Effects of heavy metal and metalloid contamination on the soil microbial response: An overview

Abstract

Heavy metals constitute a heterogeneous group of elements varying in their chemical properties and biological functions. Pollution of heavy metals in soil is of great concern for human health and functioning of ecosystem as they have toxic effects on plants, animals and human being. Contamination of soil by heavy metal results from both anthropogenic as well as natural activities. Anthropogenic activities includes mining, smelting operation, sewage sludge or wastewater, small scale industries etc. These activities may increase the levels of heavy metals in soil upto the toxic level. Heavy metals are persistent in nature, therefore get bioaccumulated in soils and they can also affect soil microbial activity. Microbial communities in soil are made up of five major groups, namely: bacteria, fungi, algae, archaea and protozoa. Among all, bacteria are the most abundant group and usually more numerous than the others. Soil microbes play vital roles in various aspects of the terrestrial ecosystem, such as soil fertility during plant growth, including agronomic activities. Soil microbial biomass represents the fraction of the soil responsible for the energy and nutrient cycling and regulation of organic matter transformation. It is through the microbial biomass, mineralization of important organic elements take place. Microbial activity is very closely related with soil fertility. Microbial biomass may be a sensitive indicator of metal stress.Its suitability in environmental monitoring as an indicator of soil pollution is limited because of its high spatial variability. The present chapter deals with various aspects of effects of heavy metal pollution and its effect on soil microbial response. © 2011 by Nova Science Publishers, Inc. All rights reserved.