Comparative evaluation of European methods for sampling and sample preparation of soils--the Portuguese contribution

The main purpose of this work was to prepare a Portuguese sampling strategy, according to the existing Portuguese recommendations, for the soil sampling exercise at Dornach in the framework of the CEEM soil project of the SMT Programme of the EU. Within this project, the results obtained from the Dornach study were compared with the results obtained by other European participants and also with the reference sampling. The objective of this comparison was to validate the method used and to evaluate possible factors of uncertainty that may arise from the application of our national guideline as well as possible advantages. Another objective, also important, was to provide information regarding the need for a harmonised procedure within the European Union related to soil sampling and sample preparation of soils. The results obtained were consistent with the results obtained by other participants, however, in the Portuguese recommendations there is a general lack of specific information that may complicate its application to polluted scenarios. In fact, those guidelines are valuable to detect the average contamination of the soil, but they are not useful to identify hot spots or the edge influence in a contaminated land. As a conclusion, the results obtained by the CEEM soil project helped to evaluate the Portuguese sampling plan. This may provide a basis for further standardisation of soil sampling for specific purposes, e.g. contaminated land, and to establish a technical support for criteria used in the accreditation of laboratories for soil sampling.     

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.     

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.     

Guidelines for sampling in Flanders (Belgium)

In Flanders, sampling guidelines for investigations on contamination of soils are in development. One detailed sampling guideline is currently available with respect to the prospective investigation in the frame of the decree related to soil sanitation. Four strategies for sampling may be followed as a function of available information about pollution sources. Guidelines indicate what has to be sampled (top soil, deeper soil, soil water), how sampling points must be determined, how the number of samples and analyses is determined and what parameters need to be analysed. The example given shows that sampling guidelines will strongly depend on the ultimate goal of a particular sampling. A sampling procedure should be developed with close consideration of practical aspects and limitations, in order to be practical, realistic and cost-effective.     

Quantifying uncertainty of the reference sampling procedure used at Dornach under different soil conditions

The reference sampling procedure, used in the CEEM soil project on a single test area at Dornach, had been applied under different soil conditions in a sampling proficiency test and in the Swiss national soil-monitoring network related to pollution (NABO). Methods of analysis of variance (ANOVA) were used to quantify sampling and analytical uncertainty. The soil sampling procedure and the chemical analysis were considered as two parts of the same measurement process and the so-called 'top-down' approach was used to quantify their combined contribution to the uncertainty. By this approach a systematic error of one sampler or of one laboratory becomes a random error when assessed as part of a multi-sampler or multi-laboratory comparison.     

An overview of the present state of standardization of soil sampling in Spain

There are no national standard soil sampling guidelines at present in Spain, although a strong need for standardization of sampling activities is evident. Some relevant publications dealing with sampling subjects are cited, and common practices in sampling and sample pre-treatment carried out in Spain for basic soil maps, soil fertility and soil contamination are briefly described. The need to standardize sampling protocols and guidelines in Spain and to harmonize them with those of the EU countries is emphasized.     

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.     

A GIS-based human health risk assessment for urban green space planning—An example from Grugliasco (Italy)

The need to develop approaches for risk-based management of soil contamination, as well as the integration of the assessment of the human health risk (HHR) due to the soil contamination in the urban planning procedures has been the subject of recent attention of scientific literature and policy makers. The spatial analysis of environmental data offers multiple advantages for studying soil contamination and HHR assessment, facilitating the decision making process. The aim of this study was to explore the possibilities and benefits of spatial implementation of a quantitative HHR assessment methodology for a planning case in a typical urban environment where the soil is contaminated. The study area is located in the city of Grugliasco a part of the Turin (Italy) metropolitan area.The soils data were derived from a site specific soil survey and the land-use data from secondary sources. In the first step the soil contamination data were geo-statistically analysed and a spatial soil contamination data risk modelling procedure designed. In order to spatially assess the HHR computer routines were developed using GIS raster tools. The risk was evaluated for several different land uses for the planned naturalistic park area.The HHR assessment indicated that the contamination of soils with heavy metals in the area is not sufficient to induce considerable health problems due to typical human behaviour within the variety of urban land uses. An exception is the possibility of direct ingestion of contaminated soil which commonly occurs in playgrounds.The HHR evaluation in a planning case in the Grugliasco Municipality confirms the suitability of the selected planning option. The construction of the naturalistic park presents one solution for reducing the impacts of soil contamination on the health of citizens. The spatial HHR evaluation using GIS techniques is a diagnostic procedure for assessing the impacts of urban soil contamination, with which one can verify planning options, and provides an important step in the integration of human health protection within urban planning procedures.     

A soil sampling strategy for mapping trace element concentrations in a test area

A sampling strategy, based on previous knowledge of a test area, was compared with a Reference Sampling in the frame of the EU-funded CEEM project. The aim was a comparison of sampling strategies for the drafting of concentration maps for a set of trace elements (Cd, Pb, Cu and Zn), with three-dimension information that can be used for risk assessment. The main constraint was that only 15 soil samples were to be analysed. The test area (in Dornach, Switzerland) included different soil types and land uses (forest, arable land and permanent grasslands). The sampling strategy proposed defined strata on the basis of land use, then applying a systematic regular sampling within each stratum. A composite sample was formed from each individual sample. In forests, H and Ah horizons were taken separately. In arable lands, a depth within the ploughed layer (0-15 cm) was analysed. In grasslands, samples were taken at two depths (0-10 and 10-20 cm) to provide information on the vertical variability. The comparison of the results obtained with those derived from the Reference Sampling allowed us to estimate if the information obtained from the proposed sampling strategy was sufficiently representative for an assessment of the level of elements considered. It was concluded that recommendations on sampling strategy depend on the interaction pattern of the element. In this case, for mobile trace elements, such as Cd, the information derived from sampling of two soil layers was not as important as that for the rest of metals studied that accumulated in the upper layer. If the H horizons in forests was not considered this led to unreliable predictions of the concentration levels, since the concentrations in H and Ah horizons differed irrespective of whether they were expressed in mg kg(-1) (the H horizon was enriched in those trace elements, except for Cd) and in mg m(-2) (the low bulk density of the H horizon led to a lower trace element level than in Ah horizon). Finally, in undisturbed systems such as grasslands, sampling 0-10 cm instead of 0-20 cm is recommended to prevent dilution of the concentration of trace elements.     

Enhanced methods for assessment of the trace element composition of Iron Age bone

Modern, ultra-trace, analytical methods, coupled with magnetic sector ICP-MS (HR-ICP-MS), were applied to the determination of a large suite of major and trace elements in Iron Age bones. The high sensitivity and un-paralleled signal-to-noise characteristics of HR-ICP-MS enabled the accurate measurement of Ag, Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, La, Li, Mg, Mn, Ni, P, Pb, Pt, Rb, Sr, U, V, and Zn in small bone sections (<75 mg). Critically, the HR-ICP-MS effectively addressed molecular interferences, which would likely have compromised data generated with quadrupole-based ICP-MS instruments. Contamination and diagenetic alteration of ancient bone are grave concerns, which if not properly addressed, may result in serious misinterpretation of data from bone archives. Analytical procedures and several chemical and statistical methods (Principal Components Analysis - PCA) were studied to assess their utility in identifying and correcting bone contamination and diagenetic alteration. Uncertainties in bone (femur) sampling were characterized for each element and longitudinal variation was found to be the dominant source of sampling variability. However the longitudinal variation in most trace elements levels was relatively modest, ranging between 9 and 17% RSD. Bone surface contamination was evaluated using sequential acid leaching. Calcium-normalized metal levels in brief, timed, dilute nitric acid leaches were compared with similarly normalized interior core metal levels to assess the degree of surface enrichment. A select group of metals (Mn, Co, Ni, Ag, Cd, and Pt) were observed to be enriched by up to a factor of 10 in the bone surface, indicating that that these elements may have a higher contamination component. However, the results of sequential acid leaching experiments indicated that the single acid leaching step was effective in removing most surface-enriched contaminants. While the leaching protocol was effective in removing contaminants associated with the bone surface, there remained potentially significant residual levels of soil-sourced contaminant tracers within the leached bone. To address this issue a mathematical procedure, based on metal/aluminum ratios, was developed to correct-for the soil-contaminant metal pools. Soil correction fractions for the primary anthropogenically mobilized metals evaluated were greatest for Pb (13.6%) followed by As (4.4%), Ag (3.9%), and Cd (0.94%). Although median soil corrections were typically low, many samples did require a much larger correction, thus both bone cleaning and soil corrections may be necessary to realize accurate endogenous bone elemental data. The results of the PCA analysis were remarkably consistent with outcomes from the chemical and elemental ratio protocols evaluated in the study, and suggest that loadings on certain factors will be helpful in screening for soil-biased samples and in identifying diagenetically altered bone. Application of these contamination evaluation and correction tools was made possible by the high-quality, multi-element, datasets produced by HR-ICP-MS. Large variations in bone core concentrations between the 80 Iron Age specimens examined were observed for all the primary trace elements and in many of the supporting elements, even after correction for major contaminant components.     

The possibilities for the EU-wide use of similar ecological risk-based soil contamination assessment tools

Soil degradation, e.g. due to soil contamination, is a serious problem in Europe. Therefore, the European Commission believes that a comprehensive EU strategy for soil protection is required. With the purpose of supporting the European soil policy, the possibilities for a common approach in the EU-wide use of ecological risks assessment methodologies are explored. For over ten years now, ecological procedures used in different countries have been discussed in international fora. More recently, within the framework of the HERACLES network a review of ecological risk assessment tools was performed, among other things. From this study it can be concluded that the inclusion of ecological risk assessment in soil quality standards shows an increasing interest in many EU Member States. The study also shows that there are many procedures for ecological risk assessment readily available in several EU countries and will be readily available in even more Member States in the nearby future. Besides, this study clearly shows quite some variation in the ecological risk assessment tools and in the resulting soil quality standards in the different countries. Therefore, an effort was made to look for potential harmonisation of these tools within the European Union. Risk assessment tools used in soil quality assessment include both political and scientific elements, which are often interwoven. Insofar differences in the existing tools originate from geographical or cultural differences between Member States or from political choices, harmonisation is not at all regarded an option. Nevertheless, several differences between existing ecological risk assessment tools have been identified, that merely originate from scientific or technical aspects. These tools could be standardized, which means that there could be a uniform tool to be used everywhere throughout the EU. The development of these harmonised risk assessment tools will imply an intensive international cooperation, with the purpose of at least making the existing differences between those tools from the Member States transparent and to investigate the possibilities for coming to similar tools from a scientific/technical perspective.     

Challenges in harmonising controls on the radioactivity of building materials within the European Union

Possibilities for harmonising controls on the radioactivity of building materials within the European Union are being discussed in a Working Party on Natural Radiation Sources established by the Article 31 Group of Experts (Euratom Treaty). The Working Party is preparing a document to aid the Article 31 Expert Group and the European Commission in considering possible recommendations and technical guidance to the Member States for the implementation of the new Basic Safety Standards Directive concerning the radioactivity of building materials. The discussions in the working party have demonstrated several challenges in the possible harmonisation of controls, many of them arising from some significant differences in national circumstances.     

Evaluation of lichen diversity as an indicator of environmental quality in the North Adriatic submediterranean region

In 2000, a standardized sampling protocol was developed by a group of European researchers to provide a repeatable and objective strategy for mapping lichen diversity as an indicator of environmental changes; this protocol is nowadays adopted in the guidelines to air quality bioindication in Italy. The present paper shows the results of a study of epiphytic lichen diversity performed according to both the new protocol and the standard methodology previously used in Italy; diversity values are based on frequency counts of all lichen species within particular sampling grids positioned on the trunks and divided in subunits. The survey was carried out in 61 sampling sites of two areas of the Friuli Venezia Giulia region (Italy) and Slovenia, characterized by similar climatic conditions and a wide range of anthropic pressure. Biodiversity values obtained following the two sampling methods are highly statistically correlated; this suggests an interpretative continuity of lichen diversity data for biomonitoring purposes. Lichen communities and diversity values occurring in natural areas, far from heavy human influences, are investigated by means of multivariate analysis of floristic releves of 11 sites. Diversity values scored in natural areas are rather variable, and are mainly influenced by the different vegetation types, Parmelion communities having lower diversity values than communities with Xanthorion elements. Evaluation scales of environmental alteration based on lichen diversity in the North Adriatic submediterranean bioclimatic area are provided. Some critical aspects of the sampling strategies are discussed.     

Planung und Durchführung eines Grundwasser-Monitorings mit Direct-Push in Nordbrandenburg

Due to high nitrogen concentrations, two groundwater bodies in Northern Brandenburg were classified under the heading “poor (chemical) condition” according to the Water Framework Directive of the European Commission. These evaluations of the “Landesumweltamt Brandenburg” were based on several investigations that compared the hydrogeochemical data with the quality norm for nitrate and with the threshold value for ammonia from the European Groundwater Directive. By sampling with direct push techniques, we re-analysed the extent of contamination in order to decide whether the water quality could be improved in a cost-effective manner. Based on the newly established data set, the area of contamination could be more precisely delineated with geostatistical techniques. This helped to determine whether the previous evaluation of local groundwater quality was still valid.     

Lead (II) detection and contamination routes in environmental sources, cookware and home-prepared foods from Zimatlán, Oaxaca, Mexico

An interdisciplinary investigation, involving environmental geochemists, epidemiologists, nurses, and anthropologists, was undertaken to determine the contamination source and pathway of an on-going outbreak of lead poisoning among migrants originating from Zimatlán, Oaxaca, Mexico and living in Seaside, California, and among their US-born children. An initial investigation in Seaside identified grasshopper foodstuff (“chapulines”) imported from Mexico and consumed as snacks, as containing alarmingly high lead concentrations (up to 2300 mg/kg). The focus in the present work concentrates on the Oaxacan area of origin of the problem in Mexico, and two potential sources of contamination were investigated: wind-borne dusts from existing mine residues as potential contaminants of soil, plant, and fauna; and food preparation practices using lead-glazed ceramic cookware.Over a three year period, sampling was conducted in Oaxaca using community-level sampling and also targeted sampling with families of cases with lead poisoning in California. In addition to fresh field chapulines, we analyzed for total lead: soil, water, mine residues, and plant materials, both from areas adjacent to or at an abandoned waste site containing mine tailings, and from fields where chapulines are collected; foodstuffs gathered in community markets or in a food transport business; and foodstuffs and cookware gathered from relatives of case families in California. Also, selected new and used lead-glazed clay cookware was extracted for lead, using 0.02 M citric acid and with 4% acetic acid.The results indicated significant presence of lead in mine wastes, in specific foodstuffs, and in glazed cookware, but no extensive soil contamination was identified. In-situ experiments demonstrated that lead incorporation in food is made very efficient through grinding of spices in glazed cookware, with the combination of a harsh mechanical action and the frequent presence of acidic lime juice, but without heating, resulting in high but variable levels of contamination.     

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.     

Baseline values for heavy metals in agricultural soils in an European Mediterranean region

Baseline values for heavy metals were proposed in Alicante (Spain), a representative agricultural area of the European Mediterranean region, as a basis to identify and assess soil contamination processes at regional level. Fifty-four agricultural plots were sampled and heavy metals concentrations were analysed for nine elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) by atomic absorption spectrometry (AAS) after acid digestion with HNO(3) and HCl in a microwave oven. Heavy metal concentrations obtained in the study area were similar to concentrations analysed by other authors within the European Mediterranean region. However, some agricultural plots with a high heavy metal content were identified by statistical treatment (boxplots) as outliers and, therefore, were not considered for establishing baseline values. Baseline values in Alicante were proposed by taking into account the statistical approach extensively used elsewhere, which refers to the increase in the mean plus twice the standard deviation. The baseline values were: 0.7 mg/kg for Cd, 11 mg/kg for Co, 36 mg/kg for Cr, 28 mg/kg for Cu, 19,822 mg/kg for Fe, 402 mg/kg for Mn, 31 mg/kg for Ni, 28 mg/kg for Pb and 83 mg/kg for Zn. The experience gained in this work further suggests that baseline values for heavy metals should be proposed in other areas. This is necessary to facilitate the identification of soil contamination processes over the whole European Mediterranean region as a basis to undertaking appropriate action to protect soil resource quality.     

Effect of gas empty bed contact time on performances of various types of rotating drum biofilters for removal of VOCs

The effects of gas empty bed contact time (EBCT), biofilter configuration, and types of volatile organic compounds (VOCs) were evaluated to assess the performance of rotating drum biofilters (RDBs), especially at low EBCT values. Three types of pilot-scale RDBs, a single-layer RDB, a multi-layer RDB, and a hybrid RDB, were examined at various gas EBCTs but at a constant VOC loading rate. Diethyl ether, toluene, and hexane were used separately as model VOC. When EBCT increased from 5.0 to 60s at a constant VOC loading rate of 2.0kgCOD/(m(3)day), ether removal efficiency increased from 73.1% to 97.6%, from 81.6% to 99.9%, and from 84.0% to 99.9% for the single-layer RDB, the multi-layer RDB, and the hybrid RDB, respectively, and toluene removal efficiency increased from 76.4% to 99.9% and from 84.8% to 99.9% for the multi-layer RDB and the hybrid RDB, respectively. When hexane was used as the model VOC at a constant loading rate of 0.25kgCOD/(m(3)day), hexane removal efficiency increased from 31.1% to 57.0% and from 29.5% to 50.0% for the multi-layer RDB and hybrid RDB, respectively. The single-layer, multi-layer, and hybrid RDBs exhibited, respectively, the lowest, middle, and highest removal efficiencies, when operated under similar operational loading conditions. Hexane exhibited the lowest removal efficiency, while diethyl ether displayed the highest removal efficiency. The data collected at the various EBCT values correlated reasonably well with a saturation model. The sensitivity of removal efficiency to EBCT varied significantly with EBCT values, VOC properties, and biofilter configurations. Process selection and design for RDB processes should consider these factors.