ASTM_D_4342_-_84_1998.pdf

Designation:D 4342 84(Reapproved 1998)Standard Practice forCollecting of Benthic Macroinvertebrates with Ponar GrabSampler1This standard is issued under the fixed designation D 4342;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the procedures for obtaining aqualitative or quantitative sample of macroinvertebrates inhab-iting a wide range of bottom substrate types,for example,coarse sand,fine gravel,clay,mud,marl,and similar sub-strates.1.2 This device is used in freshwater lakes,rivers,estuaries,reservoirs,oceans,and similar habitats.1.3 For the advantages and limitations of grab samplingdevices,see Guide D 4387.1.4 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 and health practices and determine the applica-bility of regulatory limitations prior to use.For specifichazards,see Section 5.2.Referenced Document2.1 ASTM Standards:D 4387 Guide for Selecting Grab Sampling Devices forCollecting Benthic Macroinvertebrates23.Summary of Practice3.1 The Ponar grab sampler has paired jaws that mustpenetrate beneath the surface of the substrate without disturb-ing the water surface boundary layer of the substrate,closewhen positioned properly on the bottom,and retain discretesamples of sediment while it is brought to the surface forprocessing.3.2 The standard Ponar takes a sample area of 523 cm2.3.3 A small version,the petite Ponar grab,takes a samplearea of 232 cm2and can be used in habitats where there maybe an unusual abundance of macroinvertebrates,thus eliminat-ing the need to subsample.4.Significance and Use4.1 The Ponar grab sampler is used to collect qualitative andquantitative samples from different aquatic habitats containingbenthic macroinvertebrates living on or in various types ofsubstrates.4.2 The organisms in the sample are used to define macro-invertebrate community characteristics in water quality studiesand ecological assessments.5.Hazards5.1 Inspect the Ponar grab sampler for mechanical defectsprior to use.5.2 This device cannot be used in fast flowing streams,andin habitats with large cobble or rubble stone substrates.5.3 Exercise caution at all times when handling the grab.5.4 When not in use,a safety pin lock attached to the leverbar prevents closing of the sampler until the pin is removed.5.5 The weight of the standard Ponar grab makes it neces-sary to use a winch and cable or portable crane for retrievingthe sample,and ideally the samples should be taken from astationary boat or platform.The smaller version,petite Ponargrab,is designed for hand-line operation.5.6 The petite Ponar grab is enhanced by the use of a winchand cable.6.Procedures6.1 Attach the Ponar grab to the cable and remove the safetypin with enough tension between the grab and cable so that thegrip mechanism will release only when the sampler is on thebottom.6.2 The device must have a controlled lowering speed andshall be lowered slowly because free-fall may airplane thedevice,causing the device to land improperly or causing apressure wave and blowout of the surface layer of sedimentwhen the grab reaches the bottom.6.3 Once the grab reaches the bottom,its weight will causeit to penetrate the substrate,and the slack-off on the cableallows the locking lever to release,therefore,permitting themovement that allows the horizontal locking bar to drop out ofthe locking notch and allows the jaws to close as the device israised.6.4 Now the tension on the cable is resumed.As the grab israised slowly,the lever system closes the jaws.6.5 Raise the sampler at a slow but steady rate to preventsample loss or washout.6.6 Once on board,empty into either a suitable container or1This practice is under the jurisdiction of ASTM Committee E47 on BiologicalEffects and Environmental Fate and is the direct responsibility of SubcommitteeE47.03 on Sediment Assessment and Toxicology.Current edition approved Feb.24,1984.Published October 1984.2Annual Book of ASTM Standards,Vol 11.05.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superceded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.a sieving device directly for processing.6.7 Thoroughly wash or hose the device with water so thatall sediment material is included in the sample processingbefore a replicate sample is taken.6.8 Auxiliary jaw weight can be attached to the standardPonar grab to increase its weight and is recommended forpenetrating certain hard substrates.ASTM International takes no position respecting the validity of any pa