BIOGEOCHEMICAL CYCLING IN LAKE SUPERIOR TRIBUTARIES: SEASONALITY, QUANTITY AND QUALITY OF EXPORT

摘要: Seasonal and spatial variability in environmental factors may affect dissolved organic matter composition nutrient transformation retention streams. The objective of this research was to quantify describe seasonality, quantity, quality processing export ammonium (NH4), soluble reactive phosphate (SRP), carbon (DOC) into Lake Superior through intensive study a small 1st order watershed coupled with snapshot measurements across 12 tributaries that varied size, location, wetland coverage. Our results suggest biodegradable C is exported from headwater stream year-round DOC mineralization rates can be stimulated by additions NH4 labile (Chapter 2). We found synchronously among 3 rivers size three orders magnitude. Furthermore, these 9 17% annual form, which then fuel biological activity nearshore zones Superior. Modeling historical loads suggests spring have increased fall decreased over 26 year period, but not 3). Across eleven uptake velocity explained area, discharge, fluorescence index (indicator microbial terrestrial sources; Chapter 4). Temporally detailed (every 2 4 weeks for years) indicated light availability, algal periphyton biomass, solute concentrations, pH were important predictors 5). similar magnitude during winter summer while SRP greater than Overall the greatest velocities observed