Predicting changes in hypolimnetic oxygen concentrations with phosphorus retention, temperature, and morphometry

Abstract

A statistical analysis of the rate of change in oxygen concentrations (VOD, mg O2 m−3 d−1) in 1‐m‐thick strata in the hypolimnia of 29 lakes suggests that these rates can be predicted from a knowledge of the annual retention of phosphorus by the lake sediments, the mean summer temperature of the stratum, and the morphometry of the stratum. VOD values increased as temperature and phosphorus retention increased. Rates were inversely proportional to the ratio of the volume of the stratum divided by the area of sediments that are contiguous to the stratum. The statistical model was tested by measuring VOD values in an independent group of 12 lakes. Predictions agreed well with the measured values. An analysis of the combined data explained 91% of the variance in VOD values. The regression correctly predicted the vertical variation in VOD values in lakes that exhibited negative heterograde, orthograde, and clinograde oxygen profiles. After further testing, this model should provide a method of predicting changes in oxygen concentrations in lakes that are subject to perturbations such as changes in temperature or nutrient loading.