T86 Shallow Lakes and Wetlands: Sedimentary Records and Modern Dynamics of Small Systems That Pack a Big Punch in the Carbon Cycle
Monday, 10 October 2011
8:00 AM - 12:00 PM
Room M100DE
CLIMATE CHANGE EFFECTS ON THE MECHANISMS OF INTERNAL PHOSPHORUS LOADING AND ALGAL ECOLOGY IN ALKALINE EUTROPHIC LAKES
Paper number: T86-9
Program: Technical Sessions
Time: 10:15 AM – 10:30 AM
Authors
Abstract
Recent and rapid eutrophication of two alkaline lakes followed the onset of anomalous atmospheric temperatures in central Alberta. Historical changes in sediment C, N, P content from two hypereutrophic lakes correlated with molar S:Fe and Fe:Mn ratios, and a reorganization of algal assemblages. Pore-water samples retrieved from cores collected in seven Central Alberta alkaline lakes suggested that P retention in sediments was regulated by Fe rather than Ca. Simultaneous release of alkalinity generating ions and P occurred in Fe deficient pore-water regardless of saturation with respect to hydroxyapatite. Higher temperatures, lower redox potentials and accelerated internal P-loading established positive feedbacks that lead to diminished sediment P-binding capacity of sediments via sequestration of un-reactive Fe by S and a modification of algal assemblages. As many lakes subject to internal P-loading are becoming more productive in the absence of catchment development, sediment Fe-S-P dynamics may inform efforts towards mitigating climate impacts on the water quality, the aesthetics, and the growth of harmful algal blooms in alkaline eutrophic lakes.