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Evaluation of spatial and temporal variations of surface water quality in the Nile River Damietta branch

El-Tohamy W. S., Abdel-Baki S. N., Abdel-Aziz N. E., Khidr A. A.

Ecological Chemistry and Engineering. S

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2018

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Vol. 25, nr 4

569--580

EN

The objective of this study is to reveal the spatial and temporal variations of surface water quality in this part of the River Nile with respect to heavy metals pioneerution. Seventeen parameters in total were monitored at seven sites on a monthly basis from October 2013 to September 2014. The dataset was treated using the tools of univariate and multivariate statistical analyses. Cluster analysis showed three different groups of similarity between the sampling sites reflecting the variability in physicochemical characteristics and pollution levels of the study area. Six PCs factors were identified as responsible for the data structure explaining 91 % of the total variance. These were eutrophication factor (23.2 %), physicochemical factor (20.6 %), nutrients (16.3 %) and three additional factors, affected by alkalinity and heavy metals, recorded variance less than 15 % each. Also, the heavy metals pollution index (HPI) revealed that most of the calculated values were below the critical index limit of 100. However, two higher values (124.89 and 133.11) were calculated at sites V and VI during summer due to the temperature and increased run-off in the river system.

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Protozoa in a stressed area of the Egyptian Mediterranean coast of Damietta, Egypt

Dorgham M. M., El-Tohamy W. S., Abdel-Aziz N. E., El-Ghobashi A., Qin J. G.

Oceanologia

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2013

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No. 55 (3)

733--750

EN

The Damietta coast is part of the Egyptian Mediterranean coast off the Nile Delta and has recently been polluted as a result of intensive human activities. The environmental parameters and protozoan community in the area were studied biweekly from January to December 2007. The results of the environmental parameters indicated low salinity, oxic and anoxic conditions, high nutrient levels and intensive phytoplankton growth. A total of 69 protozoan species were identified, belonging to Amoebozoa (8 species), Foraminifera (12 species), non-tintinnid ciliates (22 species) and tintinnids (27 species). The numerical density of protozoans was high over the whole area, with annual averages between 8.2 × 103 cells m-3 and 51.4 × 103 cells m-3. Spring was the most productive season for protozoans, but several distinct peaks were observed during the year at the sampling sites. The protozoan groups showed clearly different spatial patterns in both composition and abundance: whereas amoebozoans and non-tintinnid ciliates were dominant in the more polluted areas (sites IV and V), tintinnids dominated in the less polluted areas (sites, I, II and III). Several pollution indicators were recorded: amoebozoans - Centropyxis aculeata, Centropyxis sp., Cochliopodium sp., Difflugia sp.; non-tintinnids - Bursaridium sp., Frontonia atra, Holophrya sp., Paramecium sp., Paramecium bursaria, Vasicola ciliata, Vorticella sp., Strombidium sp.; tintinnids - Favella ehrenbergii, Helicostomella subulata, Leprotintinnus nordgvisti, Tintinnopsis beroidea, Stenosemella ventricosa, Tintinnopsis campanula, T. cylindrica, T. lobiancoi, Eutintinnus lusus-undae.

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Eutrophication problems in the Western Harbour of Alexandria, Egypt

Dorgham M. M., Abdel-Aziz N. E., El-Deeb K. Z., Okbah M. A.

Oceanologia

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2004

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No. 46 (1)

25-44

EN

Eutrophication-related problems in the Western Harbour of Alexandria were studied monthly from April 1999 to March 2000. Variation in salinity appeared to be the key to all changes in water quality and plankton abundance in the harbour. Both at the surface and near the bottom the salinity was lower (annual average: 35.1 and 38.3 PSU respectively) than in the open sea (39 PSU). Dissolved oxygen levels indicated poor aeration conditions along the water column (2.3-3.98 mg l-1). Average pH values were approximately similar in the two layers (8.1 and 8 respectively) but exhibited different ranges of variations. Nutrient salts varied widely, often occurring in high concentrations, with ranges of 0.12-5.7 and 0.06-2.6 žM at the surface and the bottom respectively for phosphate, 0.21-20.46 and 0.25-18.12 žM for nitrate, 0.29-3.3 and 0.23-1.66 žM for nitrite, 0.56-57.46 and 2.32-43.73 žM for ammonia and 0.3-36.3 and 0.48-38.4 žM for silicate. As a result of nutrient enrichment, phytoplankton growth was very intensive, reflected by an abnormally high concentration of chlorophyll a (annual average: 33.82 žg l-1). At the same time the death of large numbers of phytoplankton cells could be inferred from the relatively large amount of phaeopigment (annual average: 10.39 žg l-1). The high levels of nutrient salts and phytoplankton biomass together serve as a good indicator of high eutrophication levels in the Western Harbour throughout the year. These conditions clearly affected the zooplankton stock, which varied between 5.8-93.6 × 103 indiv. m-3, although for most of the time values remained at a low level (annual average: 26 728 indiv. m-3).