Presence of hazardous substances in water and fish populations of the Tajo river basin

Abstract

This study presents the levels of certain hazardous substances in water and fish from eight streams belonging to the Tajo river basin in central Spain. In order to evaluate the results, we have compared them to those obtained from a non‐polluted reference stream and also to the legal limits relative to the presence of hazardous substances in freshwater and freshwater fish. Some pollutants found to be below detection levels in the river water were present in high concentrations in fish samples. Therefore, we conclude that the legal standards of water quality for certain hazardous substances are not adequate to protect fish populations, and eventually the human population, against toxicity and bioaccumulation. Chemicals such as PCBs, DDT and Hg should be analysed not only in water but also in fish tissues and the legal criteria for freshwater quality should reflect this fact. Relevant substances in this study due to their concentrations in fish tissues are Cu, Hg, Zn, DDT, dieldrin, endrin, HCH, HCB, Iindane and PCBs. The most affected species are Cyprinus carpio and Barbus bocagei.