2 research outputs found
Speciation of some trace metals (Fe, Cu, and Cd) in El-Mex Bay waters, Alexandria, Egypt
Surface- and bottom-water samples were collected from October 1996 to August 1997 to study levels of iron, copper, and cadmium species in their dissolved labile as well as non-labile and particulate forms in the waters of El-Mex Bay. The results showed that the non-labile concentration of the metals was generally more abundant than that of the labile form: its content reached more than 90% of the total dissolved metal for Cu and more than 80% for Fe. The particulate form was almost at the level of the labile form. The annual concentration of the trace metals of the labile form was 13 µglˉ¹ for Fe; 3µglˉ¹ for Cu, and 1.2 µglˉ¹ for Cd in the surface- and bottom-waters
Eutrophication problems in the Western Harbour of Alexandria, Egypt
Eutrophication-related problems in the Western Harbour ofA lexandria 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 ofv ariations. 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 f or 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 ofn utrient enrichment, phytoplankton growth was very intensive, reflected by an abnormally high concentration ofc hlorophyll a (annual average:
33.82 μg l−1). At the same time the death ofl arge numbers ofp hytoplankton
cells could be inferred from the relatively large amount of phaeopigment (annual
average: 10.39 μg l−1). The high levels ofn utrient salts and phytoplankton biomass
together serve as a good indicator ofhig h 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)