Degradation of Cellulose and Wood Products in Polluted and Unpolluted Rivers

Natural rates of degradation of cellulose and of wood products were studied by enclosing this material in nylon sacs with 20 um diameter pores and suspending the sacs in different parts of the Gatineau and Ottawa Rivers, for periods of up to 90 days. White spruce chips and sawdust were studied, either without treatment or after chemical conversion to holocellulose or cellulose. Untreated wood was almost entirely resistant to degradation, as measured by weight loss. Conversion to holocellulose made wood quite susceptible to degradation, but conversion of holocellulose to cellulose did not increase the rate of degradation. Cotton fibres (almost pure cellulose) were less rapidly degraded than treated wood. Little or no degradation occurred in the Gatineau River, which is relatively unpolluted by sewage or industrial wastes. Much more occurred in both water and sediments of the heavily polluted Ottawa River. An especially active site was found just below the Canadian International Paper Company. These results emphasize the importance of lignin in protecting cellulose from biodegradation and suggest in which natural sites we might expect biodegradation of wood products to occur most rapidly.