Coupled dynamics of aqueous biogeochemistry in contrasting floodplain environments: Implications for Critical Zone carbon sequestration along redox gradients

Lazareva, Olesya; Kan, Jinjun; Chen, Chunmei; Sparks, Donald L.

doi:10.1016/j.apgeochem.2022.105413

Cited by 9 publications

(10 citation statements)

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“…critical zone, Fe-cycling bacteria, microbial population, redox gradients, riparian sediments and narrow slope, whereas the west bank is adjacent to a flat and wide floodplain. The soil profile consists of post-colonial oxic deposits, pre-colonial anoxic buried wetland soils underlain by suboxic valley-bottom gravel (Lazareva et al, 2022;Sawyer et al, 2014;Walter & Merritts, 2008). Soil pore water was collected by in situ borosilicate glass samplers (50 mm long, 20 mm diameter, 1 μm pore size; Ecotech) with attached PTFE (Teflon) tubes (3/1.5 mm inner/ outer diameter).…”

Section: Experimental Design and Field Samplingmentioning

confidence: 99%

“…Soil pore water was collected by in situ borosilicate glass samplers (50 mm long, 20 mm diameter, 1 μm pore size; Ecotech) with attached PTFE (Teflon) tubes (3/1.5 mm inner/ outer diameter). Six samplers were deployed on both banks (three depths each) with installation of in situ real-time monitoring sensors to measure temperature and redox (details can be found in Lazareva, 2012, Lazareva et al, 2022. No pore water was obtained from the post-colonial deposits owing to unsaturated conditions, and therefore in this study we focused on the water samples extracted from the pre-colonial buried wetland layer (Figure 1).…”

Section: Experimental Design and Field Samplingmentioning

confidence: 99%

“…Iron [Fe(II)] was determined directly in the field on a multi-analyte portable photometer (V-2000; CHEMetrics) using the phenanthroline method. Conductivity, alkalinity, dissolved organic carbon (DOC), dissolved organic matter (DOM) quality, major anions and major cations were analysed and published separately (Lazareva et al, 2022).…”

Section: Experimental Design and Field Samplingmentioning

confidence: 99%

“…3D confocal micrographs of Fe precipitates that formed when the reduced Fe was exposed to oxygen were imaged using a Multiphoton Lazareva et al, 2022;Walter and Merritts, 2008). In situ porewater samplers were installed at both east and west floodplains across the stream: EG, east gravel; EW, east wetland; WG, west gravel; WW, west wetland.…”

Section: Confocal Microscopymentioning

confidence: 99%

“…The relationships between environmental parameters and NMDS were accomplished by correlating environmental data values against the NMDS dimension scores based on Spearman's ranked correlations by using SAS (version 9.4, 2013). Environmental variables included temperature, pH, conductivity, Fe(II), alkalinity, DOC, and other ion and cations (Table 1; Lazareva et al, 2022), and the hydrological data. Significant correlations (p < 0.05) indicated environmental variables associated with differences in microbial community structure.…”

Section: Multivariate Statistical Analysis and Correlations With Envi...mentioning

confidence: 99%

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Porewater microbiomes in buried wetland soils: Synergic effects of water chemistry and redox gradients associated with hydrological processes

Kan,

Lazareva,

Oviedo‐Vargas

et al. 2024

Freshwater Biology

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Interstitial water or pore water occupies the space between soil particles and provides “hotspots” and “fluvial networks” for microbial activities in floodplain soil. However, to date, we know very little about the microorganisms living in pore water and how they respond to environmental changes. This study aimed to understand microbial distribution and assemblage in riparian pore waters, and how they respond to water chemistry and redox gradients associated with hydrological processes. We analysed the annual changes of porewater microbial communities from the east and west banks of the White Clay Creek, a site at the Christina River Basin – Critical Zone Observatory, Pennsylvania, USA. Microbial abundances were quantified by epifluorescence microscopy and detailed community structures were characterised by high‐throughput sequencing. Water chemistry and redox gradients were also monitored and recorded, and their interactions with porewater microbiomes were analysed using correlations and multivariate analyses. Abundance of microbial cells increased during summer and late autumn. Wetland porewater microbiomes mainly contained Acidobacteria, Bacteroidetes, Nitrospirae and Proteobacteria, and microbiome structures were easily distinguishable from those in the underlying hyporheic gravel layer. Seasonal dynamics of bacterial community structure in the east and west wetlands were distinct, responding to floodplain topography and associated hydrological/geochemical processes. Iron (Fe)‐cycling bacteria (mainly Gallionellaceae and Rhodoferax spp.) dominated the porewater microbiome, and their relative abundance was significantly higher in the east than the west wetland. Furthermore, Fe‐oxidising bacteria (Gallionellaceae) were negatively correlated with Fe‐reducing bacteria (Rhodoferax spp.) at the east wetland. Microbial abundances (cell density) in pore waters showed similar seasonal patterns across stream banks, but microbial community structure did not. Microbiome assembly in pore water is correlated with water chemistry and redox gradients primarily associated with local hydrological processes. As a consequence of their significance for carbon (C) mineralisation and Fe reduction at terrestrial–aquatic interfaces, microbiomes in riparian pore waters and associated microbial activity play an essential role in C and mineral dynamics. These findings will inform future studies of the response of freshwater ecosystems to hydrological dynamics influenced by global climate change.

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Section: Experimental Design and Field Samplingmentioning

confidence: 99%

Section: Experimental Design and Field Samplingmentioning

confidence: 99%

Section: Experimental Design and Field Samplingmentioning

confidence: 99%

Section: Confocal Microscopymentioning

confidence: 99%

Section: Multivariate Statistical Analysis and Correlations With Envi...mentioning

confidence: 99%

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