Distribution and Relationships of Seven Trace Elements （Cr, Fe, Mn, Ni, Co, Cu and Zn） in Freshwater Fish from Five French Fishing Areas

Abstract: The concentrations of seven essential trace elements in 149 freshwater fish from eight fish species (European eel, bream, common carp, European catfish, roach, perch, pike and pikeperch) from five different French fishing areas from contaminated and control sites were measured by inductivel y coupled plasma mass spectro metry after microwave diges tion under pressure. Differenc es in the concentration of elements in the muscles of these species we re examined and the mean levels were compared for each species with previous French and European studies. The condition factor and the differences between the control and contaminated sites and between predatory and non-predatory groups, with respect to the concentration of these elements, were also studied. Key words: Trace elements, freshwater fish, occurrence data, inductively coupled plasma-mass spectrometry (ICP-MS). 1. Introduction  Fish samples may be considered to be one of the most relevant indicators in freshwater systems for the estimation of metal pollution levels, mainly because fish are at the top of the food chain in the water ecosystem. In the same way, the monitoring of trace elements in fish is useful in order to understand their environmental distribution, emission sources and environmental behavior. Trace elements such as copper (Cu), iron (Fe), chromium (Cr) and nickel (Ni) are essential elements since they play an important role in biological systems, whereas the previously discussed lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As) are non-essential elements [1]. For the normal metabolism of fish, the essential elements must be taken up from water, food or