Abstract
Ecological assessment, needed for the establishment of admissible dose and the persistence of the effects of heavy metals on microbial communities is reviewed with reference to recent research. Developing concepts for ecological assessment give most emphasis to the exposure time to metals and to qualitative changes in the microbial communities. The potential ability of microbial communities for the development of metal-tolerant microflora should be considered carefully in relation to the exposure time. In this sense, studies on the qualitative changes in bacterial communities after heavy metal contamination, with consideration of the phylogenical relationships between the species, should provide valuable information for better interpretations and the identification of general principle in the potential ability of bacterial communities. In addition, analytical methods for the estimation of the bioeffective amount of heavy metals, which are surely necessary for the establishment of the admissible dose and the comparison of observed effects, were also reviewed.
