Seasonal variation in the composition of aquatic organic matter in some Nova Scotian brownwaters : a nuclear magnetic resonance approach

The chemical structure of aquatic organic matter from 4 freshwater sites in Nova Scotia was studied using a novel concentration technique based on reverse osmosis and freeze drying followed by carbon-13 NMR. The aromatic carbon fraction which was assumed to be refractory, remained at less than 10 per cent of the total, with a slight increase in relative importance in the autumn. Hydrological processes carrying dissolved organic matter to streams and lakes seemed to allow a selective adsorption process to occur in soils. Comparisons with results from other freshwater studies suggested that the importance of aromatic carbon had been overestimated in the past, while carbohydrate and aliphatic material was underestimated. There are 33 references.