Stoneflies as ecological engineers – hungry predators reduce fine sediments in stream beds

Water, sediment, and fish samples were collected during the Danube excursion 1988, within a coordinated sampling program of the Radiology Working Group of the “Internationale Arbeitsgemeinschaft Donauforschung ” (K.Hübel, Munich; I. Kurcz, Budapest; D.Rank, Vienna). The H-3 content of the river water and the radioactivity of the bottom sediments were measured at the BVFA Arsenal, Vienna. The determined H-3 content of the Danube water corresponds with the long-term trend in the H-3 content of the hydrosphere; the values lie in the range of 3 Bq/kg downstream from Belgrade, upstream from Belgrade they are about 4 Bq/kg. It was only in the waste water plume of the nuclear power station of Kozloduj that a slightly elevated H-3 value - 6 Bq/kg - was determined. The content of the sediments of artificial radionuclides was found, at the time of the Danube field excursion, to be almost exclusively due to the radioactive material released following the reactor accident at Chernobyl in April 1986 (mainly Cs-137 and Cs-134). As a consequence of the air currents and precipitation conditions prevailing at the time of the accident, the bottom sediments in the lower course of the Danube were less contaminated than those in the upper course. The fine sediments were found to contain over 3000 Bq/kg of Cs-137 in the upper course of the Danube.

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Effects of riparian forest thinning by two types of mechanical harvest on stream fish and habitat in northern Minnesota

Canadian Journal of Forest Research ◽

10.1139/x07-157 ◽

2008 ◽

Vol 38 (2) ◽

pp. 247-256 ◽

Cited By ~ 14

Author(s):

Nathaniel A. Hemstad ◽

Eric C. Merten ◽

Raymond M. Newman

Keyword(s):

Repeated Measures ◽

Riparian Forest ◽

Canopy Cover ◽

Stream Habitat ◽

North Central ◽

Fine Sediments ◽

Repeated Measures Analysis ◽

Stream System ◽

Tree Length ◽

Wide Scale

The response of fish communities and stream habitat to four riparian harvest treatments was studied in north-central Minnesota to determine if riparian harvest with two different harvest systems degrades stream systems. Treatments included control (no harvest), riparian control, cut-to-length riparian thin, and tree length riparian thin. Fish and habitat data were collected from 50 m reaches above, within, and downstream of each treatment 1 year preharvest (1997) and 3 years postharvest (1998–2000). Repeated measures analysis revealed few effects due to treatment; however, there was a 6%–10% significant reduction in canopy cover. Percent fine sediments increased significantly (15%) system-wide following forest harvest and persisted through 2000. This increase in fine sediments was correlated with a decrease in fish biotic integrity (r = –0.31). Habitat and fish variables were influenced more by year-to-year variation than by harvest treatment, suggesting that factors operating at a broader basin-wide scale may influence fish and habitat or mask any site-level harvest effects in this low-gradient stream system. Residual riparian basal areas ≥12.3m2/ha along reaches ≤200 m in length may be adequate to protect fish and habitat in these low-gradient streams, but basin-wide effects of harvest deserve more scrutiny.

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Statistical Modeling of Fine Sediments Dredged Using a Variable Area Dredging Suction Head to Improve Water Quality

Hydrology ◽

10.3390/hydrology8030098 ◽

2021 ◽

Vol 8 (3) ◽

pp. 98

Author(s):

Leigh A. Provost ◽

Robert Weaver ◽

Nezamoddin N. Kachouie

Keyword(s):

Climate Change ◽

Water Quality ◽

Sedimentation Rates ◽

Agricultural Lands ◽

Design Efficiency ◽

Fine Sediments ◽

Grain Sizes ◽

Fine Grain ◽

Sediment Sampling ◽

Improve Water Quality

The changing climate affects the agricultural lands, and, in turn, the changes in agricultural lands alter the watershed. A major concern regarding waterbodies is the increased sedimentation rates due to climate change. To improve the water quality, it is crucial to remove fine sediments. Using current environmental dredging methods is challenging because of the sediment volumes that must be dredged, the absence of nearby disposal sites, and the shoreline infrastructure at the dredging locations. To address these issues, we used a surgical dredging method with a variable area suction head that can easily maneuver around the docks, pilings, and other infrastructures. It can also isolate the fine grain material to better manage the dredged volumes in the seabed where nutrients are typically adhered. To this end, a statistical analysis of the dredged samples is essential to improve the design efficiency. In this work, we collected several samples using a variable area suction head with different design settings. The collected samples using each design setting were then used to model the distributions of the different grain sizes in the dredged sediments. The proposed statistical model can be effectively used for the prediction of sediment sampling outcomes to improve the gradation of the fine sediments.

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The periodic topography of ice stream beds: Insights from the Fourier spectra of mega-scale glacial lineations

Journal of Geophysical Research Earth Surface ◽

10.1002/2016jf004154 ◽

2017 ◽

Vol 122 (7) ◽

pp. 1355-1373 ◽

Cited By ~ 16

Author(s):

Matteo Spagnolo ◽

Timothy C. Bartholomaus ◽

Chris D. Clark ◽

Chris R. Stokes ◽

Nigel Atkinson ◽

...

Keyword(s):

Ice Stream ◽

Stream Beds ◽

Fourier Spectra

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Recycling and Reuse of Sediments in Agriculture: Where Is the Problem?

Sustainability ◽

10.3390/su13041648 ◽

2021 ◽

Vol 13 (4) ◽

pp. 1648

Author(s):

Giancarlo Renella

Keyword(s):

Scientific Evidence ◽

Significant Proportion ◽

Silty Clay ◽

Fine Sediments ◽

Sediment Fraction ◽

Biodegradation Process ◽

Component Material ◽

Long Time ◽

Clay Sediment ◽

International Conventions

Though suggested by international conventions for a long time, there are still several technical and legislative limitations to a complete reuse and recycling of dredged sediments. In particular, reuse of unpolluted sediments can be practiced, whereas sediment recycling is still affected by several downsides, and a significant proportion of the recycled fine sediments has no practical use and must be landfilled. However, the silty clayey fraction of the recycled sediments is rich in organic matter and macro- and micronutrients useful for plant growth. Nevertheless, sediment recycling in agriculture is not possible, even in non-food agricultural sectors, due to the lack of a permissive legislation and of consolidated supply chains. In addition to plant nutrients, the silty-clay sediment fraction may also accumulate organic and inorganic pollutants, and while the organic pollutants can be effectively biodegraded, metals and metalloids may concentrate at concentrations higher than the limits set by the environmental and agricultural legislations. In this paper, I briefly summarize the scientific evidence on the potential reuse and recycling of sediments in agriculture, and I discuss the main reasons for hindrance of sediment recycling in agriculture. I also present evidence from a real industrial biodegradation process that produces bioremediated fine sediment fractions with suitable properties as a mineral ingredient for plant-growing media. I propose that nutrient-rich recycled sediments could be reconsidered as a component material category in the new EU regulation on fertilizers.

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Influence of fine sediments on rheology properties of the self-compacting concrete

Powder Technology ◽

10.1016/j.powtec.2021.07.035 ◽

2021 ◽

Author(s):

Nongwendé Philippe Ouedraogo ◽

Frédéric Becquart ◽

Mahfoud Benzerzour ◽

Nor-Edine Abriak

Keyword(s):

The Self ◽

Self Compacting Concrete ◽

Fine Sediments

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Remote Sensing Inventory and Geospatial Analysis of Brick Kilns and Clay Quarrying in Kabul, Afghanistan

Minerals ◽

10.3390/min11030296 ◽

2021 ◽

Vol 11 (3) ◽

pp. 296

Author(s):

Jessica D. DeWitt ◽

Peter G. Chirico ◽

Marissa A. Alessi ◽

Kathleen M. Boston

Keyword(s):

Hyperspectral Image ◽

Mineral Resources ◽

Geospatial Analysis ◽

Small Scale ◽

Fine Sediments ◽

Hyperspectral Image Analysis ◽

Brick Kilns ◽

Clay Deposits ◽

High Resolution Satellite Imagery ◽

Kernel Density Analysis

Reconstruction and urban development in Kabul, Afghanistan, has prompted vast expansion of the clay quarrying and brick making industry. This study identified the extent and distribution of clay quarrying and brick kilns in the greater Kabul area between 1965 and 2018. Very high-resolution satellite imagery was interpreted to quantify and characterize the type, number, and location of brick kilns for 1965, 2004, 2011, and 2018. Geospatial analysis of kilns together with geologic data and the results of hyperspectral image analysis yielded information regarding the extent of relevant mineral resources. Finally, kernel density analysis of kiln locations for each date called attention to their shifting spatial distribution. The study found that the clay quarrying and brick making industry has expanded exponentially. The type of kilns has transitioned from artisanal style clamp kilns to small-scale Bull’s Trench Kilns (BTK), and ultimately to Fixed Chimney Bull’s Trench Kilns (FCBTK). While quarrying has occurred entirely within quaternary windblown loess and clay deposits, artisanal clamp kilns were located in fine sediments containing montmorillonite and FCBTKs have developed in sediments containing calcite and muscovite. The study’s inventory of kilns was then used to estimate kiln workforce at 27,500 workers and production at 1.579 billion bricks per year.

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Ribbed bedforms, markers of palaeo-ice stream margins, basal meltwater drainage and ice flow dynamic

10.5194/egusphere-egu21-9526 ◽

2021 ◽

Author(s):

Jean Vérité ◽

Édouard Ravier ◽

Olivier Bourgeois ◽

Stéphane Pochat ◽

Thomas Lelandais ◽

...

Keyword(s):

Flow Direction ◽

Local Stress ◽

Sediment Surface ◽

Shear Stresses ◽

Ice Streams ◽

Ice Flow ◽

Ice Stream ◽

Physical Experiments ◽

Stream Beds ◽

Ice Water

Over the three last decades, great efforts have been undertaken by the glaciological community to characterize the behaviour of ice streams and better constrain the dynamics of ice sheets. Studies of modern ice stream beds reveal crucial information on ice-meltwater-till-bedrock interactions, but are restricted to punctual observations limiting the understanding of ice stream dynamics as a whole. Consequently, theoretical ice stream landsystems derived from geomorphological and sedimentological observations were developed to provide wider constraints on those interactions on palaeo-ice stream beds. Within these landsystems, the spatial distribution and formation processes of subglacial periodic bedforms transverse to the ice flow direction &#8211; ribbed bedforms &#8211; remain unclear. The purpose of this study is (i) to explore the conditions under which these ribbed bedforms develop and (ii) to constrain their spatial organisation along ice stream beds. &#160;We performed physical experiments with silicon putty (to simulate the ice), water (to simulate the meltwater) and sand (to simulate a soft sedimentary bed) to model the dynamics of ice streams and produce analog subglacial landsystems. We compare the results of these experiments with the distribution of ribbed bedforms on selected examples of palaeo-ice stream beds of the Laurentide Ice Sheet. Based on this comparison, we can draw several conclusions regarding the significance of ribbed bedforms in ice stream contexts:<ul><li>Ribbed bedforms tend to form where the ice flow undergoes high velocity gradients and the ice-bed interface is unlubricated. Where the ribs initiate, we hypothesize that high driving stresses generate high basal shear stresses, accommodated through bed deformation of the active uppermost part of the bed.</li> <li>Ribbed bedforms can develop subglacially from a flat sediment surface beneath shear margins (i.e., lateral ribbed bedforms) and stagnant lobes (i.e., submarginal ribbed bedforms) of ice streams, while they do not develop beneath surging lobes.</li> <li>The orientation of ribbed bedforms reflects the local stress state along the ice-bed interface, with transverse bedforms formed by compression beneath ice lobes and oblique bedforms formed by transgression below lateral shear margins.</li> <li>The development of ribbed bedforms where the ice-bed interface is unlubricated reveals distinctive types of discontinuous basal drainage systems below shear and lobe margins: linked-cavities and efficient meltwater channels respectively.</li> </ul>Ribbed bedforms could thus constitute convenient geomorphic markers for the reconstruction of palaeo-ice stream margins, palaeo-ice flow dynamics and palaeo-meltwater drainage characteristics.

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Periodic alterations of the hydrological exchange in hyporheic sediments: colmation, hyporheic fauna and abiotic parameters in a second order stream during one year

10.5194/egusphere-egu21-15700 ◽

2021 ◽

Author(s):

Heide Stein ◽

Hans Jürgen Hahn

Keyword(s):

Hyporheic Zone ◽

Stream Water ◽

Anthropogenic Activities ◽

Second Order ◽

Critical Periods ◽

Order Stream ◽

Fine Sediments ◽

Stream Discharge ◽

One Year ◽

Hydrological Exchange

In this study, the temporal variability of the hydrological exchange between stream water (SW) and groundwater (GW), colmation, hyporheic invertebrate fauna, organic matter (OM) and physicochemical parameters were examined for the period of one year. Sampling and measuring were conducted monthly from May 2019 to April 2020 at the Guldenbach river, a second order stream in Rhineland-Palatinate, Germany. All hyporheic samples were extracted from a depth of 15 cm below stream bottom. Colmation was measured quantitatively in the same depth.Following the biotic and abiotic patterns found, three temporal stages of different hydrological conditions can be described:<ul><li>1) Strong floods, in February and March 2020 caused hydromorphological alterations of the river bed, leading to a decolmation of the hyporheic zone, a wash out of OM and hyporheic fauna. Due to high GW tables the vertical hydrological gradient (VHG) was positive indicating upwelling GW.</li> <li>2) In the months of Mai to August 2019 and April 2020, precipitation and stream discharge were lowest. Predominantly exfiltrating conditions were observed, while the amount of fine sediments (clay and silt) increased as well as colmation. High densities of hyporheic fauna, dominated by fine sediment dwelling taxa, were assessed.</li> <li>3) From September 2019 to January 2020 stream discharge was low. The VHG became increasingly negative, indicating downwelling SW. In accordance, colmation increased continuously, while densities of hyporheic invertebrates decreased and sediment dwellers became more dominant.</li> </ul>Precipitation, discharge events and GW table were found to be the driving factors for the annual dynamics of the hydrological exchange as well as for colmation, fauna and hydrochemistry. Electric conductivity seems a suitable indicator for the origin of water with high values in months of low precipitation and lower values after extensive precipitation events, respectively. Hyporheic fauna displayed a significant seasonality and the community structure was correlated with colmation and changes in the VHG.This pronounced seasonality seems to be typical of many streams and should be considered for the monitoring of sediments and hyporheic habitats: Seasons with lower stream discharge are probably the most critical periods for sediment conditions.We assume that the basic patterns of the dynamics observed basically reflect the natural situation in the catchment. However, the strength of surface run-off and the amount of fine sediments are mainly the result of anthropogenic activities and land use in the catchment.These findings underline the significance of dynamical processes for the assessment and implementation of the Water Framework Directive.

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Rip current evidence by hydrodynamic simulations, bathymetric surveys and UAV observation

10.5194/nhess-2017-53 ◽

2017 ◽

Cited By ~ 1

Author(s):

Guido Benassai ◽

Pietro Aucelli ◽

Giorgio Budillon ◽

Massimo De Stefano ◽

Diana Di Luccio ◽

...

Keyword(s):

Grain Size ◽

High Resolution ◽

Numerical Simulations ◽

Current System ◽

Current Evidence ◽

Rip Current ◽

Rip Currents ◽

Transport Pathways ◽

Fine Sediments ◽

Scientific Challenge

Abstract. The prediction of the formation, spacing and location of rip currents is a scientific challenge that can be achieved by means of different complementary methods. In this paper the analysis of numerical and experimental data, including UAV observation, allowed to detect the presence of rip currents and rip channels at the mouth of Sele river, in the Gulf of Salerno, southern Italy. The dataset used to analyze these phenomena consisted of two different bathymetric surveys, a detailed sediment 5 analysis and a set of high-resolution wave numerical simulations, completed with satellite and UAV observation. The grain size trend analysis and the numerical simulations allowed to identify the rip current system, forced by topographically constrained channels incised on the seabed, which were detected by high resolution bathymetric surveys. The study evidenced that on the coastal area of the Sele mouth grain-size trends are controlled by the contribution of fine sediments, which exhibit suspended transport pathways due to rip currents and longshore currents. The results obtained were confirmed by satellite and UAV 10 observations in different years.

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