Riparian Microtopography Affects Event‐Driven Stream DOC Concentrations and DOM Quality in a Forested Headwater Catchment

Blaurock, Katharina; Garthen, Phil; Silva, Maria Paula da; Beudert, Burkhard; Gilfedder, Benjamin; Fleckenstein, Jan H.; Peiffer, Stefan; Lechtenfeld, Oliver J.; Hopp, Luisa

doi:10.1029/2022jg006831

Cited by 4 publications

(3 citation statements)

References 141 publications

(200 reference statements)

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“…These areas at the interface between the terrestrial and aquatic ecosystems can exert an important control on stream biogeochemical cycling (Naiman & Décamps, 1997). Research in temperate and boreal regions has shown that discrete points along the riparian corridor can play a significant role in transferring both DOC (Blaurock et al., 2022; Lupon et al., 2023; Ploum et al., 2021) and DIC (Leith et al., 2015; Öquist et al., 2009) to adjacent streams. It is reasonable to expect that these findings from northern regions would also apply to tropical streams.…”

Section: Discussionmentioning

confidence: 99%

Seasonal Wetlands Make a Relatively Limited Contribution to the Dissolved Carbon Pool of a Lowland Headwater Tropical Stream

Solano,

Duvert,

Hutley

et al. 2024

JGR Biogeosciences

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Wetlands process large amounts of carbon (C) that can be exported laterally to streams and rivers. However, our understanding of wetland inputs to streams remains unclear, particularly in tropical systems. Here we estimated the contribution of seasonal wetlands to the C pool of a lowland headwater stream in the Australian tropics. We measured dissolved organic and inorganic C (DOC and DIC) and dissolved gases (carbon dioxide—CO2, methane—CH4) during the wet season along the mainstem and in wetland drains connected to the stream. We also recorded hourly measurements of dissolved CO2 along a ‘stream–wetland drain–stream’ continuum, and used a hydrological model combined with a simple mass balance approach to assess the water, DIC and DOC sources to the stream. Seasonal wetlands contributed ∼15% and ∼16% of the DOC and DIC loads during our synoptic sampling, slightly higher than the percent area (∼9%) they occupy in the catchment. The riparian forest (75% of the DOC load) and groundwater inflows (58% of the DIC load) were identified as the main sources of stream DOC and DIC. Seasonal wetlands also contributed marginally to stream CO2 and CH4. Importantly, the rates of stream CO2 emission (1.86 g C s−1) and DOC mineralization (0.33 g C s−1) were much lower than the downstream export of DIC (6.39 g C s−1) and DOC (2.66 g g C s−1). This work highlights the need for further research on the role of riparian corridors as producers and conduits of terrestrial C to tropical streams.

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Section: Discussionmentioning

confidence: 99%

Seasonal Wetlands Make a Relatively Limited Contribution to the Dissolved Carbon Pool of a Lowland Headwater Tropical Stream

Solano,

Duvert,

Hutley

et al. 2024

JGR Biogeosciences

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“…Warmer summer and early fall temperatures are favorable for the accumulation of a larger pool of available DOC (Strohmeier et al., 2013). With disrupted flow in a non‐perennial stream, DOC may be stranded in the hyporheic zone (Harjung et al., 2019), tiny pockets of stream water (Granados et al., 2020), and shallow OM‐rich soils adjacent to the stream (Blaurock et al., 2022). Summer storms occurring after disconnected conditions not only briefly reconnect channel sources but also increase hydrologic connectivity to accumulated DOC in wetter pockets of the riparian zone (Blaurock et al., 2022).…”

Section: Discussionmentioning

confidence: 99%

“…With disrupted flow in a non‐perennial stream, DOC may be stranded in the hyporheic zone (Harjung et al., 2019), tiny pockets of stream water (Granados et al., 2020), and shallow OM‐rich soils adjacent to the stream (Blaurock et al., 2022). Summer storms occurring after disconnected conditions not only briefly reconnect channel sources but also increase hydrologic connectivity to accumulated DOC in wetter pockets of the riparian zone (Blaurock et al., 2022). Drying‐rewetting cycles occurring during summer and early fall then provide small flushes that gather up stored DOC, whether from in‐channel pools or more distal terrestrial sources, and stimulate new biogeochemical transformations with changing DO and redox conditions.…”

Section: Discussionmentioning

confidence: 99%

Carbon Biogeochemistry and Export Governed by Flow in a Non‐Perennial Stream

Bretz,

Murphy,

Hotchkiss

2023

Water Resources Research

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Non‐perennial headwaters experience extremes in flow conditions that likely influence carbon fate. As surface waters contract through dry periods, reconnect during storms, and re‐expand or dry again, there is a great deal of variability in carbon emissions and export. We measured discharge, dissolved oxygen, carbon dioxide (CO2), and dissolved organic carbon (DOC) continuously in a persistent pool at the base of a non‐perennial, forested headwater stream in the southeastern United States to characterize how flow changes affect carbon emissions and export as the stream expands and shrinks. We also compared carbon concentrations and export during different stream flow categories before and after fall wet‐up. CO2 concentrations were high when discharge was lowest (median = 10.2 mg L−1) and low during high flows (3.2 mg L−1) and storms (1.1 mg L−1). High CO2 concentrations led to high emissions on a per area basis during low flow times, but whole‐channel stream CO2 emissions were limited by the small surface area of the stream during periods of surface water disconnection. DOC concentration varied by season (range = 0.1–16.2 mg L−1) with large pulses during smaller summer storms. We found that CO2 and DOC concentrations differed among binned stages of stream flow. As non‐perennial streams become more prevalent across the southeastern United States due to shifts in climate, the relationships between flow and carbon movement into and out of stream networks will become increasingly critical to understanding stream carbon biogeochemistry.

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A rapid method to quantify sub-micrometer polystyrene particles in aqueous model systems by TOC analysis

Schmidtmann,

Peiffer

2024

Micropl.&Nanopl.

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For several laboratory experiments with microplastics, a simple and fast quantification method is advantageous. At the same time, the requirements are often lower compared to microplastic detection from environmental samples. We determined the concentration of non-purgable organic carbon of polystyrene (PS) particles (diameter 0.5, 1, 2, 6 μm) in suspension with known concentrations. Commercially available PS particles were used to test the Total Organic Carbon (TOC) analyzer method for quantifying microplastics in the lower micrometer range under absence of other organic compounds. Addition of iron or aluminum hydroxide to the samples prior to the measurement increased the recovery from 52.9 to 89.7% relative to measurements in the absence of metal hydroxides. With increasing particle size, the recovery in the presence of iron hydroxides decreased from 95.1% at 0.5 μm to 67.1% at 6 μm PS particles and in the presence of aluminum hydroxides from 92.6% at 0.5 μm to 88.9% at 6 μm PS particles. We conclude that metal hydroxides have a catalytic effect on the thermocatalytic oxidation of PS particles and allow a complete conversion to CO2 for a successful quantification of PS particles using a TOC analyzer. Especially for particles larger than 0.5 μm, in the absence of metal hydroxides, the TOC device is not able to fully oxidize the PS particle to CO2 and subsequently detect its concentration. Thus, TOC analysis of PS particles in the presence of metal hydroxides provides a cheap and simple alternative for quantifying microplastic particles in the lower micrometer range for laboratory experiments (e.g. sedimentation studies) where no other organic substances are present.

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Riparian Microtopography Affects Event‐Driven Stream DOC Concentrations and DOM Quality in a Forested Headwater Catchment

Cited by 4 publications

References 141 publications

Seasonal Wetlands Make a Relatively Limited Contribution to the Dissolved Carbon Pool of a Lowland Headwater Tropical Stream

Seasonal Wetlands Make a Relatively Limited Contribution to the Dissolved Carbon Pool of a Lowland Headwater Tropical Stream

Carbon Biogeochemistry and Export Governed by Flow in a Non‐Perennial Stream

A rapid method to quantify sub-micrometer polystyrene particles in aqueous model systems by TOC analysis

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