Dissolved organic matter accumulation, reactivity, and redox state in ground water of a recharge wetland

Wetlands ◽  
2008 ◽  
Vol 28 (3) ◽  
pp. 747-759 ◽  
Author(s):  
Natalie Mladenov ◽  
Philippa Huntsman-Mapila ◽  
Piotr Wolski ◽  
Wellington R. L. Masamba ◽  
Diane M. McKnight
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Ground Water ◽  
Redox State ◽  
Organic Matter Accumulation

scholarly journals Coupled Biotic-Abiotic Processes Control Biogeochemical Cycling of Dissolved Organic Matter in the Columbia River Hyporheic Zone

2021 ◽  
Vol 2 ◽  
Author(s):  
Jane D. Fudyma ◽  
Rosalie K. Chu ◽  
Nathalia Graf Grachet ◽  
James C. Stegen ◽  
Malak M. Tfaily
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Ground Water ◽  
River Water ◽  
Microbial Activity ◽  
Hyporheic Zone ◽  
Light Exposure ◽  
Abiotic Factors ◽  
Columbia River ◽  
Transformation Pathways

A critical component of assessing the impacts of climate change on watershed ecosystems involves understanding the role that dissolved organic matter (DOM) plays in driving whole ecosystem metabolism. The hyporheic zone—a biogeochemical control point where ground water and river water mix—is characterized by high DOM turnover and microbial activity and is responsible for a large fraction of lotic respiration. Yet, the dynamic nature of this ecotone provides a challenging but important environment to parse out different DOM influences on watershed function and net carbon and nutrient fluxes. We used high-resolution Fourier-transform ion cyclotron resonance mass spectrometry to provide a detailed molecular characterization of DOM and its transformation pathways in the Columbia river watershed. Samples were collected from ground water (adjacent unconfined aquifer underlying the Hanford 300 Area), Columbia river water, and its hyporheic zone. The hyporheic zone was sampled at five locations to capture spatial heterogeneity within the hyporheic zone. Our results revealed that abiotic transformation pathways (e.g., carboxylation), potentially driven by abiotic factors such as sunlight, in both the ground water and river water are likely influencing DOM availability to the hyporheic zone, which could then be coupled with biotic processes for enhanced microbial activity. The ground water profile revealed high rates of N and S transformations via abiotic reactions. The river profile showed enhanced abiotic photodegradation of lignin-like molecules that subsequently entered the hyporheic zone as low molecular weight, more degraded compounds. While the compounds in river water were in part bio-unavailable, some were further shown to increase rates of microbial respiration. Together, river water and ground water enhance microbial activity within the hyporheic zone, regardless of river stage, as shown by elevated putative amino-acid transformations and the abundance of amino-sugar and protein-like compounds. This enhanced microbial activity is further dependent on the composition of ground water and river water inputs. Our results further suggest that abiotic controls on DOM should be incorporated into predictive modeling for understanding watershed dynamics, especially as climate variability and land use could affect light exposure and changes to ground water essential elements, both shown to impact the Columbia river hyporheic zone.

Alluvial ground water influences dissolved organic matter biogeochemistry of pools within intermittent dryland streams

2015 ◽  
Vol 61 (8) ◽  
pp. 1228-1241 ◽  
Author(s):  
Andre R. Siebers ◽  
Neil E. Pettit ◽  
Grzegorz Skrzypek ◽  
Jason B. Fellman ◽  
Shawan Dogramaci ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Ground Water

Increases in humic and bioavailable dissolved organic matter in a forested New England headwater stream with increasing discharge

2016 ◽  
Vol 67 (9) ◽  
pp. 1279 ◽  
Author(s):  
Henry F. Wilson ◽  
Peter A. Raymond ◽  
James E. Saiers ◽  
William V. Sobczak ◽  
Na Xu
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
New England ◽  
Aquatic Ecosystems ◽  
Redox State ◽  
Headwater Stream ◽  
Four Component Model ◽  
Parallel Factor ◽  
Aquatic Sciences ◽  
Hillslope Processes

Understanding the processes controlling the transfer of organic matter from terrestrial to aquatic ecosystems is of fundamental importance for the aquatic sciences. Over the course of a full year, fluorescence, absorbance and bioavailability of dissolved organic matter (DOM) were characterised in Bigelow Brook, a forested headwater stream in Massachusetts, USA. Parallel factor analysis (PARAFAC) identified a four-component model to describe observed DOM fluorescence (C1–C4). Component C2 exhibited the characteristics of a more humic-like fluorophore, with a potentially more reduced redox state and increased with discharge, whereas more fulvic-like (C1) and protein-like (C3, C4) fluorophores decreased. Under both dark and light-exposed conditions, percentage bioavailable dissolved organic carbon (%BDOC) increased with discharge (R2 = 0.37 and R2 = 0.56). C2 and specific absorptivity (SUVA) were reduced following BDOC incubations, whereas C1, C3 and C4 increased. These changes to DOM characteristics with increasing discharge were observed under both baseflow and stormflow conditions, indicating that with rising watertable, loading from a large riparian or hyporheic pool of organic matter is likely occurring. Other headwater streams, where loading is controlled by hillslope processes, are likely to exhibit a similar pattern of increasing export of more humic and bioavailable DOM during hydrologic events.

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