Details

Autor(en) / Beteiligte

• Gilevska, Tetyana
• Passeport, Elodie
• Shayan, Mahsa
• Seger, Edward
• Lutz, Edward J.
• West, Kathryn A.
• Morgan, Scott A.
• Mack, E. Erin
• Sherwood Lollar, Barbara

Titel

Determination of in situ biodegradation rates via a novel high resolution isotopic approach in contaminated sediments

Ist Teil von

• Water research (Oxford), 2019-02, Vol.149, p.632-639

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A key challenge in conceptual models for contaminated sites is identification of the multiplicity of processes controlling contaminant concentrations and distribution as well as quantification of the rates at which such processes occur. Conventional protocol for calculating biodegradation rates can lead to overestimation by attributing concentration decreases to degradation alone. This study reports a novel approach of assessing in situ biodegradation rates of monochlorobenzene (MCB) and benzene in contaminated sediments. Passive diffusion samplers allowing cm-scale vertical resolution across the sediment-water interface were coupled with measurements of concentrations and stable carbon isotope signatures to identify zones of active biodegradation of both compounds. Large isotopic enrichment trends in 13C were observed for MCB (1.9–5.7‰), with correlated isotopic depletion in 13C for benzene (1.0–7.0‰), consistent with expected isotope signatures for substrate and daughter product produced by in situ biodegradation. Importantly in the uppermost sediments, benzene too showed a pronounced 13C enrichment trend of up to 2.2‰, providing definitive evidence for simultaneous degradation as well as production of benzene. The hydrogeological concept of representative elementary volume was applied to CSIA data for the first time and identified a critical zone of 10–15 cm with highest biodegradation potential in the sediments. Using both stable isotope-derived rate calculations and numerical modeling, we show that MCB degraded at a slower rate (0.1–1.4 yr−1 and 0.2–3.2 yr−1, respectively) than benzene (3.3–84.0 yr−1) within the most biologically active zone of the sediment, contributing to detoxification. [Display omitted] •Simultaneous biodegradation of MCB and benzene identified in sediments using CSIA.•Novel approach to calculate in situ degradation rates via high-resolution profiles.•New CSIA approach identifies of critical zone of maximum biodegradation potential.