Levels of Dissolved Organic Carbon and Characterization of Dissolved Organic Matter in Water from Wetlands

Abstract

The research aimed at investigating the levels of dissolved organic carbon (DOC) and structural compositions of dissolved organic matter from Jebba, Lokoja, Nguru and Baturiya wetlands. Spectrophotometric, Fourier Transformed Infra-Red (FTIR) and gas chromatography-mass spectrometric methods were used. The average values obtained for DOC in the various wetlands were10.8±0.43, 13.7±1.50, 8.27±1.64 and 13.0±2.34    mg/l, Jebba, Lokoja, Nguru and Baturiya respectively during the dry season and 8.24±1.03, 11.1±1.01, 7.45±0.73 and 10.1±2.43 mg/l for Jebba, Lokoja, Nguru and Baturiya respectively during wet season. The Specific Ultra-Violet Absorption (SUVA) values recorded were 4.83±0.01, 8.52±0.01, 6.08±0.01, 6.25±0.015 and 5.60±0.01 L/mg.m in Lokoja, Nguru, Baturiya Jebba and Matara-Uku respectively. This revealed that the wetlands contain aromatic hydrophobic organic matters which absorb strongly in the UV region, have high affinity for chlorine and a high trihalomethane (THM) formation potential. The infrared spectrum (FTIR) results indicated that the DOM of these wetlands contain the phenolic hydroxyl groups, hydroxyl groups, Carbon-carbon conjugated double bond of aromatic family and free carboxyl groups. The gas chromatography-mass spectrometry, (GC-MS) analysis revealed the presence of 2-Docosen-1-ol, Trifluoro-3-pentadecen-2-one, Eicosan-1-al, Tricosane-1,1-diol, 9-Octadecenoic acid,4-propylheptadecanehexadecanote and Ethenoxypentane. Analysis of variance (ANOVA) and Turkey’s test indicated  significant difference (p<0.05) between the DOC concentrations in both the wet and the dry seasons. High DOC concentrations in water have been implicated for THM formation.