The freshwater dissolved organic matter fluorescence-total organic carbon relationship

The fluorescent properties of dissolved organic matter (DOM) enable comparisons of humic-like (H-L) and fulvic-like (F-L) fluorescence intensities with dissolved organic carbon (DOC) in aquatic systems. The fluorescence-DOC relationship differed in gradient, i.e. the fluorescence per gram of carbon, and in the strength of the correlation coefficient. We compare the fluorescence intensity of the F-L and H-L fractions and DOC of freshwater DOM in north Shropshire, England, featuring a river, wetland, spring, pond and sewage DOM sources. Correlations between fluorescence and DOC varied between sample sites. Wetland water samples for the F-L peak gave the best correlation, r = 0.756; the lowest correlation was from final treated sewage effluent, r = 0.167. The relationship between fluorescence and DOC of commercially available International Humic Substances Society standards were also examined and they generally showed a lower fluorescence per gram of carbon for the F-L peak than the natural samples, whereas peat wetland DOM gave a greater fluorescence per gram of carbon than river DOM. Here, we propose the strength of the fluorescence-DOC correlation to be a useful tool when discriminating sources of DOM in fresh water. Copyright (c) 2007 John Wiley & Sons, Ltd.