A natural, contaminant-impacted groundwater microbial community from the Hanford Site 300 Area Integrated Field Research Challenge site in eastern Washington. 16S rRNA gene pyrosequencing of groundwater bacteria and archaea across three well clusters and multiple depths showed strong temporal and spatial community dynamics linked to Columbia River water intrusion, depth, nitrate, uranium, and redox conditions. The community includes Proteobacteria, Bacteroidetes, Actinobacteria, Acidobacteria, OP3, low-abundance archaea, and functional guilds such as putative methane oxidizers, sulfur oxidizers, ammonia-oxidizing archaea, and metal reducers.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Proteobacteria/Pseudomonadota — ontology label: Pseudomonadota | NCBITaxon:1224 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
PRIMARY_PRODUCER
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DOMINANT |
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| Bacteroidetes aquifer bacteria — ontology label: Bacteroidota | NCBITaxon:976 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
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DOMINANT |
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| Actinobacteria/Actinomycetota aquifer bacteria — ontology label: Actinomycetota | NCBITaxon:201174 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
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DOMINANT |
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| aquifer archaea, including ammonia-oxidizing archaea — ontology label: Archaea | NCBITaxon:2157 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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ABUNDANT |
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Ecological Interactions
The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.
Columbia River Intrusion Community Turnover
Field 16S profiles showed temporal community turnover associated with seasonal Columbia River intrusion, particularly near the water table. The authors identify intrusion as a structuring influence using hydrology and nitrate-based mixing estimates. These positive field observations do not isolate nitrate from transported cells or other covarying environmental changes, or show that community turnover causes electron-donor/acceptor flux. The four canonical broad taxon groups are a curated subset, not the complete sampled community.
Participating Taxa: Proteobacteria/Pseudomonadota, Bacteroidetes aquifer bacteria, Actinobacteria/Actinomycetota aquifer bacteria, aquifer archaea, including ammonia-oxidizing archaea
Metabolites: nitrate (CHEBI:17632 · MediaIngredientMech · CMMMech)
Evidence
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PMID:22456444 - SUPPORT (IN_VIVO)"The shift in community composition associated with the large dynamics in Actinobacteria ACK-M1 and other clades suggested that river water intrusion could have significant impacts on microbial community composition."
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PMID:22456444 - SUPPORT (IN_VIVO)"Here, we demonstrate that Columbia River water intrusion affects microbial community composition in the aquifer, 250 m from the shoreline."
Putative Guild Patterns and Inferred Redox Resource Dynamics
PARTIAL - spatial and temporal 16S OTU patterns assigned to putative methane-oxidizing and metal-reducing guilds suggest changing electron-donor and electron-acceptor availability. This is a functional and resource-dynamics inference from community profiles, not direct measurement of annual metabolic flux or demonstrated niche partitioning. The broad canonical taxon subset does not identify every guild member.
Participating Taxa: Proteobacteria/Pseudomonadota, Bacteroidetes aquifer bacteria, Actinobacteria/Actinomycetota aquifer bacteria, aquifer archaea, including ammonia-oxidizing archaea
Metabolites: nitrate (CHEBI:17632 · MediaIngredientMech · CMMMech)
Evidence
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PMID:22456444 - PARTIAL (COMPUTATIONAL)"Spatial and temporal patterns for several 16S rRNA gene operational taxonomic units associated with particular physiological functions (for example, methane oxidizers and metal reducers) suggests dynamic changes in fluxes of electron donors and acceptors over an annual cycle."
Putative Redox Guilds in Depth-Stratified Sampling
Selected cached excerpts report higher proportions of putative ammonia-oxidizing archaea, methane oxidizers and metal reducers. Separate Methods excerpts describe sampling across 10-17 m, including near the Hanford-Ringold contact. The extracted guild sentence does not preserve its precise depth comparison, and full-body verification was unavailable. Guild assignments suggest functional potential, not measured ammonia oxidation, methane oxidation or uranium reduction by each canonical group. These excerpts do not establish resource-mediated niche partitioning or a causal sequence from inferred annual flux.
Participating Taxa: Proteobacteria/Pseudomonadota, Bacteroidetes aquifer bacteria, Actinobacteria/Actinomycetota aquifer bacteria, aquifer archaea, including ammonia-oxidizing archaea
Metabolites: nitrate (CHEBI:17632 · MediaIngredientMech · CMMMech), uranium(VI) (CHEBI:32992 · MediaIngredientMech · CMMMech)
Biological Processes:
- nitrification (GO:0019329 · PathwayMech)
Evidence
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PMID:22456444 - SUPPORT (IN_VIVO)"we observed a higher proportion of putative ammonia-oxidizing Archaea, methane oxidizers and metal reducers."
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PMID:22456444 - PARTIAL (COMPUTATIONAL)"Spatial and temporal patterns for several 16S rRNA gene operational taxonomic units associated with particular physiological functions (for example, methane oxidizers and metal reducers) suggests dynamic changes in fluxes of electron donors and acceptors over an annual cycle."
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which processes connect river intrusion, guild composition and redox activity?
The primary abstract and selected cached snippets support hydrologic composition associations and putative guild patterns. They do not establish community turnover causing electron flux or flux causing depth enrichment; both former arrows are removed. Resolve transported cells, mixing, geochemistry, absolute population dynamics and directly measured metabolic rates before assigning selective mediation or niche partitioning. The local cache is selected snippets despite its full_text label; PMC CAPTCHA and publisher/Europe PMC failures prevented complete Methods/Results verification. The abstract also proposes top-down biological control, but no new predation branch is inferred here. The four canonical taxa are an incomplete broad roster, not guild-resolved partners. Non-graph metadata is preserved, not recertified. The selected guild-enrichment sentence lacks its spatial comparator; do not assign it specifically to the formation contact or a redox transition without primary-body verification.
Attaches to: ecological_interactions#Columbia River Intrusion Community Turnover, ecological_interactions#Putative Guild Patterns and Inferred Redox Resource Dynamics, ecological_interactions#Putative Redox Guilds in Depth-Stratified Sampling
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Columbia River water intrusion | nitrate mixing signal from 0.4 mg nitrate/L river water and 25 mg nitrate/L groundwater | N/A |
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| Vertical aquifer sampling depth | 10 m water-table, 13 m mid-Hanford formation, and 17 m near Hanford-Ringold contact | N/A |
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| Hanford 300 Area contaminant context | uranium and inorganic contaminants from historical nuclear materials production | N/A |
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