Using microbial community functioning as the complementary environmental condition indicator: A case study of an iron deposit tailing area

Various indices of soil microbial community and physiochemical properties at an iron deposit tailing area were investigated to evaluate the use of microbial community behavior as a complemental indicator of soil condition to traditional quality indices. Besides basal respiration rate and microbial carbon, the BIOLOG® method was applied to estimate the microbial ability in utilizing different carbon sources. Ordination methods to obtain a biological characterization of sampling sites, and principal response curve methods to reveal the carbon utilizing ability during the whole cultivating process were utilized in this study. The Nemerow composite index, which was used to assess the heavy metal contamination based on six total metal contents, hardly detected the overall discrepancy. However, there were significant differences in microbial functioning parameters at the five sampling plots, which provided more information about the environmental condition. The increases of certain metal contents and pH were accompanied by higher basal respirations (BAS). The increase of BAS did not correspond with the increase of carbon utilization and the higher level of microbial carbon contents. On the whole, these findings indicated that microbes can provide complementary information about different degrees of contamination and can be regarded as a usefully environmental indicator.

► We studied the microbial community behavior at an iron deposit tailing area to evaluate their use as soil quality indicator.
► Iron tailing have various influences to the environments and biological conditions.
► Biological indices were much more sensitive than traditional environmental indices, such as Nemerow index.
► With proper analyzing methods, biological indices can be used as complemental environmental condition indicator.