Certified reference materials to support a European thematic strategy for soil protection: the EUROSOILS (IRMM-443) experience.

The recent proposal of thematic strategy for soil protection by the European Commission outlines that knowledge of problems associated with soil has increased considerably based on surveys, monitoring systems and data networks. Although this information is very useful, its value for the policy-making process is limited due to a lack of comparability. From this unsatisfying situation the need arises to develop an EU-wide monitoring system accompanied by suitable matrix reference materials. Experiences gained from the development and certification of IRMM-443 (The EUROSOILS) show how to approach the complex problem of providing suitable (i.e. representative) soil CRMs for the arising analytical needs to support existing and upcoming EU legislation. This paper presents briefly the quantitative findings of a certification exercise (adsorption coefficients for atrazine, lindane and 2,4-D, as well as pH in suspension). A comparison of these results with those of an intercomparison exercise organised in 1989 by the German UBA on very similar soils shows the significant improvement in the determination of soil adsorption coefficients that was induced by the EUROSOIL project. Indicative values of total and organic carbon content and nitrogen according to ISO Standards are also presented.Furthermore, the idea of reference soils and derived reference materials (for analytical purposes) as well as reference matrices (substrates for ecotoxicological testing) is highlighted and set into the context of horizontal standardisation of methods.

Certification of the European reference soil set (IRMM-443--EUROSOILS). Part I. Adsorption coefficients for atrazine, 2,4-D and lindane.

The European Commission has characterised and certified a set of six European soils (the EUROSOILS) under the number IRMM-443. After a successful validation and trial period with a preliminary batch it was decided to produce a new batch of certified reference materials. Part I of this paper describes the certification of adsorption coefficients for atrazine, 2,4-D and lindane in these soils. The adsorption coefficients were determined according to OECD Test Guideline 106. Additionally, the underlying principles for the value assignment process according to the GUM and their practical application to the numerical data obtained during the certification exercise according to ISO Guide 34 and 35 are discussed.

Certification of the European Reference Soil Set (IRMM-443--EUROSOILS). Part II. Soil-pH in suspensions of water and CaCl2.

IRMM-443 re-groups a set of six European Reference Soils (EUROSOILS), which had been certified for their adsorption coefficients for atrazine, 2,4-D and lindane (Certification of the European Reference Soil Set (IRMM-443-EUROSOILS)-Part I. Adsorption coefficients for atrazine, 2,4-D and lindane. Sci Total Environ, in press). The certification of these parameters was complemented by an additional certification of pH in suspension as well by the determination of indicative values for total nitrogen, organic and total carbon content. While Part I explained the principles of the value assignment process and discussed their application to the adsorption coefficients, Part II presents the certified values for pH as well as the indicative values for N(tot), C(tot) and C(org). In addition, the assessment of uncertainty components for stability and homogeneity, which have been included in the final uncertainty budget, is discussed.

Mercury determination in solid phases from application of the modified BCR-sequential extraction procedure: a valuable tool for assessing its mobility in sediments.

The present paper presents a feasibility study for the evaluation of mercury mobility in sediments by application of the modified BCR three-step sequential extraction procedure (BCR-SEP). The aim of the study was to evaluate the effect of acidification, reduction and oxidation processes on mercury mobility from sediments, once the SEP was validated with other trace metals. As extractable mercury amounts were mostly found below detection limits of the advanced mercury analyser (AMA-254) used for measuring the extracts (L.D.<0.5 ng), the use of a solid sampling atomic absorption spectrometer with a specially designed furnace for Hg atomisation was found to be an optimal technique to quantify Hg in the solid residues coming from the SEP. With this approach, mercury was found to be hardly mobile and only for one of the moderately polluted sediments (BCR CRM 320), extractable mercury (exchangeable fraction, BCR procedure step 1) has been found. An oxidation step with H(2)O(2) was required to obtain extractability up to 64% of the total content in a highly polluted lagoon sediment.

Role of water reuse for enhancing integrated water management in Europe and Mediterranean countries.

Recycling water is an important aspect of water resource and environment management policies, ensuring reliable alternative water resources, reducing environmental pollution and achieving a more sustainable form of development. This paper focuses on wastewater reuse as a strategy for integrated water management. Key economic, financial, regulatory, social and technical factors that help to make water reuse projects successful are reviewed. Selected examples from Northern and Western Europe and arid and semi-arid Mediterranean regions illustrate the contribution of wastewater reuse to integrated management of water resources.

Recent developments in the field of environmental reference materials at the JRC Ispra.

The production of reference materials for environmental analysis started in the Joint Research Centre at Ispra/Italy in 1972 with the objective of later certification by the BCR, but for obvious budget reasons only a fraction of the total production achieved at Ispra ever reached certification level, although all materials were produced according to the severe quality requirements requested for certified reference materials. Therefore, the materials not destinated to certification are in growing demand as inter-laboratory test materials and as laboratory reference materials, for internal quality control, e.g., by control charts. The history of reference material production within the Joint Research Centre is briefly reviewed and the latest additions described. New developments such as micro-scale reference materials intended for analytical methods requiring sample intakes at milligram or sub-milligram level and therefor not finding supply on the reference material market, and "wet" environmental reference materials, which meet more precisely the "real-world" environmental analysis conditions, are presented and the state-of-the-art discussed.

EUROSOILS--a set of CRMs for comparability of soil-measurements.

An overview is given on the development, properties, and application of the European reference soil set--the EUROSOILS. The introduction of this new type of reference material has, for the first time, enabled comparison of data related to the interaction of chemical substances with the soil, and thus, improvement of soil quality. Because of their unforeseen success, a second generation of EUROSOILS had been produced and the range of application extended to other types of measurement related to the soil matrix--soil pH, carbon and nitrogen content, particle-size distribution and cation-exchange capacity. Other fields of application include analytical method development or testing of soil decontamination techniques. On the basis of the success of the EUROSOIL concept and the need for a common basis for comparison of soil-related data in Europe and beyond, the European Commission's Institute for Reference Materials and Measurements decided to certify several properties of the second EUROSOIL-generation, thus establishing a common QA/ QC system for soil-related data. The main features of the EUROSOILS, their origin, the necessary field and laboratory work, and some interesting background information about the project are presented in this paper.

Harmonized protocol and certified reference material for the determination of extractable contents of phosphorus in freshwater sediments--a synthesis of recent works.

An analytical protocol for the determination of the extractable phosphorus contents in freshwater sediments has been harmonized through interlaboratory studies in the frame of the Standards Measurements and Testing Program of the European Commission. A homogeneous and stable sediment reference material has been prepared and certified on the basis of this protocol named SMT protocol, and will be available in spring of 2001. The SMT protocol, together with the reference material, are useful tools in the field of water management, especially at a time when quality assurance and data comparability are of paramount importance in laboratory analysis. The knowledge of the bioavailable forms of phosphorus is important not only for sediments but also for sludge and soils. Therefore, the SMT protocol could be extended to these materials and new CRMs could be prepared. The SMT protocol was used in a study of a reservoir, which allowed to calculate the P stock, therefore helping to predict the restoration delay of the lake. The paper describes the protocol and the CRM, and gives a brief outline of the case study.

Certification of the extractable contents of Cd, Cr, Cu, Ni, Pb and Zn in a freshwater sediment following a collaboratively tested and optimised three-step sequential extraction procedure.

Sequential extraction procedures have been used during the last decades to study and determine trace element mobility in aquatic sediments. However, the results obtained are operationally defined and, therefore, the significance of the analytical results is related to the extraction scheme used. So, there is a need for suitable reference materials for this type of study to enable the validation of the methodologies and to control the quality of the measurements. This paper describes the preparation of a sediment reference material, BCR-701, the homogeneity and stability studies and the analytical work performed for the certification of the extractable contents of some trace elements, following a collaboratively tested and optimised sequential (three-step) extraction procedure. The paper contains all the results and gives the methods used to certify the extractable contents (mass fractions expressed as mg kg-1 on a dry matter basis) of Cd, Cr, Cu, Ni, Pb and Zn in all steps. Moreover, indicative values are given for the aqua regia extractable contents of the six elements in the sediment and the residue obtained after sequential extraction.

A new organic-rich soil reference material certified for its EDTA- and acetic acid- extractable contents of Cd, Cr, Cu, Ni, Pb and Zn, following collaboratively tested and harmonised procedures.

There is an increasing requirement for assessment of the bioavailable metal fraction and the mobility of trace elements in soils upon disposal. One of the approaches is the use of leaching procedures, but the results obtained are operationally defined; therefore, their significance is highly dependent on the extraction protocol performed. So, for this type of study, there is a need for reference materials that allow the quality of measurements to be controlled. This paper describes the steps involved in the certification of an organic-rich soil reference material, BCR-700, for the EDTA- and acetic acid-extractable contents of some trace elements, following collaboratively tested and harmonised extraction procedures. Details are given for the preparation of the soil, homogeneity and stability testing, analytical procedures and the statistical selection of data to be included in the certification.

Development of a harmonised phosphorus extraction procedure and certification of a sediment reference material.

A harmonised procedure for the determination of the forms of phosphorus in freshwater sediments, developed in the frame of the European Programme, Standards, Measurements and Testing (SMT) has been used for a certification campaign for a reference material. This operationally defined scheme is a good compromise between method performance and reproducibility. Furthermore, the method is rather simple to implement and could be used by water managers on a routine basis. A homogeneous and stable sediment reference material has been prepared and will be available before mid 2001. The so-called SMT protocol, together with the reference material, are useful tools in the field of water management, especially at a time when quality assurance is of paramount importance in laboratory analyses. Knowledge of the bioavailable forms of phosphorus is important not only for analysis of sediments but also for sludge and soils. Therefore, the SMT protocol could be extended to these materials.

Harmonisation and quality assurance in pre-analytical steps of soil contamination studies--conclusions and recommendations of the CEEM Soil project.

The paper summarises the project's results and consequences including expert's statements. Based on sampling strategies and methodological details which have been recognised to be critical for the comparability of the results of soil contamination studies, recommendations are given towards harmonisation of soil sampling guidelines, improvement of quality assurance of pre-analytical steps and inclusion of soil sampling into accreditation systems. Recommended approaches to improve QA and QC in soil sampling are: harmonised guidelines; specified SOPs; written sampling (strategy) plans; defined qualification and experience of sampling personnel; sampling records; regular interlaboratory comparisons (proficency tests) for sampling; and inclusion of sampling and sample preparation into accreditation procedures. Needs for further research in the field of pre-analytical phases of soil contamination studies are outlined and further R&D projects are encouraged.

Description of the test area and reference sampling at Dornach.

The selected test area for the comparative evaluation of European methods on sampling and sample preparation of soils (CEEM Soil) at Dornach near Basel (Switzerland) is located at approximately 400 m a.S.l. on the north-west rolling footslope of the Jura mountain chain that has a temperate climate. The area is known to be airborne polluted by emissions of a non-ferrous metal recycling plant. The geology is dominated by Jurassic limestone and (decarbonated) loess loam. The land use is deciduous forest (beech, oak) in the upper part and traditional cherry orchards with permanent grassland which have mostly been converted into arable land. The detailed soil survey distinguishes four different soil mapping units in the test area of 0.61 ha. The reference sampling was performed in a 190-m-long and 20-40 m large transect area following four devices: (1) composite samples (0-10 cm and 0-20 cm), each from 25 stratified single samples of 61 squares of 10 x 10 m; (2) hypotheses and soil horizon-based composite samples at nine locations; (3) horizon-related samples from the four described soil profiles representing the mapping units; and (4) three soil cores with 5-cm interval samples taken in the major land use units. Altogether 301 reference soil samples were taken.

Analytical aspects of the CEEM soil project.

In the past, exercises aiming at an assessment of data uncertainty in environmental analysis were usually restricted to the analysis step, while sampling and pre-analytical sample treatment was largely ignored. Collaborative studies on the quantification of sampling errors require, besides a suitable and well characterized test site, the availability of a reference laboratory for the analysis of all of the samples taken in the context of the study by all participants and also test methods which do not contribute large and variable uncertainties due to long and complex analytical methodologies. Here we summarize the major analytical aspects of a European project on the identification and quantification of sampling influences on the determination of lead, cadmium, copper and zinc in soil. The participant group included the leading soil analysis laboratories in Europe; the test site at Dornach (CH) was well suited for the purpose and showed high metal gradients and differentiated land use. The analytical methods (wavelength-dispersive X-ray fluorescence spectrometry and solid-state Zeeman AAS) used in the study showed stable performance characteristics within the confidence interval of the certified reference materials used for the measurement quality control over the entire project period. Additionally, double-blind tests on split samples showed agreement of data in very narrow limits thus demonstrating the reliability of the reference database.

Objectives, concept and design of the CEEM soil project.

Within the member countries of the European Union, different strategies and guidelines for the sampling and the preparation of soils are used to investigate soil contamination. As a consequence, there is reasonable doubt that the results gained by applying these different strategies and methods are comparable. In general, the relative contribution of sampling and sample preparation to the total uncertainty in soil contamination studies is a subject of speculation than of knowledge. For this purpose, the first European soil sampling inter-comparison test was organised as a project under the Standards, Measurement and Testing Programme of the European Commission. The aim of this project was to analyse and to compare the existing guidelines, the degree and the state of standardisation in this field in the European countries, and to compare their results when applied on the same test area under comparable conditions by representative sampling teams. The results of the project in general demonstrate that sampling and sample preparation errors reach about the same order of magnitude as errors caused in the chemical analysis. However, there are great differences depending on the elements investigated and their concentration ranges, as well as on pedological and land-use conditions in the test area. Consequently, sampling and sample preparation require the same attentiveness and equivalent measures for quality assurance (QA) and quality control (QC) as the chemical analysis, which has not been the case up to now. Insufficient comparability of the results is illustrated by the fact that different participants arrive at different conclusions for up to 61% of tested soil quality criteria (e.g. threshold levels). The methods and results of the project are presented in detail in the six following papers within this volume. The following 13 papers present some key studies and specific contributions of the participants, as well as synoptical papers of the invited experts in standardisation and accreditation.

European soil sampling guidelines for soil pollution studies.

The soil sampling guidelines used in European countries (ESSG), as kindly provided by the national institutions which participated in the project, have been recorded, studied, evaluated and presented in this paper. The aim has been to ascertain what soil sampling guidelines exist in Europe; to detect similarities and differences (comparable results), advantages and deficiencies; to identify incompatible strategies and evaluate how methodologies might affect data quality; to investigate sources of deviations or uncertainties; to improve comparability and representativeness of soil sampling; to investigate the need for harmonised sampling guidelines; and to develop suggestions for standard operating procedures (SOP). Soil sampling guidelines throughout Europe differ as to whether they are applied by law, or used throughout the country. In some countries these are ISO/DIS related or based (ISO 10381-1, 1995; ISO 10381-2, 1995), or are produced by a scientific society or a standardisation body. As far as sampling strategy is concerned, not all sampling guidelines clearly describe the sampling scale, the specifications for contamination risk precautions, the sampling plan and protocol structure and the pre-analysis treatment of the soil samples. The purpose for sampling, in descending order of frequency, is soil pollution, soil fertilisation, general soil monitoring, background risk assessment, or else it is not specified. The majority of countries do not sample the top organic matter separately. Sampling depth is either related to the morphogenetic horizon or to ad hoc sampling depth, which is not specified in all cases. They suggest mass- and volume-related soil sampling, while the sampling pattern is not presented in all national guidelines. The criteria for area, site, unit, sub-unit, and point selection are mainly based on pedology and land use, following the history and pre-screening information or geology, or is site related. Some guidelines suggest the division of sampling units into sub-units. The sampling pattern is mainly grid sampling, grid and random sampling, or not mentioned. Sampling density inside the sampling unit either varies greatly or it is not mentioned, while the size of the sampling unit varies widely. Most guidelines require the collection of composite instead of simple samples, while some prefer sampling soil profiles. In the European SSG many technical details and steps are either not defined or vary, while in the pre-analysis treatment quality assurance (QA) and quality control (QC) approaches are used either both in the lab and in the field, or only in the field, or are not mentioned. The common points and the points in which harmonisation could be started or achieved are discussed.

Comparative soil sampling in the Dornach site (Switzerland) for soil three-dimensional pollution description.

Fifteen institutions from 13 European countries and Switzerland participated in a comparative test sampling at the Dornach site, near Basel in Switzerland. They received the site description and were asked to develop their own sampling plans, based on their national guidelines for a three-dimensional description of the Pb, Zn, Cu and Cd pollution, with a maximum of 15 samples. The comparative sampling test took place in late August 1997. The sampling plans and records, provided by the participants, were compared and evaluated in terms of sampling strategy throughout the site, the sampling strategy inside the sampling unit, strategy at the sampling point and last minute alteration of the sampling plans in the field. The object of this was to define the similarities and the differences in the sampling plans and identify the crucial steps inducing error or uncertainty which should be harmonized throughout Europe. The number of the total composite samples varied from 4 to 16, while the number of sampling points varied from 4 to 224 and the sampling density varied from 0.25 to 16 single samples per 100 m2. The number of 10 x 10 m2 quadrats from which samples were taken varied from 3 to 56, out of the total 61. The number of sampling units varied between 3 and 12. The criteria in descending order of frequency were: both land use and pedology, land use, pedology. The majority of the national participants divided the sampling units into two or three sub-units, while seven participants collected replicate composite samples from the same sampling unit. Only one sampled from the existing profiles, eight national representatives ignored the plough depth. The sampling pattern inside the sampling unit was in descending order of frequency: random, point sampling, regular, 'W' and 'X' shaped sampling. The number of single samples in the composite varied from 1 to 20. Most of the national participants sampled to pre-defined (ad-hoc) sampling depths, while others sampled soil horizons and others both. The maximum soil depth sampled also varied from 20 to 117 cm. Most participants mixed in the top organic matter horizon while others sampled it separately. Most sampled separately the top Ah horizon in the forest while the rest mixed it with the underlying soil horizon. The last-minute sampling plan alterations were in: the sampling depth (nine), the movement of sampling points (five), the reduction of sub-samples in the composite sample (four), changes in the number of sampling units (three), ignoring the bottom sample (three), not sampling the L/H layer (three) although this was planned, unplanned sampling of the L/H layer (two) and changing the number of planned samples (two). This study has highlighted the need for soil sampling harmonization throughout Europe for pollution and soil quality determination.

Quantitative evaluation of the CEEM soil sampling intercomparison.

The aim of the CEEM soil project was to compare and to test the soil sampling and sample preparation guidelines used in the member states of the European Union and Switzerland for investigations of background and large-scale contamination of soils, soil monitoring and environmental risk assessments. The results of the comparative evaluation of the sampling guidelines demonstrated that, in soil contamination studies carried out with different sampling strategies and methods, comparable results can hardly be expected. Therefore, a reference database (RDB) was established by the organisers, which acted as a basis for the quantitative comparison of the participants' results. The detected deviations were related to the methodological details of the individual strategies. The comparative evaluation concept consisted of three steps: The first step was a comparison of the participants' samples (which were both centrally and individually analysed) between each other, as well as with the reference data base (RDB) and some given soil quality standards on the level of concentrations present. The comparison was made using the example of the metals cadmium, copper, lead and zinc. As a second step, the absolute and relative deviations between the reference database and the participants' results (both centrally analysed under repeatability conditions) were calculated. The comparability of the samples with the RDB was categorised on four levels. Methods of exploratory statistical analysis were applied to estimate the differential method bias among the participants. The levels of error caused by sampling and sample preparation were compared with those caused by the analytical procedures. As a third step, the methodological profiles of the participants were compiled to concisely describe the different procedures used. They were related to the results to find out the main factors leading to their incomparability. The outcome of this evaluation process was a list of strategies and methods, which are problematic with respect to comparability, and should be standardised and/or specified in order to arrive at representative and comparable results in soil contamination studies throughout Europe. Pre-normative recommendations for harmonising European soil sampling guidelines and standard operating procedures have been outlined in Wagner G, Desules A, Muntau H, Theocharopoulos S. Comparative Evaluation of European Methods for Sampling and Sample Preparation of Soils for Inorganic Analysis (CEEM Soil). Final Report of the Contract SMT4-CT96-2085, Sci Total Environ 2001;264:181-186. Wagner G, Desaules A, Munatu H. Theocharopolous S, Quevauvaller Ph. Suggestions for harmonising sampling and sample pre-treatment procedures and improving quality assurance in pre-analytical steps of soil contamination studies. Paper 1.7 Sci Total Environ 2001b;264:103-118.

Estimation of soil adsorption coefficients of organic compounds by HPLC screening using the second generation of the European reference soil set.

The European reference soil set was introduced as common basis for a better comparability of soil sorption data measured within the framework of chemical testing of environmental chemicals. The success of the EUROSOILS, as the set is commonly called, convinced the European Commission's Joint Research Centre to evaluate the possibility of producing a remake of these unique and new type of reference materials maintaining the principal sorption-controlling properties of the soils. In this paper the recently proposed second generation of the EUROSOILS is used to evaluate a HPLC-screening technique for the estimation of soil adsorption coefficients of organic chemicals. It could be shown that the derived correlations between HPLC capacity factors of the test substances and the respective soil adsorption coefficients resulting from batch experiments with the second version of the EUROSOILS agreed with those derived for the first generation of reference soils at a different occasion.

River sediment (S-37)--a new analytical quality control material ensuring comparability of chlorinated hydrocarbon analysis during an international environmental study in China.

A sediment reference material (S-37) was prepared as analytical quality control material to be used within an international project on polychlorinated hydrocarbon analysis in two Chinese rivers. The raw material was sampled during a cruise on Yangtse River and transported afterwards to the JRC Ispra for further processing. The material was treated according to the general principles applicable for candidate reference material production. After a thorough homogeneity study of the bulk the material was bottled. A total of 1,080 bottles each containing 50 g of dry sediment powder was obtained. Final homogeneity and stability testing proved the material to be fit for the purpose. Isotope dilution GC/MS was used to establish target values for pentachlorobenzene (1.17 +/- 0.08 ng/g), hexachlorobenzene (3.60 +/- 0.17 ng/g), octachlorostyrene (0.19 +/- 0.01 ng/g), pentachloroanisole (0.52 +/- 0.02 ng/g), alpha-HCH (0.70 +/- 0.05 ng/g), beta-HCH (1.38 +/- 0.18 ng/g), gamma-HCH (0.83 +/- 038 ng/g), 2,4'-DDT (0.36 +/- 0.04 ng/g), 2,4'-DDE (0.29 +/- 0.02 ng/g), 2,4'-DDD (0.49 +/- 0.02), 4,4'-DDT (3.42 +/- 0.47 ng/g), 4,4'-DDD (1.29 +/- 0.17 ng/g), PCB 28 (0.11 +/- 0.01 ng/g), PCB 52 (0.09 +/- 0.003 ng/g), PCB 101 (0.07 +/- 0.003 ng/g), PCB 138 (0.06 +/- 0.003 ng/g) and PCB 153 (0.06 +/- 0.003 ng/g). Furthermore, indicative values for major and minor constituents as well as for polychlorinated dibenzodioxines and -furanes were measured.