This study focuses on the comparative assessment of the environmental dynamics of dissolved organic carbon in subtropical wetlands. DOC was determined using persulphate UV-visible spectrophotometric method. The averaged values for DOC during the one-year samplings ranged from 7.454±0.73 to 13.686±1.50 mg/l, in the wetlands studied. These values are above the 4 mg/l, limits set for DOC in water. SUVA values in the wetlands are 4.83 L/mg.m, 8.52 L/mg.m, 6.08 L/mg.m, 6.25 L/mg.m and 5.60 L/mg.m in Lokoja, Nguru, Baturiya Jebba and Uatara-Uku respectively. This is indicative of the presence of humic, highly aromatic hydrophobic matter associated with high UV absorbance, high chlorine demand and a high trihalomethane (THM) formation potential. The infrared spectrum showed the structural composition of the humic acid present in the wetlands. FTIR results indicated that the DOM of these wetlands contain the phenolic hydroxyl groups, hydroxyl groups, conjugated double bond of aromatic family (C=C), and free carboxyl groups. Analysis of variance (ANOVA) indicated that there is significant difference (p<0.05) between the DOC concentrations in both the wet and the dry seasons while high DOC concentrations in water has been implicated for trihalomethane formation.

Keywords: Dissolved organic carbon, Dissolved organic matter, FTIR, wetlands