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Analytical Chemistry Division (V)


Number: 2000-033-1-500

Title: Assessment of uncertainty associated with soil sampling in agricultural, semi-natural, urban and contaminated environments (SOILSAMP)

Coordinator(s): A. Fajgelj

Remarks: Coordinated by the Italian National Environmental Protection Agency (Agenzia Nazionale per la Protezione dell'Ambiente, ANPA)

Completion Date: 2005 - Project completed

The main objective of the project is to establish quantification of uncertainty components connected to the most widely used methodologies for soil sampling in agricultural, semi-natural, urban and contaminated sites.

A lot of effort has been invested in recent years by various international organizations and bodies in the harmonization and preparation of guidance documents on proper quantification of uncertainty in chemical measurements. All these was/is done with the aim to achieve better international comparability between results produced by testing or calibration laboratories.

However, the uncertainty associated with field sampling is normally left out from the uncertainty quantification process and has not been satisfactorily covered yet in any of the existing guidance documents. The SOILSAMP project is to fill this gap in the field of soil analysis.

The validation of the different sampling procedures will be performed with a collaborative approach. All the participants will contribute directly to the elaboration of the technical reports, evaluating the work outcomes and discussing the technical doucments needed.

A first meeting of the Expert Advisory Group took place in Udine, Italy between Dec. 18 and 19, 2000. 22 participants from 5 countries and 3 international organizations attended the meeting.

The meeting objectives were:

  • Presentation and selection of the test areas with reference to agricultural soils and semi-natural soils for the intercomparison.
  • Characterization of the reference sampling.
  • Definition and quantification of the uncertainty in reference sampling (identification of uncertainty sources).
  • Uncertainty acceptable for reference sampling (acceptance criteria).
  • Selection of the sampling strategy for the reference sampling.
  • Selection of sampling techniques (devices) for agricultural and semi-natural areas.
  • Definition of elements to be considered for sampling procedures/protocols.
  • Discussion of the nomenclature (terminology) to be used in the project.
  • To define further steps in the project.

The following soil parameters and their uncertainties will be investigated: texture (stones and gravel), sand, silt, clay, pH, carbonate, organic carbon, total nitrogen, available P, K, Ca, Mg, Fe, Mn, Cd, Cr, Hg, Ni, Cu and Zn. Instrumental neutron activation analysis (INAA), a non-destructive technique with a low matrix effect for most of the analytes, was selected as a method of choice for actual trace element determinations.

It is worth mentioning that soil as a matrix is only one example where the gap on uncertainty assessment in sampling exists. Taking into account a large number of sample/analyte combinations, e.g. soil/trace elements, soil/radionuclides, soil/organic contaminants, etc., there is still a lot of research opportunities and room for improvement.

All documents, transparencies and other material used during the meeting are available upon request. Meetings of the Expert Advisory Groups are planned to take place twice per year.


A second meeting was organised by the Environmental Protection Agency, Rome, Italy between June 11 and 12, 2002. 17 participants from five countries and three international organisations attended the meeting.

The main purpose of this meeting was to review the present status of the project, to evaluate results obtained so far, and to select a new sampling site for the intercomparison exercise in contaminated environment.

The experimental activities carried out from July 2001 to July 2002 included:

  • the comparative sampling (by using three different sampling devices), completed;
  • 150 soil samples collected, dried (36-40 C), sieved (stones pick-up, soil agglomerates crushing by PVC balls and rotate sieve up to < 2 mm), reduced (quartering and splitting) and milled (planetary-balls mill with grinding jars and balls in agate).
  • test portions of about 250 mg analyzed by INAA (K0 standardization method) for trace element content (J. Stefan Institute, Ljubljana, Slovenia);
  • test samples of about 150-200 g were analyzed for pedo-chemical parameters (Institute for Promotion and Development of Agriculture (ERSA), Udine, Italy.
  • 150 samples analyzed for particle size at the International Atomic Energy Agency - Laboratories Seibersdorf.

All results were extensively discussed and it was confirmed that the agricultural site selected (Pozzuolo del Friuli) is suitable as a reference site for testing the soil sampling equipment. From the technical point of view, the first phase of the project is now concluded.

Beside technical findings, one additional result of this project is a compilation of existing and some new terms related to soil sampling and associated uncertainty. It is planned to publish this compilation as IUPAC recommendations within the next half of the year. Although the assessment of uncertainty associated with the soil sampling in agricultural areas represents only a part of the complete project, the results obtained are extensive and very informative. For this reason it was concluded to publish a report on this part as a separate document. It will be published in Italian and English language.

The second part of the project will now start with the assessment of sampling uncertainty in contaminated areas. For this purpose a highly contaminated site was selected in Scarlino (Grosseto, Italy.) Next meeting of the Expert Advisory Group is planned for the first quarter 2003.

July 2003 - A draft is submitted to public review for comment until 30 November 2003
> see provisional recommendations

> Nov 2004 report update (pdf file - 12KB)

Project completed - IUPAC Recommendations published in Pure Appl. Chem. 77(5), 827-841, 2005

Last update: 9 May 2005

Page last modified 9 May 2005.
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