Overland phosphorus export in the Gaspereau River watershed: Application to a lake capacity model (Nova Scotia)

The effects of land use and geology on the export of phosphorus to lakes were studied over a 12-month period at ten streams within the Gaspereau River watershed, located in central Nova Scotia. Three of the stream catchments were characterized by native forest, three by deforestation and four by agriculture. Four of the sites were located on igneous bedrock and the remaining six on metamorphic bedrock.; The annual average export from forested igneous watersheds (32.7 mg m −2 yr−1) was much lower than from clear-cut igneous watersheds (48.0 mg m−2 yr−1) and agricultural igneous watersheds (62.4 mg m−2 yr −1). Similarly, on metamorphic bedrock, the mean export from forested watersheds (19.1 mg m−2 yr−1) differed from those having clear-cuts (32.1 mg m−2 yr −1) and agriculture (35.8 mg m−2 yr −1). There were also apparent differences between sites having variable geology but similar land use.; Application of the results of this study to a model previously developed to assess the capacity for development of lakes within the Gaspereau watershed resulted in considerable improvement in the model's ability to predict total phosphorus concentrations.