Radiochemical Analysis of Orthophosphate Concentrations and Seasonal Changes in the Flux of Orthophosphate to Seston in Two Canadian Shield Lakes

摘要: Seasonal changes in the concentration and dynamics of phosphate–phosphorus were studied two small lakes, one oligotrophic artificially eutrophied. Because molybdate blue phosphate technique frequently overestimates concentrations, three radiochemical assays used. One, involving sephadex fractionation, was unsatisfactory because long period required for high molecular weight phosphorus fractions to reach isotopic equilibrium. The second method unusable both epilimnion waters within Experimental Lakes Area, its low sensitivity, hypolimnion waters, due interference from nonphosphate compounds. third method, Rigler's bioassay, indicated that PO4-P lakes seldom exceeded 0.1 μg∙L−1, even under anoxic conditions. Organisms, not mineral reactions, appeared regulate at all depths lakes.Key words: dynamics, orthophosphate