SIST ISO 19258:2006

SLOVENSKI STANDARD
SIST ISO 19258:2006
01-december-2006
.DNRYRVWWDO±1DYRGLOR]DGRORþDQMHYUHGQRVWLQDUDYQHJDR]DGMD
Soil quality -- Guidance on the determination of background values
Qualité du sol -- Guide pour la détermination des valeurs de bruit de fond
Ta slovenski standard je istoveten z: ISO 19258:2005
ICS:
13.080.99 Drugi standardi v zvezi s Other standards related to
kakovostjo tal soil quality
SIST ISO 19258:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 19258:2006

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SIST ISO 19258:2006

INTERNATIONAL ISO
STANDARD 19258
First edition
2005-12-15


Soil quality — Guidance on the
determination of background values
Qualité du sol — Guide pour la détermination des valeurs de bruit
de fond





Reference number
ISO 19258:2005(E)
©
ISO 2005

---------------------- Page: 3 ----------------------

SIST ISO 19258:2006
ISO 19258:2005(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.


©  ISO 2005
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland

ii © ISO 2005 – All rights reserved

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SIST ISO 19258:2006
ISO 19258:2005(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 General. 3
5 Procedures. 3
5.1 General. 3
5.2 Objectives and technical approaches . 4
5.2.1 General. 4
5.2.2 Substances and parameters. 4
5.2.3 Study area. 6
5.2.4 Time period. 7
5.2.5 Scale of sampling (Support) . 7
5.3 Evaluation of existing data . 7
5.3.1 General. 7
5.3.2 Completeness of data sets/minimum requirements . 8
5.3.3 Comparability of data (Sampling, nomenclatures, analyses) . 8
5.3.4 Elimination of outliers . 9
5.4 Collection of new data. 9
5.4.1 Sampling. 9
5.4.2 Soil analysis. 12
5.5 Data processing and presentation. 13
5.5.1 Statistical evaluation of data . 13
5.5.2 Data presentation and reporting . 14
6 Data handling/quality control . 15
Annex A (informative) Scale of sampling. 17
Annex B (informative) Outlier tests . 19
Bibliography . 23

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SIST ISO 19258:2006
ISO 19258:2005(E)
Foreword
ISO (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 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 Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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 all such patent rights.
ISO 19258 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 7, Soil and site
assessment.

iv © ISO 2005 – All rights reserved

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SIST ISO 19258:2006
INTERNATIONAL STANDARD ISO 19258:2005(E)

Soil quality — Guidance on the determination of background
values
1 Scope
This International Standard provides guidance on the principles and main methods for the determination of
pedo-geochemical background values and background values for inorganic and organic substances in soils.
This International Standard gives guidance on strategies for sampling and data processing and identifies
methods for sampling and analysis.
This International Standard does not give guidance on the determination of background values for
groundwater and sediments.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 10381-1, Soil quality — Sampling — Part 1: Guidance on the design of sampling programmes
ISO 10381-5, Soil quality — Sampling — Part 5: Guidance on the procedure for the investigation of urban and
industrial sites with regard to soil contamination
ISO 11074:2005, Soil quality — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11074 and the following apply.
3.1
background content
content of a substance in a soil resulting from both natural geological and pedological processes and including
diffuse source inputs
3.2
background value
statistical characteristic (3.8) of the background content
3.3
contaminant
substance or agent present in the soil as a result of human activity
NOTE There is no assumption in this definition that harm results from the presence of the contaminant.
© ISO 2005 – All rights reserved 1

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SIST ISO 19258:2006
ISO 19258:2005(E)
3.4
diffuse source input
input of a substance emitted from moving sources, from sources with a large area or from many sources
NOTE 1 The sources can be cars, application of substances through agricultural practices, emissions from town or
region, deposition through flooding of a river.
NOTE 2 Diffuse source input usually leads to sites that are relatively uniformly contaminated. At some sites, the input
conditions may nevertheless cause a higher local input such as near the source or where atmospheric deposition/rain is
increased.
[ISO 11074:2005]
3.5
pedo-geochemical content
content of a substance in a soil resulting from natural geological and pedological processes, excluding any
addition of human origin
NOTE It may be hardly possible to determine the precise pedo-geochemical content of certain substances in a soil
due to anthropogenic diffuse contamination.
3.6
pedo-geochemical background value
statistical characteristic (3.8) of the pedo-geochemical content
NOTE Any estimate of pedo-geochemical background value will be prone to a certain amount of error given the
uncertainty associated with determining the pedo-geochemical content.
3.7
soil
upper layer of the Earth's crust composed of mineral parts, organic substance, water, air and living organisms
[ISO 11074:2005]
3.8
statistical characteristic
numerical value calculated from a variate of a chosen parameter of the population
EXAMPLE Examples of the statistical characteristics are the mean, the median, the standard deviation or the
percentiles of the ordered frequency distribution.
3.9
study area
three-dimensional definition of the area where samples are to be obtained from and thus for which the
background value(s) are to be estimated
3.10
support
size, shape and orientation of a soil sample
NOTE For the purpose of analysing spatial variation in soils geostatistically (by estimation of the variogram of a soil
property), the support should be the same at each sampling site.
3.11
variate
set of observed values of a variable
EXAMPLE A variate could for instance be the series of numbers of the concentration of a substance in soil or
numerous, individual soil samples.
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SIST ISO 19258:2006
ISO 19258:2005(E)
4 General
Soils retain the evidence of their past history including impacts due to natural events or human activities.
Chemical impacts related to human activities can be detected in soils all over the world, even in regions far from
any source of contamination. For this reason, the background contents of inorganic and organic substances in
soils consist of a pedo-geochemical fraction and an anthropogenic fraction. The ratio of these fractions varies
widely depending on the type of substances, the type of soil and land use, and the kind and extent of external
impacts.
For many inorganic substances, the background content of unpolluted soils is dominated by the pedo-
geochemical content and consequently by the mineralogical composition of the soils parent material. Pedogenetic
processes may lead to a redistribution (enrichment/impoverishment) and consequently to a horizon-specific
differentiation of the substances within a soil profile. Persistent organic substances in soils originate more often
from non-natural sources and therefore the background content of soils is governed by the kind and extent of
diffuse contamination from non-soil sources.
In practice, it is often difficult to distinguish clearly between the pedo-geochemical and the anthropogenic fraction
of the background content of soils. Nonetheless, a detailed knowledge of the background content as well as of its
natural fraction for the substances of concern is essential both for any evaluation of the current status of soils for
environmental or land use related aspects or just for scientific purposes within the scope of pedology or
geochemistry. To this end, so-called background values in terms of the statistical characteristics of both, the pedo-
geochemical and the anthropogenic fraction have to be determined.
A variety of different objectives can be identified for the determination of background values of inorganic and/or
organic substances in soils. The objectives themselves provide insufficient information to define the technical
programme that will produce the desired background values. Thus a number of technical approaches have to be
defined which together form the basis of the technical programme.
This guidance provides essential aspects of sampling strategies and procedures, minimum requirements
regarding the necessary steps and ways of sample pre-treatment, analytical methods and statistical
evaluation procedures for determining sound and comparable background values.
Guidance is given for
a) evaluating existing data from different data sources and
b) setting up complete investigation programs aiming to compile background values for a clearly defined
three-dimensional picture of the soil.
These situations are representing the two extreme starting positions for the process of compiling background
values. In practice, a third intermediate situation may be dealt with when additional data need to be collected
because the quantity or quality of the existing data is insufficient.
5 Procedures
5.1 General
The procedures to determine background values encompass aspects of sampling (strategy, procedure), soil
analysis (pre-treatment, extraction and measurement), data processing and presentation. In general, two
starting positions can be distinguished, namely
a) the evaluation of existing data mostly from different data sources, and
b) the collection of new data based on an appropriate investigation strategy.
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SIST ISO 19258:2006
ISO 19258:2005(E)
5.2 Objectives and technical approaches
5.2.1 General
Before commencing any survey on background values in soils it is of crucial importance to define the objective
of the survey and the related technical approach.
The objective is, in general terms, the definition of 'why' background values are to be determined. The
technical approaches describe aspects like the 'where', 'what', 'how' and 'when'. Together the technical
approaches determine the technical programme that will provide the required background values.
NOTE It should be noted that a technical approach that is fit for one objective, will often be unfit for other objectives.
The objectives for defining background values might be:
⎯ to identify the current contents of substances in soils, e.g. in the context of soil-related directives;
⎯ to assess the degree of contamination by human activities;
⎯ to derive reference values for soil protection;
⎯ to define soil values for reuse of soil material and waste;
⎯ to calculate critical levels and tolerable additional critical loads;
⎯ to identify areas/sites with atypically enhanced levels of element contents due to geogenic reasons or
human impact;
⎯ etc.
In order to meet the objective, the technical approaches might include the following.
⎯ Definition of the substances and parameters
⎯ For example, the background values to be estimated may be the total heavy metal content or the
bioavailable heavy metal content. (See 5.2.2)
⎯ Definition of the study area
⎯ The (three-dimensional) definition of the area where samples are to be obtained from. This has to be
a detailed description of what is to be considered as the study area, and what is not. (See 5.2.3.)
⎯ Definition of the time period of interest:
⎯ Are the historical or current contents relevant for the objective? (See 5.2.4.)
⎯ Definition of the size and geometry (support) of the area sampled at a sampling location. (See 5.2.5.)
5.2.2 Substances and parameters
Background values can be determined for all kinds of inorganic and organic substances in soils as well as soil
characteristics. In practice, the more persistent and immobile compounds are of primary interest because of
their potential to adsorb and accumulate in soil, whereas remobilization and intrinsic biodegradation are of
less significance.
As well as the substances of concern, basic soil parameters and site characteristics (see 5.4.1.3) need to be
provided to assist in interpretation of the contents of substances. A number of so-called basic soil parameters
influence soil processes that affect the contents of inorganic and organic substances. Table 1 lists these
parameters which should be analysed according to the given International Standards.
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SIST ISO 19258:2006
ISO 19258:2005(E)
Within the group of inorganic substances, trace elements (e.g. heavy metals, micronutrients) are most often
analysed (Table 2). Concerning the analytical methods, a distinction has to be drawn between different
extraction/preparation methods (Table 2), whereof very few determine the total content which may be needed
for instance for calculating element stocks. Besides total contents, the (eco-) toxicologically more relevant
mobile fractions (Table 2) are of increasing interest, e.g. if pathway-related questions are to be examined.
Analysis of parameters in Table 2 should be carried out according to International Standards given in Table 2.
Table 1 — Basic soil parameters
Parameter Method ISO International Standard
Texture Sieving, sedimentation ISO 11277
Fraction of coarse material Sieving ISO 11277
Amount of non-soil material Sieving/visual control ISO 11259, ISO 11277
Bulk density Direct measurement of undisturbed ISO 11272
soil samples, estimation form soil
water retention curves
pH pH-electrode ISO 10390
Content of organic carbon Dry combustion ISO 14235
Cation exchange capacity, exchangeable cations BASECOMP ISO 11260
BaCl ISO 13536
2

Carbonate content CO-evolution ISO 10693
2
Table 2 — Examples for the analysis of inorganic substances
Parameter Speciation/form Extraction/preparation ISO International Standard
Method
Extraction/preparation Determination
Metalloids, e.g. ISO 14869-1 ISO 14869-1
Alkaline fusion + X-ray
Total
fluorescence HF + HCIO
4

arsenic and selenium ISO 14869-2 ISO 11047
Metals, Pseudo total aqua regia ISO 11466 ISO 11047
barium, cadmium, EDTA
Complexing
chromium, cobalt, DTPA ISO 14870 ISO 11047
copper, iron, lead, NaNO
3
manganese, mercury, NH NO
4 3

Exchangeable
molybdenum, nickel, CaCl
2

thallium, zinc KCl

Cyanides Water soluble H O, leaching tests See NOTE. See NOTE.
2
NOTE There are a variety of extraction and analytical methods for soil-water in the series of International Standards on water
quality which may also be applicable. However, it is important to confirm that they will work with the extracts obtained form particular soil
material.
Surveys on organic substances usually refer to persistent compounds. The persistent organic contaminants
listed in Table 3 are some of the more commonly encountered, but the list is not complete. Analysis should be
carried out according to International Standards listed in Table 3.
Various methods are used for the analysis of organic substances. The aim of these methods is usually to
extract the greatest possible quantity of organic substances from soils. It is important to recognize that organic
compounds may be extracted from naturally occurring organic materials (e.g. organic matter, decaying
vegetation, peat, charcoal), and that non-specific analyses in particular may, therefore, give misleading results.
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SIST ISO 19258:2006
ISO 19258:2005(E)
Table 3 — Examples for the analysis of organic substances
Substance/groups of substances Method ISO International Standard
PAH Soxhlet/HPLC/UV ISO 13877
Thin-layer chromatography ISO 7981-1
RP C-18/HPLC ISO 7981-2
GC/MS ISO 18287
Dioxins/Furane
Chlorophenols Hexane/GC/ECD ISO 8165-1
Chlorpesticides RP C-18/HPLC/UV ISO 11369
PCBs GC-ECD ISO 10382
Chlornaphthalene
Chlorparafin
Bromodiphenylethers
NOTE There are a variety of extraction and analytical methods for water in the series of International Standards on water quality
which may also be applicable. However it is important to confirm that they will work with the extracts obtained from a particular soil
material.
When collecting new data for determining background values, it is recommended that the investigation
program be designed with regard to additional questions that could arise in future. In most cases, carrying out
new sampling campaigns is much more expensive than analysing additional substances in the first place. To
this end, a suitable storage of soil samples for subsequent analyses of organic or inorganic substances is of
crucial importance. Besides the substances of concern (Tables 2 and 3) and additional soil parameters
(Table 1), it is essential to provide a comprehensive site description (see 5.4.1.3) for interpretation purposes.
The documentation of all the actions taken is of utmost importance if the data measured is to be of use for
other assessments in future investigations.
5.2.3 Study area
The definition of the study area (3.9) can be based on two different principles, that is:
⎯ a purely spatial definition (X, Y, Z), defining the contours of the study area by the coordinates within which
the study area lies. Apart from the definition in a horizontal plane, the soil depth that is to be studied
should also be defined;
⎯ a typological definition of the study area, based on one or more characteristic(s), e.g. soil type (for
example, the A-horizon of a specific soil type), land use (also considering the potential effects on the
background values), elevation level, etc.
Of course, it is possible to mix the spatial and typological definition of the study area.
EXAMPLE Examples of a mix of the spatial and typological definition of the study area might be:
— the grassland in a county or province;
— the A-horizon in an area defined by X- and Y-coordinates.
The definition of the study area must be detailed at a level where there cannot be any misinterpretation on
what is and what is not part of the study area. For an unambiguous definition of the study area, all actual point
and diffuse sources within the study area need to be defined. As the general objective is to determine
background values, a safety zone around that (type of) source might be defined and thereby excluding parts
of the more generally defined study area. It might also result in specific zones for which the data is to be
considered separately from the rest of the study area.
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SIST ISO 19258:2006
ISO 19258:2005(E)
The definition of the study area as described is independent of whether the soil samples are still to be taken,
or whether already existing soil samples (or results) are to be used. In the latter situation, the detailed
definition of the study area will define which samples/results are to be included or excluded.
5.2.4 Time period
Background values are influenced both by the natural processes (pedogenesis, biogeochemical cycles) as
well as by diffuse source input. Two different time scales can be distinguished:
⎯ the period in which the background value may significantly vary due to natural processes;
⎯ the period in which the background value will most probably only change due to human influences
(except for large scale natural phenomena).
The second period is generally smaller than the first one.
It might be that a specific historic period is of interest when measuring background values. When a soil layer is
formed during this same period, it is indeed possible to determine background values for a certain time period.
When background values are to be re-determined after a period of time in order to determine if changes occur,
the time period between measurements should be based on (see also ISO 16133):
⎯ the expected enrichment of substances in soils (accumulation for example due to diffuse source input);
⎯ the expected loss of substances in soils (for example, due to leaching, biodegradation or plant uptake);
⎯ changes in concentration level that can be determined both analytically and statistically.
5.2.5 Scale of sampling (Support)
Variability in concentrations is by definition a scale-related characteristic. Depending on the volume for which
an analytical result is to be considered representative, the variability in concentrations encountered might be
different. The scale — or in more technical terms the (geo-statistical) support (3.10) — is therefore an
important technical aspect on which a decision is to be made prior to data collection.
For (mainly) two-dimensional surveys, the support is the size (and geometry) of the area sampled at a
sampling location.
The study will always involve a certain soil layer of depth. However, as in the horizontal plane, the dimensions
are much larger than in the vertical plane, the support in soil surveys is most often defined in a two-
dimensional way.
More information on support is given in Annex A.
5.3 Evaluation of existing data
5.3.1 General
When using existing data, specific care must be taken concerning the quality and comparability of data
particularly if the data originate from different sources. Data with appropriate information have to be
harmonized in a step-wise procedure with regard to the specific evaluation objectives. In general, the
harmonization of data sets results in a more or less significant reduction of the respective variate. Nonetheless,
the procedure of harmonization of data sets is inevitable to produce a sound and reliable evaluation. The
respective harmonization strategy should encompass aspects like
a) the check of the completeness of the data sets related to minimum requirements,
b) the harmonization of different sampling strategies, references, nomenclatures and analytical procedures,
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SIST ISO 19258:2006
ISO 19258:2005(E)
c) the identification and elimination of contaminated samples (excluded from the population of background
values by definition).
5.3.2 Completeness of data sets/minimum requirements
In order to ensure a minimum level of data quality, it is essential to provide sufficient and sound information of
the data, for instance
⎯ the date of sampling,
⎯ the procedure used to select sampling locations (plots),
⎯ the scale of sampling (e.g. support),
⎯ the site location (coordinates),
⎯ the sampling depth intervals,
⎯ the number and configuration of samples (e.g. regular grid or random sampling) taken at a sampling
location (plot),
⎯ the method used to extract and analyse the components (including quality assurance and detection limits),
⎯ the site-specific information (e.g. pedology/lithology, land use).
This information can be used to screen the data on their suitability for the objective of compiling background
values.
The definition of minimum requirements on information of the data set depends, amongst others, on the
substances of concern, the area and spatial reference to be considered and the approach pursued to achieve
an adequate spatial representatio
...

INTERNATIONAL ISO
STANDARD 19258
First edition
2005-12-15


Soil quality — Guidance on the
determination of background values
Qualité du sol — Guide pour la détermination des valeurs de bruit
de fond





Reference number
ISO 19258:2005(E)
©
ISO 2005

---------------------- Page: 1 ----------------------

ISO 19258:2005(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.


©  ISO 2005
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland

ii © ISO 2005 – All rights reserved

---------------------- Page: 2 ----------------------

ISO 19258:2005(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 General. 3
5 Procedures. 3
5.1 General. 3
5.2 Objectives and technical approaches . 4
5.2.1 General. 4
5.2.2 Substances and parameters. 4
5.2.3 Study area. 6
5.2.4 Time period. 7
5.2.5 Scale of sampling (Support) . 7
5.3 Evaluation of existing data . 7
5.3.1 General. 7
5.3.2 Completeness of data sets/minimum requirements . 8
5.3.3 Comparability of data (Sampling, nomenclatures, analyses) . 8
5.3.4 Elimination of outliers . 9
5.4 Collection of new data. 9
5.4.1 Sampling. 9
5.4.2 Soil analysis. 12
5.5 Data processing and presentation. 13
5.5.1 Statistical evaluation of data . 13
5.5.2 Data presentation and reporting . 14
6 Data handling/quality control . 15
Annex A (informative) Scale of sampling. 17
Annex B (informative) Outlier tests . 19
Bibliography . 23

© ISO 2005 – All rights reserved iii

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ISO 19258:2005(E)
Foreword
ISO (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 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 Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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 all such patent rights.
ISO 19258 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 7, Soil and site
assessment.

iv © ISO 2005 – All rights reserved

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INTERNATIONAL STANDARD ISO 19258:2005(E)

Soil quality — Guidance on the determination of background
values
1 Scope
This International Standard provides guidance on the principles and main methods for the determination of
pedo-geochemical background values and background values for inorganic and organic substances in soils.
This International Standard gives guidance on strategies for sampling and data processing and identifies
methods for sampling and analysis.
This International Standard does not give guidance on the determination of background values for
groundwater and sediments.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 10381-1, Soil quality — Sampling — Part 1: Guidance on the design of sampling programmes
ISO 10381-5, Soil quality — Sampling — Part 5: Guidance on the procedure for the investigation of urban and
industrial sites with regard to soil contamination
ISO 11074:2005, Soil quality — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11074 and the following apply.
3.1
background content
content of a substance in a soil resulting from both natural geological and pedological processes and including
diffuse source inputs
3.2
background value
statistical characteristic (3.8) of the background content
3.3
contaminant
substance or agent present in the soil as a result of human activity
NOTE There is no assumption in this definition that harm results from the presence of the contaminant.
© ISO 2005 – All rights reserved 1

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ISO 19258:2005(E)
3.4
diffuse source input
input of a substance emitted from moving sources, from sources with a large area or from many sources
NOTE 1 The sources can be cars, application of substances through agricultural practices, emissions from town or
region, deposition through flooding of a river.
NOTE 2 Diffuse source input usually leads to sites that are relatively uniformly contaminated. At some sites, the input
conditions may nevertheless cause a higher local input such as near the source or where atmospheric deposition/rain is
increased.
[ISO 11074:2005]
3.5
pedo-geochemical content
content of a substance in a soil resulting from natural geological and pedological processes, excluding any
addition of human origin
NOTE It may be hardly possible to determine the precise pedo-geochemical content of certain substances in a soil
due to anthropogenic diffuse contamination.
3.6
pedo-geochemical background value
statistical characteristic (3.8) of the pedo-geochemical content
NOTE Any estimate of pedo-geochemical background value will be prone to a certain amount of error given the
uncertainty associated with determining the pedo-geochemical content.
3.7
soil
upper layer of the Earth's crust composed of mineral parts, organic substance, water, air and living organisms
[ISO 11074:2005]
3.8
statistical characteristic
numerical value calculated from a variate of a chosen parameter of the population
EXAMPLE Examples of the statistical characteristics are the mean, the median, the standard deviation or the
percentiles of the ordered frequency distribution.
3.9
study area
three-dimensional definition of the area where samples are to be obtained from and thus for which the
background value(s) are to be estimated
3.10
support
size, shape and orientation of a soil sample
NOTE For the purpose of analysing spatial variation in soils geostatistically (by estimation of the variogram of a soil
property), the support should be the same at each sampling site.
3.11
variate
set of observed values of a variable
EXAMPLE A variate could for instance be the series of numbers of the concentration of a substance in soil or
numerous, individual soil samples.
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ISO 19258:2005(E)
4 General
Soils retain the evidence of their past history including impacts due to natural events or human activities.
Chemical impacts related to human activities can be detected in soils all over the world, even in regions far from
any source of contamination. For this reason, the background contents of inorganic and organic substances in
soils consist of a pedo-geochemical fraction and an anthropogenic fraction. The ratio of these fractions varies
widely depending on the type of substances, the type of soil and land use, and the kind and extent of external
impacts.
For many inorganic substances, the background content of unpolluted soils is dominated by the pedo-
geochemical content and consequently by the mineralogical composition of the soils parent material. Pedogenetic
processes may lead to a redistribution (enrichment/impoverishment) and consequently to a horizon-specific
differentiation of the substances within a soil profile. Persistent organic substances in soils originate more often
from non-natural sources and therefore the background content of soils is governed by the kind and extent of
diffuse contamination from non-soil sources.
In practice, it is often difficult to distinguish clearly between the pedo-geochemical and the anthropogenic fraction
of the background content of soils. Nonetheless, a detailed knowledge of the background content as well as of its
natural fraction for the substances of concern is essential both for any evaluation of the current status of soils for
environmental or land use related aspects or just for scientific purposes within the scope of pedology or
geochemistry. To this end, so-called background values in terms of the statistical characteristics of both, the pedo-
geochemical and the anthropogenic fraction have to be determined.
A variety of different objectives can be identified for the determination of background values of inorganic and/or
organic substances in soils. The objectives themselves provide insufficient information to define the technical
programme that will produce the desired background values. Thus a number of technical approaches have to be
defined which together form the basis of the technical programme.
This guidance provides essential aspects of sampling strategies and procedures, minimum requirements
regarding the necessary steps and ways of sample pre-treatment, analytical methods and statistical
evaluation procedures for determining sound and comparable background values.
Guidance is given for
a) evaluating existing data from different data sources and
b) setting up complete investigation programs aiming to compile background values for a clearly defined
three-dimensional picture of the soil.
These situations are representing the two extreme starting positions for the process of compiling background
values. In practice, a third intermediate situation may be dealt with when additional data need to be collected
because the quantity or quality of the existing data is insufficient.
5 Procedures
5.1 General
The procedures to determine background values encompass aspects of sampling (strategy, procedure), soil
analysis (pre-treatment, extraction and measurement), data processing and presentation. In general, two
starting positions can be distinguished, namely
a) the evaluation of existing data mostly from different data sources, and
b) the collection of new data based on an appropriate investigation strategy.
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ISO 19258:2005(E)
5.2 Objectives and technical approaches
5.2.1 General
Before commencing any survey on background values in soils it is of crucial importance to define the objective
of the survey and the related technical approach.
The objective is, in general terms, the definition of 'why' background values are to be determined. The
technical approaches describe aspects like the 'where', 'what', 'how' and 'when'. Together the technical
approaches determine the technical programme that will provide the required background values.
NOTE It should be noted that a technical approach that is fit for one objective, will often be unfit for other objectives.
The objectives for defining background values might be:
⎯ to identify the current contents of substances in soils, e.g. in the context of soil-related directives;
⎯ to assess the degree of contamination by human activities;
⎯ to derive reference values for soil protection;
⎯ to define soil values for reuse of soil material and waste;
⎯ to calculate critical levels and tolerable additional critical loads;
⎯ to identify areas/sites with atypically enhanced levels of element contents due to geogenic reasons or
human impact;
⎯ etc.
In order to meet the objective, the technical approaches might include the following.
⎯ Definition of the substances and parameters
⎯ For example, the background values to be estimated may be the total heavy metal content or the
bioavailable heavy metal content. (See 5.2.2)
⎯ Definition of the study area
⎯ The (three-dimensional) definition of the area where samples are to be obtained from. This has to be
a detailed description of what is to be considered as the study area, and what is not. (See 5.2.3.)
⎯ Definition of the time period of interest:
⎯ Are the historical or current contents relevant for the objective? (See 5.2.4.)
⎯ Definition of the size and geometry (support) of the area sampled at a sampling location. (See 5.2.5.)
5.2.2 Substances and parameters
Background values can be determined for all kinds of inorganic and organic substances in soils as well as soil
characteristics. In practice, the more persistent and immobile compounds are of primary interest because of
their potential to adsorb and accumulate in soil, whereas remobilization and intrinsic biodegradation are of
less significance.
As well as the substances of concern, basic soil parameters and site characteristics (see 5.4.1.3) need to be
provided to assist in interpretation of the contents of substances. A number of so-called basic soil parameters
influence soil processes that affect the contents of inorganic and organic substances. Table 1 lists these
parameters which should be analysed according to the given International Standards.
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ISO 19258:2005(E)
Within the group of inorganic substances, trace elements (e.g. heavy metals, micronutrients) are most often
analysed (Table 2). Concerning the analytical methods, a distinction has to be drawn between different
extraction/preparation methods (Table 2), whereof very few determine the total content which may be needed
for instance for calculating element stocks. Besides total contents, the (eco-) toxicologically more relevant
mobile fractions (Table 2) are of increasing interest, e.g. if pathway-related questions are to be examined.
Analysis of parameters in Table 2 should be carried out according to International Standards given in Table 2.
Table 1 — Basic soil parameters
Parameter Method ISO International Standard
Texture Sieving, sedimentation ISO 11277
Fraction of coarse material Sieving ISO 11277
Amount of non-soil material Sieving/visual control ISO 11259, ISO 11277
Bulk density Direct measurement of undisturbed ISO 11272
soil samples, estimation form soil
water retention curves
pH pH-electrode ISO 10390
Content of organic carbon Dry combustion ISO 14235
Cation exchange capacity, exchangeable cations BASECOMP ISO 11260
BaCl ISO 13536
2

Carbonate content CO-evolution ISO 10693
2
Table 2 — Examples for the analysis of inorganic substances
Parameter Speciation/form Extraction/preparation ISO International Standard
Method
Extraction/preparation Determination
Metalloids, e.g. ISO 14869-1 ISO 14869-1
Alkaline fusion + X-ray
Total
fluorescence HF + HCIO
4

arsenic and selenium ISO 14869-2 ISO 11047
Metals, Pseudo total aqua regia ISO 11466 ISO 11047
barium, cadmium, EDTA
Complexing
chromium, cobalt, DTPA ISO 14870 ISO 11047
copper, iron, lead, NaNO
3
manganese, mercury, NH NO
4 3

Exchangeable
molybdenum, nickel, CaCl
2

thallium, zinc KCl

Cyanides Water soluble H O, leaching tests See NOTE. See NOTE.
2
NOTE There are a variety of extraction and analytical methods for soil-water in the series of International Standards on water
quality which may also be applicable. However, it is important to confirm that they will work with the extracts obtained form particular soil
material.
Surveys on organic substances usually refer to persistent compounds. The persistent organic contaminants
listed in Table 3 are some of the more commonly encountered, but the list is not complete. Analysis should be
carried out according to International Standards listed in Table 3.
Various methods are used for the analysis of organic substances. The aim of these methods is usually to
extract the greatest possible quantity of organic substances from soils. It is important to recognize that organic
compounds may be extracted from naturally occurring organic materials (e.g. organic matter, decaying
vegetation, peat, charcoal), and that non-specific analyses in particular may, therefore, give misleading results.
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ISO 19258:2005(E)
Table 3 — Examples for the analysis of organic substances
Substance/groups of substances Method ISO International Standard
PAH Soxhlet/HPLC/UV ISO 13877
Thin-layer chromatography ISO 7981-1
RP C-18/HPLC ISO 7981-2
GC/MS ISO 18287
Dioxins/Furane
Chlorophenols Hexane/GC/ECD ISO 8165-1
Chlorpesticides RP C-18/HPLC/UV ISO 11369
PCBs GC-ECD ISO 10382
Chlornaphthalene
Chlorparafin
Bromodiphenylethers
NOTE There are a variety of extraction and analytical methods for water in the series of International Standards on water quality
which may also be applicable. However it is important to confirm that they will work with the extracts obtained from a particular soil
material.
When collecting new data for determining background values, it is recommended that the investigation
program be designed with regard to additional questions that could arise in future. In most cases, carrying out
new sampling campaigns is much more expensive than analysing additional substances in the first place. To
this end, a suitable storage of soil samples for subsequent analyses of organic or inorganic substances is of
crucial importance. Besides the substances of concern (Tables 2 and 3) and additional soil parameters
(Table 1), it is essential to provide a comprehensive site description (see 5.4.1.3) for interpretation purposes.
The documentation of all the actions taken is of utmost importance if the data measured is to be of use for
other assessments in future investigations.
5.2.3 Study area
The definition of the study area (3.9) can be based on two different principles, that is:
⎯ a purely spatial definition (X, Y, Z), defining the contours of the study area by the coordinates within which
the study area lies. Apart from the definition in a horizontal plane, the soil depth that is to be studied
should also be defined;
⎯ a typological definition of the study area, based on one or more characteristic(s), e.g. soil type (for
example, the A-horizon of a specific soil type), land use (also considering the potential effects on the
background values), elevation level, etc.
Of course, it is possible to mix the spatial and typological definition of the study area.
EXAMPLE Examples of a mix of the spatial and typological definition of the study area might be:
— the grassland in a county or province;
— the A-horizon in an area defined by X- and Y-coordinates.
The definition of the study area must be detailed at a level where there cannot be any misinterpretation on
what is and what is not part of the study area. For an unambiguous definition of the study area, all actual point
and diffuse sources within the study area need to be defined. As the general objective is to determine
background values, a safety zone around that (type of) source might be defined and thereby excluding parts
of the more generally defined study area. It might also result in specific zones for which the data is to be
considered separately from the rest of the study area.
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ISO 19258:2005(E)
The definition of the study area as described is independent of whether the soil samples are still to be taken,
or whether already existing soil samples (or results) are to be used. In the latter situation, the detailed
definition of the study area will define which samples/results are to be included or excluded.
5.2.4 Time period
Background values are influenced both by the natural processes (pedogenesis, biogeochemical cycles) as
well as by diffuse source input. Two different time scales can be distinguished:
⎯ the period in which the background value may significantly vary due to natural processes;
⎯ the period in which the background value will most probably only change due to human influences
(except for large scale natural phenomena).
The second period is generally smaller than the first one.
It might be that a specific historic period is of interest when measuring background values. When a soil layer is
formed during this same period, it is indeed possible to determine background values for a certain time period.
When background values are to be re-determined after a period of time in order to determine if changes occur,
the time period between measurements should be based on (see also ISO 16133):
⎯ the expected enrichment of substances in soils (accumulation for example due to diffuse source input);
⎯ the expected loss of substances in soils (for example, due to leaching, biodegradation or plant uptake);
⎯ changes in concentration level that can be determined both analytically and statistically.
5.2.5 Scale of sampling (Support)
Variability in concentrations is by definition a scale-related characteristic. Depending on the volume for which
an analytical result is to be considered representative, the variability in concentrations encountered might be
different. The scale — or in more technical terms the (geo-statistical) support (3.10) — is therefore an
important technical aspect on which a decision is to be made prior to data collection.
For (mainly) two-dimensional surveys, the support is the size (and geometry) of the area sampled at a
sampling location.
The study will always involve a certain soil layer of depth. However, as in the horizontal plane, the dimensions
are much larger than in the vertical plane, the support in soil surveys is most often defined in a two-
dimensional way.
More information on support is given in Annex A.
5.3 Evaluation of existing data
5.3.1 General
When using existing data, specific care must be taken concerning the quality and comparability of data
particularly if the data originate from different sources. Data with appropriate information have to be
harmonized in a step-wise procedure with regard to the specific evaluation objectives. In general, the
harmonization of data sets results in a more or less significant reduction of the respective variate. Nonetheless,
the procedure of harmonization of data sets is inevitable to produce a sound and reliable evaluation. The
respective harmonization strategy should encompass aspects like
a) the check of the completeness of the data sets related to minimum requirements,
b) the harmonization of different sampling strategies, references, nomenclatures and analytical procedures,
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ISO 19258:2005(E)
c) the identification and elimination of contaminated samples (excluded from the population of background
values by definition).
5.3.2 Completeness of data sets/minimum requirements
In order to ensure a minimum level of data quality, it is essential to provide sufficient and sound information of
the data, for instance
⎯ the date of sampling,
⎯ the procedure used to select sampling locations (plots),
⎯ the scale of sampling (e.g. support),
⎯ the site location (coordinates),
⎯ the sampling depth intervals,
⎯ the number and configuration of samples (e.g. regular grid or random sampling) taken at a sampling
location (plot),
⎯ the method used to extract and analyse the components (including quality assurance and detection limits),
⎯ the site-specific information (e.g. pedology/lithology, land use).
This information can be used to screen the data on their suitability for the objective of compiling background
values.
The definition of minimum requirements on information of the data set depends, amongst others, on the
substances of concern, the area and spatial reference to be considered and the approach pursued to achieve
an adequate spatial representation of the point-related data.
Apart from the information listed above, the type and degree of accuracy, e.g. of site-specific information
depends on soil and other parameters influencing the behaviour and hence the contents of the substances in
soils. For instance, inorganic substances need to be related at first priority to lithogenic soil properties due to
their predominant geogenic origin, whereas the content of organic substances of soils is more strongly
correlated to, e.g. land-use-related parameters.
5.3.3 Comparability of data (Sampling, nomenclatures, analyses)
Different sampling strategies may have a crucial impact on the comparability of data sets. Problems arise here
in particular through the comparison of horizon versus depth level-related samples and that of mixed versus
individual samples. Further on, the representative nature of the variate for a sample population with regard to
the same s
...

NORME ISO
INTERNATIONALE 19258
Première édition
2005-12-15


Qualité du sol — Guide pour la
détermination des valeurs de bruit de
fond
Soil quality — Guidance on the determination of background values




Numéro de référence
ISO 19258:2005(F)
©
ISO 2005

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ISO 19258:2005(F)
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Publié en Suisse

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ISO 19258:2005(F)
Sommaire Page
Avant-propos. iv
1 Domaine d'application. 1
2 Références normatives. 1
3 Termes et définitions. 1
4 Généralités. 3
5 Modes opératoires. 3
5.1 Généralités. 3
5.2 Objectifs et approches techniques. 4
5.2.1 Généralités. 4
5.2.2 Substances et paramètres . 4
5.2.3 Zone d'étude. 6
5.2.4 Période. 7
5.2.5 Échelle d'échantillonnage (support). 7
5.3 Évaluation de données existantes . 8
5.3.1 Généralités. 8
5.3.2 Exhaustivité des ensembles de données/exigences minimales . 8
5.3.3 Comparabilité des données (échantillonnage, nomenclatures, analyses). 9
5.3.4 Élimination des valeurs aberrantes . 9
5.4 Collecte de nouvelles données . 9
5.4.1 Échantillonnage . 9
5.4.2 Analyse du sol. 13
5.5 Traitement et présentation des données . 14
5.5.1 Évaluation statistique des données. 14
5.5.2 Présentation des données et rapport . 15
6 Exploitation des données/contrôle qualité . 16
Annexe A (informative) Échelle d'échantillonnage . 17
Annexe B (informative) Test de détection des valeurs aberrantes . 19
Bibliographie . 23

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ISO 19258:2005(F)
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée
aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec
la Commission électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI,
Partie 2.
La tâche principale des comités techniques est d'élaborer les Normes internationales. Les projets de Normes
internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur
publication comme Normes internationales requiert l'approbation de 75 % au moins des comités membres
votants.
L'attention est appelée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable de ne
pas avoir identifié de tels droits de propriété et averti de leur existence.
L'ISO 19258 a été élaborée par le comité technique ISO/TC 190, Qualité du sol, sous-comité SC 7, Évaluation
des sols et des sites.

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NORME INTERNATIONALE ISO 19258:2005(F)

Qualité du sol — Guide pour la détermination des valeurs de
bruit de fond
1 Domaine d'application
La présente Norme internationale fournit des lignes directrices concernant la détermination des valeurs de
bruit de fond pédogéochimiques et des valeurs de bruit de fond des substances inorganiques et organiques
dans les sols.
La présente Norme internationale fournit également des lignes directrices en matière de stratégies
d'échantillonnage et de traitement des données et identifie des méthodes d'échantillonnage et d'analyse.
En revanche, la présente Norme internationale ne donne pas de lignes directrices concernant la détermination
des valeurs de bruit de fond pour les eaux souterraines et les sédiments.
2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent document. Pour les
références datées, seule l'édition citée s'applique. Pour les références non datées, la dernière édition du
document de référence s'applique (y compris les éventuels amendements).
ISO 10381-1, Qualité du sol — Échantillonnage — Partie 1: Lignes directrices pour l'établissement des
programmes d'échantillonnage
ISO 10381-5, Qualité du sol — Échantillonnage — Partie 5: Lignes directrices pour la procédure
d'investigation des sols pollués en sites urbains et industriels
ISO 11074:2005, Qualité du sol — Vocabulaire
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions donnés dans l'ISO 11074:2005 et les suivants
s'appliquent.
3.1
teneur de fond
teneur d'une substance présente dans un sol du fait de processus géologiques et pédologiques naturels, y
compris des apports dus à une source diffuse
3.2
valeurs de bruit de fond
caractéristiques statistiques (3.8) de la teneur de fond
3.3
contaminant
substance ou agent présent dans le sol du fait de l'activité humaine
NOTE Cette définition n'implique aucunement que la présence du contaminant se traduit par un dommage.
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ISO 19258:2005(F)
3.4
apports dus à une source diffuse
apport d'une substance émise par des sources mobiles, des sources de grande étendue ou plusieurs sources
NOTE 1 Les sources peuvent être des automobiles, l'utilisation de substances dans le cadre de pratiques agricoles, les
émissions d'une ville ou d'une rivière, les dépôts dus aux crues d'une rivière.
NOTE 2 Les apports dus à une source diffuse conduisent habituellement à des sites à contamination relativement
uniforme. Pour certains sites, les conditions peuvent néanmoins être des facteurs d'augmentation de l'apport local,
comme à proximité de la source ou à l'endroit où les dépôts atmosphériques/pluviaux s'intensifient.
[ISO 11074:2005]
3.5
teneur pédogéochimique
teneur d'une substance présente dans un sol du fait de processus géologiques et pédologiques naturels, à
l'exception des substances introduites dans les sols du fait de l'activité humaine
NOTE Il peut être difficilement possible de déterminer la teneur pédogéochimique précise en certaines substances
d'un sol, du fait d'une contamination anthropogène diffuse.
3.6
valeur de bruit de fond pédogéochimique
caractéristiques statistiques (3.8) de la teneur pédogéochimique
NOTE Les estimations d'une valeur de bruit de fond pédogéochimique seront enclines à certaines erreurs, étant
donné l'incertitude associée à la détermination de la teneur pédogéochimique.
3.7
sol
couche supérieure de la couche terrestre, composée de parties minérales, de substance organique, d'eau,
d'air et d'organismes vivants
[ISO 11074:2005]
3.8
caractéristique statistique
valeur numérique calculée à partir de la variable aléatoire d'un paramètre choisi de la population
NOTE Exemples de caractéristiques statistiques: la moyenne, la valeur médiane, l'écart-type ou les percentiles de la
distribution de fréquence.
3.9
zone d'étude
définition tridimensionnelle de la zone où les échantillons doivent être prélevés et, par conséquent, pour
laquelle la ou les valeurs de bruit de fond doivent être estimées
3.10
support
taille, forme et orientation d'un échantillon de sol
NOTE Pour l'analyse géostatistique de la variation spatiale des sols (par estimation du variogramme d'une propriété
du sol), il convient que le support soit identique pour tous les sites d'échantillonnage.
3.11
variable aléatoire
ensemble des valeurs observées d'une variable
NOTE Une variable aléatoire peut, par exemple, correspondre à la série de valeurs de concentration d'une
substance dans le sol, pour de nombreux échantillons de sol distincts.
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ISO 19258:2005(F)
4 Généralités
Les sols conservent les traces de leur passé, y compris les impacts liés à des événements naturels ou aux
activités humaines. Il est possible de détecter les impacts chimiques relatifs aux activités humaines dans les
sols du monde entier, même dans les endroits éloignés de toute source de contamination. C'est pourquoi les
teneurs de bruit de fond des substances inorganiques et organiques dans les sols se composent d'une
fraction pédogéochimique et d'une fraction anthropogène. Le rapport de ces fractions varie largement en
fonction du type de substances, du type de sol et de son utilisation, ainsi que du type et de l'ampleur des
impacts externes.
Pour de nombreuses substances inorganiques, la teneur de bruit de fond des sols non pollués est dominée
par la teneur pédogéochimique et, par conséquent, par la composition minéralogique de la roche mère des
sols. Les processus pédogénétiques peuvent conduire à une redistribution (enrichissement/appauvrissement)
et, par conséquent, à une différenciation spécifique aux horizons des substances au sein d'un profil de sol.
Les substances organiques persistantes dans les sols proviennent le plus souvent de sources non naturelles
et la teneur de fond des sols est donc régie par le type et l'ampleur de la contamination diffuse par des
sources non pédologiques.
Dans la pratique, il est souvent difficile de distinguer clairement les fractions pédogéochimique et
anthropogène de la teneur de fond des sols. Néanmoins, une connaissance approfondie de la teneur de fond
ainsi que de la fraction naturelle des substances à inventorier est essentielle, que ce soit pour l'évaluation de
l'état actuel des sols du point de vue des aspects environnementaux ou de l'usage du sol, ou pour des études
scientifiques touchant à la pédologie ou à la géochimie. Pour ce faire, les valeurs de bruit de fond, en termes
de caractéristiques statistiques de la fraction pédogéochimique et de la fraction anthropogène, doivent toutes
deux être déterminées.
Il est possible d'identifier différents objectifs pour la détermination des valeurs de bruit de fond de substances
inorganiques et/ou organiques dans les sols. Les objectifs proprement dits ne fournissent pas suffisamment
d'informations pour définir le programme technique qui produira les valeurs de bruit de fond souhaitées. Par
conséquent, il faut définir plusieurs approches techniques qui, ensemble, formeront la base de ce programme
technique.
Ces lignes directrices indiquent les aspects essentiels des stratégies d'échantillonnage et des modes
opératoires, les exigences minimales concernant les étapes requises et les modes de prétraitement des
échantillons, les méthodes analytiques et les procédures d'évaluation statistique destinées à déterminer des
valeurs de bruit de fond fiables et comparables.
Ces lignes directrices sont données pour permettre
a) l'évaluation des informations existantes à partir de différentes sources de données, et
b) la mise en place de programmes d'investigation complets destinés à acquérir les valeurs de bruit de fond
afin d'obtenir une image tridimensionnelle et clairement définie du sol.
Ces deux situations représentent les deux situations initiales extrêmes du processus d'acquisition des valeurs
de bruit de fond. Dans la pratique, une troisième situation intermédiaire peut se présenter lorsqu'il est
nécessaire de collecter des données supplémentaires en raison de la quantité ou de la qualité insuffisantes
des informations existantes.
5 Modes opératoires
5.1 Généralités
Les modes opératoires pour déterminer les valeurs de bruit de fond englobent des aspects liés à
l'échantillonnage (stratégie, mode opératoire), à l'analyse des sols (prétraitement, prélèvement et mesurage)
ainsi qu'au traitement et à la présentation des données. En général, il est possible d'identifier deux situations
initiales, à savoir
a) l'évaluation des données existantes provenant principalement de sources d'informations différentes, et
b) la collecte de nouvelles données en fonction d'une stratégie d'investigation appropriée.
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5.2 Objectifs et approches techniques
5.2.1 Généralités
Avant d'entamer une étude sur les valeurs de bruit de fond des sols, il est crucial de définir l'objectif de l'étude
et l'approche technique associée.
De manière générale, l'objectif consiste à expliquer «pourquoi» il faut déterminer les valeurs de bruit de fond.
Les approches techniques décrivent des aspects comme «où», «quoi», «comment» et «quand». Ensemble,
les approches techniques déterminent le programme technique qui fournira les valeurs de bruit de fond
requises.
Il convient de remarquer qu'une approche technique qui correspond à un objectif bien spécifique se révélera
souvent inappropriée à d'autres objectifs.
Les objectifs pour définir les valeurs de bruit de fond pourraient être les suivants:
⎯ identifier la teneur actuelle de substances dans les sols, par exemple dans le cadre des directives
relatives aux sols;
⎯ évaluer le degré de contamination par des activités humaines;
⎯ en déduire des valeurs de référence pour la protection des sols;
⎯ définir des valeurs pour la réutilisation du matériau du sol et des déchets;
⎯ calculer les niveaux critiques et les charges supplémentaires critiques tolérables;
⎯ identifier les zones/sites présentant des niveaux anormalement élevés de teneurs en éléments pour des
raisons géogéniques ou en raison de l'impact humain;
⎯ etc.
Afin d'atteindre cet objectif, les approches techniques pourraient inclure les éléments suivants.
⎯ Définition des substances et des paramètres:
par exemple, les valeurs de bruit de fond à estimer peuvent être la teneur totale ou biodisponible en
métaux lourds (voir 5.2.2).
⎯ Définition de la zone d'étude:
la définition (tridimensionnelle) de la zone où les échantillons doivent être prélevés; celle-ci doit décrire en
détail ce qui est considéré comme la zone d'étude et ce qui ne l'est pas (voir 5.2.3).
⎯ Définition de la période concernée: la teneur historique ou actuelle est-elle pertinente pour l'objectif visé?
(Voir 5.2.4.)
⎯ Définition de la dimension et de la géométrie (support) de la zone de prélèvement à l'emplacement
d'échantillonnage (voir 5.2.5).
5.2.2 Substances et paramètres
Il est possible de déterminer les valeurs de bruit de fond pour tous les types de substances inorganiques et
organiques présentes dans les sols, ainsi que les caractéristiques de ces derniers. Dans la pratique, les
composés les plus persistants et les plus immobiles sont les plus intéressants en raison de leur potentiel
d'adsorption et d'accumulation dans le sol, alors que la remise en mouvement et la biodégradation intrasèque
sont d'une plus faible importance.
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De même que les substances concernées, il est nécessaire de fournir les paramètres de base des sols et les
caractéristiques des sites (voir 5.4.1.3) pour faciliter l'interprétation des teneurs en substances. Un certain
nombre de «paramètres de base du sol» influencent les processus du sol, qui affectent à leur tour les teneurs
en substances inorganiques et organiques. Le Tableau 1 dresse la liste des paramètres qu'il convient
d'analyser selon les Normes internationales données.
Au sein du groupe des substances inorganiques, les éléments traces (par exemple les métaux lourds, les
micronutriments) sont ceux qui sont le plus souvent analysés (Tableau 2). Concernant les méthodes
analytiques, il est nécessaire de faire la distinction entre les différentes méthodes de digestion/d'extraction
(Tableau 2), dont très peu déterminent la teneur totale qui peut, par exemple, être nécessaire pour calculer
les éléments. Outre la teneur totale, les fractions mobiles plus pertinentes sur le plan (éco-)toxicologique
(Tableau 2) revêtent un intérêt croissant, par exemple si les questions relatives aux voies d'exposition doivent
être examinées. Il est recommandé de réaliser l'analyse des paramètres du Tableau 2 selon les Normes
internationales indiquées au Tableau 2.
Tableau 1 — Paramètres de base du sol
Paramètre Méthode Norme internationale ISO
Texture Tamisage, sédimentation ISO 11277
Fraction de matériau grossier Tamisage ISO 11277
Quantité de matériaux non pédologiques Tamisage/contrôle visuel ISO 11259, ISO 11277
Mesurage direct d'échantillons
de sol non perturbés, estimation
Masse volumique en vrac ISO 11272
à partir des courbes de rétention
d'eau du sol
pH Électrode pH ISO 10390
Teneur en carbone organique Combustion sèche ISO 14235
BASECOMP ISO 11260
Capacité d'échange cationique,
cations échangeables
BaCl ISO 13536

2
Teneur en carbonate Évolution du CO ISO 10693
2
Tableau 2 — Exemples pour l'analyse de substances inorganiques
Norme internationale ISO
Méthode d'extraction/
Paramètre Spéciation/Forme
de préparation
Extraction/préparation Détermination
Métalloïdes, par exemple Fusion alcaline + ISO 14869-1 ISO 14869-1
Total
fluorescence de rayons X
arsenic et sélénium ISO 14869-2 ISO 11047
HF + HCIO

4
Métaux: Pseudo-totale Eau régale ISO 11466 ISO 11047
baryum, EDTA
Complexable
cadmium, chrome, DTPA ISO 14870 ISO 11047
cobalt, cuivre, fer, NaNO

3
manganèse, mercure, NH NO

4 3
Échangeable ISO 11047
molybdène, nickel, CaCl

2
plomb, thallium, zinc KCl
Cyanures Soluble dans l'eau H O, essais de lixiviation Voir NOTE Voir NOTE
2
NOTE Il existe diverses méthodes d'extraction et méthodes analytiques pour l'eau du sol dans la série de Normes internationales
sur la qualité de l'eau qui pourront également être applicables. Toutefois, il est important de confirmer qu'elles conviendront aux extraits
obtenus à partir d'un matériau de sol particulier.

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ISO 19258:2005(F)
Les études portant sur les substances organiques se rapportent généralement aux composés persistants. Les
contaminants organiques persistants indiqués dans le Tableau 3 sont quelques-uns des plus couramment
rencontrés, mais la liste est incomplète. L'analyse doit être réalisée conformément aux Normes
internationales indiquées au Tableau 3.
Différentes méthodes sont utilisées pour l'analyse des substances organiques. Leur but est généralement
d'extraire la plus grande quantité possible de substances organiques présentes dans les sols. Il est important
de ne pas oublier que des composés organiques peuvent être extraits de matériaux organiques d'origine
naturelle (par exemple matière organique, végétation en décomposition, tourbe, charbon de bois) et que des
analyses non spécifiques, en particulier, peuvent donc produire des résultats erronés.
Tableau 3 — Exemples d'analyse des substances organiques
Substances/groupes de substances Méthode Norme internationale ISO
HAP Soxhlet/HPLC/UV ISO 13877
Chromatographie en couche mince ISO 7981-1
RP C-18/HPLC ISO 7981-2
GC/MS ISO 18287
Dioxines/Furanes
Chlorophénols Hexane/GC/ECD ISO 8165-1
Pesticides chlorés RP C-18/HPLC/UV ISO 11369
PCB GC-ECD ISO 10382
Chloronaphtalène
Paraffine chlorée
Bromodiphényléthers
NOTE Il existe diverses méthodes d'extraction et méthodes analytiques pour l'eau dans la série de Normes internationales sur la
qualité de l'eau qui pourront également être applicables. Toutefois, il est important de confirmer qu'elles conviendront aux extraits
obtenus à partir d'un matériau de sol particulier.
Pour recueillir de nouvelles données pour déterminer les valeurs de bruit de fond, il est recommandé de
concevoir le programme d'investigation en tenant compte des autres questions susceptibles de surgir à
l'avenir. Dans la plupart des cas, réaliser de nouvelles campagnes d'échantillonnage revient bien plus cher
que d'analyser des substances supplémentaires dès le départ. Ainsi, il est crucial de bien stocker les
échantillons de sol pour de futures analyses des substances organiques ou inorganiques. Outre les
substances concernées (Tableaux 2 et 3) et les paramètres supplémentaires des sols (Tableau 1), il est
essentiel de fournir une description détaillée du site (voir 5.4.1.3) à des fins d'interprétation. La documentation
de toutes les actions entreprises est de la plus haute importance si les données mesurées doivent servir à
d'autres évaluations lors de futures investigations.
5.2.3 Zone d'étude
La définition de la zone d'étude (3.9) peut reposer sur deux principes différents, à savoir:
⎯ une définition purement spatiale (X, Y, Z), délimitant le pourtour de la zone d'étude à l'aide des
coordonnées au sein desquelles elle se trouve. En plus de la définition dans le plan horizontal, il convient
également de définir la profondeur du sol à étudier;
⎯ une définition typologique de la zone d'étude, basée sur une ou plusieurs caractéristiques telles que le
type de sol (par exemple, l'horizon A d'un type de sol spécifique), l'usage du sol (en tenant compte
également des effets potentiels sur les valeurs de bruit de fond), l'altitude, etc.
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Il est évidemment possible de combiner les définitions spatiale et typologique de la zone d'étude.
NOTE Exemples de combinaison des définitions spatiale et typologique de la zone d'étude:
⎯ les pâturages d'un département ou d'une région;
⎯ l'horizon A sur une zone définie par des coordonnées X et Y.
La définition de la zone d'étude doit être aussi détaillée que nécessaire pour ne laisser aucune place aux
erreurs d'interprétation entre ce qui fait partie ou non de cette zone. Pour décrire de manière univoque la zone
d'étude, il est nécessaire de définir toutes les sources ponctuelles et diffuses qu'elle contient réellement.
L'objectif général consistant à déterminer les valeurs de bruit de fond, une zone de sécurité autour de ce type
de source peut être définie, en excluant ainsi des parties de la zone d'étude plus généralement définie. Les
données provenant de ces zones de sécurité peuvent être exclues de la zone d'étude, ou bien être
considérées séparément de celles du reste de la zone d'étude.
La définition de la zone d'étude telle que décrite ici reste inchangée, que les échantillons de sol soient à
prélever ou qu'ils soient déjà disponibles (ou les résultats correspondants). Dans ce dernier cas, la définition
détaillée de la zone d'étude établira quels échantillons/résultats doivent être inclus ou exclus.
5.2.4 Période
Les valeurs de bruit de fond sont influencées à la fois par les processus naturels (pédogenèse, cycles
biogéochimiques) et par les apports dus à une source diffuse. Deux échelles de temps peuvent être
distinguées:
⎯ la période pendant laquelle la valeur de bruit de fond peut varier considérablement en raison de
processus naturels;
⎯ la période pendant laquelle la valeur de bruit de fond changera le plus probablement uniquement en
raison d'influences humaines (à l'exception des phénomènes naturels à grande échelle).
La seconde période est généralement plus courte que la première.
Il se peut qu'une période historique spécifique se révèle intéressante lors du mesurage des valeurs de bruit
de fond. Si une couche du sol s'est formée lors de la période considérée, il est possible d'y déterminer des
valeurs de bruit de fond pour cette période.
Si les valeurs de bruit de fond doivent être redéterminées après un certain temps afin de déceler d'éventuels
changements, il convient que l'intervalle entre les mesurages soit fondé sur les éléments suivants (voir
également l'ISO 16133):
⎯ l'enrichissement prévu des substances dans les sols (accumulation, par exemple, du fait d'apports dus à
une source diffuse);
⎯ la perte prévue des substances dans les sols (par exemple due à la lixiviation, à la biodégradation ou à
l'absorption par les plantes);
⎯ les modifications du niveau de concentration, qui peuvent être déterminées à la fois de manière
analytique et statistique.
5.2.5 Échelle d'échantillonnage (support)
La variabilité des concentrations est, par définition, une caractéristique liée à l'échelle. Suivant le volume pour
lequel un résultat analytique doit être considéré comme représentatif, la variabilité des concentrations
rencontrées peut être différente. L'échelle — ou en termes plus techniques, le support (géostatistique)
(3.10) — est donc un aspect technique important pour lequel une décision doit être prise avant la collecte des
données.
Pour les études (principalement) bidimensionnelles, le support est la dimension (et la géométrie) de la zone
échantillonnée à un emplacement d'échantillonnage.
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ISO 19258:2005(F)
L'étude impliquera toujours une couche de sol d'une certaine profondeur. Toutefois, comme, dans le plan
horizontal, les dimensions sont beaucoup plus
...