ASTM_D_3731_-_20.pdf

Designation:D373120Standard Practices for Measurement ofChlorophyll Content of Algae in Surface Waters1This standard is issued under the fixed designation D3731;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These practices include the extraction and the measure-ment of chlorophyll a,b,and c,and pheophytin a in freshwaterand marine plankton and periphyton.Three practices areprovided as follows:1.1.1 Spectrophotometric,trichromatic practice for measur-ing chlorophyll a,b,and c.1.1.2 Spectrophotometric,monochromatic practice for mea-suring chlorophyll a corrected for pheophytin a;and formeasuring pheophytin a.1.1.3 Fluorometric practice for measuring chlorophyll acorrected for pheophytin a;and for measuring pheophytin a.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are given in Section 8.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent Water3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard,refer toTerminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 chlorophyll,na class of pigments involved in pho-tosynthesis.3.2.2 periphyton,nmicroorganisms growing on sub-merged objects,commonly consisting of bacteria,algae,protozoa,and rotifers.3.2.3 pheopigments(phaeopigments),nanon-photosynthetic pigment which is the degradation product ofalgal chlorophyll pigments.3.2.4 plankton,nnonmotileorweaklyswimmingorganisms,usually microscopic,that drift or are carried alongby currents in surface waters,commonly consisting of bacteria,algae,protozoa,rotifers,and microcrustacea.4.Summary of Practices4.1 The chlorophyll and related compounds are extractedfrom the algae with 90%aqueous acetone.The concentrationof the pigments is determined by measuring the light absorp-tion or fluorescence of the extract.5.Significance and Use5.1 Data on the chlorophyll content of the algae have thefollowing applications:5.1.1 To provide estimates of algal biomass and productiv-ity.5.1.2 To provide general information on the taxonomiccomposition(major groups)of the algae,based on the relativeamounts of chlorophyll a,b,and c,and the physiologicalcondition of algal communities,which is related to the relativeabundance of pheopigments.5.1.3 To determine long-term trends in water quality.5.1.4 To determine the trophic status of surface waters.5.1.5 To detect adverse effects of pollutants on plankton andperiphyton in receiving waters.5.1.6 To determine maximum growth rates and yields inalgal growth potential tests.6.Interferences and Special Considerations6.1 Pigment ExtractionThe chlorophylls are only poorlyextracted,if at all,from some forms of algae,such as thecoccoid green algae,unless the cells are disrupted,whereas1These practices are under the jurisdiction of ASTM Committee D19 on Waterand are the direct responsibility of Subcommittee D19.24 on Water Microbiology.Current edition approved June 1,2020.Published June 2020.Originallyapproved in 1979.Last previous edition approved in 2012 as D3731 87(2012).DOI:10.1520/D3731-20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.other algae,such as the diatoms,give up their pigments veryreadily when merely steeped in acetone.Since natural commu-nities of algae usually consist of a wide variety of taxa thatdiffer in their resistance to extraction,it is necessary to disruptthe cells routinely to ensure maximum recovery of the chloro-phyl