-C18, /Ph) and by the presence of alkenes. C13, and C14, linear alkylbenzenes were found at concentrations of 478 - 1954 ng/g. and point to pollutant inputs from wastewaters. Polycyclic aromatic hydrocarbons were present in low concentrations below the GC detection limit. The observed seasonal and spatial variations were linked to the magnitude of inputs from marine and land-based pollutant discharges.展开更多
The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and rel...The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and related to 23 families of vascular plants are recorded. Asteraceae, Poaceae, Chenopodiaceae, Brassicaceae, Fabaceae and Zygophyllaceae are the largest families, and therophytes (41.89) and chamaephytes (24.32%) are the most frequent, indicating a typical desert life-form spectrum. Chorological analysis revealed that 25 of the studied species were Mediterranean taxa, Saharo-Sindian chorotypes, either pure or penetrated into other regions, comprised 47 species. After application of the TWINSPAN and DCA programs, 4 vegetation groups (A-D) were identified, groups A and B were dominated by Achillea santolina, group C was codominated by Zygophyllm coccinum and Launaea spinosa and group D was dominated by Leptadenia pyrotechnica. Groups A and B may represent the vegetation types of the Western Mediterranean coast of Egypt, while groups C and D may represent the Wadi Hagul. The linear correlation of soil variables with the importance values of some dominant species and the application of Canonical Correspondence Analysis (CCA-biplot) indicates significant associations between the floristic composition of the studied area and the edaphic factors such as electrical conductivity, pH, calcium carbonate, sulphates, bicarbonate, cations (Na+, K+, Ca++ and Mg++) and PAR.展开更多
文摘In order to evaluate the contamination of the Moroccan Mediterranean coasts by persistent organic pollutants we studied hydrocarbons and linear alkylbenzenes in bivalve tissues (cockles) collected seasonally from several points along the western Moroccan coasts in the Mediterranean Sea. Two fractions corresponding to non aromatic and aromatic hydrocarbons were analyzed by GC/FID and GC/MS. Non aromatic hydrocarbon concentrations vary in the range of 24.1 - 2731 μg/g dry weight (dw) while total n-alkanes vary from 2.2 to 68.2 μg/g. Few exceptions were noted with values up to 243 μg/g (dw), which is high compared to other Mediterranean sites. The presence of an important unresolved complex mixture (UCM) indicated a significant petroleum contamination, confirmed by the identification of 17α(H), 21β(H) hopanes. Biogenic contributions were also detected within the n-alkane distribution (n-C17, n-C18, n-C27, n-C29, n-C17, /Pr, n-C18, /Ph) and by the presence of alkenes. C13, and C14, linear alkylbenzenes were found at concentrations of 478 - 1954 ng/g. and point to pollutant inputs from wastewaters. Polycyclic aromatic hydrocarbons were present in low concentrations below the GC detection limit. The observed seasonal and spatial variations were linked to the magnitude of inputs from marine and land-based pollutant discharges.
文摘The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and related to 23 families of vascular plants are recorded. Asteraceae, Poaceae, Chenopodiaceae, Brassicaceae, Fabaceae and Zygophyllaceae are the largest families, and therophytes (41.89) and chamaephytes (24.32%) are the most frequent, indicating a typical desert life-form spectrum. Chorological analysis revealed that 25 of the studied species were Mediterranean taxa, Saharo-Sindian chorotypes, either pure or penetrated into other regions, comprised 47 species. After application of the TWINSPAN and DCA programs, 4 vegetation groups (A-D) were identified, groups A and B were dominated by Achillea santolina, group C was codominated by Zygophyllm coccinum and Launaea spinosa and group D was dominated by Leptadenia pyrotechnica. Groups A and B may represent the vegetation types of the Western Mediterranean coast of Egypt, while groups C and D may represent the Wadi Hagul. The linear correlation of soil variables with the importance values of some dominant species and the application of Canonical Correspondence Analysis (CCA-biplot) indicates significant associations between the floristic composition of the studied area and the edaphic factors such as electrical conductivity, pH, calcium carbonate, sulphates, bicarbonate, cations (Na+, K+, Ca++ and Mg++) and PAR.
