Chlorophyll degradation products which can be extracted from sediments with 90% acetone and which show maximal light absorption in the red end of the spectrum at a wave length of 667 mμ (90% acetone as the solvent) are here collectively defined as sedimentary chlorophyll. A quantitative method is described for the determination of sedimentary chlorophyll. Results from six different sediment profiles are presented. The nature of sedimentary chlorophyll is unknown, except that it consists of at least three chlorophyll degradation products. Sedimentary chlorophyll has been found in samples aged up to 11,000 years. In any one profile the fluctuations in sedimentary chlorophyll content may be used to infer changes in the abundance of chlorophyll-bearing plant tissues, but only with the greatest caution.
Reasons why experimental lake studies form a useful addition to more conventional laboratory experiments and observational field studies of eutrophication are discussed. The developmental history of the Experimental Lakes Area is given, including reasons for the location and a general description of the area set aside for experimental manipulation.
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