1、Designation: D7929 14Standard Guide forSelection of Passive Techniques for Sampling GroundwaterMonitoring Wells1This standard is issued under the fixed designation D7929; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 standard provides guidance and information onpassive sampling techniques for collecting groundwater frommonitorin
3、g wells. Passive groundwater samplers are able toacquire a sample at a discrete depth or interval in a well,without the active transport associated with a pump or purgetechnique (1).2Passive groundwater sampling is a type ofno-purge groundwater sampling method where the samplersare left in the well
4、for a predetermined period of time prior tocollecting the sample.1.2 Methods for sampling monitoring wells include low-flow purging and sampling methods, traditional well-volumepurging and sampling methods, post-purge grab samplingmethods (for example, using a bailer), passive no-purge sam-pling met
5、hods, and active no-purge sampling methods such asusing a bailer to collect a sample without purging the well.Thisguide focuses on passive no-purge sampling methodologies forcollecting groundwater samples. These methodologies includethe use of diffusion samplers, accumulation samplers, andpassive-gr
6、ab samplers. This guide provides information on theuse, advantages, disadvantages, and limitations of each of thesepassive sampling technologies.1.3 ASTM Standard D653 provides standard terminologyrelevant to soil, rock, and fluids contained in them. ASTMStandard D4448 provides a standard guide to s
7、ampling ground-water wells, and ASTM Standards D5903 and D6089 provideguides for planning and documenting a sampling event.Groundwater samples may require preservation (GuideD6517), filtration (Guide D6564), and measures to pack andship samples (Guide D6911). Standard D7069 provides guid-ance on the
8、 quality control and quality assurance of samplingevents. ASTM Standard D5092 provides standard practice forthe design and installation of groundwater monitoring wells,ASTM Standard D5521 provides a standard guide for devel-oping groundwater monitoring wells in granular aquifers, andD6452 provides a
9、 standard guide for purging methods used ingroundwater quality investigations. Consult ASTM StandardD6724 for a guide on the installation of direct-push ground-water monitoring wells andASTM Standard D6725 for a guideon the installation of direct-push groundwater monitoring wellswith pre-pack screen
10、s.1.4 The values stated in SI Units are to be regarded as thestandard. Values in inches (such as with well diameters) aregiven in parentheses, and are provided for information. Use ofunits other than SI shall not be regarded as nonconforming withthis standard.1.5 This guide provides information on p
11、assive groundwatersampling in general and also provides a series of considerationswhen selecting a passive groundwater sampling method.However, it does not recommend a specific course of action,and not all aspects of this guide may be applicable in all fieldsituations. This document cannot replace e
12、ducation or experi-ence and should be used in conjunction with professionaljudgment. This ASTM standard is not intended to represent orreplace the standard of care by which the adequacy of a givenprofessional service must be judged, nor should this documentbe applied without consideration of a proje
13、cts many uniqueaspects. The word “standard” in the title of this documentmeans only that the document has been approved through theASTM consensus process.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of t
14、his 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:D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged
15、 in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4750 Test Method for Determining Subsurface LiquidLevels in a Borehole or Monitoring Well (Observation1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct respon
16、sibility of Subcommittee D18.21.04 on GroundwaterSample Collection and Handling.Current edition approved Aug. 15, 2014. Published October 2014. DOI:10.1520/D7929-14.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International, 100 Barr
17、Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Well) (Withdrawn 2010)3D4448 Guide for Sampling Ground-Water Monitoring WellsD5092 Practice for Design and Installation of GroundwaterMonitoring WellsD5521 Guide for Development of Groundwater MonitoringWells in Granular Aqui
18、fersD5903 Guide for Planning and Preparing for a GroundwaterSampling EventD6089 Guide for Documenting a Groundwater SamplingEventD6452 Guide for Purging Methods for Wells Used forGroundwater Quality InvestigationsD6517 Guide for Field Preservation of GroundwaterSamplesD6564 Guide for Field Filtratio
19、n of Groundwater SamplesD6724 Guide for Installation of Direct Push GroundwaterMonitoring WellsD6725 Practice for Direct Push Installation of PrepackedScreen Monitoring Wells in Unconsolidated AquifersD6911 Guide for Packaging and Shipping EnvironmentalSamples for Laboratory AnalysisD7069 Guide for
20、Field QualityAssurance in a Ground-waterSampling Event3. Terminology3.1 For common definition of terms about soil and rock andthe fluids contained in them, refer to Terminology in D653.3.2 Explanation of Terms Specific to this Standard:3.2.1 passive environmental sampling, nis a group ofsampling tec
21、hnologies that were first developed to sample air,were subsequently adapted to sample soil vapor, and now arebeing used to sample water. In the scientific literature, passivesampling in air, soil, and water has been defined as anysampling technique based on the free flow of analyte moleculesfrom the
22、 sampled medium to a receiving phase in a samplingdevice as a result of a difference between the chemicalpotentials of the analytes in the two media (2 and 3). Thesepassive sampling devices are usually based on diffusionthrough a diffusion barrier or permeation through a membrane(2 and 3). Uptake of
23、 analytes follows a standard uptake curvewhere uptake initially is linear, followed by a period of timewhere uptake is no longer linear (that is, becomes curvilinear),and finally equilibration is reached. Analytes are retained in asuitable medium within the passive sampler, known as areference or re
24、ceiving phase, which can be a solvent, chemicalreagent, or a porous adsorbent (2 and 3). There are two mainaccumulation regimes, kinetic and equilibrium, and these aredescribed based on the devices physical basis of operation asdefined below.3.2.1.1 equilibrium samplers, npassive samplers that havea
25、n exposure time that is sufficiently long to permit establish-ment of thermodynamic equilibrium between the sampledmedium and receiving phase (3).3.2.1.2 integrative or kinetic samplers, npassive samplersthat work in the linear uptake phase (of a standard uptakecurve) where the rate of desorption of
26、 analytes from thereceiving phase to the sampled medium is negligible (2 and 3).These samplers provide a total mass for the time they aredeployed, which can be converted to concentration values insome cases.3.2.2 groundwater sampling, nmost groundwater sam-pling methods currently involve purging the
27、 well prior tosample collection although, samples can be collected withoutpurging the well as long as the data-quality objectives of theinvestigation are met. Additional information on active sam-pling methods that involve purging the well can be found inGuides D4448 and D6452.3.2.2.1 no-purge groun
28、dwater sampling, nsampling meth-ods that differ from active purging-and-sampling methods forsampling groundwater (as described in Guide D6452) in thatthere is no requirement to remove water from the well prior tosampling. Thus, without purging the well, no-purge methodscan collect a sample using an
29、active method (such as pumping,suction, bailing) or a passive method.3.2.2.2 passive groundwater sampling, na type of no-purge groundwater sampling method where the samplers aredeployed in the well at one or more target depths within thewell screen or open bore hole and are then left in the well for
30、a predetermined period of time prior to collecting the sample(rather than collecting a sample immediately). These samplingmethods do not use pumping, suction, or bailing to collect thesample and thus do not induce stress on the aquifer (GuideD4448).3.2.3 passive-groundwater samplers, nare deployed i
31、n thewell for a set period of time prior to sample collection; this iseither an equilibration time or a deployment time that is basedupon linear uptake of the analytes by the sampler. All of thesedevices provide a sample from a specific location within thewell screen or borehole. Spatial integration
32、, if any, is a result ofnatural ambient flow of the sampled medium. These samplerscan be classified by the mechanism used to collect the sampleand include: diffusion samplers (4 and 5), accumulationsamplers (1, 6), and passive-grab samplers.3.2.3.1 diffusion samplers, nusually contain deionized(DI)
33、or distilled water inside a membrane and rely on diffusionof analytes through the membrane to reach equilibrium withconcentrations in the well. These samplers are an equilibriumtype of passive sampler (as defined in 3.2.3). The length of theequilibration period depends primarily upon the types ofana
34、lytes, the membrane material, the rate of exchange of waterin the well, and temperature of the well water.3.2.3.2 accumulation samplers, ntypically consist of amembrane that houses a sorbent medium, either liquid orparticulate, and rely on diffusion and sorption to accumulateanalytes in the sampler.
35、 Although, these samplers can be usedas either an integrative or equilibrium sampler, adsorptivesamplers are prone to saturation effects and other reactionswhich make them less suitable for equilibrium sampling (7).When these samplers are used in the integrative (or kinetic)mode, the sampling time m
36、ust be within the linear portion ofthe uptake curve.3The last approved version of this historical standard is referenced onwww.astm.org.D7929 1423.2.3.3 passive-grab samplers, nare grab samplers thatcollect a whole water sample and require an equilibrationperiod prior to sample collection. Passive-g
37、rab samplers shouldnot disturb the water column during sample collection, shouldbe able to collect a sample at the target depth(s) in the well, andshould be able to isolate the sample inside the sampler prior toremoving it from the well.3.2.3.4 equilibration period, nthe suggested deploymentperiod f
38、or all passive-grab and diffusion samplers and accu-mulation samplers when they are used as equilibrium samplers.The appropriate deployment period depends upon one or moreof the following factors: the time needed for environmentaldisturbances caused by sampler deployment to dissipate andambient cond
39、itions in the well to return, the time needed forequalization of analyte concentrations with surrounding con-centrations in the well water, and the time needed to reducelosses due to sorption of the analytes by the sampler materialsto negligible levels.3.2.3.5 deployment time, na term used for an ac
40、cumula-tion sampler that is being used as an integrative (or kinetic)sampler and is a function of the time needed for the sampler toachieve quantitative levels of uptake of the target analytes. Foraccurate quantitative measurements, the deployment time mustbe within the linear portion of the uptake
41、curve of the samplerfor the analytes of interest.4. Significance and Use4.1 GeneralIn the past ten (plus) years, the InterstateTechnology Regulatory Council (ITRC) has provided severaltechnical and regulatory documents on the use of passivegroundwater sampling methods (1, 4-6). Collectively, thesedo
42、cuments have provided information and references on thetechnical basis for their use, comparison of sampling resultswith more traditional sampling methods, descriptions of theirproper use, limitations, and a survey of their acceptance anduse by responding state regulators.4.1.1 Because of the large
43、number of passive samplers thathave been developed over the past fifteen years for varioustypes of environmental sampling, it is beyond the scope of thisstandard to discuss separately each of the methods that could orcan be used to sample groundwater. Extensive literaturereviews on diffusion- and ac
44、cumulation-passive samplers canbe found in the scientific literature (that is, 3, 7-13). Thesereviews provide information on a wide variety of passivesampling devices for use in air, soil vapor, and water.Areviewpaper on the use of diffusion and accumulation-type passivesamplers specifically for sam
45、pling volatile organic compounds(VOCs) in groundwater (14) includes information on otherpassive samplers that are not included in the ITRC documents(1, 6) and discusses their use with respect to measuring massflux.4.2 UsePassive samplers are deployed at a pre-determineddepth, or depths, within a wel
46、l for a pre-determined period oftime and should remain submerged for their entire deploymenttime. All of the passive technologies described in this docu-ment rely on the sampling device being exposed to thegroundwater during deployment and the continuous flushing ofthe open or screened interval of t
47、he well by ambient ground-water flow (15) to produce water quality conditions in the wellbore that effectively mimic those conditions in the aquiferadjacent to the screen or open interval. For samplers thatrequire the establishment of equilibrium, it is important that theequilibration period be long
48、 enough to allow the well torecover from any disturbance caused by placing the sampler inthe well and to prevent, or reduce, losses of analytes from thewater sample by sampler materials due to sorption. For kineticaccumulation samplers (used as kinetic samplers), it is impor-tant that the deployment
49、 time is long enough that quantitativeuptake can occur but not so long that uptake is no longer in thelinear portion of the uptake curve (that is, has becomecurvilinear).4.2.1 As with all types of groundwater sampling methods,the appropriate use of passive methods assumes that the wellhas been properly located (laterally and vertically), designed,constructed, and was adequately developed (as described inGuide D5521) and maintained (as described in PracticesD5092 and D6725, or Guide D6724). These measures arenecessary so that the well is in hydraulic communication withthe
