Tracking the degradation of fresh particulate organic matter in permeable riverbed sediments using FT-ICR-MS and metagenomic/transcriptomic sequencing
EMSL Project ID
60033
Abstract
The hyporheic zone, where groundwater and river water mix within riverine corridors, represents a highly active zone of biogeochemical cycling in which key transformations of many critical elements take place at the aquatic-terrestrial interface. The near-surface riverbed, in particular, is a hot spot of biogeochemical activity, because the abundance of organic matter and associated microorganisms are several orders of magnitude higher than corresponding concentrations in the water column. This project builds upon a current DOE Subsurface Biogeochemical Research (SBR) project on the transport and metabolism of fresh, photosynthetically-derived particulate organic matter (POM) in near-surface riverbed sediments at the PNNL SFA Hanford 300 Area study site. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and polar metabolomics (LC-MS) analysis of solid and aqueous phase organic compounds will be combined with metagenomic and transcriptomic sequencing at to track the degradation of fresh POM in Hanford 300 Area riverbed sediments. Analysis of extracellular organic and inorganic metabolites will also be conducted to help constrain bulk biogeochemical fluxes associated with organic matter metabolism. The scope of these studies is well beyond the fiscal and technical capabilities of our current SBR-funded research; hence the project represents a logical target for collaboration with EMSL and JGI through the FICUS program. The combined analyses will be applied to samples from in situ “POM trap” deployments designed to constrain riverbed POM input rate and composition, as well as in situ sediment reactors and controlled batch reactor experiments designed to reveal pathways and biogeochemical fluxes associated with POM degradation as influenced by hydrologically-driven changes in redox conditions. The field and laboratory studies will be conducted in summer and fall of 2021 and thus align properly with the FICUS FY2022 timeline. Materials representative of all sample types will be available for pilot-scale studies prior to full-scale project sample analysis. Our proposed investigation of the molecular biogeochemistry of POM degradation in Columbia River sediments is of direct relevance to the Hyrdro-biogeochemistry Focused Topic Area of the FICUS program. The proposed research also directly addresses Subsurface Biogeochemical Research Program objectives to quantify how biological behavior and molecular transformations control the mobility of nutrients within watersheds. Utilization of molecular scale organic compound composition information obtained from EMSL and JGI, together with high throughput genomic sequence information obtained through JGI, will allow us to link genetic information to the transformation of organic compounds within the riverbed environment, with implications for predicting the flux and cycling of key nutrients (e.g. C, N, P) as well as contaminants whose fate is linked to organic matter metabolism within riverine ecosystems. The results from this study will be linked to hydrobiogeochemical data and modeling within and beyond our current SBR project to further constrain the mechanisms and pathways of fresh POM degradation in riverine systems undergoing hydrologic fluctuations. In this sense, the proposed work directly addresses the overarching SBR objective to advance a robust, predictive understanding of how watersheds function as integrated hydrobiogeochemical systems. In addition, the proposed development of omics-driven, substrate-explicit microbiological models will leverage DOE’s ongoing investment in pipelines designed to connect genomics databases (i.e. KBase) and automated omics-driven model generation tools for the purpose of linking microbiological and reactive transport computational tools to enhance quantitative understanding of ecosystem function.
Project Details
Project type
FICUS Research
Start Date
2021-10-01
End Date
2023-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members