Mahlon G. Kelly

Evaluating eutrophication potential from river community productivity

Abstract Measurements of dissolved oxygen, temperature and solar radiation were used to estimate net community production (P-R), respiration (R), gross production (P), and the P:R ratio for six rivers during the summer of 1974. Analysis of these data and comparison with a subjective ranking of the “eutrophy” of the rivers based on nutrient and chlorophyll data showed that productivity measurements in streams can be used to evaluate eutrophication potential. No single parameter or index proved reliable, but a discriminant analysis suggested that the use of respiration and the P:R ratio in conjunction can be useful. Also, the degree of temporal variability of community metabolism was a consistently good indicator of water quality. The analyses suggest that the eutrophication potential of an “unknown” river can be determined by comparing several weeks of productivity data for summer, low-flow conditions with the data presented here.

The calibration of a phytoplankton growth model using batch culture data

The feasibility of applying nonlinear parameter estimation techniques to data from batch culture of phytoplankton is studied using simulated data. A Monod-type model for nutrient uptake and growth in phytoplankton is used for the simulation. A parameter estimation procedure is applied to these data before and after they are noise-corrupted, to obtain back-calculated values of the parameter in the model. The results indicate that nonlinear parameter estimation is well suited fpr analytical interpretation of batch-culture data.

Automated Measurement of River Productivity for Eutrophication Prediction

A method for monitoring net and gross community oxygen productivity, community respiration, photosynthetic efficiency, and reaeration coefficient has been tested in five contrasting rivers. The technique uses relatively inexpensive digital data collection and processing, and allows detection of incipient eutrophication due to nutrient input and excess oxygen demand from organic waste input. Oxygen concentration, temperature, and solar radiation are recorded over a 24-h period and are the data used to calculate the parameters necessary for water quality monitoring. A few weeks data, taken during summer low-flow conditions, are then used to discriminate water quality.