BS ISO 14388-3-2014 Soil quality Acid-base accounting procedure for acid sulfate soils Suspension peroxide oxidation combined acidity and sulfur (SPOCAS) methodology《土质 酸式硫酸盐土壤的酸碱会.pdf

1、BSI Standards PublicationBS ISO 14388-3:2014Soil quality Acid-baseaccounting procedure for acidsulfate soilsPart 3: Suspension peroxide oxidationcombined acidity and sulfur (SPOCAS)methodologyBS ISO 14388-3:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 1

2、4388-3:2014.The UK participation 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 ar

3、e responsible for its correctapplication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 78162 9ICS 13.080.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theSta

4、ndards Policy and Strategy Committee on 30 September 2014.Amendments issued since publicationDate Text affectedBS ISO 14388-3:2014 ISO 2014Soil quality Acid-base accounting procedure for acid sulfate soils Part 3: Suspension peroxide oxidation combined acidity and sulfur (SPOCAS) methodologyQualit d

5、u sol Mthode de comptage acide-base pour les sols sulfats acides Partie 3: Mthode par oxydation au peroxyde en suspension combine lacidit et aux sulfures (SPOCAS)INTERNATIONAL STANDARDISO14388-3First edition2014-08-01Reference numberISO 14388-3:2014(E)BS ISO 14388-3:2014ISO 14388-3:2014(E)ii ISO 201

6、4 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part 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, wit

7、hout prior written permission. Permission can be requested from either ISO at the address below or ISOs member body 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 Switz

8、erlandBS ISO 14388-3:2014ISO 14388-3:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 24 Principle 24.1 Actual acidity and retained acidity 24.2 Titratable peroxide acidity, excess acid neutralizing capacity an

9、d potential sulfidic acidity 25 Reagents 26 Apparatus . 57 Procedure for determination of pHKCland TAA . 67.1 Preparation of the suspension . 67.2 Measurement of pHKCl.67.3 Measurement of TAA 78 Calculation of TAA . 89 Procedure for determination of sulfur (SKCl), calcium (CaKCl) and magnesium (MgKC

10、l) extractable with 1 mol/l potassium chloride . 810 Calculation of SKCl, CaKCland MgKCl. 911 Procedure for determination of peroxide pH (pHOX), titratable peroxide acidity (TPA) and excess acid neutralizing capacity (ANCE) 911.1 Peroxide digestion of sample 911.2 Measurement of pHOX.1011.3 Carbonat

11、e modification (HCl titration to pH 4) .1111.4 Decomposition of excess peroxide 1111.5 Measurement of titratable peroxide acidity (TPA) .1212 Calculation of TPA and ANCE.1312.1 Notation . 1312.2 TPA without carbonate modification 1312.3 ANCE(or TPA) with carbonate modification 1413 Procedure for det

12、ermining peroxide sulfur (SP), calcium (CaP) and magnesium (MgP) .1414 Calculation of peroxide sulfur (SP), calcium (CaP) and magnesium (MgP) .1515 Procedure for determining acid extractable sulfur in soil residue after peroxide oxidation (SRAS) 1515.1 General 1515.2 Rinsing of peroxide digested soi

13、l residue, extraction with 4 mol/l hydrochloric acid and determination of extractable sulfur . 1616 Calculation of SRAS1616.1 Calculation of acidity attributed to SRAS(acid-base accounting) .1617 Calculation of TSA .1718 Calculation of SPOS, CaAand MgA.1719 Precision 1720 Test report 18Bibliography

14、.20BS ISO 14388-3:2014ISO 14388-3:2014(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 bo

15、dy interested in a subject for which 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 Electrot

16、echnical Commission (IEC) on all matters 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 IS

17、O documents should be noted. This 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 res

18、ponsible for identifying any or all 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 give

19、n for the convenience of users and 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

20、 URL: Foreword - Supplementary informationThe 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 sulf

21、ate soils: Part 1: Introduction and 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) methodologyiv ISO 2014 All rights reservedBS ISO 14388-3:2014ISO 14388

22、-3:2014(E)IntroductionThe SPOCAS suite uses the suspension peroxide oxidation combined acidity and sulfur (SPOCAS) method as the basis for determining an acid-base account for acid sulfate soils. Like the chromium suite, a decision-tree type process is followed (Figure 1). Various components of soil

23、 acidity and/or alkalinity are determined, depending on pH. Once the decision-tree process is completed, the various components can be used to calculate an acid-base account.The results required to complete the acid-base accounting vary with the soils existing acidity, as represented by pHKCl. Table

24、 A.2 in ISO 14388-1:1)shows the analyses required for the SPOCAS suite. This table uses results reported in acidity units. Alternatively, results in equivalent sulfur units may be utilized.1) To be published. ISO 2014 All rights reserved vBS ISO 14388-3:2014ISO 14388-3:2014(E)Keya Acidity titration

25、c Cation/acid neutralising e Alternatively, SNASmay be substituted for SRASb Sulfur determination d Calculated parameterFigure 1 Flow diagram of SPOCAS suitevi ISO 2014 All rights reservedBS ISO 14388-3:2014INTERNATIONAL STANDARD ISO 14388-3:2014(E)Soil quality Acid-base accounting procedure for aci

26、d sulfate soils Part 3: Suspension peroxide oxidation combined acidity and sulfur (SPOCAS) methodologyWARNING Persons using this International Standard should be familiar with usual laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its

27、 use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.1 ScopeThis part of ISO 14388 specifies a suite of methods used to determine net acidity in acid sulfate soils. This part of ISO 14388 spec

28、ifies a method for the determination of pH in a 1 mol/l potassium chloride soil suspension (pHKCl) and where required, titratable actual acidity (TAA). Following this, potassium chloride extractable sulfur (SKCl), calcium (CaKCl) and magnesium (MgKCl) are determined. On a separate test portion, foll

29、owing digestion with 30 % hydrogen peroxide, peroxide pH (pHOX), titratable peroxide acidity (TPA) and excess acid neutralizing capacity (ANCE) are determined. Following this, peroxide sulfur (SP), calcium (CaP) and magnesium (MgP) are determined. On samples where jarosite is present, or where pHKCl

30、is 6,5 a HCl titration to pH 4 is performed, followed by an additional peroxide digest step. This allows the calculation of excess acid neutralizing capacity (ANCE), i. e. the available ANC in excess of that needed to neutralize the potential acidity from the presence of sulfides or other acid gener

31、ating species in the soil.After appropriate dilution of the soil suspension, peroxide sulfur (SP), calcium (CaP) and magnesium (MgP) are measured by suitable analytical technique(s). These analytes allow the calculation of various other soil parameters. Acid neutralizing capacity can also be calcula

32、ted from reacted calcium (CaA) and magnesium (MgA) results (i. e. the difference in soluble calcium and magnesium before and after peroxide oxidation).Potential sulfidic acidity, (the acidity latent in reduced inorganic iron sulfide compounds), can be determined as peroxide oxidizable sulfur (SPOS)

33、(the calculated difference between peroxide sulfur (SP) peroxide and KCl-extractable sulfur (SKCl).5 ReagentsAll 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 should be verified by perfo

34、rming 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).2) To be published.2 ISO 2014 All rights reservedBS ISO 14388-3:2014ISO 14388-3:2014(E)5.1 Calibration so

35、lutions for the pH meter5.1.1 GeneralFor pH determinations, buffer solutions as specified in 5.1.2 and 5.1.3 are sufficient for calibrating the pH meter. It is the responsibility of the analytical laboratory to verify the accuracy of the buffer solutions.NOTE Commercially available buffer solutions

36、covering a comparable pH range may be used.5.1.2 Buffer solution, pH 4,00 at 20 CDissolve 10,21 g 0,01 g of potassium hydrogen phthalate (C8H5KO4) in water and dilute to 1 000 ml.5.1.3 Buffer solution, pH 6,88 at 20 CDissolve 3,40 g 0,005 g of potassium dihydrogen phosphate (KH2PO4) and 3,55 g 0,005

37、 g of disodium hydrogen phosphate (Na2HPO4) in water and dilute to 1 000 ml.5.1.4 Buffer solution, pH 9,22 at 20 C (see Clause 4 in ISO 14254:2001)Dissolve 3,81 g 0,005 g of disodium tetraborate decahydrate (Na2B4O7 10 H2O) in water and dilute to 1 000 ml.NOTE The buffer solutions as specified in 5.

38、1.2, 5.1.3 and 5.1.4 are stable for one month when stored in polyethylene bottles.5.2 Copper chloride solution, 400 mg Cu/l as CuCl2 2 H2ODissolve 1,073 g of copper (II) chloride dihydrate (CuCl2 2 H2O) in water and dilute to 1 000 ml at 20 C.5.3 Hydrochloric acid (HCl), 1,16 g/ml5.4 Hydrochloric ac

39、id solution, 0,5 mol/lAdd 50 ml of concentrated hydrochloric acid (5.3) with stirring to approximately 700 ml of water. Cool to room temperature, transfer to a 1 l volumetric flask and fill to the mark with water. Standardize against disodium tetraborate decahydrate (Na2B4O7 10 H2O) and calculate mo

40、larity of hydrochloric acid solution (C3).Solutions made by diluting commercially available ampoules may also be used.5.5 Hydrochloric acid solution, 4 mol/lAdd 400 ml of hydrochloric acid (5.3) with stirring to approximately 400 ml of water. Cool to room temperature, transfer to a 1 l volumetric fl

41、ask and fill to the mark with water.5.6 Hydrogen peroxide (H2O2), 30 % (w/w) (bulk peroxide for digestion)WARNING HYDROGEN PEROXIDE IS A CORROSIVE OXIDIZING AGENT. CONTACT WITH COMBUSTIBLE MATERIAL MAY CAUSE FIRE. AVOID CONTACT WITH SKIN AND EYES.5.6.1 Checking acidity of hydrogen peroxideHydrogen p

42、eroxide solutions (5.6) can contain appreciable acidity, especially if the pH is less than 3,5. If the pH is less than 3,5 then the acidity of the peroxide should be quantified to ascertain whether the blank is unacceptably high. Add 20 ml of 30 % hydrogen peroxide (5.6) to 30 ml of water and note t

43、he pH. Follow the same procedure as for a sample digest, including the decomposition of peroxide with copper chloride solution and addition of potassium chloride. Measure the pH and titrate to pH 6,5 (if ISO 2014 All rights reserved 3BS ISO 14388-3:2014ISO 14388-3:2014(E)required) and calculate the

44、acidity of the blank. If the titration for the blanks yields a result in excess of the equivalent of 6 mmol H+/kg, then either switch to another batch of hydrogen peroxide with lower acidity, or alternatively partially neutralize the 30 % peroxide to a pH of approximately 5,0 with sodium hydroxide s

45、olution (5.10.2). In either case, repeat the blank determination to ensure acceptably low acidity.5.6.2 Checking sulfur content of hydrogen peroxideAs sulfur is commonly measured in solutions following TPA determination, the sulfur content of the peroxide should be determined. Acceptable sulfur valu

46、es are below 0,000 5 % S.NOTE Technical grade peroxides are not recommended as they are usually acid stabilized and vary considerably between bottles in both sulfur content and pH.5.7 Hydrogen peroxide H2O2, 30 % (w/w) (pH adjusted)NOTE 1 This reagent is used to oxidize ferrous ions in the final tit

47、ration. This reagent is not for the digestion of samples (for which see 5.6).Where pH of bulk peroxide (5.6) is less than 5,5, adjust pH to 5,5 0,1 by adding 0,05 mol/l sodium hydroxide (5.10.2) drop-wise with stirring, ensuring that this pH value remains stable thereafter.NOTE 2 Refer to Warning in

48、 5.6.5.8 Potassium chloride solution, 1 mol/lDissolve 74,55 g of potassium chloride in water, transfer to a 1 000 ml volumetric flask and fill to the mark with water.5.9 Potassium chloride solution, 2,66 mol/lDissolve 198,80 g of potassium chloride in water, transfer to a 1 000 ml volumetric flask a

49、nd fill to the mark with water.5.10 Sodium hydroxide (NaOH) solutions5.10.1 0,25 mol/l sodium hydroxide solutionDissolve 10,1 g 0,1 g of sodium hydroxide in water, transfer quantitatively to a 1 000 ml volumetric flask and fill to the mark with water. Standardize against potassium hydrogen phthalate previously dried for 4 h at 105 C and stored in a desiccator. Calculate the molarity of the sodium hydroxide solution (C1).Solutions made by diluting commercially available ampoules may also be used.5.10.2