Quantification of Po-210 and Pb-210 as tracer of sediment resuspension rate in a shallow riverine system: Case study from southeast Michigan, USA

2020 ◽  
Vol 222 ◽  
pp. 106339
Author(s):  
Mark Baskaran ◽  
Rajalakshmi Mudbidre ◽  
Linda Schweitzer
Keyword(s):  
Sediment Resuspension ◽  
Resuspension Rate

scholarly journals Can recreational scuba divers alter natural gross sedimentation rate? A case study from a Mediterranean deep cave

2010 ◽  
Vol 67 (5) ◽  
pp. 871-874 ◽  
Author(s):  
Antonio Di Franco ◽  
Gaetano Ferruzza ◽  
Pasquale Baiata ◽  
Renato Chemello ◽  
Marco Milazzo
Keyword(s):  
Sedimentation Rate ◽  
Sediment Resuspension ◽  
Sediment Traps ◽  
Potential Effect ◽  
Potential Threat ◽  
Sediment Grain Size ◽  
Scuba Divers ◽  
Ecological Importance ◽  
Recreational Scuba

Abstract Di Franco, A., Ferruzza, G., Baiata, P., Chemello, R., and Milazzo, M. 2010. Can recreational scuba divers alter natural gross sedimentation rate? A case study from a Mediterranean deep cave. – ICES Journal of Marine Science, 67: 871–874. Submarine caves are environments with features distinguishing them from other littoral habitats but, despite their ecological importance, their response to anthropogenic disturbance has been seldom verified. One potential threat affecting natural communities within caves is represented by recreational scuba diving. Divers' disturbance within marine caves is mainly related to physical contacts and increased sediment resuspension potentially affecting sessile organisms. The aim was to assess the potential effect of recreational divers' frequentation on the natural gross sedimentation rate (GSR) in a Mediterranean deep-water cave. To achieve this, sediment traps were deployed along a scuba trail before, during, and after the peak season for tourist-related diving. No effects of divers' frequentation were evident in terms of alteration of natural GSR, but findings will need to be validated for other caves to asses whether potential disturbance depends on frequentation levels and/or cave characteristics, i.e. sediment grain size or cave depth.

Dynamics of Sediment Resuspension in the Inner Harbor Under Different Forcing Conditions: A Case Study of Ulsan, Korea

2018 ◽  
Vol 85 ◽  
pp. 451-455
Author(s):  
Ho Kyung Ha ◽  
Jun Young Seo ◽  
Yoon Ho Jung ◽  
Hun Jun Ha ◽  
Soo Bin Kim ◽  
...  
Keyword(s):  
Sediment Resuspension

On the influence of sediment resuspension on deep-ocean Pa-231 and Th-230 cycling: Roles of turbulent mixing and differential scavenging

2020 ◽  
Author(s):  
Siyuan-Sean Chen ◽  
Olivier Marchal ◽  
Paul Lerner ◽  
Dan McCorkle ◽  
Michiel Rutgers van der Loeff
Keyword(s):  
New England ◽  
North Atlantic ◽  
Turbulent Mixing ◽  
Sediment Resuspension ◽  
Potential Temperature ◽  
Deep Ocean ◽  
Sharp Decrease ◽  
Meridional Overturning Circulation ◽  
Nepheloid Layer ◽  
Resuspension Rate

<p>The naturally-occurring particle-reactive radionuclides protactinium-231 (<sup>231</sup>Pa) and thorium-230 (<sup>230</sup>Th) are used as tracers of a variety of oceanic processes, both at present and in the past. Most notably, the sediment <sup>231</sup>Pa/<sup>230</sup>Th ratio has been used to infer changes in the Atlantic Meridional Overturning Circulation over the last (de)glaciation. However, recent measurements along the U.S. GEOTRACES North Atlantic transect (GA03) revealed two features which are at odds with current understanding about <sup>231</sup>Pa and <sup>230</sup>Th behaviour in the ocean: (i) a sharp decrease in dissolved <sup>231</sup>Pa and <sup>230</sup>Th activities with depth below 2000-4000 m and (ii) very large particulate <sup>231</sup>Pa and <sup>230</sup>Th activities near the bottom, at a number of stations between the New England continental shelf and Bermuda. Concomitant measurements of particulate matter concentration and potential temperature showed that both features are associated with the benthic nepheloid layer (BNL) and the bottom mixed layer (BML) that are present at these stations.</p><p>Here we develop and apply a simplified model of the exchange of particles, <sup>231</sup>Pa, and <sup>230</sup>Th between the BNL and the upper sediment, to explore the extent to which the radionuclide anomalies observed near the bottom at a number of GA03 stations can be explained by local sediment resuspension. We find that the model can broadly reproduce the observed anomalies at two stations where samples for radionuclide analyses were collected near the seafloor. Sensitivity tests with the model show that the <sup>231</sup>Pa/<sup>230</sup>Th ratio of particles in the BML and the sediment varies by a factor of 3 as the sediment resuspension rate fluctuates within a range consistent with observational estimates. The modelled variability is comparable to the spatial variability of <sup>231</sup>Pa/<sup>230</sup>Th of suspended particles in the modern North Atlantic and to the variability of Atlantic sediment <sup>231</sup>Pa/<sup>230</sup>Th records across the last (de)glacial period. Two factors are found to contribute to the modelled sensitivity of the sediment <sup>231</sup>Pa/<sup>230</sup>Th to sediment resuspension rate: the vertical turbulent mixing in the BML and the differential scavenging intensity of Pa and Th due to variation in particle concentration. Overall, our study indicates that the exchange of material between the BNL and the upper sediment can affect the particulate <sup>231</sup>Pa/<sup>230</sup>Th ratio in the bottom water and the sediment, which may complicate the use of sediment <sup>231</sup>Pa/<sup>230</sup>Th as a palaeoceanographic tracer.</p>

scholarly journals Sediment Resuspension Due to Near‐Bed Turbulent Effects: A Deep Sea Case Study on the Northwest Continental Slope of Western Australia

2018 ◽  
Vol 123 (10) ◽  
pp. 7102-7119 ◽  
Author(s):  
Sarik Salim ◽  
Charitha Pattiaratchi ◽  
Rafael O. Tinoco ◽  
Ravindra Jayaratne
Keyword(s):  
Continental Slope ◽  
Western Australia ◽  
Deep Sea ◽  
Sediment Resuspension

The regularity of wind-induced sediment resuspension in Meiliang Bay of Lake Taihu

2014 ◽  
Vol 70 (1) ◽  
pp. 167-174 ◽  
Author(s):  
Jianjian Wang ◽  
Yong Pang ◽  
Yiping Li ◽  
Yawen Huang ◽  
Junjie Jia ◽  
...  
Keyword(s):  
Wind Speed ◽  
Release Rate ◽  
Lake Taihu ◽  
Sediment Resuspension ◽  
Quantitative Relationship ◽  
Phosphorus Release ◽  
Hydrodynamic Conditions ◽  
Wind Speeds ◽  
Resuspension Rate ◽  
Meiliang Bay

Contaminants released by wind-induced sediment resuspension could influence the water quality in shallow lakes. This study aims to reveal the quantitative relationship between wind speed (v) and sediment resuspension rate (r) in Meiliang Bay of Lake Taihu. The study was conducted in three steps. First, the in situ wind speed and current velocity were measured over a period of 2 days in Meiliang Bay to establish the relationship between wind and hydrodynamic conditions; second, an indoor experiment was conducted in a cylindrical simulator with sediment from the study area to determine sediment resuspension rates under different hydrodynamic conditions; and third, linkages between sediment resuspension and wind were determined. The average sediment resuspension rate was highly correlated with the wind speed (R2 = 0.99), and was expressed by r = 20.72v2.034 at wind speeds in the range of 0–14 m/s. The critical wind speed for sediment resuspension is about 7 m/s. Under these conditions, the average resuspension rate could reach 1,000 g/(m2d), with a total phosphorus release rate of 1.1 g/(m2d) and a total nitrogen release rate of 18.1 g/(m2d).

The Genesis and Internal Dynamics of El Salvador's People's Revolutionary Army, 1970–1976

2014 ◽  
Vol 38 (01) ◽  
pp. 102-129
Author(s):  
ALBERTO MARTÍN ÁLVAREZ ◽  
EUDALD CORTINA ORERO
Keyword(s):  
Latin America ◽  
El Salvador ◽  
Early Years ◽  
Left Wing ◽  
Internal Dynamics ◽  
Internal Coherence ◽  
The 1960S

AbstractUsing interviews with former militants and previously unpublished documents, this article traces the genesis and internal dynamics of the Ejército Revolucionario del Pueblo (People's Revolutionary Army, ERP) in El Salvador during the early years of its existence (1970–6). This period was marked by the inability of the ERP to maintain internal coherence or any consensus on revolutionary strategy, which led to a series of splits and internal fights over control of the organisation. The evidence marshalled in this case study sheds new light on the origins of the armed Salvadorean Left and thus contributes to a wider understanding of the processes of formation and internal dynamics of armed left-wing groups that emerged from the 1960s onwards in Latin America.

Culture and the plasticity of perception

2020 ◽  
Vol 43 ◽  
Author(s):  
Michael Lifshitz ◽  
T. M. Luhrmann
Keyword(s):  
Cultural Context ◽  
Sensory Experience ◽  
Cultural Learning ◽  
The World

Abstract Culture shapes our basic sensory experience of the world. This is particularly striking in the study of religion and psychosis, where we and others have shown that cultural context determines both the structure and content of hallucination-like events. The cultural shaping of hallucinations may provide a rich case-study for linking cultural learning with emerging prediction-based models of perception.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

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