1、BRITISH STANDARD BS 7755-3.11: 1995 ISO 11048: 1995 Soil quality Part 3: Chemical methods Section 3.11 Determination of water-soluble and acid-soluble sulfate ICS 13.080BS7755-3.11:1995 This British Standard, having been prepared under the directionof the Health and Environment Sector Board, waspubl
2、ished under the authorityof the Standards Boardand comes into effect on 15 December 1995 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference EH/4/3 Draft for comment 93/502653 ISBN 0 580 24877 1 Committees responsible for this British Standard The prepar
3、ation of this British Standard was entrusted by Technical Committee EH/4, Soil quality, to Subcommittee EH/4/3, Chemical methods, upon which the following bodies were represented: Association of Consulting Scientists Association of Public Analysts British Ceramic Research Ltd. British Gas plc Britis
4、h Society of Soil Science Department of the Environment (Drinking Water Inspectorate) Department of Trade and Industry (Laboratory of the Government Chemist) National Rivers Authority Royal Society of Chemistry Society of Chemical Industry Soil Survey and Land Research Centre Water Research Centre W
5、ater Services Association of England and Wales Amendments issued since publication Amd. No. Date CommentsBS7755-3.11:1995 BSI 06-1999 i Contents Page Committees responsible Inside front cover National foreword iii Section 1. General 1.1 Scope 1 1.2 Normative references 1 1.3 Principle 1 1.4 Applicab
6、ility and limitations 2 Section 2. Pretreatment of samples and determination of dry matter contents 2.1 Scope 3 2.2 Determination of dry matter content 3 2.3 Preparation of soil samples for extraction with water in the mass : volume ratio 1 soil : 5 water, or for extraction with dilute acid 3 2.4 Pr
7、eparation of soil samples for extraction with water in the mass : volume ratio of 1 soil : 2 water 3 Section 3. Extraction of soil with water at a mass : volume ratio of 1 soil : 5 water 3.1 Principle 5 3.2 Preparation of 1 : 5 water extract 5 3.3 Determination of dry matter content 5 Section 4. Ext
8、raction of soil with water at a mass : volume ratio of 1 soil : 2 : water 4.1 Principle 6 4.2 Preparation of 1 : 2 water extract 6 4.3 Determination of dry matter content 6 Section 5. Extraction of soil with dilute hydrochloric acid 5.1 Principle 7 5.2 Preparation of acid extract 7 5.3 Determination
9、 of dry matter content 8 Section 6. Determination of sulfate in solution by a gravimetric method using barium chloride 6.1 Scope 9 6.2 Principle 9 6.3 Reagents 9 6.4 Apparatus 10 6.5 Sampling and sample preparation 10 6.6 Procedure 10 6.7 Expression of results 11 6.8 Interferences 12 6.9 Special cas
10、es 13 6.10 Notes on procedure 13 Section 7. Precision of method and test report 7.1 Repeatability and reproducibility 14 7.2 Test report 14 Annex A (informative) Results of an interlaboratory trial 15 Table 1 Conversion factors 11 Table 2 Repeatability and reproducibility standard deviations 12 Tabl
11、e 3 Tolerances to other ions 13BS7755-3.11:1995 ii BSI 06-1999 Page Table A.1 Characteristics of the soils used for the interlaboratory trial for the determination of sulfate 15 Table A.2 Results of the interlaboratory trial for the determination of sulfate in the test solution 15 Table A.3 Results
12、of the interlaboratory trial for the determination of acid-soluble sulfate in test soils 16 Table A.4 Results of the interlaboratory trial for the determination of sulfate soluble in a 1 soil : 5 water extract 16 Table A.5 Results of the interlaboratory trial for the determination of sulfate soluble
13、 in a 1 soil : 2 water extract 16 List of references Inside back coverBS7755-3.11:1995 BSI 06-1999 iii National foreword This Section of BS 7755 has been prepared by Subcommittee EH/4/3 and is identical with ISO11048:1995 Soil quality Determination of water-soluble and acid-soluble sulfate, publishe
14、d by the International Organization for Standardization (ISO). ISO 11048 was prepared by Subcommittee 3, Chemical methods, of Technical Committee ISO/TC190, Soil quality, with the active participation and approval of the UK. BS 7755 is being published in a series of Parts subdivided into Sections an
15、d Subsections that will generally correspond to particular international standards. Other Parts of BS7755 are, or will be, as follows. Part 1: Terminology and classification; Part 2: Sampling; Part 3: Chemical methods; Part 4: Biological methods; Part 5: Physical methods. A British Standard does not
16、 purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International standard Corresponding British Standa
17、rd ISO 3696:1987 BS 3978:1987 Specification for water for laboratory use (Identical) ISO 9280:1990 BS 6068 Water quality Part 2 Physical, chemical and biochemical methods Section 2.39:1991 Method for the determination of Sulfate using barium chloride and gravimetry (Identical) BS 7755 Soil quality P
18、art 3 Chemical methods ISO 11464:1994 Section 3.5:1995 Pretreatment of samples for physico-chemical analyses (Identical) ISO 11465:1993 Section 3.1:1994 Determination of dry matter and water content on a mass basis by a gravimetric method (Identical) Summary of pages This document comprises a front
19、cover, an inside front cover, pages i to iv, pages1 to 16, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankISO 11048:1995(E) BSI 06-199
20、9 1 Section 1. General 1.1 Scope This International Standard specifies procedures for the preparation of water and acid extracts of air-dried soils and soil-like materials. The sulfate content of these extracts is determined by a gravimetric method in which barium chloride is added to the water or a
21、cid extract and the precipitate of barium sulfate is dried and weighed. The sulfate content is then calculated from the mass of the material used in the analysis and the mass of barium sulfate precipitated. This International Standard is applicable to all types of air-dried soils, for example pretre
22、ated according to ISO11464. This International Standard consists of seven sections: Section 1: General; Section 2: Pretreatment of samples and determination of dry matter contents; Section 3: Extraction of soil with water at a mass : volume ratio of 1 soil : 5 water; Section 4: Extraction of soil wi
23、th water at a mass : volume ratio of 1 soil : 2 water; Section 5: Extraction of soil with dilute hydrochloric acid; Section 6: Determination of sulfate in solution by a gravimetric method using barium chloride; Section 7: Precision of method and test report. 1.2 Normative references The following st
24、andards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged
25、to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 3696:1987, Water for analytical laboratory use Specification and test methods. ISO 9280:1990, Water quality
26、Determination of sulfate Gravimetric method using barium chloride. ISO 11464:1994, Soil quality Pretreatment of samples for physico-chemical analyses. ISO 11465:1993, Soil quality Determination of dry matter and water content on a mass basis Gravimetric method. 1.3 Principle Samples of air-dried soi
27、l are extracted with: dilute hydrochloric acid; or water in a mass : volume ratio of soil : water of1: 2 or 1 : 5. The sulfate content of these extracts is determined by a gravimetric method in which barium chloride is added to the water or acid extract and the precipitate of barium sulfate is dried
28、 and weighed. The sulfate content is then calculated from the mass of soil used in the analysis and the mass of barium sulfate precipitated. Section 6 is similar to ISO9280. It is recognized that other acceptable methods for the determination of sulfate are available but these are not covered by thi
29、s International Standard. Suitable methods may include: direct barium titrimetry, inductively coupled plasma emission spectrometry, flow injection analysis using a turbidimetric method, continuous flow indirect spectrophotometry using 2-aminoperimidine, air-segmented continuous flow colorimetry usin
30、g methylthymol blue, and ion chromatography. Reference should be made to the appropriate international and national standards for information regarding the applicability and limitations of such methods.ISO 11048:1995(E) 2 BSI 06-1999 1.4 Applicability and limitations The procedures in sections3and4a
31、re considered to be relevant to the extraction of sulfate from soils and may be relevant to the assessment of the “availability” of sulfate to plants (a variety of extractants have been used for this purpose and none were shown to be generally applicable to all soil types and climates). It should be
32、 noted that there is no verified relation between water-extractable sulfate and the need for sulfur fertilization. The procedure in section4is also relevant to the potential for the attack of sulfates on building materials, especially concrete. The use of the procedures described in sections4,5and6s
33、hould enable a distinction to be made between the presence of sulfates that are highly soluble in water and those of limited solubility such as gypsum(CaSO 4 2H 2 O). Section6is applicable to concentrations of sulfate ion in solution of10mg/l and above, i.e. in relation to the methods in sections3 a
34、nd4to minimum water-soluble concentrations in air-dried soil of about50mg/kg and20mg/kg 0,005% (m/m) and0,002% (m/m) respectively and, in relation to the method in section5, to a minimum acid-soluble concentration in air-dried soil of about500mg/kg 0,05% (m/m). If concentrations in solution are lowe
35、r than this, a concentration step will be required, or a more sensitive analytical procedure than that described in section6should be used e.g. ion chromatography, inductively coupled plasma (ICP) spectrometry or atomic emission spectrometry (AES). In most instances, complete characterization of a s
36、oil, in terms of the concentrations and nature of sulfates present, will require that determinations are made following the procedure in section5and in either section3or section4or both, whichever is the more appropriate for the purpose of investigation of the soil. The methods described should be s
37、uitable for a range of “soils” including agricultural soils and materials from polluted sites. However, no method can be expected to be universally applicable, and users must recognize this fact and be prepared to deal with the analytical difficulties that may sometimes be encountered. Soils contain
38、ing sulfides may require special attention (see note7to5.1). “Soils” from some polluted sites, for example former gasworks sites and colliery spoil tips, may contain a variety of sulfur species (e.g. elemental sulfur, sulfate, sulfite, thiosulfate, thiocyanate) that may be transformed from one to an
39、other under changing chemical conditions and/or microbial action. The presence of other ions may affect solubilities. Thus, in these circumstances, particular care may be required in sample handling and preparation, and in the interpretation of the results. The limitations of the method in section6,
40、 in terms of acceptable concentrations of other ions, are defined. The tests described are strictly empirical and thus cannot be considered to measure the true sulfate content in soil, although reproducibility should be good. Because of the limited solubility of some sulfates (e.g. calcium sulfate)
41、and possible interferences from other ions, a single extraction following the procedure described in section3may not give a true measure of the “total water extractable” sulfate. This potential problem can be tackled either by repeating the extraction one or more times on the same sample, or by subs
42、tantially increasing the water : soil ratio. Another option is to use a “buffered” extraction solution which will enhance the solubility of the sulfates present, but such procedures are beyond the scope of this International Standard. If calcium is the only cation present, sulfate ion in solution wi
43、ll not exceed1 441mg at20 C. This means that the maximum amount of sulfate that can be extracted from such a soil by the procedure in section3 is about7 205mg (10g soil : 50ml water) and by the procedure in section4is about2882mg (50g soil : 100 ml water). (SO 2 4 ) SO 2 4 /l SO 2 4 /kg SO 2 4 /kgIS
44、O 11048:1995(E) BSI 06-1999 3 Section 2. Pretreatment of samples and determination of dry matter contents 2.1 Scope In this section, procedures are described for the preparation of air-dried test samples for use in the extraction procedures described in sections3to5 of this International Standard. 2
45、.2 Determination of dry matter content Determine the dry matter content of the field-moist and air-dried materials in accordance with ISO11465, but at a temperature not exceeding75 C to 80 C (there is a danger if gypsum is present that water of crystallization will be lost at higher temperatures). 2
46、.3 Preparation of soil samples for extraction with water in the mass : volume ratio 1 soil : 5 water, or for extraction with dilute acid 2.3.1 Apparatus The following items of apparatus, additional to those specified in ISO11465, allow the preparation of a single test sample. 2.3.1.1 Desiccator, con
47、taining anhydrous silica gel. 2.3.1.2 Glass container, capable of holding approximately10g of soil and fitted with a ground glass stopper. 2.3.2 Preparation of test sample Prepare each test sample for analysis from the laboratory sample as follows. Dry and prepare a laboratory sample passing a2mm si
48、eve of sufficient size, for all the tests to be performed following the procedures described in ISO11464. Divide the material passing the2mm sieve by successive riffling or another approved means (seeISO11464) to produce a sample weighing approximately100g. Mill this fraction to pass a2504m sieve. S
49、ubdivide the sample by successive riffling to obtain a test sample weighing approximately10g (additional test samples can be taken at this stage if required). Place the test sample in a suitable glass container (2.3.1.2) and dry at a temperature of not more than40 C. The test sample shall be deemed to be dry when the differences in successive weighings at intervals of4h do not exceed0,1% (m/m) of the test sample. Allow the test sample(s) to cool in a desiccator (2.3.1.1). NOTE 1It is assumed that any ma
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