ABSTRACT
The interaction of heavy metals with soil mineral components has been recently reviewed (see, for example, reviews by Naidu et al., 1995, 1996, 1997). These studies reveal that such interactions vary with both the nature and proper ties of soils, with the retention of metal cations generally increasing with increas ing soil pH. The implications of such interactions to soil and crop quality have also been studied, although the role of soil chemical factors on remediation of metal contaminated sites is challenging and still a subject of much interest. In contrast to metal-soil mineral interactions, only limited studies have been con ducted on the impact of metals on soil biodiversity, especially in relation to both bioavailability and metal-organic interactions. Where such studies have been per formed, the focus has been heavy metal toxicity and bioavailability to soil micro bial populations at the population level (Brookes et al., 1986; Chander and Brookes, 1991a,b; Martensson and Witter, 1990) or at the functional level (e.g., Giller et al., 1997). While metal contaminants may change microbial community structure and species diversity, the functional ability of the community may re main unchanged. The abundance and species composition of microbial groups reflect the total ecotoxicological, effects of heavy metals and not just the results of bioavailability at any particular time. In this chapter, by following an overview of sources of metals and their interactions in soils we aim to relate soil-metal interactions to microbial biodiversity and its potential implications to soil produc tivity.
