Geographia Polonica (1998) vol. 71, pp. 103-108 | Full text
The forecast climatic warming will cause hydrological changes on Earth which will be accompanied by changes to the chemism and quality of waters. On account of their wide-spread occurrence and permanence, it is heavy metals in the bottom sediments of surface waters which pose the greatest endangering to the natural environment. Once introduced into it, they cannot be removed, and can in suitable conditions (i.a. of reduced pH, changed redox potential, increased salinity, increased content of organic compounds) be released from bottom sediments and give rise to secondary pollution of waters in their soluble forms. It is for that reason that heavy metals have been termed "chemical time bombs".
Teresa Rudzirska-Zapaśnik, Polish Geological Institute ul. Rakowiecka 4, 00-975 Warszawa, Poland