1、Designation: D 5074 90 (Reapproved 2003)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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers unifor
3、m 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
4、for 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 us
6、e 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 beconsidere
7、d 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 This standard does not purport to add
8、ress 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.2. Referenced Documents2.1 ASTM Standards:D 1129 Termino
9、logy Relating to Water2D 3974 Practices for Extraction of Trace Elements fromSediments3D 3975 Practice for Developement and Use (Preparation) ofSamples for Collaborative Testing of Methods forAnalysisof Sediments3D 3976 Practice for Preparation of Sediment Samples forChemical Analysis3E 691 Practice
10、 for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method43. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice, refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 natural-matrix sedimentgranular rock or earthy ma-ter
11、ial 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.4. Summary of Practice4.1 Natural-matrix sediment reference samples of ad-equately defined composition and homogeneity a
12、re required forevaluating the accuracy and precision of partial or sequentialsediment leachate analyses and test methods. Referencesamples should be typical in all respects to the sample forwhich the test method is applicable. Practically, this is difficultto achieve because of the heterogeneity and
13、 compositionalvariability of natural sediments. However, natural sedimentscollected from diverse sources can be used to prepare referencesamples similar or typical in many respects to the samples forwhich the test methods are to be applicable. For a minimalsediment quality assurance testing effort,
14、and to evaluate the1This 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.Current edition approved June 10, 2003. Published August 2003. Originallyapproved in 1990. Last previous
15、 edition approved in 1999 as D 5074 90 (1999).2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 11.02.4Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.linearity of
16、test methods, reference samples should be availableto provide at 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,
17、 representative, oxidized, relativelyunpolluted, aquatic natural-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 duri
18、ng their development.5.2 The availability of defined representative 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 t
19、esting. When the compo-sition of the reference or test samples has 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.
20、3 Certified analyses of most rock, sediment, sludge, andsoil reference 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. Thes
21、eare the only feasible analytical approaches if knowledge offinite 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 witho
22、utsample destruction.5.4 Partial chemical extraction of sediments, 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
23、 on partitioning, phaseassociations, or on how trace elements are 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 t
24、ime, temperature, and so forth.5.5 The various iron and manganese 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
25、 most trace metals in naturalwater-sediment hydrologic environments. Anthropogenicsources clearly dominate in the number of sources and in totalloading to most systems, although other factors may also beimportant.5Under reducing conditions the iron and manganeseoxide coatings, organic components, an
26、d associated tracemetals may be resolubilized and remobilized. Migration 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 l
27、eachates obtained fromreduced sediments thus will probably not be 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 testin
28、gpurposes, ideally require samples closely resembling the ma-terials 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 materia
29、l collected.These include but are not limited to the following: samplinglogistics, 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
30、 notexceeding 3000 S/cm. Samples collected from higher conduc-tivity 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 samplecol
31、lection site should also be suitable for launching anynecessary sample 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 color
32、ed quartz andsilicate minerals, deposited in an aerobic environment. 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 sedimen
33、t collected should befree of detectable levels of reduced iron and 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
34、 mineral species in thesediment reference sample will result in increasing 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 con
35、taining ore minerals andreadily soluble constituents. The raw material 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 e
36、ach site should be tested usingthe procedures deemed appropriate 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 associ
37、ated water by filtration through 0.45 m membranefilter. A positive test for ferrous iron in the filtrate is indicative5Jennett, J. C., Effler, S. W., and Wixson, B. G., “Mobilization and ToxicologicalAspects of Sedimentary Contaminants,” Contaminants and Sediments, ed., Baker,R. A., Ann Arbor Scienc
38、e Publishers, Inc., Ann Arbor, MI, 1990.D 5074 90 (2003)2of reducing conditions and the sample should be discarded.When one or more suitable sediment sources have beenidentified, sufficient raw material should be collected to enablepreparation of an adequate supply of standard. The number ofstandard
39、s to be prepared and the quantity of each will varyaccording to projected 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 aluminu
40、m and iron in most aquatic sedi-ments, major and trace metal contamination 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 sh
41、ipment and storage. Large heavy dutyplastic bags may be used as liners 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 rec
42、eipt.To minimize the potential of sample decomposition or loss,samples 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
43、lesser quantities ofthe fine grained fractions due to the presence 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
44、many samples. Disag-gregate the residue obtained on drying by pulverizing 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 p
45、rocedures should notbe subjected to mechanical grinding. These procedures 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
46、parameters of interest. Inaddition, contamination for one or more 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(t
47、hinner) slurry will generally yield a residue that is easilydisaggregated.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 prepar
48、ation of mostreference samples. If minimal contamination is necessary, 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 magne
49、tic 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 the appropriate sample weight for analysisshould be based on the particle size range of the material to beanalyzed. Numerous procedures are available for determiningthe appropriate sample sizes needed to analyze heterogeneousmaterials of v
