Impact de l’utilisation du chlorure de sodium utilisé en pulvérisation pour lutter contre le développement de la jacinthe d’eau Eichhornia crassipes sur la qualité physico-chimique d’un écosystème semi-artificiel

Abstract

In order to ensure the preservation and enhancement of aquatic ecosystems threatened by the water hyacinth Eichhornia crassipes, methods based on sodium chloride NaCl have been developed to combat the proliferation of this invasive plant. This study presents the physico-chemical state of the water in a semi-artificial ecosystem following spraying of hyacinth plants based on sodium chloride (NaCl) solution and aims to preserve the ecological risks of a such a method of struggle in a real environment. The experiment was carried out in a pond 11m long and 3m wide, covering an area of 33m2. Part occupied by hyacinth plants represents 2/3 of the surface of the pond. The pond initially contained a volume of water estimated at 34,1m3. Seawater was used to spray hyacinth plants. This spraying was done in one day and the volume of solvent sprayed per m2 was 11.32L. The physico-chemical parameters of the water as well as the eutrophying chemicals were measured at the beginning (before spraying), immediately after the spraying and this every five days after spraying over a period of twenty-five days (25 days). At the end of the study, the salinity increased from 0,10 to 0,27g/L for a final volume of 13,6 m3. The concentration of nutrients in the medium increased significantly. This results in a significant increase in the conductivity of the water; consequence of the increase of the mineral salts resulting from the decomposition and the mineralization of the dead leaves of the hyacinth plants in the medium.

Keywords

• NaCl
• Eechhornia crassipes
• spraying
• physico-chemistry
• impacts.