1、Designation: G 29 96 (Reapproved 2002)Standard Practice forDetermining Algal Resistance of Plastic Films1This standard is issued under the fixed designation G 29; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice covers the determination of th
3、e suscepti-bility of plastic films to the attachment and proliferation ofsurface-growing algae.1.2 The values in SI units are to be regarded as the standard.The inch-pound units given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if a
4、ny, 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. Summary of Practice2.1 In this practice, test strips of plastic film are suspendedin glas
5、s jars maintained at room temperature. The test strips areexposed to fluorescent light and in direct contact with astandardized inoculum of the filamentous blue-green algaOscillatoria in culture medium. The sample test jars arereinoculated with fresh alga every second or third day. Acontrol using un
6、treated plastic film is used as a basis ofcomparison. The inoculum is prepared with the help of apropagation apparatus made from a small fish tank. The test isterminated at the end of two weeks, or whenever the test filmshows dense algal growth.3. Significance and Use3.1 Bodies of water, such as swi
7、mming pools, artificialponds, and irrigation ditches often are lined with plastic films.Algae tend to grow in such bodies of water under the properatmospheric conditions, and they can produce slimy andunsightly deposits on the film. The method described herein isuseful in evaluating the degree and p
8、ermanency of protectionagainst surface growth of algae afforded by various additivesincorporated in the film.4. Apparatus4.1 Propagation Tank2(see Fig. 1):4.1.1 A small fish tank (10 gal) is used to contain asimulated cooling tower, made of redwood slats, over whichculture medium is recirculated thr
9、ough a plastic tube with holespunched in the bottom. This design was developed in order toprovide ideal conditions for propagation of the algae that serveas inocula for each test. Three redwood slats are joined by twosupports in such a way that water cascades over each slat inturn from a distributor
10、 tube above the upper slat. A small, fullyimmersed recirculating pump3rests on the bottom of the tankand operates continuously to deliver the tank contents to thedistributor tube. The light required for algal propagation isprovided by a 100-W bulb placed 300 mm (12 in.) away fromthe redwood slats. A
11、 timing device turns the light on for 12 heach day.4.1.2 The propagation tank, that is used as the permanentsource of inoculum, is filled to approximately one-third capac-ity with the culture medium.4Heavy growth of Oscillatoriarapidly develops on the redwood tower and, at different phases,this grow
12、th appears light green, dark green, or black.4.2 Test Chambers (see Fig. 2):4.2.1 One-litre (1-qt) wide-mouth glass jars, 170 mm (634in.) high by 76 mm (3 in.) in inside diameter serve as testchambers wherein water containing an inoculum of the algalorganisms and strips of the plastic film are maint
13、ained incontact.4.2.2 The jars in 4.2.1 are placed in a 38-L (10-gal) fishtank, 508 by 267 by 305 mm (20 by 1012 by 12 in.) high, thatis illuminated by four 20-W “cool white” fluorescent bulbs,arranged two on each long side of the tank, at the level of thegrowing algae in the jars. The lamps are mou
14、nted on a bracketthat holds the outer surface of the bulbs 25 mm (1 in.) from thewall of the tank. The tank is filled with water to within 25 mm1This practice is under the jurisdiction of ASTM Committee G03 on Weatheringand Durability and is the direct responsibility of Subcommittee G03.04 onBiologi
15、cal Deterioration.Current edition approved Jan. 10, 2002. Published May 2002. Originallypublished as G 29 71 T. Last previous edition G 29 90.2The redwood tower should be soaked in water before use, until the water iscolorless. Water is changed daily.3Model 1 MA manufactured by the Little Giant Corp
16、., 3800 N. Tulsa Ave.,Oklahoma City, OK 73107, has been found suitable for this purpose.4Culture medium in the propagation tank is discarded, and the tank is refilledwith fresh medium at monthly intervals.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
17、2959, United States.of the top of the exposure jars in order to create uniformtemperature conditions for all jars.4.3 HomogenizerAny suitable commercial homogenizerfor preparing the algal inocula.5. Reagents and Materials5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless
18、 otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently hi
19、gh purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean distilled water or water ofequal purity.5.3 Culture Medium for Propagation ApparatusPreparethis medium by dissolving in 15 L of
20、 water the designatedamounts of the following reagents:Arnons trace metal solution (see Note 1)15mLEthylenediamine tetraacetic acid disodium salt 0.04 gFerric ammonium citrate 0.85 gMagnesium sulfate (MgSO47H2O) 10.0 gPotassium acid phosphate (K2HPO4) 12.3 gPotassium nitrate (KNO3) 12.1 gSodium citr
21、ate 2.0 gSulfuric acid, 10 % 10 mLNOTE 1Prepare this solution by combining the following reagents inthe amounts designated in 1 L of water:Boric acid 2.86 gCopper sulfate (CuSO45H2O) 0.079 gManganese chloride (MnCl24H2O) 1.18 gMolybdic oxide (MoO3) 0.018 gZinc sulfate (ZnSO47H2O) 0.22 g5.3.1 Adjust
22、to 7.2 to 7.5 pH range if necessary. The culturemedium need not be sterilized.5.4 Culture Medium for Test Chambers Dilute 50 mL ofthe culture medium in 5.3 with 950 mL of tap water and placethis medium in the test chambers.6. Test Specimens6.1 Select at random from the sample sufficient film toprepa
23、re the required number of test specimens 25 by 65 mm (1by 212 in.).6.2 When possible, use untreated film, similar in all otherrespects to the treated film, for testing in the same manner asthe test specimens, in order to verify the viability of the testorganism. If this untreated viability control m
24、aterial fails toshow any abundant growth of the test organisms, consider thetest inconclusive and repeat it.7. Procedure7.1 Attachment of SpecimensSamples are suspended ineach test chamber by means of plastic6clips hooked over aplastic or metal rod extending over the test chambers. Addi-tional means
25、 of suspension may be used as long as nobiologically active materials (for example, adhesives, cements)come in contact with the test specimens during submersion.7.2 Inoculation of Test ChambersRemove an area ofgrowth about 6 mm (14 in.) in thickness and 6.5 cm2(1 in.2)in5Reagent Chemicals, American
26、Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.
27、S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.6Chromatography clips (Chromclipst, VWR Scientific).FIG. 1 Propagation TankFIG. 2 Test ChambersG 29 96 (2002)2area from a redwood slat and place in 500 mL of test chamberculture medium (see 5.4). Homogenize until no discrete largeparticles can b
28、e seen. Then add 100 mL of this inoculum toeach test chamber containing either a test specimen or anuntreated control, and fill the jar with the culture medium.7.3 IncubationStore the inoculated test chambers underlight exposure for 12 h, then under darkness for 12 h,continually repeating this cycle
29、. Every second or third dayremove each test chamber, place in a sink, and reinoculate with100 mL the fully homogenized algae. Introduce the inoculuminto the bottom of each test chamber, allowing the samevolume of old chamber water to flow over the top of thechamber. This is done in order to simulate
30、 the addition of newwater and the continuous reinfection which occurs undernatural conditions. At the end of two weeks, an untreatedplastic film will usually develop a uniform dense coating ofalgal growth.7.4 Termination of TestAt the end of 2 weeks, or when-ever untreated films show dense algal gro
31、wth, remove the filmsfrom the test chambers and place them upon white filter papersurfaces for examination.8. Interpretation of Results8.1 Describe the extent of growth upon each surface asfollows:None 0Traces of growth (less than 10 %) 1Light growth (10 to 30 %) 2Medium growth (30 to 60 %) 3Heavy g
32、rowth (60 % to complete coverage) 49. Precision and Bias9.1 A precision and bias statement cannot be made for thispractice at this time.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this stan
33、dard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and
34、if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, w
35、hich you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).G 29 96 (2002)3
