A chlorophyll a model and its relationship to phosphorus loading plots for lakes

Abstract

A model predicting the summer concentration of cholorophyll a in a phosphorus-limited lake is derived from simple empirical and semitheoretical relationships. The model is rearranged and expressed as a phosphorus loading plot which agrees closely with the predictions of Vollenweider's model. The model can be used to gain insight into the phosphorus loading concept. The primary conclusion is that a lake's tolerance to phosphorus loading is a function of two processes: sedimentation and flushing rate. At low areal water loads, in-lake forces which remove phosphorus to the sediments predominate. At high areal water loads, flushing of phosphorus through the lake's outlet is the factor governing eutrophication. The importance of the steady state assumption is also demonstrated by using data for Lake Washington.Res., 17, 135-149, 1974. /68, pp. 1-182, Organ. Econ. Coop. Develop., Paris, 1968. Vollenweider, R. A., MiSglichkeiten und Grenzen elementarer Modelie der Stoffbilanz von Seen, Arch. Hydrobiol., 66, 1-36, 1969. Vollenweider, R. A., Input-output models with special reference to the phosphorus loading concept in limnology, Schweiz. Z. Hydrol., 37, 53-84, 1975. Vollenweider, R. A., and P. J. Dillon, The application of phosphorus loading concept to eutrophication research, Tech. Rep. 13690, 42 pp., Nat. Res. Counc. of Can., Ottawa, Ont., 1974. ( Vollenweider, R. A., The scientific basis of lake and stream eutrophication, with particular reference to phosphorus and nitrogen as eutrophication factors, Tech. Rep. DAS/DSI

The role of prediction in limnology1

“…For example, if the range of TP concentration is extended much beyond 100-300 mg m-3, the strength of the correlations weaken (StraSkraba 1980), so restriction of the theory to lakes with < 100 mg P m-3 might better define the relationship where it is most useful. Large data sets (Hern et al cited by Reckhow and Chapra 1983;Canfield and Bachmann 198 1) also show increased error even within this range, so it is possible that inclusion of lakes of different regions or type may increase error even at lower phosphorus levels. Some of the variation can be attributed to differences between artificial and natural lakes (Canfield and Bachman 198 1) or salinity (Prepas and Trew 1983), but some may also require separate analysis in regional relations (Stauffer 1985).…”

“…Statistical analyses of large data sets by Knowlton et al (1984) have shown the relative contributions to total variance from different years and from different times. These developments indicate an increasing ability to think probabilistically and one can anticipate growth in models and analytical tools to express and use observed levels of variation (Reckhow and Chapra 1983). This should allow us to minimize bias and error in current relations through better sampling design and allow more precise prediction than is presently possible.…”

Predicting Sediment and Phosphorus Loads in the Rock River Basin Using Swat

“…Data collected included volume of lakes, total phosphorus concentration in lakes, and outflow volume. Values for Ks were estimated as outlined in Chapra and Tarapchak (1976).…”

Effects of urbanization on the water quality of lakes in Eagan, Minnesota

“…(See Dillon and Rigler, 1975;Chapra and Tarapchak, 1976;Jones and Bachmann, 1976;Reckhow, 1977;Walker, 1977; all summarized in Reckhow, 1979). Methods for calculating the input data to these models are given in the Methods and Approach section.…”