Physical and chemical seawater properties of selected locations from the Libyan coast

الملخص EN

The coastal waters of the western part of the Libyan coast are occasionally subjected to the eutrophication and red tide phenomena.

The aim of this study was mainly to report some physical and chemical properties of the seawater in the vicinity of Dela- Zawia and Telleel-Sabrata at the western part of the Libyan coast, to be integrated with the general marine environmental program of the Libyan coastal waters.

The study was carried out from July 2004 to June 2005 at Dela-Zawia (subjected to sewage discharge) and Telleel-Sabrata (away from any discharge) coastlines.

Surface water samples were collected on monthly basis.

The parameters studied included Temperature, pH, salinity, dissolved oxygen, biological oxygen demand, nitrite, nitrate, ammonia, phosphate, silicate, solids (TS, TDS, TSS, TVS), and sulfate.

The ranges of seawater parameters were, temperature 14.70 -26.20°C and 15.27-23.45°C , pH values 7.75-8.22 and 8.05-8.24, salinity 34.6-38.60%o and 37.07-38.85 %o, dissolved oxygen 3.39-8.45mg/l and 5.33-8.75mg/l, and BOD5 values 0.90-4.55mg / l and 0.80-1.99mg / l at Dela-Zawia site and Telleel-Sabrata site respectively.

The nutrient salts concentration at Dela-Zawia site ranges were 0.152-0.761 umol / l for nitrite, 2.823-35.175umol / l for nitrate, 0.277-26.055umol / l for ammonia, 0.541-5.558nmol / l for phosphate, and 0.815-11.217u.mol / l foV silicate.

At Telleel-Sabrata site, 0.152-5.326umol / l for nitrite, 2.290-5.839umol/l for nitrate, 0.222-1.667umol / l for ammonia, 0.263-0.895nmol / l for phosphate, and 0.978-2.652nmol / l for silicate.

The solid materials values at Dela-Zawia site ranges were 43-399-47.305 g/1 forTS, 34.324-41.161 g / 1 for TDS, 13.507-65.385mg / l for TSS, and 5.127-10.l23g / l for TVS.

At Telleel-Sabrata site, the ranges were, 45.604-47.221g / l for TS, 39.320-41.865g / l for TDS, 10.034-22.409mg / l for TSS, and 4.100-6.869 g / 1 for TVS.

The present data showed that the Telleel-Sabrata water qualifies is typical of open sea (unpolluted water).

Also, shows that the effect ofeffluent discharge in Dela-Zawia water is still limited to a restricted area (3x5km).

Around the sewage discharge point beyond this area, the water quality is very close to that of open sea.