ASTM D3976-1992(2015) Standard Practice for Preparation of Sediment Samples for Chemical Analysis《化学分析用沉淀样品制备的标准实践规程》.pdf

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1、Designation: D3976 92 (Reapproved 2015)Standard Practice forPreparation of Sediment Samples for Chemical Analysis1This standard is issued under the fixed designation D3976; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o

2、f 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 describes standard procedures for prepa-ration of test samples (including the removal of occluded wate

3、rand moisture) of field samples collected from locations such asstreams, rivers, ponds, lakes, and oceans.1.2 These procedures are applicable to the determination ofvolatile, semivolatile, and nonvolatile constituents of sedi-ments.1.3 The values stated in SI units are to be regarded asstandard. No

4、other units of measurement are included in thisstandard.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-bilit

5、y of regulatory limitations prior to use. For a specificprecautionary statement, see Note 3.2. Referenced Documents2.1 ASTM Standards:2D596 Guide for Reporting Results of Analysis of WaterD1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits (Wit

6、hdrawn 2003)3D3370 Practices for Sampling Water from Closed ConduitsD4410 Terminology for Fluvial Sediment3. Terminology3.1 DefinitionsFor definitions of terms used in thispractice, refer to Terminologies D1129 and D4410.4. Summary of Practice4.1 Samples collected (see Practice D3370 and Specifica-t

7、ion D1192) in the field are screened to remove foreign objectsprior to homogenization for chemical examination and analy-sis. Large objects are mechanically removed and small ones areeliminated by sieving the sample through a 10-mesh (2 mmopenings) sieve.4.2 Wet, sieved samples are mixed for prelimi

8、naryhomogenization, then allowed to settle to remove most of theoccluded water.4.3 Moisture determinations are made on separate samplesfrom those analyzed for volatile or semivolatile constituents.4.4 Analyses for volatile constituents are made using wet,settled samples from which supernatant liquid

9、 has been re-moved by decantation. The results are corrected to those thatwould have been obtained on samples dried to constant weightat 105 6 2C, on the basis of a moisture determination usinga separate sample.4.5 Analyses for semivolatile constituents (for example,mercury) are made on samples prev

10、iously dried at a tempera-ture found to be adequate for the purpose, and specified in thecorresponding analytical procedure.4.6 Analyses for nonvolatile constituents are made onsamples previously dried to constant weight at 105 6 2C.4.7 A flow diagram, outlining typical procedures, is shownin Fig. 1

11、.5. Significance and Use5.1 The chemical analysis of sediments, collected from suchlocations as streams, rivers, ponds, lakes, and oceans canprovide information of environmental significance.5.2 Sediment samples are inherently heterogeneous in thatthey contain occluded water in varying and unpredict

12、ableamounts and may contain foreign objects or material notordinarily considered as sediment, the inclusion of whichwould result in inaccurate analysis.5.3 Standard methods for separating foreign objects tofacilitate homogenization will minimize errors due to poormixing and inclusion of extraneous m

13、aterial.5.4 Standardized procedures for drying provide a means forreporting analytical values to a common dry weight basis.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,and Open-Channel Flow.

14、Current edition approved Jan. 1, 2015. Published January 2015. Originallyapproved in 1980. Last previous edition approved in 2010 as D3976 92 (2010).DOI: 10.1520/D3976-92R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For

15、Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Uni

16、ted States16. Preliminary Treatment of Field Samples6.1 The analytical sample is arbitrarily defined as that whichpasses a 10-mesh (approximately 2 mm openings) sieve. Thepurpose of this is to provide a basis for discrimination ofsediment and foreign objects or materials. Stainless steel ornylon sie

17、ves may be used when inorganic constituents are to bedetermined. Stainless steel or brass sieves are suitable for usewhen organic substances are to be determined.NOTE 1For inorganic analyses, stainless steel sieves are acceptableprovided the mesh is not soldered or welded to the frame. For organican

18、alyses, organic materials such as rubber or plastics should not be usedin the storage or handling of samples.6.2 Sieve dry samples without further pretreatment andfollow the procedures given in 7.3, 7.4,or7.5, or a combina-tion thereof, as appropriate.6.3 Vigorously stir wet field samples, which may

19、 havesettled during transit, to incorporate as much field water aspossible, thereby facilitating subsequent wet sieving.NOTE 2Do not add additional laboratory water since this may extractconstituents or otherwise change the composition of the sediment.However, it is permissible to slurry the sedimen

20、t with a minimum quantityof field water collected with the sample, when necessary, to facilitatewet-sieving.6.4 Pass the wet sample, preferably as a slurry, through thesieve (plastic or stainless steel). The bottom of an appropriatesize Erlenmeyer flask may be used to gently press the sedimentthroug

21、h the sieve, as necessary.6.4.1 Manually remove foreign objects such as stones,twigs, leaves, trash, etc., which would obviously not passthrough the sieve and which may interfere with the sievingoperation.6.5 Mix the sieved material by stirring and allow it to settlefor subsequent removal of superna

22、tant liquid.6.5.1 Store the material, as prepared above, in contact withits supernatant liquid, until time of use for chemical examina-tion.NOTE 3Precaution: Samples intended for both organic and inorganiccompound analysis may undergo changes in composition during storage.The analytical method shoul

23、d specify the conditions necessary to assurerequisite stability. In the absence of specific instructions, storage at atemperature of 4C or lower for a period of time not to exceed 1 week isrecommended, although it is known that microbiological activity does notcease under these conditions.7. Prepara

24、tion of Analytical Samples7.1 Decant the supernatant liquid from the settled sedimentprepared in accordance with Section 6. Save the supernatantliquid for separate analysis of any suspended material, asnecessary.7.2 Mix the sediment, using a glass rod or porcelain spatula,to minimize stratification

25、effects due to differential rates ofsettling.7.3 Remove a number of small portions (at least ten) fromrandom locations in the sample container and composite themFIG. 1 Flow diagram for Sediment-Sample TreatmentD3976 92 (2015)2to obtain a representative sample of size suitable for determi-nation of m

26、oisture (see Section 9), or for drying to preparematerial for analysis of semivolatile or nonvolatile constitu-ents.7.4 Determine volatile constituents, using wet samples pre-pared in accordance with 7.3.7.5 Determine semivolatile and nonvolatile constituents,using samples prepared in accordance wit

27、h 7.3 and Section 8.7.5.1 Disaggregate the dried material by gently crushingany lumps or clumps in a mortar. Mix the disaggregatedmaterial and prepare a composite sample resulting fromremoval of a number of smaller portions as indicated in 7.3.The use of freeze drying facilitates sample disaggregati

28、on.8. Drying Procedure8.1 Use a sample prepared in accordance with directionsgiven in Section 7.8.2 Accurately weigh 5 to 10 g (61 mg) or 10 to 25 g (610mg) of the sediment into a previously tared porcelain dish,weighed with the same accuracy.8.2.1 When a limited amount of sample is available, themo

29、isture may be determined on 1 to 2 g samples, weighed withan accuracy of 60.1 mg. The use of samples smaller than 1 gis not recommended for moisture determination.8.3 Transfer the dishes containing the weighed sediment toan oven and dry for2hasfollows:8.3.1 For determination of semivolatile constitu

30、ents, use thetemperature (tC) specified in the analytical procedure for thatconstituent. For determination of nonvolatile constituents use105 6 2C.8.4 Cool in a desiccator, then weigh the dried samples withthe same accuracy as the wet sample.8.5 Repeat drying at hourly intervals, to a constant weigh

31、t.9. Moisture Correction and Calculations9.1 The possibility of loss of volatile constituents dictatesthe drying procedure that should be used, prior to chemicalanalysis. Volatile constituents are usually determined usingundried samples. Semivolatile constituents must be determinedusing samples drie

32、d at a temperature at which no significantlosses occur. Nonvolatile constituents are analyzed usingsamples dried at 105 6 2C.9.2 Report all analytical values (see Method D596), regard-less of how measured, on the basis of a sample dried at 105 62C to facilitate correlation of data.9.3 The following

33、equations are useful to correct analyticalresults, C (weight percent, g/g, etc.), obtained on an undriedsample or one partially dried at tC, to the basis of one dried at105 6 2C.9.3.1 Test Method ACalculate volatile constituents asfollows:Cv5 Cvl/100 2 % moisture105! (1)where:Cv= dry basis, andCvl=

34、wet basis.9.3.2 Test Method BCalculate semivolatile constituents asfollows:Csv5 Csvl100 2 % moisture!/100 2 % moisture105!where:Csv= dry basis, andCsvl= dried at tC.10. Keywords10.1 chemical analysis; nonvolatile constituents; prepara-tion; sediment samples; semivolatile; volatileASTM International

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