1、Designation: D 5074 90 (Reapproved 2008)Standard Practice forPreparation of Natural-Matrix Sediment Reference Samplesfor Major and Trace Inorganic Constituents Analysis byPartial Extraction Procedures1This standard is issued under the fixed designation D 5074; the number immediately following the de
2、signation 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 uniform
3、 procedures to develop,select, collect, prepare, and use oxidized, relatively unpolluted,aquatic natural-matrix bed-sediment reference samples for thecollaborative testing of chemical methods of analysis forsediments and similar materials. Reference samples preparedusing this practice are intended f
4、or use as natural sediments,analyzable for major, minor, and trace elements, and generalphysical/organic analyses only. The samples are not designedor tested for environmental pollutants such as trace organiccompounds.1.2 Few, if any, aquatic sediment reference materials havebeen certified, defined,
5、 or are even available for developing orevaluating partial and sequential extraction procedures. Thispractice describes factors and considerations in site selection,sample characteristics, collection, and subsequent raw sampletreatment needed to prepare natural-matrix bed-material sedi-ments for use
6、 as partial or sequential extraction procedurereference test samples. The user of this practice is cautionedthat in light of the many variables that may affect naturalmaterials, neither the list of factors included for evaluation norpreparation of natural-matrix reference samples should beconsidered
7、 as all inclusive. It is the users responsibility toensure the validity and applicability of these practices forpreparing specific-matrix samples appropriate for testing theconstituents of interest and the operationally defined extractionprocedures utilized.1.3 The values stated in SI units are to b
8、e regarded asstandard. No 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 d
9、etermine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 3974 Practices for Extraction of Trace Elements fromSedimentsD 3975 Practice for Development and Use (Preparation) ofSamples for Collaborative Testing o
10、f Methods forAnalysisof SedimentsD 3976 Practice for Preparation of Sediment Samples forChemical AnalysisE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: For definitions of terms used in this prac-tice, refer to Terminolo
11、gy D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 natural-matrix sedimentgranular rock or earthy ma-terial that has been naturally deposited in or by a water body,in which the finer grained material encloses or fills theinterstices between the larger grains or particles of sediment.
12、4. Summary of Practice4.1 Natural-matrix sediment reference samples of ad-equately defined composition and homogeneity are required forevaluating the accuracy and precision of partial or sequentialsediment leachate analyses and test methods. Referencesamples should be typical in all respects to the
13、sample forwhich the test method is applicable. Practically, this is difficultto achieve because of the heterogeneity and compositionalvariability of natural sediments. However, natural sedimentscollected from diverse sources can be used to prepare referencesamples similar or typical in many respects
14、 to the samples forwhich the test methods are to be applicable. For a minimalsediment quality assurance testing effort, and to evaluate thelinearity of test methods, reference samples should be available1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsi
15、bility of Subcommittee D19.07 on Sediments, Geomorphology,and Open-Channel Flow .Current edition approved Oct. 1, 2008. Published November 2008. Originallyapproved in 1990. Last previous edition approved in 2003 as D 5074 90 (2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org
16、, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to provide at
17、least three levels of concentration for eachmeasured parameter. Mixtures of samples of known composi-tion may also be used.5. Significance and Use5.1 The objective of this practice is to provide guidelines forthe preparation of stable, representative, oxidized, relativelyunpolluted, aquatic natural-
18、matrix bed-sediment reference testsamples. When prepared as described, such test samples shouldbe useful for collaborative methods testing, to evaluate theprecision and bias of test methods, and to evaluate test methodsperformance during their development.5.2 The availability of defined representati
19、ve natural-matrixreference or test samples, closely approximating a variety oftypical environmental samples, is a key requirement for theeffective collaborative methods evaluation and development oftest methods, and quality assurance testing. When the compo-sition of the reference or test samples ha
20、s been determined,either for operationally defined “total recoverable” leachingtechniques, or for “total analysis” determined by total dissolu-tion, the defined samples should also be suitable for analyticalquality assurance testing.5.3 Certified analyses of most rock, sediment, sludge, andsoil refe
21、rence samples are typically based on the total amountof each constituent of interest in the entire sample. “Total”chemical analysis of these samples generally requires completedecomposition or dissolution of the standard material. Theseare the only feasible analytical approaches if knowledge offinit
22、e concentrations for each element of interest in the entiresample is required. Certain instrumental methods, such asX-ray fluorescence or neutron activation analysis, may provideinformation as to the total constituent composition withoutsample destruction.5.4 Partial chemical extraction of sediments
23、, or “total re-coverable” analyses (operationally defined procedures) forselecting constituents, frequently are useful for defining “avail-able” constituent concentrations. In addition, partial chemicalextractions may also provide data on partitioning, phaseassociations, or on how trace elements are
24、 entrained. Opera-tionally defined extractable trace constituent concentrations aregenerally best obtained by using very specific reagent mixturesand extraction procedures, including method of mixing, vesselsize and shape, extraction time, temperature, and so forth.5.5 The various iron and manganese
25、 oxides and hydroxides,clay minerals, and organic solutes and particulates, that com-monly occur as coatings on most oxidized sediment particles,are generally recognized as the controls governing the concen-trations and distribution of most trace metals in naturalwater-sediment hydrologic environmen
26、ts. Anthropogenicsources clearly dominate in the number of sources and in totalloading to most systems, although other factors may also beimportant.3Under reducing conditions the iron and manganeseoxide coatings, organic components, and associated tracemetals may be resolubilized and remobilized. Mi
27、gration of thereduced solubilized species, with possible subsequent forma-tion of sulfides and so forth, and reoxidation and redepositionat some new location, may then occur. Analysis of extractabletrace constituent concentrations in leachates obtained fromreduced sediments thus will probably not be
28、 indicative of thetrace constituent concentrations initially associated with theoxidized and coated sediment grains.6. Sampling6.1 Realistic natural-matrix aquatic bed-sediment testsamples needed for test methods development and testingpurposes, ideally require samples closely resembling the ma-teri
29、als for which the test method is designed. Collection andpreparation of a realistic test sample necessitates considerationof a number of factors in addition to the presence or absence ofcertain characteristics in the raw sample material collected.These include but are not limited to the following: s
30、amplinglogistics, water chemistry, and the availability of adequatequantities of sediment with the appropriate particle sizes.6.2 The sampling site should provide easy access to freshwater with a pH of 6 to 8 and a specific conductance notexceeding 3000 S/cm. Samples collected from higher conduc-tiv
31、ity areas should be washed to remove excessive salts.Normally, flow velocities in the collection area should besufficiently low to allow deposition of the fine grained mate-rials desired in the bed material to be sampled. The samplecollection site should also be suitable for launching anynecessary s
32、ample collection craft, or have close access to boatlaunching facilities.6.3 Sufficient quantities of raw sample material should beavailable to obtain desired quantities of oxidized sediment.This should consist primarily of light colored quartz andsilicate minerals, deposited in an aerobic environme
33、nt. The rawsediment should contain only minimal quantities of particulateorganic material or total organic constituents (TOC) (no morethan 2 to 3 %), to minimize bacterial growth and the develop-ment of reducing conditions. The sediment collected should befree of detectable levels of reduced iron an
34、d manganesespecies, have no perceptible sulfide odor, and exhibit noobservable methane generation. Readily soluble materials suchas ore minerals, carbonates, chlorides, and sulfates should alsobe absent. Inclusion of relatively soluble mineral species in thesediment reference sample will result in i
35、ncreasing concentra-tions of associated major and trace parameters as a function ofincreased sample digestion times, until those phases are com-pletely dissolved. “Total” digestion analyses are generallymore appropriate for samples containing ore minerals andreadily soluble constituents. The raw mat
36、erial collected shouldalso contain an adequate fraction (10 to 20 % or greater) of thedesired particle sizes, such as 62 m and finer material.6.4 After several tentative sampling sites have been identi-fied, portions of material from each site should be tested usingthe procedures deemed appropriate
37、to evaluate the suitability ofeach for particle size distribution, chemical characteristics, andtrace constituent levels. The presence of reducing conditions ina wet sediment may be tested by separation of a small quantityof the associated water by filtration through 0.45 m membranefilter. A positiv
38、e test for ferrous iron in the filtrate is indicativeof reducing conditions and the sample should be discarded.3Jennett, J. C., Effler, S. W., and Wixson, B. G., “Mobilization and ToxicologicalAspects of Sedimentary Contaminants,” Contaminants and Sediments, ed., Baker,R. A., Ann Arbor Science Publi
39、shers, Inc., Ann Arbor, MI, 1990.D 5074 90 (2008)2When one or more suitable sediment sources have beenidentified, sufficient raw material should be collected to enablepreparation of an adequate supply of standard. The number ofstandards to be prepared and the quantity of each will varyaccording to p
40、rojected needs.7. Procedure7.1 Non-contaminating plastic buckets and scoops or TFE-flourocarbon coated metal are preferable for sample collection.Aluminum or steel shovels may also be satisfactory. Due to thelarge percentage of aluminum and iron in most aquatic sedi-ments, major and trace metal cont
41、amination from aluminum orsteel sampling tools would probably be insignificant if the finalsamples are sufficiently large and adequately mixed. Opaquefood grade plastic buckets with snap-type leakproof plasticcovers are suitable for shipment and storage. Large heavy dutyplastic bags may be used as l
42、iners in plastic cooler chests toprovide a suitable alternative.7.2 Sample PreservationNo sample preservatives shouldbe used. Refrigerate raw sediment at 4C after collection andship in iced coolers. Ship promptly and refrigerate on receipt.To minimize the potential of sample decomposition or loss,sa
43、mples should not be collected or shipped during periods oftemperature extremes.7.3 Sample DryingFreeze drying is the preferred treat-ment for processing most moist or wet sediments. Air, oven,and microwave drying will frequently yield lesser quantities ofthe fine grained fractions due to the presenc
44、e of fine materialoccurring and remaining as “large” grain size aggregates.Freeze drying reduces fine grain particle cohesion, and thenumber of aggregates resistant to disaggregation, and increasesthe percentage of fines obtained from many samples. Disag-gregate the residue obtained on drying by pul
45、verizing lumps ona plastic surface using a plastic bottle as a crusher. Gentledisaggregation in this manner minimizes formation of freshfracture surfaces caused by grain crushing. Natural-matrixsamples prepared for partial extraction procedures should notbe subjected to mechanical grinding. These pr
46、ocedures createvarying degrees of fresh mineral fractures and will result innon-representative samples if used for testing partial extractionprocedures. Leaching of the fresh fracture surfaces may yieldinvalid concentration levels for parameters of interest. Inaddition, contamination for one or more
47、 parameters may resultfrom the use of grinding equipment.7.3.1 After freeze drying, some samples with a high claycontent may still contain aggregates resistant to disaggregation.For those samples, freeze drying a higher water content(thinner) slurry will generally yield a residue that is easilydisag
48、gregated.7.4 Sample SievingSieve the disaggregated dry sedimentthrough appropriate sizes of standard calibrated sieves using atimed shaker to obtain the desired size fractions. Stainless steelsieves are probably suitable for the preparation of mostreference samples. If minimal contamination is neces
49、sary, useall plastic sieves. Metallic sieves and screens assembled withlead solder should be avoided. After samples have been driedand sieved, highly magnetic mineral fractions, if present,should be removed by use of any suitable magnetic separationdevices. After obtaining the desired size fractions, place in aVee type, or other suitable blender, and mix for several hours.Package in appropriately sized containers using sample split-ters, coning, and quartering or other suitable techniques.8. Verification of Test Sample Composition andCollaborative Testing8.1 Selection of th
