4.1 Data on the chlorophyll content of the algae have the following applications:

4.1.1 To provide estimates of algal biomass and productivity.

4.1.2 To provide general information on the taxonomic composition (major groups) of the algae, based on the relative amounts of chlorophyll a, b, and c, and the physiological condition of algal communities, which is related to the relative abundance of pheopigments.

4.1.3 To determine long-term trends in water quality.

4.1.4 To determine the trophic status of surface waters.

4.1.5 To detect adverse effects of pollutants on plankton and periphyton in receiving waters.

4.1.6 To determine maximum growth rates and yields in algal growth potential tests.

1.1 These practices include the extraction and the measurement of chlorophyll a, b, and c, and pheophytin a in freshwater and marine plankton and periphyton. Three practices are provided as follows:

1.1.1 Spectrophotometric, trichromatic practice for measuring chlorophyll a, b, and c.

1.1.2 Spectrophotometric, monochromatic practice for measuring chlorophyll a corrected for pheophytin a; and for measuring pheophytin a.

1.1.3 Fluorometric practice for measuring chlorophyll a corrected for pheophytin a; and for measuring pheophytin a.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.

1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 7.