1、BSI Standards PublicationBS ISO 14388-2:2014Soil quality - Acid-baseaccounting procedure for acidsulfate soilsPart 2: Chromium reducible sulfur (CRS)methodologyBS ISO 14388-2:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 14388-2:2014.The UK participation
2、 in its preparation was entrusted to TechnicalCommittee EH/4, Soil quality.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapp
3、lication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 78161 2ICS 13.080.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Commi
4、ttee on 30 September 2014.Amendments issued since publicationDate Text affectedBS ISO 14388-2:2014 ISO 2014Soil quality - Acid-base accounting procedure for acid sulfate soils Part 2: Chromium reducible sulfur (CRS) methodologyQualit de leau Mthode de comptage acide-base pour les sols sulfats acides
5、 Partie 2: Mthode de sulfato rduction au chromeINTERNATIONAL STANDARDISO14388-2First edition2014-08-01Reference numberISO 14388-2:2014(E)BS ISO 14388-2:2014ISO 14388-2:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part
6、of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body
7、 in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 14388-2:2014ISO 14388-2:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v
8、1 Scope . 12 Normative references 13 Terms and definitions . 24 Principle 24.1 Potential sulfidic acidity 24.2 Actual acidity and retained acidity 24.3 Acid neutralizing capacity . 25 Reagents for analysis of chromium reducible sulfur 26 Apparatus . 47 Procedure for determining chromium reducible su
9、lfur . 58 Calculation of SCR. 79 Reagents for determination of pHKCland TAA . 810 Procedure for determination of pHKCland TAA . 910.1 Preparation of the suspension . 910.2 Measurement of pHKCl.910.3 Measurement of TAA . 1011 Calculation of TAA 1112 Procedure for determination of sulfur (SKCl), calci
10、um (CaKCl), and magnesium (MgKCl) extractable with 1 mol/l potassium chloride 1113 Calculation of SKCl, CaKCl, and MgKCl.1214 Reagents for determination of sulfur (SHCl), calcium (CaHCl), and magnesium (MgHCl) extractable with hydrochloric acid .1215 Procedure for determination of sulfur (SHCl), cal
11、cium (CaHCl), and magnesium (MgHCl) extractable with hydrochloric acid .1216 Calculation of net acid-soluble sulfur (SNAS), calcium (CaNAS), and magnesium (MgNAS) .1317 Reagents for determining acid neutralizing capacity by back-titration (ANCBT) 1318 Procedure for determining acid neutralizing capa
12、city by back-titration (ANCBT) 1418.1 Hotplate digestion with hydrochloric acid solution 1418.2 Titration of unreacted acid in digested soil suspension .1419 Alternatives for determination of acid neutralizing capacity 1520 Precision 1521 Test report 16Bibliography .18BS ISO 14388-2:2014ISO 14388-2:
13、2014(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for whi
14、ch a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all m
15、atters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This
16、document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or al
17、l such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and
18、 does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary inf
19、ormationThe committee responsible for this document is ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil characteristics.ISO 14388 consists of the following parts, under the general title Soil quality Acid-base accounting procedure for acid sulfate soils: Part 1: Introduction an
20、d definitions, symbols and acronyms, sampling and sample preparation Part 2: Chromium reducible sulfur (CRS) methodology Part 3: Suspension peroxide oxidation combined acidity and sulfur (SPOCAS) suite analysisiv ISO 2014 All rights reservedBS ISO 14388-2:2014ISO 14388-2:2014(E)IntroductionThe objec
21、tive of this part of ISO 14388 is to determine the net acidity (or alkalinity) of acid sulfate soils by providing a streamlined approach for determination of the various components of soil acidity and/or alkalinity, depending on pH. The chromium suite combines the measurement of chromium reducible s
22、ulfur (SCR) with various measures of existing acidity and acid neutralizing capacity (ANC) using a decision-tree based on the value of pHKCl(Figure 1) as the basis for determining an acid-base account for acid sulfate soils.The results required to determine net acidity vary with the soils actual aci
23、dity, as represented by pHKCl. Table A.1 of ISO 14388-1 shows the analyses required for the Chromium suite. This table uses results reported in acidity units. Alternatively, results in sulfur units can be utilized.Keya acidity titrationb sulfur determinationc acid neutralising determinationd calcula
24、ted parameterFigure 1 Chromium suite flow diagram ISO 2014 All rights reserved vBS ISO 14388-2:2014BS ISO 14388-2:2014Soil quality - Acid-base accounting procedure for acid sulfate soils Part 2: Chromium reducible sulfur (CRS) methodologyWARNING Persons using this part of ISO 14388 should be familia
25、r with usual laboratory practice. This part of ISO 14388 does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions
26、.1 ScopeThis part of ISO 14388 specifies a suite of methods used to determine the net acidity in acid sulfate soils. This part of ISO 14388 specifies a method for measuring chromium reducible sulfur (SCR) by iodimetric titration of distilled hydrogen sulfide trapped as zinc sulfide, following acidic
27、 chromous chloride digestion. This method determines inorganic sulfides (e.g. pyrite, marcasite, greigite, mackinawite) and elemental sulfur in acid sulfate soil without interferences from organic sulfur and oxidized forms of sulfur such as sulfate.On a separate test portion of soil, the pH in a 1 m
28、ol/l KCl soil suspension (pHKCl) is determined. When pHKClis 6,5, and hence where there is a chance of acid neutralizing capacity (ANC) being present, ANC can be estimated by various methods such as inorganic carbon analysis (e. g. CINby combustion furnace according to ISO 10694), and ANC by back ti
29、tration (ANCBT). In this manner, a full acid-base account can be made of the soil.5 Reagents for analysis of chromium reducible sulfurAll reagents shall be of analytical grade. Deionised or glass distilled water of grade 2 as defined in ISO 3696 shall be used throughout.The purity of all reagents sh
30、ould be verified by performing a blank test for the presence of sulfur, calcium, and magnesium. Reagents should also be tested for the presence of these elements whenever a change in source is made (e. g. brand or batch).Commercially available ampoules of standardized solutions can also be used wher
31、e available.2 ISO 2014 All rights reservedBS ISO 14388-2:2014ISO 14388-2:2014(E)5.1 Chromium powder.NOTE Different sources or batches of chromium powder can yield different blank values.CAUTION CHROMIUM DUST CAN BE TOXIC IF INHALED AND CAN REPRESENT A COMBUSTION RISK. AVOID THE USE OF VERY FINE CHRO
32、MIUM POWDER.5.2 Ethanol (C2H5OH), 95 % solution.5.3 Hydrochloric acid (HCl), 1,16 g/ml.5.4 Hydrochloric acid solution, 6 mol/l.Dilute concentrated hydrochloric acid (5.3) with water.5.5 Iodine solution, 0,012 5 mol/l.Dissolve 22,5 g 0,1 g of potassium iodide in water and add 3,2 g 0,01 g of iodine.
33、After the iodine has dissolved, dilute to 1 l with water. Standardize iodine solution against the standardised 0,025 mol/l sodium thiosulfate solution (5.8) using the starch solution (5.9) as an indicator. Calculate the molarity (C) of the iodine solution, in moles per litre, according to Formula (1
34、):CFDE12=(1)whereD is the titration volume of standard sodium thiosulfate solution, in millilitres (ml);E is the volume of iodine solution titrated, in millilitres (ml);F is the molarity of sodium thiosulfate solution used, in mole per litre (mol/l);The iodine solution should be standardised on a da
35、ily basis, or immediately prior to use.5.6 Nitrogen gas, high purity grade.5.7 Sodium hydroxide solution (NaOH), 6 mol/l.CAUTION Solid sodium hydroxide is caustic and hygroscopic, and should be stored away from water.Dissolve 240 g 1 g of solid sodium hydroxide in water, then transfer quantitatively
36、 to a 1-l volumetric flask. Cool to room temperature and fill to the mark with water.5.8 Sodium thiosulfate solution, 0,025 0 mol/l (standardized).Accurately weigh 6,205 g 0,001 g of Na2S2O3 5 H2O and dissolve in water. Transfer quantitatively to a 1-l volumetric flask. Add 1,5 ml 0,01 ml of 6 mol/l
37、 sodium hydroxide solution (5.7) and fill to the mark with water. Standardize against potassium iodate or potassium dichromate solutions.NOTE Commercially available ampoules of standardized sodium thiosulfate solution can also be used.5.9 Starch indicator solution.Dissolve 2,0 g 0,1 g of arrowroot s
38、tarch and 0,20 g 0,01 g of salicylic acid in 100 ml of hot water. Allow to cool to room temperature before use. ISO 2014 All rights reserved 3BS ISO 14388-2:2014ISO 14388-2:2014(E)5.10 Zinc acetate/2,8 % ammonia solution (trapping solution).Dissolve 30 g 0,5 g of zinc acetate dihydrate in 750 ml wat
39、er. Add 100 ml of 28 % ammonia solution. Transfer to 1-l volumetric flask and fill to the mark with water.6 ApparatusGrade A volumetric glassware shall be used throughout. Volumetric flasks shall comply with ISO 1042 and pipettes shall comply with ISO 648 and ISO 835-1, ISO 835-2 and ISO 835-3. The
40、use of volumetric glassware shall conform to ISO 8655-1, ISO 8655-2, and ISO 8655-3.6.1 Automatic titration instrument or pH meter, with slope adjustment and temperature control capable of measuring to an accuracy of 0,01 pH units.6.2 Beaker or other container, with capacity of at least 450 ml, made
41、 of polyethylene, glass, or similar inert material.6.3 Burette, A-grade, 10 ml capacity, graduated at 0,02 ml intervals, complying with Class A according to ISO 385-1, or a similarly accurate digital burette or a suitably calibrated burette from an automatic titration instrument can be used.6.4 Cent
42、rifuge, capable of centrifuging 80 ml and 400 ml of suspension.6.5 Dispenser 1 (manual or automatic), capable of accurately dispensing 50 ml and 80 ml 0,5 ml.6.6 Double-necked digestion flask, of 250 ml capacity made of borosilicate glass, with ground-glass or quick-fit joints capable of forming a g
43、as-tight seal. Use round-bottomed flask if employing a heating mantle, or flat-bottomed for hotplates.6.7 Balance 1, capable of weighing to an accuracy of 0,01 g.6.8 Balance 2, capable of weighing to an accuracy of 0,001 g.6.9 Balance 3, capable of weighing to an accuracy of 0,000 1 g.6.10 Erlenmeye
44、r flask, of 100 ml capacity made of borosilicate glass.6.11 Filter paper, thick, medium speed, high retention.6.12 Funnel, made of glass or plastic for supporting filter paper.6.13 Glass beaker borosilicate (digestion beaker), a tall form and 250 ml capacity recommended.6.14 Heating mantle or electr
45、ic hotplate, with adjustable temperature control, capable of maintaining gentle boiling of the digestion solution.6.15 pH electrodes, glass electrode and a reference electrode, or a combination pH electrode of equivalent performance.NOTE In soil suspensions, the danger of deterioration of performanc
46、e caused by breakage or contamination of the electrodes is increased.6.16 Pasteur pipette, glass.4 ISO 2014 All rights reservedBS ISO 14388-2:2014ISO 14388-2:2014(E)6.17 Pipettes, 25 ml pipettes or piston operated volumetric apparatus (POVA) can be used.6.18 Pressure equalizing funnel, of 100 ml cap
47、acity made of borosilicate glass with ground-glass or quick-fit joints capable of forming a gas-tight seal.6.19 Reflux condenser, straight-through type with conical ground-glass joints.6.20 Sample bottle, of 100 ml to 250 ml capacity to allow efficient mixing and also to minimize the head space, mad
48、e of polyethylene or other inert material, with a tightly fitting cap or stopper to prevent leakage.Sample bottle and stopper should be made of material not containing sulfur.6.21 Shaking or mixing machine, capable of keeping soil particles continuously in suspension.NOTE For example, end-over-end s
49、haker.6.22 Steambath, or electric hotplate, with adjustable temperature control, capable of maintaining the digestion solution between 80 C and 90 C.6.23 Stirrer, overhead propeller, or magnetic type with polytetrafluoroethylene (PTFE) coated stirrer bar or stirring rod capable of stirring 400 ml of suspension.6.24 Thermometer, capable of measuring to the nearest 1 C and complying with Type C according to ISO 1770 is required, connected to an automatic titrator or pH meter.6.25 Titration vessel, capacity
