Concentrations and Kinetics of Phosphorus Fractions Along the Trophic Gradient of Lake Memphremagog

Published relationships between chlorophyll and total phosphorus concentrations show that the amount of chlorophyll developed per unit of total P increases as total P increases. If the availability of phosphorus changes with lake trophy, this should be reflected in the proportion of total P found in different analytical fractions. From June 1975 to September 1976, the concentrations of total phosphorus, soluble phosphorus, orthophosphate, large molecular weight phosphorus (> 5000 mol wt) and small molecular weight phosphorus (< 400 mol wt) were measured at six sites along the phosphorus-production gradient of Lake Memphremagog; 32P-PO4 was used to follow short-term exchanges between available orthophosphate and other fractions. Total P declined threefold among sites but the proportion of different fractions remained relatively constant which suggests that any disproportionate loss from one compartment is made good by exchanges with the others. On average, soluble P formed\of total P, soluble reactive phos...