ASTM_D_4135_-_82_2012.pdf

Designation:D413582(Reapproved 2012)Standard Practice forSampling Phytoplankton With Depth-Integrating Samplers1This standard is issued under the fixed designation D4135;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 This practice covers the procedures for obtaining quan-titative samples of a phytoplankton community by use ofdepth-integrating sampler.The method is suitable for use inflowing waters.1.2 This standard does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D4137 Practice for Preserving Phytoplankton Samples3.Summary of Practice3.1 A depth-integrated sample is collected by means of asampler that integrates stream discharge as a function of depth.The velocity of flow in a stream,as well the density ofphytoplankton,varies both vertically and horizontally.Depthintegration is used to collect a sample that is weightedaccording to the velocity at each increment of depth.3Thephytoplankton may be preserved as dictated by the objectivesof the study.4.Significance and Use4.1 The advantages of the depth-integrating samplers are asfollows:4.1.1 The samplers provide the only means by which arepresentative sample of phytoplankton can be obtained from astream.4.1.2 The variety of sampler designs result in the availabil-ity of a sampler that can be used in virtually all velocities offlow.4.1.3 Samples of known volumes can be obtained.4.1.4 A quantitative sample is obtained.Nanno-and ultra-plankton are not lost from the sampling device.4.1.5 Some of the samplers can be used in water up to 55 mdeep.4.1.6 Many of the samplers are light-weight and can be usedwithout auxiliary equipment.4.2 The disadvantages of the depth-integrating samplers areas follows:4.2.1 The samplers can be used only in flowing streamshaving a velocity greater than 1.5 ft3/s.4.2.2 Some of the samplers are heavy and require the use ofauxiliary equipment,such as a crane with hoist.4.2.3 The collection of samples can be very time-consuming.4.3 There are several special considerations that shall beobserved when using depth-integrating samplers.They are asfollows:4.3.1 The nozzle of the sampler should be inspected peri-odically for chips,cracks,or other signs of damage andreplaced as necessary.4.3.2 The sample from each vertical profile must be com-bined with other similar samples in a common container.If thecombined sample is subsequently subdivided,it must bethoroughly mixed before doing so.5.Apparatus5.1 Several depth-integrating samplers are in widespreaduse in water-quality studies and have been described bySubcommittee D19.07 on Sedimentation,4(Figs.1-3).All thesamplers have the same basic design.They consist of ahydrodynamically designed,weighted body into which isplaced the sample container.The rear of the sampler containsseveral vanes for stabilizing the sampler into the direction ofstream flow.The size and weight of the samplers vary.Thecommon sampler types have been designated as DH-49,DH-74,P-61,and D-77 by Subcommittee D19.07.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.24 on Water Microbiology.Current edition approved Sept.1,2012.Published October 2012.Originallyapproved in 1982.Last previous edition approved in 2004 as D4135 82(2004).DOI:10.1520/D4135-82R12.2For 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.3Colby,B.R.,“Relationship of Sediment Discharge to Streamflow,”U.S.Geology Survey,Open-File Report,1956,170 pp.4Subcommittee on Sedimentation,Interagency Committee on Water Resources,“Determination of Fluvial Sediment Discharge,”Federal Interagency Commissionon Water Resources,Minneapolis,MN,Report,Vol 14,1963,151 pp.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Procedure6.1 One of the best sampling techniques currently acceptedby hydrologists for use in such situations is the equal-transitrate(ETR)method.5In this method,the standard suspended-sediment sampler is used to collect a discharge-weightedsample.Samples are taken at a number of equally spacedverticals in the cross section.The transit rate of the sampler,which is the rate of movement of the sampler from the watersurface to the stream bed and back to the surface,should be thesame at all verticals.Samples collected in each vertical arecomposited into a