Essai d’évaluation de la qualité des eaux de ruissellement du bassin versant de la lagune de Bizerte

Abstract

The lagoon of
Bizerte, located on north-eastern Tunisia, constitute a receiving basin of a well expanding hydrographic network.
In order to assess the impact of natural and anthropogenic factors on the runoff water of the catchment area of
this lagoon, a sampling campaign of water was carried out on February 2003 (period of the rise in the water
level) on the downstream of fifteen streams.
The samples of water collected were subject to in situ measure of physico-chemical parameters (Temperature, pH and dissolved oxygen) and laboratory analyses of chlorophyll a and the different organic and inorganic dissolved forms of nitrogen and phosphorus. Results showed that the runoff waters are, on the whole, well oxygenated and are neuter to thoughtlessly alkaline. Those sampled on the downstream of Merazig and Guenniche rivers, situated respectively on the northwest and on the south-east of Bizerte lagoon, are, on the whole, the most loaded with nitrogen and phosphorus compounds. The application of the principal component analysis (PCA) to these data showed two groups of water and confirmed that the water of Merazig and Guenniche rivers stand out from the others.