Version 2 2023-12-20, 19:45Version 2 2023-12-20, 19:45
Version 1 2023-12-18, 16:36Version 1 2023-12-18, 16:36
journal contribution
posted on 2023-12-20, 19:45authored byKatarzyna H. Kucharzyk, Fadime Kara Murdoch, John Wilson, Mandy Michalsen, Frank E. Löffler, Robert W. Murdoch, Jack D. Istok, Paul B. Hatzinger, Larry Mullins, Amy Hill
Chlorinated
volatile organic compound (cVOC) degradation
rate constants
are crucial information for site management. Conventional approaches
generate rate estimates from the monitoring and modeling of cVOC concentrations.
This requires time series data collected along the flow path of the
plume. The estimates of rate constants are often plagued by confounding
issues, making predictions cumbersome and unreliable. Laboratory data
suggest that targeted quantitative analysis of Dehalococcoides
mccartyi (Dhc) biomarker genes (qPCR)
and proteins (qProt) can be directly correlated with reductive dechlorination
activity. To assess the potential of qPCR and qProt measurements to
predict rates, we collected data from cVOC-contaminated aquifers.
At the benchmark study site, the rate constant for degradation of cis-dichloroethene
(cDCE) extracted from monitoring data was 11.0 ± 3.4 yr–1, and the rate constant predicted from the abundance of TceA peptides
was 6.9 yr–1. The rate constant for degradation
of vinyl chloride (VC) from monitoring data was 8.4 ± 5.7 yr–1, and the rate constant predicted from the abundance
of TceA peptides was 5.2 yr–1. At the other study
sites, the rate constants for cDCE degradation predicted from qPCR
and qProt measurements agreed within a factor of 4. Under the right
circumstances, qPCR and qProt measurements can be useful to rapidly
predict rates of cDCE and VC biodegradation, providing a major advance
in effective site management.