Eutrophication problems in the Western Harbour of Alexandria, Egypt

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 µM at the surface and the bottom respectively for phosphate, 0.21-20.46 and 0.25-18.12 µM for nitrate, 0.29-3.3 and 0.23-1.66 µM for nitrite, 0.56-57.46 and 2.32-43.73 µM for ammonia and 0.3-36.3 and 0.48-38.4 µM 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 µg 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 µg 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)

A new record for aliphatic and polycyclic aromatic hydrocarbon accumulation in the surficial sediments of El Mex Bay, Alexandria, Egypt after 19 years from the first one

Petroleum hydrocarbons were identified and quantified in the surficial sediments of El-Mex Bay, Alexandria during 2013 and 2014. The results were compared with a previous study in 1995. Contamination by aliphatic hydrocarbons in the sediments of the Bay was found to be magnified by about 3 folds from the former study. It was found that the two n-alkanes C21 and C32 were the highly concentrated aliphatic among all the other alkanes with mean concentrations approaching 300 ng g−1 dry wt., while PAHs in the surficial sediments appeared to be clearly magnified to about 17-fold. The total PAH concentrations at the different stations in the Bay ranged between 1123 and 8654 ng g−1 dry wt. Various PAH concentration diagnostic ratios: LMW/HMW, Fluo/Py, Fluo/[Fluo + Py] and the isomeric ratios BbF/BaP against BkF/BaP were applied to identify the source of pollution by PAHs in the sediments of the Bay. All the above mentioned ratios were indicating pyrolytic origin of PAHs in the sediments with very weak evidence of petrogenic sources at few sites. Natural n-Alkanes Ratio (NAR) was used to assess the origin of aliphatic hydrocarbons