EXPORTS OF CARBON AND NITROGEN FROM RIVER BASINS IN CANADAS ATLANTIC PROVINCES

The loss of carbon and organic nitrogen from the terrestrial ecosystem via streams and rivers is dependent on a number of factors such as basin vegetation, geography, geology, climate, and hydrology. We studied the export of dissolved carbon and nitrogen from 26 rivers varying in size from 45 to 92,500 km(2) located in Atlantic Canada. Twenty-four of the basins studied were free of significant anthropogenic activity and were covered with coniferous and mixed hardwood forests. Our results showed that total organic carbon loss from the region, normalized for area, was approximately 29 kg ha(-1) yr(-1), while inorganic C was considerably lower at 4.3 kg ha(-1) yr(-1). We developed predictive statistical models using total precipitation, basin size, and basin slope to predict the export of organic carbon and nitrogen. Our results suggest that increases in regional precipitation will most likely increase the loss of organic carbon and nitrogen from terrestrial systems. We also found that inorganic carbon and nitrogen were not influenced by precipitation. Inorganic carbon seemed more influenced by geology, and inorganic nitrogen seemed more influenced by basin slope.