The NSO-HET substance group includes creosote-like pollutants and is classified similarly to PAHs and BTEX aromatics as hazardous to groundwater. The quantification of the microbial degradation of NSO-HET is therefore highly important when assessing monitored and enhanced natural attenuation (MNA/ENA). The aim of this research project is to develop a method to quantify the microbial and chemical-oxidative degradation of NSO-heterocycles using flow cytometry and isotope fractionation (IF).
The quantification/assessment of the degradation of creosote-like NSO-heterocycles (NSO-HET) for natural/stimulated microbial degradation as well as for the use of in-situ chemical oxidation (ISCO) is problematic because to date there are no methods to quantify the microbial degradation of NSO-HET via IF or any experiences on the effectiveness of ISCO methods in terms of the degradation of NSO-HET. For N-/ S-HET, degradation involves not just a 13C/12C-IF but it is highly likely that fractionation of 15N/14N or 34S/32S also occurs. The microbial degradation and the chemical oxidation of the NSO-HET is first investigated under controlled laboratory conditions with model and real groundwater, and the fractionation effects of the NSO-HET are determined. The microbial and chemical laboratory experiments for this research project were conducted at TZW. TZW developed an ISCO method for the degradation of NSO-HET and a biomonitoring method using flow cytometry to rapidly detect bacterial growth during degradation. The13C/12C-, 15N/14N- and 34S/ 35S-IF method was developed at Hydroisotop GmbH.
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