Use and Relevance of Analytical Intercomparison Exercises in Monitoring the Marine Environment

Abstract

The results of several intercomparison exercises for heavy metals and organochlorine residues in marine samples are reviewed. We conclude that, with few exceptions, the levels of agreement between the participating analysts are not good enough to allow them all to take part in multilaboratory monitoring programs, particularly with respect to monitoring residues in fish to determine whether they comply with standards set for human consumption or for comparing levels of contamination in different areas. Reproducibility of analysis is generally better at the higher concentrations and may be sufficient to measure a decrease in contamination following the removal of a highly polluting discharge. However, at the lower concentrations existing in cleaner environments many techniques that analysts currently use may be unable to achieve a degree of precision (or accuracy) sufficient to measure long-term trends in contamination. Analyses carried out by individual laboratories for the purpose of measuring trends in contamination levels must include regular intralaboratory checks to ensure a constant level of performance throughout the period of study.