Effect of Water-Column pH on Sediment-Phosphorus Release Rates in Upper Klamath Lake, Oregon, 2001

摘要

The intent of the investigation was to determine whether the phosphorus release from Upper Klamath Lake sediments, at the photosynthetically elevated pH values measured in the lake, could account for the rapid increase in total phosphorus concentration observed each spring. The study was designed to investigate both the areal phosphorus release rates from sediments at a stable sediment-water interface and the desorption of phosphorus from suspended sediments that would occur during a wind-induced sediment resuspension event. The former investigation is referred to as the Stable Interface Study; the latter is referred to as the Resuspended Sediment Study. An additional objective incorporated into the experimental design was to elevate pH in a manner that would simulate the water chemistry changes that occur during algal photosynthesis. This was then followed by the addition of a small amount of strong base to elevate the pH in the column further for comparison. Additional experimental design objectives were to incorporate a ratio of sediment surface area to water column volume that is characteristic of the lake into the Stable Interface Study, and to use a sediment concen- tration representative of an extreme, but not rare, wind event in the Resuspended Sediment Study. Because of the nature of column studies in the laboratory, many study designs incorporate an unrealistically large sediment surface area to water column volume ratio when investigating processes at the sediment/water interface and an unrealistically high sediment concentration when investigating resuspension events.