1 Natural History Museum of Denmark, Natural History Museum of Denmark, Faculty of Science, Københavns Universitet2 Terrestrial Ecology, Department of Biology, Faculty of Science, Københavns Universitet3 Section for Environmental Chemistry and Physics, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet4 Geological Survey of Denmark and Greenland5 DCA - Nationalt Center for Fødevarer og Jordbrug6 Environmental Chemistry and Physics, Department of Basic Sciences and Environment, Faculty of Life Sciences, Københavns Universitet7 Natural History Museum of Denmark, Natural History Museum of Denmark, Faculty of Science, Københavns Universitet8 Terrestrial Ecology, Department of Biology, Faculty of Science, Københavns Universitet9 Environmental Chemistry and Physics, Department of Basic Sciences and Environment, Faculty of Life Sciences, Københavns Universitet
We investigated microbiota in surface and subsurface soil from a site, above steam-treated deep sub-soil originally contaminated with chlorinated solvents. During the steam treatment, the surface soil reached temperatures c. 30°C higher than the temperature in untreated soil; whereas the subsurface soil, at a depth of about 40 cm, reached a temperature c. 45°C higher than untreated soil. The soil was examined prior to, during, and 6, 12, 14, 20 and 31 months after treatment. Numbers of bacteria cultivable at 42°C increased significantly in subsurface soil. Similarly, substrate utilization in ECOLOG plates, incubated at 42°C, increased from less than 10% of available carbon sources in the untreated soil to more than 60% of the available carbon sources in the steam-treated soil. Aspergillus fumigatus was quantified as an example of heat-tolerant fungi normally found in compost. These organisms are rarely detected in Danish soils but high numbers (c. 105 hyphal forming units g−1) occurred in the treated soil up to 31 months after the steam-treatment. We conclude that steam-treatment leads to changes of the microbial communities. Some changes are temporary while others can last for years after termination of the steam-treatment; reflecting different strategies that soil microorganisms follow.
Environmental Technology, 2014, Vol 35, Issue 6, p. 773-780