Anthropogenic sediment traps and network dislocation in a lowland UK river

2021 ◽  
Author(s):  
Ian D. L. Foster ◽  
John Boardman ◽  
Jennine L. Evans ◽  
Ruth Copeland‐Phillips ◽  
Atish N. Vadher ◽  
...  
Keyword(s):  
Sediment Traps ◽  
Network Dislocation

scholarly journals Watershed Suspended Sediment Supply and Potential Impacts of Dam Removals for an Estuary

2021 ◽  
Author(s):  
David K. Ralston ◽  
Brian Yellen ◽  
Jonathan D. Woodruff
Keyword(s):  
Suspended Sediment ◽  
River Estuary ◽  
Dam Removal ◽  
Hudson River ◽  
Sediment Traps ◽  
Sediment Supply ◽  
Watershed Area ◽  
Natural Lakes ◽  
Sediment Deposits ◽  
Dam Removals

AbstractObservations and modeling are used to assess potential impacts of sediment releases due to dam removals on the Hudson River estuary. Watershed sediment loads are calculated based on sediment-discharge rating curves for gauges covering 80% of the watershed area. The annual average sediment load to the estuary is 1.2 Mt, of which about 0.6 Mt comes from side tributaries. Sediment yield varies inversely with watershed area, with regional trends that are consistent with substrate erodibility. Geophysical and sedimentological surveys in seven subwatersheds of the Lower Hudson were conducted to estimate the mass and composition of sediment trapped behind dams. Impoundments were classified as (1) active sediment traps, (2) run-of-river sites not actively trapping sediment, and (3) dammed natural lakes and spring-fed ponds. Based on this categorization and impoundment attributes from a dam inventory database, the total mass of impounded sediment in the Lower Hudson watershed is estimated as 4.9 ± 1.9 Mt. This represents about 4 years of annual watershed supply, which is small compared with some individual dam removals and is not practically available given current dam removal rates. More than half of dams impound drainage areas less than 1 km2, and play little role in downstream sediment supply. In modeling of a simulated dam removal, suspended sediment in the estuary increases modestly near the source during discharge events, but otherwise effects on suspended sediment are minimal. Fine-grained sediment deposits broadly along the estuary and coarser sediment deposits near the source, with transport distance inversely related to settling velocity.

scholarly journals Programmed cell death in diazotrophs and the fate of organic matter in the western tropical South Pacific Ocean during the OUTPACE cruise

2018 ◽  
Vol 15 (12) ◽  
pp. 3893-3908 ◽  
Author(s):  
Dina Spungin ◽  
Natalia Belkin ◽  
Rachel A. Foster ◽  
Marcus Stenegren ◽  
Andrea Caputo ◽  
...  
Keyword(s):  
Cell Death ◽  
Organic Matter ◽  
Pacific Ocean ◽  
Programmed Cell Death ◽  
South Pacific ◽  
Sediment Traps ◽  
Vertical Flux ◽  
Filamentous Cyanobacterium ◽  
Chl A ◽  
South Pacific Ocean

Abstract. The fate of diazotroph (N2 fixers) derived carbon (C) and nitrogen (N) and their contribution to vertical export of C and N in the western tropical South Pacific Ocean was studied during OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment). Our specific objective during OUTPACE was to determine whether autocatalytic programmed cell death (PCD), occurring in some diazotrophs, is an important mechanism affecting diazotroph mortality and a factor regulating the vertical flux of organic matter and, thus, the fate of the blooms. We sampled at three long duration (LD) stations of 5 days each (LDA, LDB and LDC) where drifting sediment traps were deployed at 150, 325 and 500 m depth. LDA and LDB were characterized by high chlorophyll a (Chl a) concentrations (0.2–0.6 µg L−1) and dominated by dense biomass of the filamentous cyanobacterium Trichodesmium as well as UCYN-B and diatom–diazotroph associations (Rhizosolenia with Richelia-detected by microscopy and het-1 nifH copies). Station LDC was located at an ultra-oligotrophic area of the South Pacific gyre with extremely low Chl a concentration (∼ 0.02 µg L−1) with limited biomass of diazotrophs predominantly the unicellular UCYN-B. Our measurements of biomass from LDA and LDB yielded high activities of caspase-like and metacaspase proteases that are indicative of PCD in Trichodesmium and other phytoplankton. Metacaspase activity, reported here for the first time from oceanic populations, was highest at the surface of both LDA and LDB, where we also obtained high concentrations of transparent exopolymeric particles (TEP). TEP were negatively correlated with dissolved inorganic phosphorus and positively coupled to both the dissolved and particulate organic carbon pools. Our results reflect the increase in TEP production under nutrient stress and its role as a source of sticky carbon facilitating aggregation and rapid vertical sinking. Evidence for bloom decline was observed at both LDA and LDB. However, the physiological status and rates of decline of the blooms differed between the stations, influencing the amount of accumulated diazotrophic organic matter and mass flux observed in the traps during our experimental time frame. At LDA sediment traps contained the greatest export of particulate matter and significant numbers of both intact and decaying Trichodesmium, UCYN-B and het-1 compared to LDB where the bloom decline began only 2 days prior to leaving the station and to LDC where no evidence for bloom or bloom decline was seen. Substantiating previous findings from laboratory cultures linking PCD to carbon export in Trichodesmium, our results from OUTPACE indicate that nutrient limitation may induce PCD in high biomass blooms such as displayed by Trichodesmium or diatom–diazotroph associations. Furthermore, PCD combined with high TEP production will tend to facilitate cellular aggregation and bloom termination and will expedite vertical flux to depth.

Measurement of organic loading under an open-ocean aquaculture cage, using sediment traps on the bottom

2007 ◽  
Vol 23 (6) ◽  
pp. 661-667 ◽  
Author(s):  
P. Rapp ◽  
W. R. Ramírez ◽  
J. A. Rivera ◽  
M. Carlo ◽  
R. Luciano
Keyword(s):  
Sediment Traps ◽  
Open Ocean ◽  
Organic Loading ◽  
Open Ocean Aquaculture

scholarly journals Spatiotemporal variability of sedimentary organic matter supply and recycling processes in coral reefs of Tayrona National Natural Park, Colombian Caribbean

2014 ◽  
Vol 11 (11) ◽  
pp. 2977-2990 ◽  
Author(s):  
E. Bayraktarov ◽  
C. Wild
Keyword(s):  
Organic Matter ◽  
Coral Reef ◽  
Coastal Upwelling ◽  
Sediment Traps ◽  
Sedimentary Organic Matter ◽  
Spatiotemporal Variability ◽  
Water Current ◽  
Labile Organic Matter ◽  
Natural Park ◽  
River Mouths

Abstract. Sediments are fundamental for the function of oligotrophic coral reef ecosystems because they are major places for organic matter recycling. The Tayrona National Natural Park (TNNP, Colombian Caribbean) is located between the population center Santa Marta (>455 000 inhabitants) in the southwest and several river mouths in the east. Here, coral reef sediments experience pronounced changes in environmental conditions due to seasonal coastal upwelling, but knowledge of relevant spatiotemporal effects on organic matter supply to the sediments and recycling processes is not available. Therefore, sediment traps were deployed monthly over 14 months complemented by assessment of sedimentary properties (e.g., porosity, grain size, content of particulate organic matter and pigments) and sedimentary O2 demand (SOD) at water-current-exposed and sheltered sites along distance gradients (12–20 km) to Santa Marta and the eastern river mouths (17–27 km). Findings revealed that seasonal upwelling delivered strong (75–79% of annual supply) pulses of labile organic matter mainly composed of fresh phytoplankton detritus (C : N ratio 6–8) to the seafloor. Sedimentary chlorophyll a contents and SOD increased significantly with decreasing distance to the eastern rivers, but only during upwelling. This suggests sedimentary organic matter supply controlled by nutrient-enriched upwelling waters and riverine runoff rather than by the countercurrent-located city of Santa Marta. Organic matter pulses led to significantly higher SOD (more than 30%) at the water-current-sheltered sites as compared to the exposed sites, ensuing a rapid recycling of the supplied labile organic matter in the permeable silicate reef sands.

scholarly journals The Role of Attenuation and Land Management in Small Catchments to Remove Sediment and Phosphorus: A Modelling Study of Mitigation Options and Impacts

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1227 ◽  
Author(s):  
Russell Adams ◽  
Paul Quinn ◽  
Nick Barber ◽  
Sim Reaney
Keyword(s):  
Beneficial Effect ◽  
Natural Attenuation ◽  
Sediment Traps ◽  
Small Decrease ◽  
Flood Peak ◽  
Actual Type ◽  
Flood Flows ◽  
Small Catchments ◽  
Catchment Runoff

It is well known that soil, hillslopes, and watercourses in small catchments possess a degree of natural attenuation that affects both the shape of the outlet hydrograph and the transport of nutrients and sediments. The widespread adoption of Natural Based Solutions (NBS) practices in the headwaters of these catchments is expected to add additional attenuation primarily through increasing the amount of new storage available to accommodate flood flows. The actual type of NBS features used to add storage could include swales, ditches, and small ponds (acting as sediment traps). Here, recent data collected from monitored features (from the Demonstration Test Catchments project in the Newby Beck catchment (Eden) in northwest England) were used to provide first estimates of the percentages of the suspended sediment (SS) and total phosphorus (TP) loads that could be trapped by additional features. The Catchment Runoff Attenuation Flux Tool (CRAFT) was then used to model this catchment (Newby Beck) to investigate whether adding additional attenuation, along with the ability to trap and retain SS (and attached P), will have any effect on the flood peak and associated peak concentrations of SS and TP. The modelling tested the hypothesis that increasing the amount of new storage (thus adding attenuation capacity) in the catchment will have a beneficial effect. The model results implied that a small decrease of the order of 5–10% in the peak concentrations of SS and TP was observable after adding 2000 m3 to 8000 m3 of additional storage to the catchment.

scholarly journals Soil and Water Conservation in Rainfed Vineyards with Common Sainfoin and Spontaneous Vegetation under Different Ground Conditions

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1058 ◽  
Author(s):  
Nahed Ben-Salem ◽  
Sara Álvarez ◽  
Manuel López-Vicente
Keyword(s):  
Water Conservation ◽  
Cover Crop ◽  
Sediment Traps ◽  
Sediment Yields ◽  
Rainfall Depth ◽  
Ephemeral Gullies ◽  
Ground Conditions ◽  
Spontaneous Vegetation ◽  
The Mean ◽  
Moisture Conditions

Soil erosion seriously affects vineyards. In this study, the influence of two vegetation covers on topsoil moisture and the effect of different physiographic conditions on runoff and sediment yields were evaluated in a rainfed vineyard formed by four fields (NE Spain) during 15 months. One field had spontaneous vegetation in the inter-row areas, and three fields had a cover crop of common sainfoin. Moisture conditions were dry and stable in the vineyards’ rows, wet and very variable in the inter-row areas and wet and very stable in the corridors. Topsoil moisture in the areas with common sainfoin was much higher than in the rows (62–70%), whereas this difference was lower with spontaneous vegetation (40%). Two runoff and sediment traps (STs) were installed in two ephemeral gullies, and 26 time-integrated surveys (TIS) were done. The mean runoff yields were 9.8 and 13.5 L TIS−1 in ST2 and ST3. Rainfall depth (12 mm) and erosivity (5.2 MJ mm ha−1 h−1) thresholds for runoff initiation were assessed. The mean turbidity was 333 (ST2) and 19 (ST3) g L−1. Changes in the canopy covers (grapevines and vegetation covers), topography and rainfall parameters explained the runoff and sediment dynamics.

scholarly journals Sonic anemometry and sediment traps to evaluate the effectiveness of windbreaks in preventing wind erosion

2017 ◽  
Vol 74 (6) ◽  
pp. 425-435 ◽  
Author(s):  
Alejandro López ◽  
Diego Luis Valera ◽  
Francisco Domingo Molina-Aiz ◽  
Francisco Javier Lozano ◽  
Carlos Asensio
Keyword(s):  
Wind Erosion ◽  
Sediment Traps

scholarly journals Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic

2018 ◽  
Vol 15 (8) ◽  
pp. 2289-2307 ◽  
Author(s):  
Nolwenn Lemaitre ◽  
Hélène Planquette ◽  
Frédéric Planchon ◽  
Géraldine Sarthou ◽  
Stéphanie Jacquet ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
North Atlantic ◽  
Deep Convection ◽  
Sediment Traps ◽  
Heterotrophic Activity ◽  
Physical Forcing ◽  
The North ◽  
Poc Export ◽  
Order Of Magnitude ◽  
The North Atlantic

Abstract. The remineralisation of sinking particles by prokaryotic heterotrophic activity is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May–June 2014) using the particulate biogenic barium (excess barium; Baxs) proxy. Important mesopelagic (100–1000 m) Baxs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure, and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Baxs content (up to 727 pmol L−1), which was attributed to an intense bloom averaging 6 mg chl a m−3 between January and June 2014 and by an intense 1500 m deep convection in the central Labrador Sea during the winter preceding the sampling. This downwelling could have promoted a deepening of the prokaryotic heterotrophic activity, increasing the Baxs content. In comparison, the temperate province, characterized by the lowest Baxs content (391 pmol L−1), was sampled during the bloom period and phytoplankton appear to be dominated by small and calcifying species, such as coccolithophorids. The Baxs content, related to oxygen consumption, was converted into a remineralisation flux using an updated relationship, proposed for the first time in the North Atlantic. The estimated fluxes were of the same order of magnitude as other fluxes obtained using independent methods (moored sediment traps, incubations) in the North Atlantic. Interestingly, in the subpolar and subtropical provinces, mesopelagic POC remineralisation fluxes (up to 13 and 4.6 mmol C m−2 d−1, respectively) were equalling and occasionally even exceeding upper-ocean POC export fluxes, deduced using the 234Th method. These results highlight the important impact of the mesopelagic remineralisation on the biological carbon pump of the studied area with a near-zero, deep (> 1000 m) carbon sequestration efficiency in spring 2014.

Seasonal deposition of phytodetritus to the deep-sea floor

1986 ◽  
Vol 88 ◽  
pp. 265-279 ◽  
Author(s):  
A. L. Rice ◽  
D. S. M. Billett ◽  
J. Fry ◽  
A. W. G. John ◽  
R. S. Lampitt ◽  
...  
Keyword(s):  
Deep Sea ◽  
Benthic Communities ◽  
Time Lapse ◽  
Sediment Traps ◽  
Temporal Variations ◽  
Sea Floor ◽  
Porcupine Seabight ◽  
The Past ◽  
Sea Bed ◽  
Seasonal Deposition

SynopsisEvidence has accumulated over the past twenty years to suggest that the deep-sea environment is not as constant as was at one time thought, but exhibits temporal variations related to the seasonally in the overlying surface waters. Recent results from deep-moored sediment traps suggest that this coupling is mediated through the sedimentation of organic material, while observations in the Porcupine Seabight indicate that in this region, at least, there is a major and rapid seasonal deposition of aggregated phytodetritus to the sea-floor at slope and abyssal depths.This paper summarises the results of the Porcupine Seabight studies over the past five years or so, using time-lapse sea-bed photography and microscopic, microbiological and chemical analyses of samples of phytodetritus and of the underlying sediment. The data are to some extent equivocal, but they suggest that the seasonal deposition is a regular and dramatic phenomenon and that the material undergoes relatively little degradation during its passage through the water column. The mechanisms leading to the aggregation of the phytodetritus have not been identified, and it is not yet known whether the phenomenon is geographically widespread nor whether it is of significance to the deep-living mid-water and benthic communities.

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