Scientific Background: Isotope field studies

Isotopic monitoring of in situ biodegradation for diverse contaminants have been described within the scientific literature. Here are a few selected studies:

In a landfill plume, which was dominanted by methanogenic and sulfate reducing conditions, microbial degradation of BTEX and naphthalene was demonstrated (10).
At a gas plant site, anaerobic biological attenuation of several BTEX compounds was verified and quantified by isotope fractionation (2, 9, 11).
A BTEX plume of a previous hydrogenation plant was dominated by sulfate reducing conditions. In situ degradation of benzene and toluene could be determined by isotope monitoring (1, 12).
After a tanker-truck accident, the anaerobic biodegradation of toluene was calculated via isotope fractionation (7).
Isotope enrichment of tetrachlorethene was used to quantify microbial degradation in groundwater contaminated by a dry cleaning plant (13).
Biological dechlorination of CAHs was investigated and quantified in anaerobic groundwater below a military air base (6).
At another air base, enhanced biodegradation of cis-1,2-dichlorethene was verified and calculated by isotope monitoring (8).
Close to a former repository of chlorinated compounds, biodegradation pathways were elucidated by using sotopic fractionation (3).
Extensive contamination at an industrial site was investigated for biodegradation of chlorobenzene. The anaerobic degradation of monochlorobenzene was shown by isotope measurements (4).
The investigation of carbon and hydrogen isotopes elucidated the anaerobic and aerobic biodegradation of MTBE at several oil spill sites (5, 14).

More contaminated sites, where natural attenuation was successfully demonstrated by isotope monitoring:

Contaminant	Location	Incident	Geology	Authors
BTEX, PAK	Hamburg	Oil leakage	Sand, marl	Richnow & Meckenstock 1999, 10
BTEX	Vejen, DK	Landfill	Porous, glacial	Vieth et al. 2001
BTEX	Zeitz	Oil industrial site	Quaternary/ tertiary	Vieth et al. 2001, 2005
BTEX	Gneisenau	Coking plant	Porous & jointed	Pfeifer et al. 2003
BTEX	Zeitz	Oil industrial site	Quaternary/ tertiary	Fischer et al. 2004
BTEX	Ingolstadt	Oil leakage	Quaternary	Morasch et al. 2002/2003
BTEX	Stuttgart	Gas plant	Quaternary, heterogenuous	Steinbach et al. 2004
BTEX	South-England	Oil leakage	Chalk, jointed	Spence et al. 2005
BTEX, PAK	Stuttgart	Gas plant	Quaternary, heterogenuous	Griebler et. al. 2004
CKW	Bitterfeld	Industrial site	Quaternary/ tertiarygravel/ sand	Kaschl et al. 2005
CKW	Connecticut, USA	Industrial site	gravel/sand; ENA: permanganate	Hunkeler et al. 2003
CKW	Leipzig	Dry-cleaner	Quaternary/ tertiary	Vieth et. al. 2003
CKW	Texas, USA	Airfield	sand/clay; ENA: permanganate	Morill et. al. 2005
CKW	Idaho, USA	Test field	Basalt, jointed; ENA: permanganate	Song et al. 2002
CKW	Canada	Landfill	sand/clay-layers	Hunkeler et al. 2005
MTBE	New Jersey, USA	Petrol station	sand/clay-layers, riparian zone	Kolhatkar et al. 2002
MTBE	South America	Landfill	Heterogenuous, multiple sources	Zwank et al. 2005
MTBE	South-England	Oil leakage	Chalk, jointed	Spence et al. 2005
MTBE	12 x California, USA	Petrol stations	12 sites	Kuder et al. 2005
MTBE	Zurich, CH	Oil leakage	gravel/sand, heterogenuous	Berg et al. 2005

= in collaboration with associates from Isodetect