Abiotic Controls on the Tropic Status of Oligotrophic Water

University Of Maine, Orono ME

Investigators

Abstract

This research will investigate how the elements aluminum (Al) and phosphorus (P), both originally from soil, interact in water moving through soil pores to downstream lakes in ways that prevent P from being biologically available to algae in surface waters. This causes oligotrophic conditions (i.e., water with very low nutrient concentrations). Solid aluminum hydroxide will adsorb and can permanently capture P from the water if the acidity is low. Changes in the acidity of surface waters from "acid rain", climate change, or other factors should induce changes in the interaction between Al and P, and thus changes in the biological productivity of surface waters. These water quality responses will be investigated with laboratory and field experiments, studies at four long-term watershed sites (in Maine, West Virginia, and the Czech Republic), and dynamic process-oriented mathematical models. Phosphorus is commonly the limiting nutrient for organisms in streams and lakes. An excessive supply of P to surface water from natural sources or human activities can cause eutrophication (highly productive water), a condition that can have undesirable effects. The supply of P to many surface waters is high, but the majority of the P is not available for biota, causing oligotrophic conditions. This research will explain the conundrum of high fluxes of P in ecosystems, yet oligotrophic conditions in associated surface waters.