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1
Cattaneo, A., N. Babonneau, G. Ratzov, G. Dan-Unterseh, K. Yelles, R. Bracène, B. Mercier de Lépinay, A. Boudiaf, and J. Déverchère. "Searching for the seafloor signature of the 21 May 2003 Boumerdès earthquake offshore central Algeria." Natural Hazards and Earth System Sciences 12, no. 7 (July 10, 2012): 2159–72. http://dx.doi.org/10.5194/nhess-12-2159-2012.
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Abstract. Shaking by moderate to large earthquakes in the Mediterranean Sea has proved in the past to potentially trigger catastrophic sediment collapse and flow. On 21 May 2003, a magnitude 6.8 earthquake located near Boumerdès (central Algerian coast) triggered large turbidity currents responsible for 29 submarine cable breaks at the foot of the continental slope over ~150 km from west to east. Seafloor bathymetry and backscatter imagery show the potential imprints of the 2003 event and of previous events. Large slope scarps resulting from active deformation may locally enhance sediment instabilities, although faults are not directly visible at the seafloor. Erosion is evident at the foot of the margin and along the paths of the numerous canyons and valleys. Cable breaks are located at the outlets of submarine valleys and in areas of turbiditic levee overspilling and demonstrate the multi-source and multi-path character of the 2003 turbiditic event. Rough estimates of turbidity flow velocity are not straightforward because of the multiple breaks along the same cable, but seem compatible with those measured in other submarine cable break studies elsewhere. While the signature of the turbidity currents is mostly erosional on the continental slope, turbidite beds alternating with hemipelagites accumulate in the distal reaches of sediment dispersal systems. In perspective, more chronological work on distal turbidite successions offshore Algeria offers promising perspectives for paleoseismology reconstructions based on turbidite dating, if synchronous turbidites along independent sedimentary dispersal systems are found to support triggering by major earthquakes. Preliminary results on sediment core PSM-KS23 off Boumerdès typically show a 800-yr interval between turbidites during the Holocene, in accordance with the estimated mean seismic cycle on land, even if at this stage it is not yet possible to prove the earthquake origin of all the turbidites.
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Patton, J. R., C. Goldfinger, A. E. Morey, C. Romsos, B. Black, and Y. Djadjadihardja. "Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones." Natural Hazards and Earth System Sciences 13, no. 4 (April 4, 2013): 833–67. http://dx.doi.org/10.5194/nhess-13-833-2013.
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Abstract. Turbidite deposition along slope and trench settings is evaluated for the Cascadia and Sumatra–Andaman subduction zones. Source proximity, basin effects, turbidity current flow path, temporal and spatial earthquake rupture, hydrodynamics, and topography all likely play roles in the deposition of the turbidites as evidenced by the vertical structure of the final deposits. Channel systems tend to promote low-frequency components of the content of the current over longer distances, while more proximal slope basins and base-of-slope apron fan settings result in a turbidite structure that is likely influenced by local physiography and other factors. Cascadia's margin is dominated by glacial cycle constructed pathways which promote turbidity current flows for large distances. Sumatra margin pathways do not inherit these antecedent sedimentary systems, so turbidity currents are more localized.
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Naruse, Hajime, and Kento Nakao. "Inverse modeling of turbidity currents using an artificial neural network approach: verification for field application." Earth Surface Dynamics 9, no. 5 (September 3, 2021): 1091–109. http://dx.doi.org/10.5194/esurf-9-1091-2021.
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Abstract. Although in situ measurements in modern frequently occurring turbidity currents have been performed, the flow characteristics of turbidity currents that occur only once every 100 years and deposit turbidites over a large area have not yet been elucidated. In this study, we propose a method for estimating the paleo-hydraulic conditions of turbidity currents from ancient turbidites by using machine learning. In this method, we hypothesize that turbidity currents result from suspended sediment clouds that flow down a steep slope in a submarine canyon and into a gently sloping basin plain. Using inverse modeling, we reconstruct seven model input parameters including the initial flow depth, the sediment concentration, and the basin slope. A reasonable number (3500) of repetitions of numerical simulations using a one-dimensional layer-averaged model under various input parameters generates a dataset of the characteristic features of turbidites. This artificial dataset is then used for supervised training of a deep-learning neural network (NN) to produce an inverse model capable of estimating paleo-hydraulic conditions from data on the ancient turbidites. The performance of the inverse model is tested using independently generated datasets. Consequently, the NN successfully reconstructs the flow conditions of the test datasets. In addition, the proposed inverse model is quite robust to random errors in the input data. Judging from the results of subsampling tests, inversion of turbidity currents can be conducted if an individual turbidite can be correlated over 10 km at approximately 1 km intervals. These results suggest that the proposed method can sufficiently analyze field-scale turbidity currents.
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Ono, Kenya, Hajime Naruse, Qifeng Yao, Zhirong Cai, Sojiro Fukuda, and Miwa Yokokawa. "Multiple scours and upward fining caused by hydraulic jumps: implications for the recognition of cyclic steps in the deepwater stratigraphic record." Journal of Sedimentary Research 93, no. 4 (April 1, 2023): 243–55. http://dx.doi.org/10.2110/jsr.2021.142.
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ABSTRACT Hydraulic jumps control the bypass, erosion, and depositional processes of Froude-supercritical turbidity currents, so they represent a significant process for understanding the development of submarine geomorphology. Hydraulic jumps actively occur from submarine canyons to fans, where the seafloor slope is relatively steep. Turbidites in such areas comprise large-scale bedforms called cyclic steps, and they exhibit complex internal structures, including localized erosion and the accumulation of coarse-grained fining-upward sequences. However, it is unclear which turbidity-current properties are reflected in the heterogeneous depositional characteristics and grain-size sorting of these deposits. To this end, we conducted flume experiments to reproduce deposits associated with the hydraulic jumps of surge-type flows. Turbidity-current surges were repeatedly generated in an experimental flume with a knickpoint that transitioned from a steep to a gentle slope, resulting in cyclic steps. Overall, the upstream migration of the cyclic steps produced a downstream-upward-fining succession of turbidites. However, hydraulic jumps occurred at several places over the trough to the stoss side of the step in a single flow due to the non-uniform and unsteady flow state of the surge-type turbidite succession. As a result, the reproduced succession exhibited multiple local scours and coarse-grained fill in the lower parts of the turbidites. This suggests that multiple local scours and fining-upward trends are discriminant characteristics of cyclic-step deposits formed by surge-type supercritical turbidity currents.
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Van Daele, Maarten, Peter J. Haeussler, Robert C. Witter, Nore Praet, and Marc De Batist. "The Sedimentary Record of the 2018 Anchorage Earthquake in Eklutna Lake, Alaska: Calibrating the Lacustrine Seismograph." Seismological Research Letters 91, no. 1 (November 20, 2019): 126–41. http://dx.doi.org/10.1785/0220190204.
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Abstract The 30 November 2018 Mw 7.1 Anchorage earthquake caused modified Mercalli intensities of V¼ to V½ at Eklutna Lake (south central Alaska). A few hours after the earthquake, a “dirt streak” was observed on the lake surface, followed by a peak in sediment turbidity values (∼80 times normal) at a drinking water facility, which receives water from the lake through a pipe. These observations hint toward turbidity currents triggered by the earthquake in Eklutna Lake. Here, we study 32 short sediment cores retrieved from across Eklutna Lake and observe a millimeter‐to‐centimeter scale turbidite that can be confidently attributed to the 2018 earthquake in all coring locations. X‐ray computed tomography, grain‐size, and color‐spectral analyses of the turbidite show that it shares physical characteristics with the turbidite generated by the 1964 Mw 9.2 Great Alaska earthquake, while it is considerably different from turbidites caused by historical floods. The 2018 turbidite reaches its largest thickness in the inflow‐proximal basin, but when compared to the 1964 turbidite and thereby canceling out local site effects, it is relatively thick in the inflow‐distal sub‐basin. The latter was exposed to stronger shaking during the 2018 earthquake, and this relative thickness trend may therefore be attributed to shaking intensity and gives an indication of the location of the earthquake epicenter relative to the basin axis. Furthermore, in contrast to the 1964 turbidite, which was sourced from both deltas and hemipelagic slopes, the 2018 turbidite was sourced from deltas only, as evidenced by its distribution. These results confirm that while it is generally accepted that shaking intensities of ≥VI are needed to trigger turbidity currents from hemipelagic slopes, intensities as low as V¼ can be sufficient to trigger turbidity currents from deltaic slopes. Our results show that proglacial lakes can sensitively record differences in shaking intensity and that investigating deposits from recent earthquakes is crucial to calibrate the lacustrine seismograph.
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Ho, Viet Luan, Robert M. Dorrell, Gareth M. Keevil, Robert E. Thomas, Alan D. Burns, Jaco H. Baas, and William D. McCaffrey. "Dynamics and deposition of sediment-bearing multi-pulsed flows and geological implication." Journal of Sedimentary Research 89, no. 11 (November 26, 2019): 1127–39. http://dx.doi.org/10.2110/jsr.2019.62.
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ABSTRACT Previous studies on dilute, multi-pulsed, subaqueous saline flows have demonstrated that pulses will inevitably advect forwards to merge with the flow front. On the assumption that pulse merging occurs in natural-scale turbidity currents, it was suggested that multi-pulsed turbidites that display vertical cycles of coarsening and fining would transition laterally to single-pulsed, normally graded turbidites beyond the point of pulse merging. In this study, experiments of dilute, single- and multi-pulsed sediment-bearing flows (turbidity currents) are conducted to test the linkages between downstream flow evolution and associated deposit structure. Experimental data confirm that pulse merging occurs in laboratory-scale turbidity currents. However, only a weak correspondence was seen between longitudinal variations in the internal flow dynamics and the vertical structure of deposits; multi-pulsed deposits were documented, but transitioned to single-pulsed deposits before the pulse merging point. This early transition is attributed to rapid sedimentation-related depletion of the coarser-grained suspended fraction in the laboratory setting, whose absence may have prevented the distal development of multi-pulsed deposits; this factor complicates estimation of the transition point in natural-scale turbidite systems.
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Hidayat, Jafron Wasiq, Karyadi Baskoro, and Rini Sopiany. "Struktur Komunitas Mollusca Bentik Berbasis Kekeruhan Di Perairan Pelabuhan Tanjung Emas Semarang." Bioma : Berkala Ilmiah Biologi 10, no. 2 (April 25, 2012): 65. http://dx.doi.org/10.14710/bioma.10.2.65-73.
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The breakwater of Tanjung Emas Seaport is designed to absorb seawave as well as increase ships stability.Such water stability will trigger the light and small particles to deposite onto the bottom of the water body,eventhough these are easily re-suspended and initiate to create turbidity. Turbididty is one factor affecting Mollusccommunity. In facing the global climate changes, there will be a seriuos problem triggering the turbidity of theseawater and so do the organims. Researh were aimed to study the benthic Mollusc community in different turbiditylevels. Justified ramdom sampling was applied in 14 stations. Community structure of the molluscs were analizeddiscriptively as well as through Shannon-Wiener (H’) and evenness (e) indeces.Result showed that turbidity in PTES varies between 06,750 – 45,250 NTU. Such qualities were relativelyhigh range and can be tolerated by several given species, mainly Gafrarium tumidum, Nuculana acuta and Pyrenesp. These three above species could live within such high turbidity levels, since some of material are part of theirdiets without disturbing their respiration fuction. The highest diversity index H’ was 1,68 and found in Station 5,which is in accordance with its highest turbididyt level 45,250 NTU. The smalest turbidity level occured in Station 8and it was related to smaller diversity index (0,24). There was a tendency, the smaller the turbidity levels the smallerthe diversity indices. Such relatonship was consistence to the other three stations, namely 9,10 and 11. Exceptionwas found in Station 1, where different dominant species occured and diversity index was relatively high. It isbelieved these are related to the presence of warm outlet of Indonesia Power sewage reaching 32,5 centdegree.
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AKA, Natchia, Abou Traoré, Nadi Paul Dangui, and Yao Dakro Albert Gboko. "Suivi de la turbidité et des matières en suspension dans les rivières côtières en milieu tropical : cas de la Mé et de l’Agneby (sud-est de la Cote d’Ivoire)." Journal of Applied Biosciences 183 (March 31, 2023): 19103–22. http://dx.doi.org/10.35759/jabs.183.1.
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Au Sud de la Côte d’Ivoire, l’État fait recours aux rivières côtières Mé et Agnéby pour pallier le déficit en eau potable destinée aux populations. Cependant, la forte turbidité et les concentrations élevées des matières en suspension dans ces cours d’eaux sont des indicateurs de la dégradation de leur qualité. Objectif Cette étude vise à évaluer la dynamique de la turbidité et des Matières en Suspension (MES) au cours du temps. Méthodologie et Résultats Pour ce faire, des mesures journalières de turbidité et de MES ont été réalisées sur un total de 277 échantillons d’eau prélevés dans la Mé et de 261 dans l’Agnéby sur la période allant de juin 2019 à mai 2020. Les concentrations en MES et ses différentes composantes ont été déterminées par gravimétrie et la turbidité par néphélométrie. La représentation graphique en nuage de points des couples de données turbidité-MES a permis d’établir la nature de leur relation. Les résultats montrent que dans la Mé, les concentrations en MES varient de 20 à 1000 mg/L et la turbidité oscille entre 53,94 et 1845 NTU. Ces valeurs élevées perdurent toute la durée de l’étude et indiquent que les eaux sont de qualité médiocre. Par contre, dans l’Agnéby, les eaux sont de qualité bonne à moyenne. Elles sont moins chargées en MES, avec des valeurs comprises entre 2 et 300 mg/L et une turbidité comprise entre 3,89 et 242 NTU. Pour des teneurs élevées en MES, la fraction minérale l’emporte sur la fraction organique. La grande variabilité des MES et de la turbidité des eaux est liée aux activités agricoles et d’extraction de sable ainsi que de l’orpaillage illégal. Il existe une très bonne corrélation linéaire entre la turbidité et les MES dans la Mé contrairement à l’Agnéby. Conclusion et Application des résultats : Cette étude a mis en lumière les conséquences de l’orpaillage illégal sur la qualité de la rivière Mé. C’est un outil d’aide à la décision qui permettra la surveillance en continu de la qualité des cours d’eau par la mesure de la turbidité seulement et la prise de décisions par les États contre le fléau de l’orpaillage Mots-clés : Rivières côtières, Mé, Agnéby, turbidité, Matières en Suspension 19103 Aka et al., J. Appl. Biosci. Vol : 183, 2023 Suivi de la turbidité et des matières en suspension dans les rivières côtières en milieu tropical : cas de la Mé et de l’Agneby (sud-est de la Cote d’Ivoire) Monitoring turbidity and total solid suspended in coastal rivers in tropical environment: case of Mé and Agnéby (southeast of Côte d’Ivoire) ABSTRACT In the south of Côte d'Ivoire, the State uses the Mé and Agnéby coastal rivers to make up for the lack of drinking water to supply the populations. However, the high turbidity and high concentrations of Total suspended solids in these watercourses are indicators of the deterioration of their quality. Objective: To evaluate the dynamics of turbidity and Total suspended solids (TSS) over time. Methodology and results: To do this, daily turbidity and TSS measurements were taken on a total of 277 water samples taken from the Mé and 261 from the Agnéby over the period from June 2019 to May 2020. TSS concentrations and its various components were determined by gravimetry and turbidity by nephelometry. The graphical representation in point cloud of the turbidity-TSS data pairs made it possible to establish the nature of their relationship. The results show that in the Mé, the TSS concentrations vary from 20 to 1000 mg/L and the turbidity oscillates between 53.94 and 1845 NTU. These high values persist throughout the duration of the study and indicate that the water is of poor quality. On the other hand, in Agnéby, the waters are of good to average quality. They are less loaded with suspended solids, with values between 2 and 300 mg/L and the turbidity is between 3.89 and 242 NTU. For high SS contents, the mineral fraction prevails over the organic fraction. The great variability of suspended solids and water turbidity is linked to agricultural activities and sand extraction as well as illegal gold panning. There is a very good linear correlation between turbidity and suspended solids in the Mé unlike in the Agnéby. Conclusions and applications of results: This study shed light on the consequences of illegal gold panning on the quality of the Mé River. It is a decision support tool that will allow continuous monitoring of the quality of waterways by measuring turbidity and decision-making by States against the scourge of gold panning. Keywords: Coastal Rivers, Mé, Agnéby, turbidity, suspended solids
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Hill, Jenna C., Janet T. Watt, Daniel S. Brothers, and Jared W. Kluesner. "Submarine canyons, slope failures and mass transport processes in southern Cascadia." Geological Society, London, Special Publications 500, no. 1 (2020): 453–75. http://dx.doi.org/10.1144/sp500-2019-169.
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AbstractMarine turbidite records have been used to infer palaeoseismicity and estimate recurrence intervals for large (>Mw7) earthquakes along the Cascadia Subduction Zone. Conventional models propose that upper slope failures are funneled into submarine canyons and develop into turbidity flows that are routed down-canyon to deep-water channel and fan systems. However, the sources and pathways of these turbidity flows are poorly constrained, leading to uncertainties in the connections between ground shaking, slope failure and deep-water turbidites. We examine the spatial distribution of submarine landslides along the southern Cascadia margin to identify source regions for slope failures that may have developed into turbidity flows. Using multibeam bathymetry, sparker multichannel seismic and chirp sub-bottom data, we observe relatively few canyon head slope failures and limited evidence of large landslides on the upper and middle slope. Most of the submarine canyons are draped with sediment infill in the upper reaches and do not appear to be active sediment conduits during the recent sea-level highstand. In contrast, there is evidence of extensive mass wasting of the lower slope and non-channelized downslope flows. Contrary to previous studies, we propose that failures along the lower slope are the primary sources for deep-sea seismoturbidites in southern Cascadia.
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Normandeau, Alexandre, and D. Calvin Campbell. "Recurrence of turbidity currents on glaciated continental margins: A conceptual model from eastern Canada." Journal of Sedimentary Research 90, no. 10 (October 1, 2020): 1305–21. http://dx.doi.org/10.2110/jsr.2020.66.
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ABSTRACT Turbidity currents in submarine canyons transport large volumes of sediment and carbon to the deep sea and are known to present a major risk to submarine infrastructure. Understanding the origin, the triggers, the recurrence, and the timing of these events is important for predicting future events and mitigating their impact. Depending on the morphological and latitudinal setting of submarine canyons, different external controls will govern the recurrence of turbidity currents. Here, we assess the recurrence of turbidity currents in shelf-incising submarine canyons off eastern Canada in order to examine the effects of external forcings such as glacier retreat and sea level on the deep-water sedimentary record. We used multibeam bathymetry, sub-bottom profiles, and the analysis of turbidites in sediment cores to infer the triggers of turbidity currents over time and propose a conceptual model for the activity of turbidity currents during glacial retreat. The chronostratigraphy of turbidites shows that turbidity current activity in the glaciated The Gully submarine canyon (eastern Canada) was highest between 24 ka cal BP (LGM) and 17 ka cal BP, with > 100 turbidites per 1,000 yr, when the ice sheet was directly delivering sediment to submarine canyons. As the ice margin retreated, the dominant sediment supply switched to glaciofluvial and then to longshore drift, while RSL remained low. The recurrence of turbidity currents nonetheless decreased drastically to < 10 per 1000 yr during that time, pre-dating the rise in RSL. This timing suggests that the reduction of turbidity-current activity is closely linked to retreating glaciers rather than to sea-level rise, which occurred later. Following the retreat of the ice sheet, sea level rose progressively to drown the shallow banks on the continental shelf, and turbidity currents ceased being active after 13 ka cal BP. In the late Holocene, landslide and concomitant turbidity-current recurrence increased to 1 per 1,000 yrs, with at least four new events recorded in deep water. This study shows that glacial sediment supply and sea level controlled the type of sediment supply to the continental slope, which in turn controlled the triggers of turbidity currents over time and the flushing of sediment to the deep water. By comparing with other glaciated margins, we propose a conceptual model explaining the recurrence of turbidity currents, taking into account RSL change and the position of the ice margin relative to the shelf edge. This conceptual model can help predict turbidity-current activity and offshore geohazards on other ancient and modern glaciated continental margins.
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Nelson, C. H., J. Gutiérrez Pastor, C. Goldfinger, and C. Escutia. "Great earthquakes along the Western United States continental margin: implications for hazards, stratigraphy and turbidite lithology." Natural Hazards and Earth System Sciences 12, no. 11 (November 1, 2012): 3191–208. http://dx.doi.org/10.5194/nhess-12-3191-2012.
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Abstract. We summarize the importance of great earthquakes (Mw &gtrsim; 8) for hazards, stratigraphy of basin floors, and turbidite lithology along the active tectonic continental margins of the Cascadia subduction zone and the northern San Andreas Transform Fault by utilizing studies of swath bathymetry visual core descriptions, grain size analysis, X-ray radiographs and physical properties. Recurrence times of Holocene turbidites as proxies for earthquakes on the Cascadia and northern California margins are analyzed using two methods: (1) radiometric dating (14C method), and (2) relative dating, using hemipelagic sediment thickness and sedimentation rates (H method). The H method provides (1) the best estimate of minimum recurrence times, which are the most important for seismic hazards risk analysis, and (2) the most complete dataset of recurrence times, which shows a normal distribution pattern for paleoseismic turbidite frequencies. We observe that, on these tectonically active continental margins, during the sea-level highstand of Holocene time, triggering of turbidity currents is controlled dominantly by earthquakes, and paleoseismic turbidites have an average recurrence time of ~550 yr in northern Cascadia Basin and ~200 yr along northern California margin. The minimum recurrence times for great earthquakes are approximately 300 yr for the Cascadia subduction zone and 130 yr for the northern San Andreas Fault, which indicates both fault systems are in (Cascadia) or very close (San Andreas) to the early window for another great earthquake. On active tectonic margins with great earthquakes, the volumes of mass transport deposits (MTDs) are limited on basin floors along the margins. The maximum run-out distances of MTD sheets across abyssal-basin floors along active margins are an order of magnitude less (~100 km) than on passive margins (~1000 km). The great earthquakes along the Cascadia and northern California margins cause seismic strengthening of the sediment, which results in a margin stratigraphy of minor MTDs compared to the turbidite-system deposits. In contrast, the MTDs and turbidites are equally intermixed on basin floors along passive margins with a mud-rich continental slope, such as the northern Gulf of Mexico. Great earthquakes also result in characteristic seismo-turbidite lithology. Along the Cascadia margin, the number and character of multiple coarse pulses for correlative individual turbidites generally remain constant both upstream and downstream in different channel systems for 600 km along the margin. This suggests that the earthquake shaking or aftershock signature is normally preserved, for the stronger (Mw ≥ 9) Cascadia earthquakes. In contrast, the generally weaker (Mw = or <8) California earthquakes result in upstream simple fining-up turbidites in single tributary canyons and channels; however, downstream mainly stacked turbidites result from synchronously triggered multiple turbidity currents that deposit in channels below confluences of the tributaries. Consequently, both downstream channel confluences and the strongest (Mw ≥ 9) great earthquakes contribute to multi-pulsed and stacked turbidites that are typical for seismo-turbidites generated by a single great earthquake. Earthquake triggering and multi-pulsed or stacked turbidites also become an alternative explanation for amalgamated turbidite beds in active tectonic margins, in addition to other classic explanations. The sedimentologic characteristics of turbidites triggered by great earthquakes along the Cascadia and northern California margins provide criteria to help distinguish seismo-turbidites in other active tectonic margins.
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Kawagucci, Shinsuke, Tetsuya Miwa, Dhugal J. Lindsay, Eri Ogura, Hiroyuki Yamamoto, Kenichiro Nishibayashi, Hiroyuki Yokooka, Shotaro Nishi, Ayu Takahashi, and Sangkyun Lee. "Deep-sea water displacement from a turbidity current induced by the Super Typhoon Hagibis." PeerJ 8 (December 9, 2020): e10429. http://dx.doi.org/10.7717/peerj.10429.
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Turbidity currents are the main drivers behind the transportation of terrestrial sediments to the deep sea, and turbidite deposits from such currents have been widely used in geological studies. Nevertheless, the contribution of turbidity currents to vertical displacement of seawater has rarely been discussed. This is partly because until recently, deep-sea turbidity currents have rarely been observed due to their unpredictable nature, being usually triggered by meteorological or geological events such as typhoons and earthquakes. Here, we report a direct observation of a deep-sea turbidity current using the recently developed Edokko Mark 1 monitoring system deployed in 2019 at a depth of 1,370 m in Suruga Bay, central Japan. A turbidity current occurred two days after its probable cause, the Super Typhoon Hagibis (2019), passed through Suruga Bay causing devastating damage. Over aperiod of 40 hours, we observed increased turbidity with turbulent conditions confirmed by a video camera. The turbidity exhibited two sharp peaks around 3:00 and 11:00 on October 14 (Japan Standard Time). The temperature and salinity characteristics during these high turbidity events agreed with independent measurements for shallow water layers in Suruga Bay at the same time, strongly suggesting that the turbidity current caused vertical displacement in the bay’s water column by transporting warmer and shallower waters downslope of the canyon. Our results add to the previous few examples that show meteorological and geological events may have significant contributions in the transportation of shallower seawater to the deep sea. Recent technological developments pertaining to the Edokko Mark 1 and similar devices enable straightforward, long-term monitoring of the deep-seafloor and will contribute to the understanding of similar spontaneous events in the deep ocean.
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Starek, Dušan, Vladimír Šimo, Silvia Antolíková, and Tomáš Fuksi. "Turbidite sedimentology, biostratigraphy and paleoecology: A case study from the Oligocene Zuberec Fm. (Liptov Basin, Central Western Carpathians)." Geologica Carpathica 70, no. 4 (August 1, 2019): 279–97. http://dx.doi.org/10.2478/geoca-2019-0016.
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Abstract Outcrops of a thick turbiditic succession are exposed on the northern bank of the Liptovská Mara reservoir near Liptovská Ondrašová and Ráztoky. The section consists of rhythmic, predominantly thin- to medium-bedded turbidites of the Rupelian age. Their biostratigraphy is based on the calcareous nannofossils. Facies associations of these deposits represent different components of depositional lobe deposits in the turbidity fan system, including mainly the lobe fringe and lobe distal fringe/inter-lobe facies associations and locally the medium bedded deposits of the lobe off-axis facies association. This interpretation is supported by statistical analysis. The deep-sea turbiditic deposits contain trace fossil associations, which include deep-tier fodinichnia and domichnia up to shallow-tier graphoglyptids. Paleocurrent measurements indicate that the majority of sedimentary material was transported from SW and W.
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Baas, Jaco H., Niall D. Tracey, and Jeff Peakall. "Sole marks reveal deep-marine depositional process and environment: Implications for flow transformation and hybrid-event-bed models." Journal of Sedimentary Research 91, no. 9 (September 30, 2021): 986–1009. http://dx.doi.org/10.2110/jsr.2020.104.
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ABSTRACT Deposits of sediment gravity flows in the Aberystwyth Grits Group (Silurian, west Wales, United Kingdom) display evidence that sole marks are suitable for reconstructing depositional processes and environments in deep-marine sedimentary successions. Based on drone imagery, 3D laser scanning, high-resolution sedimentary logging, and detailed descriptions of sole marks, an outcrop 1600 m long between the villages of Aberarth and Llannon was subdivided into seven lithological units, representing: a) mudstone-poor, coarse-grained and thick-bedded submarine channel fills, dominated by the deposits of erosive high-density turbidity currents with flute marks; b) mudstone-rich levee deposits with thin-bedded, fine-grained sandstones formed by low-density turbidity currents that scoured the bed to form flute marks; c) channel–lobe transition-zone deposits, dominated by thick beds, formed by weakly erosive, coarse-grained hybrid events, with pronounced mudstone-rich or sandstone-dominated debritic divisions and groove marks below basal turbiditic divisions, and with subordinate amounts of turbidites and debris-flow deposits; d) tabular, medium- to thick-bedded turbiditic sandstones with flute marks and mixed sandstone–mudstone hybrid event beds mainly with groove marks, interpreted as submarine lobe-axis (or off-axis) deposits; and e) tabular, thin- to medium-bedded, fine-grained, mainly turbiditic sandstones mostly with flute marks, formed in a lobe-fringe environment. Both lobe environments also comprised turbidites with low-amplitude bed waves and large ripples, which are interpreted to represent transient-turbulent flows. The strong relationship between flute marks and turbidites agrees with earlier predictions that turbulent shear flows are essential for the formation of flute marks. Moreover, the observation as part of this study that debris-flow deposits are exclusively associated with groove marks signifies that clay-charged, laminar flows are carriers for tools that are in continuous contact with the bed. A new process model for hybrid event beds, informed by the dominance of tool marks, in particular grooves, below the basal sand division (H1 division of Haughton et al. 2009) and by the rapid change from turbidites in the channel to hybrid event beds in the channel–lobe transition zone, is proposed. This model incorporates profound erosion of clay in the channel by the head of a high-density turbidity current and subsequent transformation of the head into a debris flow following rapid lateral flow expansion at the mouth of the channel. This debris flow forms the groove marks below the H1 division in hybrid event beds. A temporal increase in cohesivity in the body of the hybrid event is used to explain the generation of the H1, H2, and H3 divisions (sensuHaughton et al. 2009) on top of the groove surfaces, involving a combination of longitudinal segregation of bedload and vertical segregation of suspension load. This study thus demonstrates that sole marks can be an integral part of sedimentological studies at different scales, well beyond their traditional use as indicators of paleoflow direction or orientation.
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Baas, Jaco H., Niall D. Tracey, and Jeff Peakall. "Sole marks reveal deep-marine depositional process and environment: Implications for flow transformation and hybrid-event-bed models." Journal of Sedimentary Research 91, no. 9 (September 30, 2021): 986–1009. http://dx.doi.org/10.2110/jsr.2020.104.
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ABSTRACT Deposits of sediment gravity flows in the Aberystwyth Grits Group (Silurian, west Wales, United Kingdom) display evidence that sole marks are suitable for reconstructing depositional processes and environments in deep-marine sedimentary successions. Based on drone imagery, 3D laser scanning, high-resolution sedimentary logging, and detailed descriptions of sole marks, an outcrop 1600 m long between the villages of Aberarth and Llannon was subdivided into seven lithological units, representing: a) mudstone-poor, coarse-grained and thick-bedded submarine channel fills, dominated by the deposits of erosive high-density turbidity currents with flute marks; b) mudstone-rich levee deposits with thin-bedded, fine-grained sandstones formed by low-density turbidity currents that scoured the bed to form flute marks; c) channel–lobe transition-zone deposits, dominated by thick beds, formed by weakly erosive, coarse-grained hybrid events, with pronounced mudstone-rich or sandstone-dominated debritic divisions and groove marks below basal turbiditic divisions, and with subordinate amounts of turbidites and debris-flow deposits; d) tabular, medium- to thick-bedded turbiditic sandstones with flute marks and mixed sandstone–mudstone hybrid event beds mainly with groove marks, interpreted as submarine lobe-axis (or off-axis) deposits; and e) tabular, thin- to medium-bedded, fine-grained, mainly turbiditic sandstones mostly with flute marks, formed in a lobe-fringe environment. Both lobe environments also comprised turbidites with low-amplitude bed waves and large ripples, which are interpreted to represent transient-turbulent flows. The strong relationship between flute marks and turbidites agrees with earlier predictions that turbulent shear flows are essential for the formation of flute marks. Moreover, the observation as part of this study that debris-flow deposits are exclusively associated with groove marks signifies that clay-charged, laminar flows are carriers for tools that are in continuous contact with the bed. A new process model for hybrid event beds, informed by the dominance of tool marks, in particular grooves, below the basal sand division (H1 division of Haughton et al. 2009) and by the rapid change from turbidites in the channel to hybrid event beds in the channel–lobe transition zone, is proposed. This model incorporates profound erosion of clay in the channel by the head of a high-density turbidity current and subsequent transformation of the head into a debris flow following rapid lateral flow expansion at the mouth of the channel. This debris flow forms the groove marks below the H1 division in hybrid event beds. A temporal increase in cohesivity in the body of the hybrid event is used to explain the generation of the H1, H2, and H3 divisions (sensuHaughton et al. 2009) on top of the groove surfaces, involving a combination of longitudinal segregation of bedload and vertical segregation of suspension load. This study thus demonstrates that sole marks can be an integral part of sedimentological studies at different scales, well beyond their traditional use as indicators of paleoflow direction or orientation.
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Jethra, Ravi. "Turbidity measurement." ISA Transactions 32, no. 4 (December 1993): 397–405. http://dx.doi.org/10.1016/0019-0578(93)90075-8.
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Sadar, Michael J. "Turbidity Revealed." Opflow 33, no. 1 (January 2007): 24–26. http://dx.doi.org/10.1002/j.1551-8701.2007.tb00007.x.
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OLIVERO, E. B., and M. I. LÓPEZ CABRERA. "HELMINTHOPSIS AND CYLINDRICHNUS ICHNOGUILDS FROM MIOCENE THIN-BEDDED TURBIDITES, TIERRA DEL FUEGO, ARGENTINA." Palaios 38, no. 9 (September 30, 2023): 371–93. http://dx.doi.org/10.2110/palo.2022.058.
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Abstract Miocene thin-bedded turbidites from Tierra del Fuego record scarce graphoglyptids and two unusual ichnoguilds composed of diminutive elite trace fossils. The first, a monoichnospecific Cylindrichnus ichnoguild, consists of crowded, post-depositional burrows formed in surface sediments during the final phase of turbidite deposition. The second, a pre-depositional Helminthopsis ichnoguild, consists of dense aggregates of simple trails, mainly Helminthopsis and Helminthoidichnites, occupying a very shallow tier in organic-rich mud covering the sea floor prior to turbidite deposition. The trace makers of Cylindrichnus were opportunistic suspension/detritus feeding organisms, probably polychaetes, which bloomed during high flux of labile organic matter brought to internal and external levees by turbidity currents. The trace makers of Helminthopsis and Helminthoidichnites were probably nematodes that grazed on organic-rich muddy sediments with abundant disseminated pyrite associated with Kinneyia-like and other problematic wrinkle structures, suggesting sulfur-cycling chemosynthetic microbial communities originated during interturbidite phases. The rhythmical alternation of the Cylindrichnus and Helminthopsis ichnoguilds clearly differentiate the thin-bedded turbidites of the Viamonte Formation from channel-levee complexes elsewhere, stressing the point that ichnoassemblages reflect sets of environmental parameters and not necessarily particular depositional settings.
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Hanafie, Ahmad, Ilham Idrus, Wahyuddin Achmad, and Warits Al Qadri. "PENGARUH FLOKULASI MELALUI PENAMBAHAN ASAM FOSFAT (H3P04) TERHADAP KUALITAS GULA RAFINASI DI PT. MAKASSAR TENE." Journal Industrial Engineering and Management (JUST-ME) 2, no. 01 (June 28, 2021): 31–38. http://dx.doi.org/10.47398/justme.v2i01.15.
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Mutu gula rafinasi merupakan salah satu hal yang sangat perlu di perhatikan, karena akan mempengaruhi kesehatan konsumen. Pada Penelitian ini bertujuan untuk meningkatkan kualitas gula rafinasi dengan cara mengurangi flok pada gula rafinasi dengan metode flokulasi menggunakan koagulan H3PO4 (asam fosfat). Untuk menentukan timbulnya flok pada gula rafinasi dengan penambahan bahan kimia yaitu H3PO4 (asam fosfat) dengan variabel pH (4, 5, dan 6) serta satu sampel tanpa penambahan asam fosfat dan di panaskan dengan suhu 800C selama 15 menit agar larutan gula cepat larut. Setelah larut dinginkan larutan gula hingga suhu ruang kemudian analisa kadar Turbiditas, TSS, Brixnya. Kemudian larutan gula didiamkan serta diamati dengan detensi waktu selama 1- 3 hari. Setelah diamati dilakukan penyaringan flok pada larutan gula dengan kertas saring 0.8 µm yang telah diketahui bobot kosongnya dengan bantuan pompa vakum, dan timbang kertas saring beserta flok kemudian hitung kadar flok. Setelah penyaringan selesai larutan gula di periksa kembali kandungan Turbiditas, TSS, dan Brix. Nilai kandungan Turbiditas, TSS, dan Brix yang bagus yaitu pada penambahan asam fosfat 0.03 ml pada pH 4, di mana kadar sebelum di simpan pada hari ke 2 nilai Turbiditas 0.50 NTU, TSS 1 ppm, dan 21.97 %, serta kadar nilai kandungan Turbiditas, TSS, dan Brix setelah penyimpanan hari ke 3 yaitu Turbiditas 0.49 NTU, TSS 1 ppm, dan 21.87 %.
Refined sugar quality is one thing that really needs to be considered because it will affect the health of consumers. this study aims to improve the quality of refined sugar by reducing flocculation in refined sugar by using the flocculation method using H3PO4 coagulant (phosphoric acid). To determine the emergence of floc in refined sugar with the addition of a chemical, namely H3PO4 (phosphoric acid) with variable pH (4, 5, and 6) and one samples without the addition of phosphoric acid and heated at 800C for 15 minutes so that the sugar solution dissolves quickly. After dissolving, cool the sugar solution to room temperature then analyze the levels of Turbidity, TSS, and Brix. Then the sugar solution is left to stand and observed with a detention time of 1-3 days. After being observed, the floc filter was carried out in the sugar solution with 0.8 µm filter paper which had known the empty weight with the help of a vacuum pump and weighed the filter paper and the floc then calculated the floc content. After the filtering is complete, the sugar solution is checked again for the content of Turbidity, TSS, and Brix. The good value of Turbidity, TSS, and Brix content is the addition of 0.03 ml phosphoric acid at pH 4, where the levels before being stored on the second day the Turbidity value is 0.50 NTU, TSS 1 ppm, and 21.97%, as well as the levels of the value of the Turbidity content, TSS, and Brix after storage on the 3rd day, namely Turbidity 0.49 NTU, TSS 1 ppm, and 21.87%.
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Pouderoux, H., G. Lamarche, and J. N. Proust. "Building an 18 000-year-long paleo-earthquake record from detailed deep-sea turbidite characterisation in Poverty Bay, New Zealand." Natural Hazards and Earth System Sciences 12, no. 6 (June 27, 2012): 2077–101. http://dx.doi.org/10.5194/nhess-12-2077-2012.
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Abstract. Two ~20 m-long sedimentary cores collected in two neighbouring mid-slope basins of the Paritu Turbidite System in Poverty Bay, east of New Zealand, show a high concentration of turbidites (5 to 6 turbidites per meter), interlaid with hemipelagites, tephras and a few debrites. Turbidites occur as both stacked and single, and exhibit a range of facies from muddy to sandy turbidites. The age of each turbidite is estimated using the statistical approach developed in the OxCal software from an exceptionally dense set of tephrochronology and radiocarbon ages (~1 age per meter). The age, together with the facies and the petrophysical properties of the sediment (density, magnetic susceptibility and P-wave velocity), allows the correlation of turbidites across the continental slope (1400–2300 m water depth). We identify 73 synchronous turbidites, named basin events, across the two cores between 819 ± 191 and 17 729 ± 701 yr BP. Compositional, foraminiferal and geochemical signatures of the turbidites are used to characterise the source area of the sediment, the origin of the turbidity currents, and their triggering mechanism. Sixty-seven basin events are interpreted as originated from slope failures on the upper continental slope in water depth ranging from 150 to 1200 m. Their earthquake trigger is inferred from the heavily gullied morphology of the source area and the water depth at which slope failures originated. We derive an earthquake mean return time of ~230 yr, with a 90% probability range from 10 to 570 yr. The earthquake chronology indicates cycles of progressive decrease of earthquake return times from ~400 yr to ~150 yr at 0–7 kyr, 8.2–13.5 kyr, 14.7–18 kyr. The two 1.2 kyr-long intervals in between (7–8.2 kyr and 13.5–14.7 kyr) correspond to basin-wide reorganisations with anomalous turbidite deposition (finer deposits and/or non deposition) reflecting the emplacement of two large mass transport deposits much more voluminous than the "classical" earthquake-triggered turbidites. Our results show that the progressive characterisation of a turbidite record from a single sedimentary system can provide a continuous paleo-earthquake history in regions of short historical record and incomplete onland paleo-earthquake evidences. The systematic description of each turbidite enables us to infer the triggering mechanism.
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Hage, S., V. V. Galy, M. J. B. Cartigny, S. Acikalin, M. A. Clare, D. R. Gröcke, R. G. Hilton, et al. "Efficient preservation of young terrestrial organic carbon in sandy turbidity-current deposits." Geology 48, no. 9 (May 29, 2020): 882–87. http://dx.doi.org/10.1130/g47320.1.
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Abstract Burial of terrestrial biospheric particulate organic carbon in marine sediments removes CO2 from the atmosphere, regulating climate over geologic time scales. Rivers deliver terrestrial organic carbon to the sea, while turbidity currents transport river sediment further offshore. Previous studies have suggested that most organic carbon resides in muddy marine sediment. However, turbidity currents can carry a significant component of coarser sediment, which is commonly assumed to be organic carbon poor. Here, using data from a Canadian fjord, we show that young woody debris can be rapidly buried in sandy layers of turbidity current deposits (turbidites). These layers have organic carbon contents 10× higher than the overlying mud layer, and overall, woody debris makes up >70% of the organic carbon preserved in the deposits. Burial of woody debris in sands overlain by mud caps reduces their exposure to oxygen, increasing organic carbon burial efficiency. Sandy turbidity current channels are common in fjords and the deep sea; hence we suggest that previous global organic carbon burial budgets may have been underestimated.
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Sibarani, Riama, and Ferry Febriansyah. "PERANCANGAN ALAT PENDETEKSI KEKERUHAN DAN PENGURASAN AIR." JURNAL LIMITS 20, no. 2 (December 20, 2023): 23–30. http://dx.doi.org/10.59134/jlmt.v20i2.604.
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Kualitas air merupakan suatu faktor utama untuk pertumbuhan dan keberlangsungan hidup. Untuk menjaga kualitas air aqurium diperlukan suatu alat yang mampu mendeteksi tingkat kekeruhan dan menguras air yang kotor dan mengisi aquarium secara otomatis. Alat dirancang dengan menggunakan ESP32 dan Turbidity Sensor(TDS) yang berfungsi untuk mendeteksi tingkat kekeruhan air. Alat HC-SR04 digunakan untuk menentukan ketinggian volume air saat pengurasan dan pengisian air akuarium. Sensor Turbidty menampilkan informasitingkat kekeruhan air ditampilkan di layar LCD. Jika sensor Turbidity mendeteksi tingkat kekeruhan air mencapai angka yg sudah ditentukan maka alat ini akan mengirimkan pesan notifikasi melalui telegram kepada pengguna. Pengguna mengirimkan perintah untuk melakukan pengirasan dan pengisian air.
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Hesse, Reinhard, Sung Kwun Chough, and Allan Rakofsky. "The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel." Canadian Journal of Earth Sciences 24, no. 8 (August 1, 1987): 1595–624. http://dx.doi.org/10.1139/e87-155.
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The Northwest Atlantic Mid-Ocean Channel (NAMOC) is one of the largest deep-sea channels of the world's oceans. During the late Cenozoic glacial period, the channel played a major role in the depositional history of the Labrador Sea and northwest Atlantic in controlling sedimentation of a broad (approx. 500 m thick and 200 km wide) lens of turbidites. This sediment sequence interfingers laterally with the acoustically transparent pelagic and contourite facies found in the Labrador Basin. The meandering channel is a depositional–erosional feature formed by submarine mass flows, predominantly turbidity currents.The channel contains a meandering talweg that appears to be associated with a sequence of submarine point bars containing thick-bedded, coarse-grained turbidites and gravel layers (channel-fill facies). Old channel positions on seismic profiles indicate that the channel has migrated laterally up to 30 km both to the west and to the east.Natural levees flank the channel for its entire length, extending laterally into turbidite plains 60–100 km wide. The spill-over facies comprises thin-bedded, fine-grained turbidites dominated by thinly laminated muds. Individual units of parallel-laminated mud, which result from single turbidity currents overtopping the channel banks, average 3 cm in thickness. A layer by layer correlation of a sequence of spill-over turbidites is possible between two adjacent cores 70 km apart. Coarse-grained off-channel sediments recently discovered on both levees at distances up to 55 km from the NAMOC occur in tributary channels.Turbidity current activity in the channel probably started with the onset of glaciation at about mid-Pliocene time and ceased at about 7000 years BP, when deglaciation proceeded rapidly. The sedimentation rate for the last episode of overbank deposition on the levees, which probably occurred between 11 000 and 7000 years BP, is 13 cm/1000 years. Towards the end of glacial episodes the northwestern Labrador Sea was probably covered with sea ice.
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Ho, Viet Luan, Robert M. Dorrell, Gareth M. Keevil, Alan D. Burns, and William D. McCaffrey. "Scaling Analysis of Multipulsed Turbidity Current Evolution With Application to Turbidite Interpretation." Journal of Geophysical Research: Oceans 123, no. 5 (May 2018): 3668–84. http://dx.doi.org/10.1029/2017jc013463.
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Plink-Björklund, Piret, and Ron J. Steel. "Initiation of turbidity currents: outcrop evidence for Eocene hyperpycnal flow turbidites." Sedimentary Geology 165, no. 1-2 (March 2004): 29–52. http://dx.doi.org/10.1016/j.sedgeo.2003.10.013.
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Li, Yuting, and Peter D. Clift. "Controls on grain-size variability in the Holocene fill of the Indus Submarine Canyon." Journal of Sedimentary Research 93, no. 2 (February 8, 2023): 71–87. http://dx.doi.org/10.2110/jsr.2022.038.
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ABSTRACT What processes control grain size and bed thickness in submarine canyon deposits? Erosive, shelf-cutting canyons contrast with accretionary basin-floor submarine fan accretionary channels because the former tightly constrain turbidity flows in deep channels. This study addresses such a deep-water depositional system in the Indus Submarine Canyon using a series of cores collected along the canyon. Grain-size analysis was conducted for turbidite and hemipelagic sediment deposited in the Holocene Indus Submarine Canyon mostly by diffuse, fine-grained turbidity currents and hemipelagic hypopycnal plumes. We investigate the links between sedimentary grain size, bedding thickness, facies, and canyon morphology. Well-sorted silt in layers mostly < 2 cm thick dominates the canyon. Core sites in the canyon located downstream of knickpoints have coarser, less well sorted sediments because of current acceleration in these areas and then the slowing of flows downslope. Sediments fine with increasing height above the canyon thalweg, implying deposition from a turbulent plume head. The great depth of the canyon, caused by the exceptionally wide shelf and steep slope, prevents channel overspill which controls sedimentation and channel form in submarine fans. Thalweg sediment fines down-canyon into the mid canyon, where sediment bypassing is inferred. The thickest turbidites are found in the sinuous lower canyon where the gradient shallows from ∼ 0.7° to 0.3°. However, canyon gradient has little impact on mean grain size, but does correlate with bed thickness. The active canyon channel, located in a channel belt gradually becomes less steep, more meandering, and narrower farther downstream. Sinuosity is an influence on turbidite bedding thickness but does not control grain size, in contrast to the situation in submarine-fan channel–levee complexes. Compared to the well-known, more proximal Monterey Canyon of California the grain sizes are much finer, although both systems show evidence of > 200 m plume heads.
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Gregory, John. "Turbidity and beyond." Filtration & Separation 35, no. 1 (January 1998): 63–67. http://dx.doi.org/10.1016/s0015-1882(97)83117-5.
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Gregory, J. "Turbidity and beyond." Filtration & Separation 35, no. 1 (January 1998): 62. http://dx.doi.org/10.1016/s0015-1882(98)90665-6.
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Saiyar, Hafdiarsya, and Mohammad Noviansyah. "IDENTIFICATION OF WATER TURBIDITY WITH TURBIDITY SENSOR BASED ON ARDUINO." Jurnal Riset Informatika 3, no. 4 (September 3, 2021): 395–400. http://dx.doi.org/10.34288/jri.v3i4.277.
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Water is an important need for all living things, especially humans. Humans need water with quality that meets the physical, microbiological, chemical, and radiological requirements contained in the mandatory and additional parameters. The selection of these parameters is very important to meet the requirements of good water, namely tasteless, odorless, and colorless. Meanwhile, there are three parameters used for water identification, namely pH parameters, turbidity levels, and temperature parameters. From these problems, the authors examine the detection of water quality, especially water turbidity. The author tries to make a tool that can detect the level of turbidity of water with a turbidity sensor as a detector of the level of turbidity in the water, Arduino Uno as a processor for the data results that have been detected, and a 16x2 LCD as a display of turbidity level measurement results in the form of turbidity values and descriptions of the water being tested. The measurement range that can be detected by this tool is from 0 – 3000 NTU. The research method used is direct observation of the selected object, namely the author's home environment, and conducting library research related to the Arduino microcontroller. The purpose of this study was to determine and detect the level of water quality in the community. As one of the tools or alternatives for the community to find out or detect the level of water quality early.
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Grenier, J. C., A. De La Casinière, and T. Cabot. "Atmospheric Turbidity Analyzed by Means of Standardized Linke's Turbidity Factor." Journal of Applied Meteorology 34, no. 6 (June 1995): 1449–58. http://dx.doi.org/10.1175/1520-0450(1995)034<1449:atabmo>2.0.co;2.
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Heerema, Catharina J., Matthieu J. B. Cartigny, Ricardo Silva Jacinto, Stephen M. Simmons, Ronan Apprioual, and Peter J. Talling. "How distinctive are flood-triggered turbidity currents?" Journal of Sedimentary Research 92, no. 1 (January 11, 2022): 1–11. http://dx.doi.org/10.2110/jsr.2020.168.
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ABSTRACT Turbidity currents triggered at river mouths form an important highway for sediment, organic carbon, and nutrients to the deep sea. Consequently, it has been proposed that the deposits of these flood-triggered turbidity currents provide important long-term records of past river floods, continental erosion, and climate. Various depositional models have been suggested to identify river-flood-triggered turbidite deposits, which are largely based on the assumption that a characteristic velocity structure of the flood-triggered turbidity current is preserved as a recognizable vertical grain size trend in their deposits. Four criteria have been proposed for the velocity structure of flood-triggered turbidity currents: prolonged flow duration; a gradual increase in velocity; cyclicity of velocity magnitude; and a low peak velocity. However, very few direct observations of flood-triggered turbidity currents exist to test these proposed velocity structures. Here we present direct measurements from the Var Canyon, offshore Nice in the Mediterranean Sea. An acoustic Doppler current profiler was located 6 km offshore from the river mouth, and provided detailed velocity measurements that can be directly linked to the state of the river. Another mooring, positioned 16 km offshore, showed how this velocity structure evolved down-canyon. Three turbidity currents were measured at these moorings, two of which are associated with river floods. The third event was not linked to a river flood and was most likely triggered by a seabed slope failure. The multi-pulsed and prolonged velocity structure of all three (flood- and landslide-triggered) events is similar at the first mooring, suggesting that it may not be diagnostic of flood triggering. Indeed, the event that was most likely triggered by a slope failure matched the four flood-triggered criteria best, as it had prolonged duration, cyclicity, low velocity, and a gradual onset. Hence, previously assumed velocity-structure criteria used to identify flood-triggered turbidity currents may be produced by other triggers. Next, this study shows how the proximal multi-pulsed velocity structure reorganizes down-canyon to produce a single velocity pulse. Such rapid-onset, single-pulse velocity structure has previously been linked to landslide-triggered events. Flows recorded in this study show amalgamation of multiple velocity pulses leading to shredding of the flood signal, so that the original initiation mechanism is no longer discernible at just 16 km from the river mouth. Recognizing flood-triggered turbidity currents and their deposits may thus be challenging, as similar velocity structures can be formed by different triggers, and this proximal velocity structure can rapidly be lost due to self-organization of the turbidity current.
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Ercilla, Gemma, Russell B. Wynn, Belén Alonso, and Jesús Baraza. "Initiation and evolution of turbidity current sediment waves in the Magdalena turbidite system." Marine Geology 192, no. 1-3 (December 2002): 153–69. http://dx.doi.org/10.1016/s0025-3227(02)00553-4.
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Hall, Damien, Ran Zhao, Ian Dehlsen, Nathaniel Bloomfield, Steven R. Williams, Fumio Arisaka, Yuji Goto, and John A. Carver. "Protein aggregate turbidity: Simulation of turbidity profiles for mixed-aggregation reactions." Analytical Biochemistry 498 (April 2016): 78–94. http://dx.doi.org/10.1016/j.ab.2015.11.021.
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Annadurai, Gurusamy, S. S. Sung, and Duu-Jong Lee. "Simultaneous removal of turbidity and humic acid from high turbidity stormwater." Advances in Environmental Research 8, no. 3-4 (March 2004): 713–25. http://dx.doi.org/10.1016/s1093-0191(03)00043-1.
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Nury, Dennis, Rifqi Sufra, Mega Tiara, Siti Aisyah Rahimah Aulia, Siti Aisyah Rahimah Aulia, and Muhammad Zulfikar Luthfi. "Evaluasi Dosing Flokulan terhadap Waktu Pengendapan Juice pada Single Tray Clarifier di PT. Pemukasakti Manisindah." ISTA Online Technologi Journal 4, no. 2 (August 21, 2023): 18–27. http://dx.doi.org/10.62702/ion.v4i2.88.
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Abstrak Salah satu parameter untuk mendapatkan gula sesuai standar SNI adalah kemurnian nira. Nira merupakan cairan hasil ekstraksi tebu. Nira akan dipisahkan dari kotoran menjadi nira jernih dengan ditambahkan flokulan. Konsentrasi flokulan juga sangat berpengaruh terhadap pengendapan nira. Penelitian ini bertujuan menentukan dosis flokulan yang efektif untuk meningkatkan laju pengendapan kotoran nira dan mengetahui dosis flokulan yang dapat mempengaruhi kualitas clear juice atau nira encer. Pengujian yang dilakukan meliputi pengujian jar test, pengukuran turbiditas, pH dan pengamatan warna. Hasil penelitian menunjukkan bahwa dosis flokulan dapat mempengaruhi kualitas clear juice yang dihasilkan. Berdasarkan tiga aspek yaitu pH clear juice, laju pengendapan dan turbiditas, dosing flokulan yang baik yaitu pada 7 ppm dengan kondisi pH awal 7,8 Kata kunci: clear juice, flokulan, jar test, nira, turbiditas Abstract One of the parameters to obtain sugar according to SNI standards is the purity of nira. nira is the liquid extracted from sugarcane. Nira will be separated from impurities into clear nira by adding flocculants. Flocculant concentration is also very influential on the precipitation of nira. This study aims to determine the dose of flocculant that is effective to increase the rate of precipitation of nira impurities and determine the dose of flocculant that can affect the quality of clear juice or dilute nira. Tests conducted include jar test, turbidity measurement, pH and color observation. The results showed that the dose of flocculant can affect the quality of clear juice produced. Based on three aspects, namely clear juice pH, settling rate and turbidity, good flocculant dosing is at 7 ppm with initial pH conditions of 7.8. Keywords: clear juice, flocculant, jar test, sugarcane juice, turbidity
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Cantero, Mariano I., Alessandro Cantelli, Carlos Pirmez, S. Balachandar, David Mohrig, Thomas A. Hickson, Tzu-hao Yeh, Hajime Naruse, and Gary Parker. "Emplacement of massive turbidites linked to extinction of turbulence in turbidity currents." Nature Geoscience 5, no. 1 (November 13, 2011): 42–45. http://dx.doi.org/10.1038/ngeo1320.
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Völker, David, Thomas Reichel, Michael Wiedicke, and Christoph Heubeck. "Turbidites deposited on Southern Central Chilean seamounts: Evidence for energetic turbidity currents." Marine Geology 251, no. 1-2 (May 2008): 15–31. http://dx.doi.org/10.1016/j.margeo.2008.01.008.
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Vrbanac, Boris, Josipa Velić, and Tomislav Malvić. "Sedimentation of deep-water turbidites in the SW part of the Pannonian Basin." Geologica Carpathica 61, no. 1 (February 1, 2010): 55–69. http://dx.doi.org/10.2478/v10096-010-0001-8.
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Sedimentation of deep-water turbidites in the SW part of the Pannonian BasinThe Sava Depression and the Bjelovar Subdepression belong to the SW margin of the Pannonian Basin System, which was part of the Central Paratethys during the Pannonian period. Upper Pannonian deposits of the Ivanic-Grad Formation in the Sava Depression include several lithostratigraphic members such as Iva and Okoli Sandstone Member or their lateral equivalents, the Zagreb Member and Lipovac Marlstone Member. Their total thickness in the deepest part of the Sava Depression reaches up to 800 meters, while it is 100-200 meters in the margins of the depression. Deposits in the depression are composed of 4 facies. In the period of turbiditic activities these facies are primarily sedimented as different sandstone bodies. In the Bjelovar Subdepression, two lithostratigraphic members (lateral equivalent) were analysed, the Zagreb Member and Okoli Sandstone Member. The thickness of the Bjelovar Subdepression ranges from 50 meters along the S and SE margins to more than 350 meters along the E margin. Generally, detritus in the north-west part of the analysed area originated from a single source, the Eastern Alps, as demonstrated by sedimentological and physical properties, the geometry of the sandstone body and the fossil content. This clastic material was found to be dispersed throughout the elongated and relatively narrow Sava Depression and in the smaller Bjelovar Subdepression. Sedimentation primarily occurred in up to 200 meters water depth and was strongly influenced by the sub-aqueous paleorelief, which determined the direction of the flow of turbidity currents and sandstone body geometries. The main stream with medium- and fine-grained material was separated by two independent turbiditic flows from N-NW to the SE-E. Variability in the thickness of sandstone bodies is the result of differences in subsidence and cycles of progradation and retrogradation of turbidite fans.
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Juliantara, I. Putu Eka, Lutfi Suhendra, and Anak Agung Made Dewi Anggreni. "Karakteristik Mikroemulsi Minyak Atsiri Sirih (Piper betle L) Pada Lama Pengadukan Dan Suhu." JURNAL REKAYASA DAN MANAJEMEN AGROINDUSTRI 11, no. 3 (September 21, 2023): 341. http://dx.doi.org/10.24843/jrma.2023.v11.i03.p02.
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The betel plant (Piper betle L) is a plant that has the ability as an antifungal, antimicrobial and antioxidant. In order to make betel essential oil more efficient to use, betel essential oil is made into a microemulsion. The purpose of this study was to determine the effect of stirring time and temperature on the characteristics of betel essential oil microemulsions and to determine the best stirring time and temperature to produce betel essential oil microemulsion characteristics. This experiment used a randomized block design (RBD) using two factors, namely mixing time and temperature. The stirring time consists of 3 levels, namely 4, 6 and 8 minutes and the temperature consists of 3 levels, namely 60°C, 65°C and 70°C. The resulting data were analyzed using analysis of variance, if there were differences it was continued with the BNJ test. The results showed that the duration of stirring, temperature, and interactions between particles had a very significant effect on the value of the turbidity index on the stability of the betel essential oil microemulsion to pH and dilution of 1:1 to 1:99. And did not affect the turbidity index value of betel essential oil microemulsion, betel essential oil microemulsion turbidity index to centrifugation, and the turbidity index value on betel essential oil microemulsion stability against pH and 1:9 dilution. Stirring time of 8 minutes and temperature of 65°C is the best treatment for making betel nut essential oil microemulsion with microemulsion characteristics that have a transparent appearance, turbidity index values before and after centrifugation are 0.390 ± 0.031 and 0.343 ± 0.059, particle size is 23.1 nm ± 4.6 nm, and the largest droplet size is 22.8 nm. Betel essential oil microemulsion was stable for 8 weeks of storage. Based on the regression equation of the betel essential oil microemulsion to achieve a turbidity index value below 1% is 34 weeks or 8.5 months.
Keywords : Stirring time, Microemulsion, Piper betle L, Temperature
Tumbuhan sirih (Piper betle L) merupakan salah satu tanaman yang mempunyai kemampuan sebagai antifungi, antimikroba dan antioksidan. Agar minyak atsiri sirih lebih efisien untuk digunakan maka minyak atisiri sirih dibuat menjadi mikroemulsi. Adapun tujuan dari penelitian ini adalah untuk mengetahui pengaruh lama pengadukan dan suhu terhadap karakteristik mikroemulsi minyak atsiri sirih dan menentukan lama pengadukan dan suhu terbaik untuk menghasilkan
karakteristik mikroemulsi minyak atsiri sirih. Percobaan ini menggunakan Rancangan Acak Kelompok (RAK) menggunakan dua faktor yaitu lama pengadukan dan suhu. Lama pengadukan terdiri atas 3 level yaitu 4, 6 dan 8 menit dan suhu terdiri atas 3 level yaitu 60°C, 65°C dan 70°C. Data yang dihasilkan dianalisis menggunakan analisis varian, bila ada perbedaan dilanjutkan dengan uji BNJ. Pada hasil penelitian menunjukkan bahwa Lama pengadukan, suhu, dan interaksi antar partikel berpengaruh sangat nyata terhadap nilai indeks turbiditas pada stabilitas mikroemulsi minyak atsiri sirih terhadap pH dan pengenceran 1:1 dengan 1:99. Dan tidak berpengaruh terhadap nilai indeks turbiditas mikroemulsi minyak atsiri sirih, indek turbiditas mikroemulsi minyak atsiri sirih terhadap sentrifugasi, dan nilai indeks turbiditas pada stabilitas mikroemulsi minyak atsiri sirih terhadap pH dan pengenceran 1:9. Lama pengadukan 8 menit dan suhu 65°C merupakan perlakuan terbaik untuk membuat mikroemulsi minyak atsiri sirih dengan karakteristik mikroemulsi yang memiliki kenampakan transparan, nilai indeks turbiditas sebelum dan setelah sentrifugasi yaitu sebesar 0,390 ± 0,031 dan 0,343 ± 0,059, ukuran partikel 23,1 nm ± 4,6 nm, dan ukuran droplet terbanyak adalah 22,8 nm. Mikroemulsi minyak atsiri sirih stabil selama 8 minggu penyimpanan. Berdasarkan persamaan regresi mikroemulsi minyak atsiri sirih untuk mencapai nilai indeks turbiditas dibawah 1% adalah 34 minggu atau 8,5 bulan.
Kata kunci : Lama Pengadukaan, Mikroemulsi, Piper betle L, Suhu
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Larsen, P. H. "Soft sediment deformation structures in Silurian turbidites from North Greenland." Bulletin of the Geological Society of Denmark 35 (October 29, 1986): 19–23. http://dx.doi.org/10.37570/bgsd-1986-35-03.
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Turbidite beds in the Silurian turbidite sequence, North Greenland, show soft sediment deformation structures suggesting that the structureless (in respect of traction structures) sandstones divisions of the turbidites were deposited by direct suspension sedimentation from high-density flows. The deposits may have resulted from multiple successive depositional events within the same turbidity flow. Reworking and shear- ing of the newly formed loosely packed high-density suspension deposits caused by the still moving flow above create secondary soft sediment deformation structures which may be used as current indicators if other structures are absent (e.g. flute casts).
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Ichikawa, Kenta, Kenta Iitani, Gentaro Kawase, Koji Toma, Takahiro Arakawa, Dzung Viet Dao, and Kohji Mitsubayashi. "Mouthguard-Type Wearable Sensor for Monitoring Salivary Turbidity to Assess Oral Hygiene." Sensors 24, no. 5 (February 23, 2024): 1436. http://dx.doi.org/10.3390/s24051436.
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Salivary turbidity is a promising indicator for evaluating oral hygiene. This study proposed a wearable mouthguard-type sensor for continuous and unconstrained measurement of salivary turbidity. The sensor evaluated turbidity by measuring the light transmittance of saliva with an LED and a phototransistor sealed inside a double-layered mouthguard. The sensor was also embedded with a Bluetooth wireless module, enabling the wireless measurement of turbidity. The mouthguard materials (polyethylene terephthalate-glycol and ethylene-vinyl acetate) and the wavelength of the LED (405 nm) were experimentally determined to achieve high sensitivity in salivary turbidity measurement. The turbidity quantification characteristic of the proposed sensor was evaluated using a turbidity standard solution, and the sensor was capable of turbidity quantification over a wide dynamic range of 1–4000 FTU (formazine turbidity unit), including reported salivary turbidity (400–800 FTU). In vitro turbidity measurement using a saliva sample showed 553 FTU, which is equivalent to the same sample measured with a spectrophotometer (576 FTU). Moreover, in vivo experiments also showed results equivalent to that measured with a spectrophotometer, and wireless measurement of salivary turbidity was realized using the mouthguard-type sensor. Based on these results, the proposed mouthguard-type sensor has promising potential for the unconstrained continuous evaluation of oral hygiene.
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Voichick, Nicholas, David J. Topping, and Ronald E. Griffiths. "Technical note: False low turbidity readings from optical probes during high suspended-sediment concentrations." Hydrology and Earth System Sciences 22, no. 3 (March 12, 2018): 1767–73. http://dx.doi.org/10.5194/hess-22-1767-2018.
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Abstract. Turbidity, a measure of water clarity, is monitored for a variety of purposes including (1) to help determine whether water is safe to drink, (2) to establish background conditions of lakes and rivers and detect pollution caused by construction projects and stormwater discharge, (3) to study sediment transport in rivers and erosion in catchments, (4) to manage siltation of water reservoirs, and (5) to establish connections with aquatic biological properties, such as primary production and predator–prey interactions. Turbidity is typically measured with an optical probe that detects light scattered from particles in the water. Probes have defined upper limits of the range of turbidity that they can measure. The general assumption is that when turbidity exceeds this upper limit, the values of turbidity will be constant, i.e., the probe is “pegged”; however, this assumption is not necessarily valid. In rivers with limited variation in the physical properties of the suspended sediment, at lower suspended-sediment concentrations, an increase in suspended-sediment concentration will cause a linear increase in turbidity. When the suspended-sediment concentration in these rivers is high, turbidity levels can exceed the upper measurement limit of an optical probe and record a constant “pegged” value. However, at extremely high suspended-sediment concentrations, optical turbidity probes do not necessarily stay “pegged” at a constant value. Data from the Colorado River in Grand Canyon, Arizona, USA, and a laboratory experiment both demonstrate that when turbidity exceeds instrument-pegged conditions, increasing suspended-sediment concentration (and thus increasing turbidity) may cause optical probes to record decreasing “false” turbidity values that appear to be within the valid measurement range of the probe. Therefore, under high-turbidity conditions, other surrogate measurements of turbidity (e.g., acoustic-attenuation measurements or suspended-sediment samples) are necessary to correct these low false turbidity measurements and accurately measure turbidity.
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Lange Jensen, Lasse, Thomas Bjørn, Andreas Hein Korsgaard, Cino Pertoldi, and Niels Madsen. "Influence of Turbidity on Foraging Behaviour in Three-Spined Sticklebacks (Gasterosteus aculeatus)." Fishes 8, no. 12 (December 16, 2023): 609. http://dx.doi.org/10.3390/fishes8120609.
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Anthropogenic activities increase turbidity in coastal marine environments globally, and turbidity is particularly caused by eutrophication. Turbidity is a measurement of the scattering and absorption of light by suspended matter in water. An increase in turbidity influences visual predators and affects community structures and whole ecosystems. The three-spined stickleback (Gasterosteus aculeatus) is a widespread species in the northern hemispheric Pacific and Atlantic oceans. It is a visual predator and, therefore, a very well-suited species for studying the effects of increasing turbidity on foraging behaviour and activity. Sticklebacks used for this study were from an aquarium in the North Sea Oceanarium. They have been in the aquarium for around two months and were originally collected in a highly eutrophicated marine fjord system. They were individually placed in an observation aquarium, fed with krill, given 10 min to forage, and observed by video cameras. The video films were analysed to study stickleback predation behaviour. Experiments were repeated with four different turbidity treatments, ranging from a mean of 0.034 up to 10 NTU (nephelometric turbidity unit). Bentonite clay was used as a turbidity-increasing substance. A statistically significant difference in foraging behaviour and activity between the turbidity treatments was observed. The test subjects were found to lunge less for prey and had a higher feeding latency with increasing turbidity. Additionally, they were less active with increasing turbidity. The behavioural instability estimated as a variation in feeding latency increased with increasing turbidity but decreased at the highest turbidity value. Our study indicates an effect of turbidity-increasing events on the behaviour of the three-spined stickleback and potentially also other similar visual predators.
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SoneyeArogundade, Olanrewaju Olukemi, and Bernhard Rappenglück. "The Variation in Atmospheric Turbidity over a Tropical Site in Nigeria and Its Relation to Climate Drivers." Atmosphere 15, no. 3 (March 18, 2024): 367. http://dx.doi.org/10.3390/atmos15030367.
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Atmospheric turbidity exhibits substantial spatial–temporal variability due to factors such as aerosol emissions, seasonal changes, meteorology, and air mass transport. Investigating atmospheric turbidity is crucial for climatology, meteorology, and atmospheric pollution. This study investigates the variation in atmospheric turbidity over a tropical location in Nigeria, utilizing the Ångström exponent (α), the turbidity coefficient (β), the Linke turbidity factor (TL), the Ångström turbidity coefficient (βEST), the Unsworth–Monteith turbidity coefficient (KAUM), and the Schüepp turbidity coefficient (SCH). These parameters were estimated from a six-month uninterrupted aerosol optical depth dataset (January–June 2016) and a one-year dataset (January–December 2016) of solar radiation and meteorological data. An inverse correlation (R = −0.77) was obtained between α and β, which indicates different turbidity regimes based on particle size. TL and βEST exhibit pronounced seasonality, with higher turbidity during the dry season (TL = 9.62 and βEST = 0.60) compared to the rainy season (TL = 0.48 and βEST = 0.20) from May to October. Backward trajectories and wind patterns reveal that high-turbidity months align with north-easterly air flows from the Sahara Desert, transporting dust aerosols, while low-turbidity months coincide with humid maritime air masses originating from the Gulf of Guinea. Meteorological drivers like relative humidity and water vapor pressure are linked to turbidity levels, with an inverse exponential relationship observed between normalized turbidity coefficients and normalized water vapor pressure. This analysis provides insights into how air mass origin, wind patterns, and local climate factors impact atmospheric haze, particle characteristics, and solar attenuation variability in a tropical location across seasons. The findings can contribute to environmental studies and assist in modelling interactions between climate, weather, and atmospheric optical properties in the region.
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Rasheed, Farouk Abdullah. "Removal of Water Turbidity Using Different Coagulants." Journal of Zankoy Sulaimani - Part A 19, no. 2 (January 9, 2017): 115–26. http://dx.doi.org/10.17656/jzs.10617.
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Zhong, Guangfa, and Xiaotong Peng. "Transport and accumulation of plastic litter in submarine canyons—The role of gravity flows." Geology 49, no. 5 (January 26, 2021): 581–86. http://dx.doi.org/10.1130/g48536.1.
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Abstract Manned submersible dives discovered plastic litter accumulations in a submarine canyon located in the northwestern South China Sea, ∼150 km from the nearest coast. These plastic-dominated litter accumulations were mostly concentrated in two large scours in the steeper middle reach of the canyon. Plastic particles and fragments generally occurred on the upstream-facing sides of large boulders and other topographic obstacles, indicating obstruction during down-valley transportation. Most of the litter accumulations were distributed in the up-valley dipping slopes downstream of the scour centers. This pattern is tentatively linked to turbidity currents, which accelerated down the steep upstream slopes of the scours and underwent a hydraulic jump toward the scour centers before decelerating on the upstream-facing flank. Associated seabed sediment consisted of clayey and sandy silts, with unimodal or bimodal grain-size distributions, which are typical for turbidites. The focused distribution of the litter accumulations is therefore linked to turbidity currents that episodically flush the canyon. Our findings provide evidence that litter dispersion in the deep sea may initially be governed by gravity flows, and that turbidity currents efficiently transfer plastic litter to the deeper ocean floor.
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Shen, Ming, Siyuan Wang, Yingkui Li, Maofeng Tang, and Yuanxu Ma. "Pattern of Turbidity Change in the Middle Reaches of the Yarlung Zangbo River, Southern Tibetan Plateau, from 2007 to 2017." Remote Sensing 13, no. 2 (January 7, 2021): 182. http://dx.doi.org/10.3390/rs13020182.
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Turbidity is an important indicator of riverine conditions, especially in a fragile environment such as the Tibetan Plateau. Remote sensing, with the advantages of large-scale observations, has been widely applied to monitor turbidity change in lakes and rivers; however, few studies have focused on turbidity change of rivers on the Tibetan Plateau. We investigated the pattern of turbidity change in the middle reaches of the Yarlung Zangbo River, southern Tibetan Plateau, based on multispectral satellite imagery and in situ measurements. We developed empirical models from in situ measured water leaving reflectance and turbidity, and applied the best performed s-curve models on satellite imagery from Sentinel-2, Landsat 8, and Landsat 5 to derive turbidity change in 2007–2017. Our results revealed an overall decreasing spatial trend from the upper to lower streams. Seasonal variations were observed with high turbidity from July to September and low turbidity from October to May. Annual turbidity showed a temporally slightly declining trend from 2007 to 2017. The pattern of turbidity change is affected by the confluence of tributaries and the changes in precipitation and vegetation along the river. These findings provide important insights into the responses of riverine turbidity to climate and environmental changes on the Tibetan Plateau.
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Shen, Ming, Siyuan Wang, Yingkui Li, Maofeng Tang, and Yuanxu Ma. "Pattern of Turbidity Change in the Middle Reaches of the Yarlung Zangbo River, Southern Tibetan Plateau, from 2007 to 2017." Remote Sensing 13, no. 2 (January 7, 2021): 182. http://dx.doi.org/10.3390/rs13020182.
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Turbidity is an important indicator of riverine conditions, especially in a fragile environment such as the Tibetan Plateau. Remote sensing, with the advantages of large-scale observations, has been widely applied to monitor turbidity change in lakes and rivers; however, few studies have focused on turbidity change of rivers on the Tibetan Plateau. We investigated the pattern of turbidity change in the middle reaches of the Yarlung Zangbo River, southern Tibetan Plateau, based on multispectral satellite imagery and in situ measurements. We developed empirical models from in situ measured water leaving reflectance and turbidity, and applied the best performed s-curve models on satellite imagery from Sentinel-2, Landsat 8, and Landsat 5 to derive turbidity change in 2007–2017. Our results revealed an overall decreasing spatial trend from the upper to lower streams. Seasonal variations were observed with high turbidity from July to September and low turbidity from October to May. Annual turbidity showed a temporally slightly declining trend from 2007 to 2017. The pattern of turbidity change is affected by the confluence of tributaries and the changes in precipitation and vegetation along the river. These findings provide important insights into the responses of riverine turbidity to climate and environmental changes on the Tibetan Plateau.
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Kim, Bong Min, Hee Yun Lee, and Johng-Hwa Ahn. "Optimization of Initial Turbidity and Coagulant Concentration to Remove Turbidity Using Moringa oleifera Seed." Journal of Korean Society of Environmental Engineers 42, no. 2 (February 29, 2020): 47–54. http://dx.doi.org/10.4491/ksee.2020.42.2.47.
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Objective:Coagulation of <i>Moringa oleifera</i> seeds was studied to determine the optimal conditions in treating a turbid water.Method:Jar-test experiments were performed at various rapid mixing (90-250 rpm; 1-2 min), slow mixing (10-60 rpm; 10-50 min), initial turbidity (100-500 NTU), coagulant doses (200-1,500 mg/L), and pH (2-12) in synthetic wastewater. Response surface analysis was used to optimize the coagulation in jar-test experiments.Results and Discussion:The optimal conditions for turbidity removal with <i>M. oleifera</i> were 200 rpm of rapid-mixing speed for 1 min, 40 rpm of slow-mixing speed for 20 min, and pH 8. The coagulation efficiency was found to be dependent on initial turbidity of water samples. Highest turbidity removals (96.5%) were obtained for water with very high initial turbidity (500 NTU). The effects of initial turbidity and coagulant dose were successfully analyzed by the response surface analysis. Within the design boundaries, turbidity removal was more sensitive to changes in initial turbidity than to changes in coagulant dose.Conclusions:The quadratic model between initial turbidity and coagulant for turbidity removal was shown. <i>M. oleifera</i> can be used as a potential coagulant especially for high turbidity water.
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Murren, Clive. "Clear Thinking on Turbidity." Measurement and Control 26, no. 3 (May 1993): 83–85. http://dx.doi.org/10.1177/002029409302600306.
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