Sampling of Radionuclides in the Environment (ICRU Report 75)

This Report provides a conceptual guide for designing statistically based sampling approaches for the analysis of radionuclides in environmental media such as soil, sediment, water, plants, aquatic organisms and animals. Some causes and examples of the magnitude of the observed sampling variability are provided. General concepts and principles of statistical sampling are briefly described in a qualitative manner, including standard sampling designs with their random and systematic errors. This is followed by a presentation of equations and practical examples for estimating statistical quantities such as the means, proportions, or ratios of two quantities. Sampling to estimate spatial patterns, temporal trends, and spatio-temporal variations is briefly described. This report is also a resource to helpful and relevant statistics literature. It does not attempt to provide step-by-step guidelines for designing specific sampling protocols, nor does it provide details for the analysis of data resulting from sampling programs. For these tasks, advice, recommendations and recipes are found in the literature cited.

The present Report provides recommendations for designing statistically based sampling approaches for analysis of radionuclide concentrations in environmental media such as soil, sediments, water, plants, aquatic organisms and animals. Some causes and examples of sampling variability are discussed. The introduction is followed in Section 2 with a discussion of the causes and typical magnitudes of variability in radionuclide activity densities observed from field sampling. Such information is normally a prerequisite to the proper development of a sampling design that is likely to adequately answer the research or monitoring question at hand. Section 3 discusses statistical concepts and principles for sampling. The presentation of these concepts and principles is based on the need to understand their basis and to still find a reasonable balance between purely ideal statistical considerations and the ever-present practical constraints of time and resource availability. Which sampling design might be the most appropriate, and how many individual replicate samples might be needed to answer a specific question or to test a given hypothesis, are the type of questions dealt with in this section of the report.

Practical approaches to the estimation of statistical quantities such as averages, proportions, percentiles, inventories, and totals are discussed in Section 4. These discussions are based on statistical principles and mathematical equations, and are illustrated with actual case studies. The next topic in Section 5 deals with sampling to estimate spatial pattern, where both design-based and model-based sampling schemes are described. Methods of locating ‘hot spots’ i.e., local areas of significantly elevated activity density compared to the surrounding areas are presented. The use of geographic information systems (GIS) for the determination of spatial pattern and development of maps is described.

The final topic presented in Section 6 is sampling to estimate temporal trends or patterns to evaluate their impact. Combined with the previous one, this section describes the spatio-temporal data, i.e., the analysis of how spatial distribution patterns of radionuclides might change over time. A general summary is provided in Section 7. Various appendices, a list of quantities and units, and a glossary of specialized terms are also provided at the end of the report.

The goal of this report is to provide a broader and improved conceptual framework for increasing the quality and applicability of the science of radioecology.

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