|Titre :||Climatic changes, hydrology and trophic status of Lake Oubeira (extreme northeast of Algeria) (2019)|
|Auteurs :||Yacine Messerer, Auteur ; Abdelhalek Retima, Auteur ; Aicha B. Amira, Auteur ; Abdellah B. Djebar, Auteur|
|Type de document :||Article|
|Dans :||AACL Bioflux (12:4 August, 2019)|
|Article en page(s) :||1442-1457|
|Mots-clés :||Algérie ; lac ; Zone humide ; Impact changement climatique ; Hydrologie|
The Oubeira is the largest freshwater lake situated in the extreme eastern north part of Algeria. It is more particularly regarded as an integral part of El-Kala National Park. It is located in one of the most watered regions of the country between 800 and 900 mm. In order to characterize it from the hydrological point of view, a follow-up and a bi-monthly analysis of the volume waters and various parameters such as temperature, pH, dissolved oxygen (DO) , ammonium (NH4), nitrates (NO3), nitrites (NO2), orthophosphate (PO4), dissolved organic nitrogen (DON), dissolved organic phosphate (DOP), suspended particulate matter (SPM), particulate organic carbon (POC) and chlorophyll a were carried out between March 2004 and April 2005. The temperature of the water is similar across the whole surface of the lake and varies between 8 and 22°C. The pH is slightly acid to slightly alkaline and ranges from 6.2 to 8.9. Dissolved oxygen contents are viable with a maximum of 8.98 mg L- 1 . The water volume of the lake ranges from 23 x 106 to 59.70 x 106 m3 from one season to another. There is some compensation between the values of dissolved nutrients and organic matter over the study period. The concentrations of dissolved nutrients ranged from 0 to 21.50 μmol L- 1 for ammonium (NH4), from 0.038 to 21.58 μmol L- 1 for nitrates (NO3), and from 0 to 0.38 μmol L- 1 for orthophosphates (PO4), and for dissolved organic nitrogen (DON) from 0.58 to 67.17 μmol L- 1 and also dissolved organic phosphorus (DOP) from 0 to 2.87 μmol L- 1 . The highest concentrations of the chlorophyll a are measured during the dry season and evolve from 7.58 to 394.52 mg m- 3 . We consider that our lake passes through two trophic states. A phase through which waters of the lake are mesotrophic when the rate of renewal of the waters is important from January to May. A second phase in which waters of the lake are hypereutrophic favored is in summer season extending from June to September. This leads to the reduction of lake waters to their lowest levels. Climate warming, rainfall patterns in the study area, and the extent of clogging of the lake outfall have a major impact on the evolution of the lake waters. These phenomena could plunge the lake into an era of strict endoreism that will swing its waters towards total destruction and will result in the filling of the basin of the lake.
Key Words: Oubeira Lake, dissolved nutrients, chlorophyll a, suspended solids, water flow.
|En ligne :||http://www.bioflux.com.ro/docs/2019.1442-1457.pdf|