Immobilisation of heavy metals to enhance biological degradation of organic soil contaminants

Wien

2014

S. 21

Artikel aus einer ZeitschriftUnselbständiges Werk

200190145

According to the Austrian Environment Agency (UBA) there are more than 2000 contaminated sites in Austria in need of remediation. Mixed contaminations (organic plus inorganic pollutants) represent a frequently occurring contamination type. Conventional remediation techniques like "dig and dump" are costly and limited in scale. Plant- and microbe-based alternatives, e.g. phytoremediation options, offer a cheap and environmentally friendly approach that can be applied on larger areas. However, the application of phytoremediation techniques to mixed contaminated sites may be tricky due to the potential inhibition of biodegradation processes by the presence of heavy metals in soil. Therefore, the objective of this study is to test the hypothesis that the degradation of organic pollutants can be enhanced by immobilising interfering heavy metals. As part of the ISOMON project ("Isotope application for remediation, aftercare and monitoring of contaminated sites"), this 3 year study aims to identify the influence of heavy metal immobilisation on the degradation of organic pollutants, and to determine chemical, physical and biological measures further accelerating these processes. Degradation of organic pollutants is monitored by analysis of the carbon isotope ratio (12C/13C) using compound specific isotope analysis (CSIA). The influence of heavy metals on organic pollutant degradation will be assessed by using 13C-phospholipid fatty acid analysis (13C-PLFA). Application of 13C-labeled phenanthrene will allow the identification of microbial groups responsible for the degradation process. The influence of heavy metal immobilisation on the degradation of organic pollutants will first be analyzed in a laboratory batch trial, followed by a greenhouse experiment and a field trial. For metal immobilisation and enhanced biodegradation, distinct mineral and organic soil amendments (iron oxides, gravel sludge, biochar) are deployed, partly in combination with fast-growing and pollution-tolerant woody plants (willow, black locust and alder).