Streambank Legacy Sediments in Surface Waters: Phosphorus Sources or Sinks?

Inamdar, Shreeram; Sienkiewicz, Nathan; Lutgen, A.; Jiang, G.; Kan, Jinjun

doi:10.3390/soilsystems4020030

Cited by 13 publications

(7 citation statements)

References 65 publications

(147 reference statements)

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“…Perturbations of sediment and nutrients to stream networks significantly impact hydrologic, biological, and chemical functions in downstream aquatic and riparian environments (Graeber et al, 2012;Inamdar et al, 2012;Walter et al, 2007). Thus, quantification of physical and chemical consequences of legacy sediment influx, including volumes of eroded soil/sediment and associated nutrients, will improve our understanding and modeling of nutrient pollution in Piedmont streams and reservoirs (Inamdar et al, 2020(Inamdar et al, , 2021. Moreover, determining sediment and nutrient volumes is an essential constraint in ongoing efforts to reduce the contributions of non-point source nutrient loading to the eutrophication of rivers and estuaries along the Atlantic coast (e.g., Bhattacharya & Osburn, 2020;Fleming et al, 2019;Lebo et al, 2012;Paerl, 2009;Paerl et al, 2010).…”

Section: Anthropogenic Impacts On Hillslope Erosionmentioning

confidence: 99%

Channel head response to anthropogenic landscape modification: A case study from the North Carolina Piedmont, USA, with implications for water quality

Atkins

Wegmann

Bohnenstiehl

2022

Earth Surf Processes Landf

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European-American settlement of the south-eastern United States introduced agricultural practices that included extensive clearing of forested hillslopes to support food and cash-crop agriculture. This land disturbance has long-term effects on stream morphology by displacing channel heads down-valley, impacting downstream sediment and nutrient supply as channel heads migrate back up-valley towards their pre-disturbance locations. This study investigates 40 stream channels in William B. Umstead State Park in the Piedmont of North Carolina using relationships between local slope and contributing drainage areas to predict channel head locations and compare these to their observed positions. Further, expected eroded sediment and nutrient contributions are quantified using migration distances and sampled soils near channel heads. Of the 40 investigated channel heads, 23 are located down-valley from their predicted location by an average of 174.4 m AE 109.6(1 À σ). Using this distance and average channel cross-sectional area, 1.6 AE 1.4 m 2(1 À σ), the expected future erosion per channel is 282.6 AE 177.6 m 3 (1 À σ).Drainage density was used to extrapolate volumes to the 23 km 2 park using a conservative estimate that 50% of the first-order channel heads will migrate up-valley, implying an additional 90.4 AE 56.8 Â 10 3 m 3 (1 À σ) of sediment is expected to erode from the study area. Finally, scaling these volume estimates to sampled soil nutrient values indicates that approximately 1053 AE 662 t (68% confidence) of carbon, 51 AE 32 t of total nitrogen, and 15 AE 9 t of phosphorus are anticipated to enter the fluvial system in response to channel head migration from within the confines of this state park, representing only 1% of the land area in Wake County. These findings suggest that regional water quality challenges posed by suspended sediments and nutrients will persist for hundreds to perhaps thousands of years from non-point sources as first-order channels continue to erode headward towards their equilibrium landscape positions.

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Section: Anthropogenic Impacts On Hillslope Erosionmentioning

confidence: 99%

Channel head response to anthropogenic landscape modification: A case study from the North Carolina Piedmont, USA, with implications for water quality

Atkins

Wegmann

Bohnenstiehl

2022

Earth Surf Processes Landf

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“…Milldams also alter the hydrologic environment with high stream and groundwater levels upstream (typically equal to the height of the dam) and lower levels and drier conditions downstream (Sherman et al, 2022). The high-water levels and wet and stagnant conditions upstream of the dams promote hypoxic and anoxic conditions in stream and riparian sediments with consequences for carbon and nitrogen biogeochemistry and cycling (Inamdar et al, 2020Hripto et al, 2022;Peck et al, 2022Peck et al, , 2023. In contrast, when dams are removed, upstream stream and groundwater levels drop rapidly resulting in drained and oxic riparian sediments (Lewis et al, 2021) that are susceptible to fluvial and subaerial erosive processes (Wolman, 1959;Fox et al, 2016;Gellis et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Mill dams impact microbiome structure and depth distribution in riparian sediments

et al. 2023

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IntroductionDamming has substantially fragmented and altered riverine ecosystems worldwide. Dams slow down streamflows, raise stream and groundwater levels, create anoxic or hypoxic hyporheic and riparian environments and result in deposition of fine sediments above dams. These sediments represent a good opportunity to study human legacies altering soil environments, for which we lack knowledge on microbial structure, depth distribution, and ecological function.MethodsHere, we compared high throughput sequencing of bacterial/ archaeal and fungal community structure (diversity and composition) and functional genes (i.e., nitrification and denitrification) at different depths (ranging from 0 to 4 m) in riparian sediments above breached and existing milldams in the Mid-Atlantic United States.ResultsWe found significant location- and depth-dependent changes in microbial community structure. Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Chloroflexi, Acidobacteria, Planctomycetes, Thaumarchaeota, and Verrucomicrobia were the major prokaryotic components while Ascomycota, Basidiomycota, Chytridiomycota, Mortierellomycota, Mucoromycota, and Rozellomycota dominated fungal sequences retrieved from sediment samples. Ammonia oxidizing genes (amoA for AOA) were higher at the sediment surface but decreased sharply with depth. Besides top layers, denitrifying genes (nosZ) were also present at depth, indicating a higher denitrification potential in the deeper layers. However, these results contrasted with in situ denitrification enzyme assay (DEA) measurements, suggesting the presence of dormant microbes and/or other nitrogen processes in deep sediments that compete with denitrification. In addition to enhanced depth stratification, our results also highlighted that dam removal increased species richness, microbial diversity, and nitrification.DiscussionLateral and vertical spatial distributions of soil microbiomes (both prokaryotes and fungi) suggest that not only sediment stratification but also concurrent watershed conditions are important in explaining the depth profiles of microbial communities and functional genes in dammed rivers. The results also provide valuable information and guidance to stakeholders and restoration projects.

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“…Prevailing theory is that P is retained within the stream during low flows and suddenly remobilized during high flows, especially for point-source-affected reaches (Demars et al, 2005;Jarvie et al, 2011Jarvie et al, , 2012Sharpley et al, 2013). Field studies have observed that (a) large amounts of legacy P can accumulate within streambeds (Lannergård et al, 2020;McCallister & Logan, 1978;McDaniel et al, 2009), (b) P retention and remobilization can be highly spatially variable (Casillas-Ituarte et al, 2020;Inamdar et al, 2020), and (c) P retention and remobilization can be highly temporally variable (Jarvie et al, 2005(Jarvie et al, , 2006. To capture these dynamics, a watershed model must explicitly track in-stream P stores and simulate the processes by which P is retained and remobilized.…”

Section: Introductionmentioning

confidence: 99%

Updating SWAT+ to Clarify Understanding of In‐Stream Phosphorus Retention and Remobilization: SWAT+P.R&R

Wallington

Cai

2023

Water Resources Research

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Efforts to reduce riverine phosphorus (P) loads have not been as fruitful as expected or hoped. One reason for the failure of these efforts appears to be that models used for watershed P management have understated and misrepresented the role of in‐stream processes in shaping watershed P export. Here, we update the latest release of the Soil and Water Assessment Tool (SWAT+), a widely used watershed management model, to better represent in‐stream P retention and remobilization (SWAT+P.R&R). We add new streambed pools where P is stored and tracked, and we incorporate three new processes driving in‐stream P dynamics: (a) deposition and resuspension of sediment‐associated P, (b) diffusion of dissolved P between the water column and streambed, and (c) adsorption and desorption of mineral P. The objective of this modeling work is to provide a diagnostic tool that enables researchers to challenge existing assumptions regarding how watersheds store, transform, and transport P. Here, in a first diagnostic analysis, SWAT+P.R&R helps reconcile in‐stream P retention theory (that P is retained at low flows and remobilized at high flows) and a discordant data set in our validation watershed. SWAT+P.R&R results (a) clarify that the theorized relationship between P retention and flow is only valid (for this point‐source affected testbed, at least) at the temporal scale of a single rising‐or‐falling hydrograph limb and (b) illustrate that hysteresis obscures the relationship at longer temporal scales. Future work using SWAT+P.R&R could further challenge assumptions regarding timescales of in‐stream P legacies and sources of P load variability.

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Streambank Legacy Sediments in Surface Waters: Phosphorus Sources or Sinks?

Cited by 13 publications

References 65 publications

Channel head response to anthropogenic landscape modification: A case study from the North Carolina Piedmont, USA, with implications for water quality

Channel head response to anthropogenic landscape modification: A case study from the North Carolina Piedmont, USA, with implications for water quality

Mill dams impact microbiome structure and depth distribution in riparian sediments

Updating SWAT+ to Clarify Understanding of In‐Stream Phosphorus Retention and Remobilization: SWAT+P.R&R

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