The influence of soil organic carbon on interactions between microbial parameters and metal concentrations at a long-term contaminated site

An in-depth analysis of actinobacterial communities shows their high diversity in grassland soils along a gradient of mixed heavy metal contamination

“…This study considered soils with a range of heavy metal concentrations which were previously demonstrated to affect soil functions, namely respiration and dehydrogenase activity, which both significantly decreased with the increasing total (Mühlbachová et al 2015). We have now demonstrated that the abundance of bacteria estimated using qPCR decreased significantly with the increasing concentrations of Cu and Zn in the soil, while the abundance of Actinobacteria was not affected and the Actinobacteria/bacteria ratio tended to increase (Supplementary Table 2).…”

“…Metal mining ceased in 1972, but the smelter still processes secondary lead and cadmium sources. The present levels of heavy metal contamination are reported from the soils over the period >30 years which makes this area suitable for the exploration of longterm heavy metal contamination (Kalac et al 1991;Mühlbachová 2011;Mühlbachová et al 2015).…”

“…The study sites for this study were selected to represent a long-term gradient of total heavy metal content (Cu, Zn, Cd, Zn, Pb and As) which was due to the variable distance from a local polymetallic smelter. Although the available concentrations of heavy metals may seem to be more relevant for studying biological effects, we have decided to base the analyses on the total heavy metal content for several reasons: (i) the metal availability can be variable in time both short-term and longterm and there is not sufficient information on the history of heavy metal availability in the area; (ii) availability of heavy metals is highly affected by the method used for extraction, for example, in the area of study, two routinely used methods delivered estimates differing almost by one order of magnitude (Mühlbachová et al 2015), and this makes comparisons to other studies where heavy metal availability was estimated difficult; and (iii) for the area of this study, the correlations of total and available heavy metal contents were found to be both linear and highly significant. Also, the effects of total and available heavy metals on soil functions (respiration, dehydrogenase activity) were both significant (Mühlbachová et al 2015).…”

Evaluation of Potential Methane Generation in the Investigation of an Abandoned Contaminated Landfill in Santiago, Chile

“…However, there is no definitive, common methodology applied to all situations. To deal with this limitation, several comparative models have been developed to establish the presence of abnormal levels of contaminants at a specific site under study (Aslibekian and Moles, 2003;Muhlbachova et al, 2015;Rodríguez et al, 2015;Wen et al, 2015;Khan et al, 2008). For example, since 1995 in the United Kingdom it has been known that soils within 1 to 3 km of metal smelters may contain up to 15 times the natural values of Pb in the soil and also may present high concentrations of Cd at distances as far as 40 km from the originating industrial activity (Aslibekian and Moles, 2003).…”

“…In polluted soils, interactions between heavy metals, organic matter content and microorganisms have been correlated (Muhlbachova et al, 2015). Increasing concentrations of metals in the urban environment have been studied, wherein concentrations of…”