SOURCES OF PHOSPHORUS AND NITROGEN FOR LAKES ON AFOGNAK ISLAND1

• Main Authors: Richard C. Dugdale, Vera A. Dugdale
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Kodiak; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.527.5961; http://www.aslo.org/lo/toc/vol_6/issue_1/0013.pdf

The contribution of inlet streams to the phosphorus and nitrogen budgets of two lakes on Afognak Island (Kodiak Region), Alaska has been studied with special rcfercncc to the mor-phology of the associated watcrshcds. One lake drains a steep, vast watershed; the other, a relatively flat, restricted enc. Streams coming from the stccpcr slopes show a lower PO4-1’ conccntrntion than those coming from shallow slopes as might be expcctcd from runoff-rcsidcnce considerations. Exactly the opposite is found when the nitrate conccntmtion of thcsc streams is cxamincd, i.e., only the strcnms nrisiing on steep slopes show apprccinblc amounts of nitrate. Phosphorus appearing in the inlets probably originates in the Katmai ash which lies just under the humus layer of soil. Three distinct layers of ash occur nor-mally. A complex pattcrn of phosphorus distribution can probably be attributed to diffcr-cnces in the permeability of thcsc layers to water. A model has been constructed as an aid to intcrprctation of the cl&a. Thickets of nitrogen fixing alders, founcl only along steep stream banks, may bc the source of the nitrate content of these streams.