Study on fluorescence characteristics and sources of dissolved organic matter in Bandama River used in drinking water supply (Côte d'Ivoire)

Résumé

Surface waters are the main source of drinking water in many regions. Increasing organic carbon concentrations are one cause for concern in sub-saharan africa since both dissolved organic matter (DOM) can transport contaminants and adversely affect drinking water treatment processes. We present a study of characteristics of dissolved organic matter in the Bandama River. This river supplies drinking water to many urban and agricultural areas in Côte d'Ivoire. We have characterized the organic matter of these waters through the determination of dissolved organic carbon (DOC) and using fluorescence. The minimum (3.51 mg.L^-1) and maximum (9.21 mg.L^-1) DOC mean value were found in Bandama River. Specific UV-Vis absorption at 254 nm (SUVA) for DOC from rainy season was higher than the one of dry season.

The aromatic and humic DOM constituents in stream water therefore increased significantly during rainy season and were attributed to the contributions from sources such as litter leach ate and soil water. Three fluorescence components including humic-like substances (excitation peak at 400 nm, emission peak at 525 nm), humic-like substances (250 (330)/430 nm), and tryptophan-like materials (220 (275)/320 nm) were identified in water dissolved organic matter using excitation emission matrix (EEM) analysis. However, there were significant differences in the distributions of these three components for water DOM from different stations. Positive correlations were found among the fluorescence characteristics and other parameters of DOM.  

Our results demonstrate that EEM could be a feasible approach for characterizing DOM in water from different origin and can be used to further study complex DOM in rivers.