Journal articles: 'Sedimentation and deposition – Vermont'

1

Brakenridge, G. Robert, Peter A. Thomas, Laura E. Conkey, and Jane C. Schiferle. "Fluvial Sedimentation in Response to Postglacial Uplift and Environmental Change, Missisquoi River, Vermont." Quaternary Research 30, no. 2 (September 1988): 190–203. http://dx.doi.org/10.1016/0033-5894(88)90023-3.

Full text

Abstract:

Three lithologically distinct alluvial units of Holocene age can be distinguished along trenched cross sections of the Missisquoi valley bottom. The oldest is of early Holocene age, and the associated floodplain had aggraded to nearly its present level by 8000 14C yr B.P. At that time, early Archaic projectile points were deposited in a fire hearth 50 cm below the surface. Abandonment of this floodplain was followed by the development of an A-E-Bt soil profile. Accumulation of a younger floodplain had begun by 6400 14C yr B.P. and local sedimentation persisted to ca. 500 14C yr B.P., as indicated by radiocarbon dates of buried woody debris (including large logs) and of charcoal. Alluvium of the modern floodplain began accreting after A.D. 1860 and contains machine-cut square nails, whiteware ceramics, and coal clinker. Previous locations of the river channel can be reconstructed from relict surfaces marked by paleosols, the preserved depositional stratigraphy, and the radiocarbon samples. Immediately after regression of the Champlain Sea from this part of the valley, and before 8000 14C yr B.P., the river incised late Fleistocene marine silts and clays at an average rate of at least 1 m/100 yr. After the interval of downcutting, episodic lateral migration became the dominant process, with the rate varying between 0 and 4 m/100 yr. The early Holocene incision was most likely a lagged response to postglacial crustal rebound, whereas strong soil development and floodplain stability between 8000 and 6400 14C yr B.P. may reflect an independently documented warmer, and perhaps drier, climate in New England at this time. Finally, the post-A.D. 1860 period of active floodplain sedimentation may have been a response to timber clear-cutting, row crop agriculture, and cattle and sheep grazing in the watershed.

APA, Harvard, Vancouver, ISO, and other styles

2

Photiades, A., N. Carras, V. Bortolotti, M. Fazzuoli, and G. Principi. "THE LATE EARLY CRETACEOUS TRANSGRESSION ON THE LATERITES IN VOURINOS AND VERMION MASSIFS (WESTERN MACEDONIA, GREECE)." Bulletin of the Geological Society of Greece 40, no. 1 (June 8, 2018): 182. http://dx.doi.org/10.12681/bgsg.16510.

Full text

Abstract:

Three stratigraphical sections from eastern Vourinos (Rhodiani area) to eastern Vermion massifs revealed the same age of the latérite events affecting the serpentinized ophiolite complex after its emplacement on the Pelagonian domain. All of them consist from their base upwards of serpentinized harzburgite slivers with lateritic unconformities on the top, followed by transgressive upper Lower Cretaceous neritic limestones. At Kteni locality (Rhodiani area), a laterite horizon, lying on top of serpentinites, is covered by transgressive neritic limestones with Salpingoporella urladanasi, assigning a Barremian - Albian age, followed by Orbitolinidae limestones. At Tsimodia locality (NNW to the previous), the latente horizon, lying on karstified Upper Jurassic reef limestones (which are the top member of a carbonate platform body tectonically lying on the ophiolites), is trans gres s ively overlain by iron-rich pisolith levels and Aptian limestones of the wackes tone-muds tone type, also containing Salpingoporella urladanasi, followed by Cenomanian Orbitolina limestones. Finally, the third examined locality, further north-eastward to the previous, is situated at the eastern slopes of Vermion massif and more precisely at the NWpart of Koumaria village. There, it can again be observed that the lateritized serpentinite slivers are overlain transgress ively by neritic limestones with Salpingoporella urladanasi, passing upwards into Upper Cretaceous recrystallized limestones with Orbitolinidae and rudist fragments and, finally, toflysch deposition. These features allow to recognize that the emersion and the consecutive lateritization of the thrust-emplaced ophiolites in Vourinos and Vermion massifs in the northern Pelagonian domain, starting from the Latest Jurassic, was followed by a marine transgression beginning from the Barremian - Albian, firstly under restricted and brackish carbonate platform conditions, marked by the presence of the dasycladalean alga Salpingoporella urladanasi, followed by normal salinity carbonate platform conditions. The neritic sedimentation was stable until the Early Cenomanian. Subsequently, a deepening, earlier at Vourinos and later at Vermion, resulted in deposition of pelagic and turbiditic carbonates and then offlysch.

APA, Harvard, Vancouver, ISO, and other styles

3

Keeler, Gerald J., Lynne E. Gratz, and Khalid Al-wali. "Long-term Atmospheric Mercury Wet Deposition at Underhill, Vermont." Ecotoxicology 14, no. 1-2 (March 2005): 71–83. http://dx.doi.org/10.1007/s10646-004-6260-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Stovin, Virginia R., and Adrian J. Saul. "Sedimentation in Storage Tank Structures." Water Science and Technology 29, no. 1-2 (January 1, 1994): 363–72. http://dx.doi.org/10.2166/wst.1994.0684.

Full text

Abstract:

Although storage tanks provide an effective means of reducing the magnitude and frequency of combined sewer overflow discharges, and thereby of alleviating urban watercourse pollution, poorly designed storage structures frequently suffer from maintenance problems arising from sedimentation. The development of design guidelines that optimise the self-cleansing operation of storage structures is clearly a priority for urban drainage research. This paper describes a system that has been developed to study sediment deposition in laboratory model-scale storage structures. The patterns of deposition resulting from a selection of flow regimes are described, and the need for time-varying and time series storm tests is highlighted. Sedimentation patterns are shown to predominantly depend on the flow field, and the critical bed shear stresses for deposition and erosion in the model situation are identified. Hence, the potential application of numerical models to the design problem is discussed.

APA, Harvard, Vancouver, ISO, and other styles

5

Bonnas, Sylvia, Jan Tabellion, and Jürgen Haußelt. "Effect of Particle Size Distribution and Sedimentation Behaviour on Electrophoretic Deposition of Ceramic Suspensions." Key Engineering Materials 314 (July 2006): 69–74. http://dx.doi.org/10.4028/www.scientific.net/kem.314.69.

Full text

Abstract:

By systematic interaction of sedimentation and electrical field in electrophoretic deposition the particle size distribution of the deposited green body can be influenced. This can be employed for producing coatings with a very smooth surface by deposition of only the nanosized fraction of a conventional powder with broad or non-monomodal size distribution, thus avoiding preceding classification. In this paper, the preparation of stabilised slurries is described focussing on the criteria particle size distribution, zeta-potential and sedimentation behaviour. The effectiveness of the interaction of sedimentation and electrophoretic deposition is to be shown.

APA, Harvard, Vancouver, ISO, and other styles

6

Kerkweg, A., J. Buchholz, L. Ganzeveld, A. Pozzer, H. Tost, and P. Jöckel. "Technical Note: an implementation of the dry removal processes DRY DEPosition and SEDImentation in the Modular Earth Submodel System (MESSy)." Atmospheric Chemistry and Physics Discussions 6, no. 4 (July 24, 2006): 6853–901. http://dx.doi.org/10.5194/acpd-6-6853-2006.

Full text

Abstract:

Abstract. We present the submodels DRYDEP and SEDI for the Modular Earth Submodel System (MESSy). Gas phase and aerosol dry deposition are calculated within DRYDEP, whereas SEDI deals with aerosol particle sedimentation. Dry deposition velocities depend on the near-surface turbulence and the physical and chemical properties of the surface cover (e.g. the roughness length, soil pH or leaf stomatal exchange). The dry deposition algorithm used in DRYDEP is based on the big leaf approach and is described in detail within this Technical Note. The sedimentation submodel SEDI contains two sedimentation schemes: a simple upwind zeroth order scheme and a first order approach.

APA, Harvard, Vancouver, ISO, and other styles

7

Kerkweg, A., J. Buchholz, L. Ganzeveld, A. Pozzer, H. Tost, and P. Jöckel. "Technical Note: An implementation of the dry removal processes DRY DEPosition and SEDImentation in the Modular Earth Submodel System (MESSy)." Atmospheric Chemistry and Physics 6, no. 12 (October 12, 2006): 4617–32. http://dx.doi.org/10.5194/acp-6-4617-2006.

Full text

Abstract:

Abstract. We present the submodels DRYDEP and SEDI for the Modular Earth Submodel System (MESSy). Dry deposition of gases and aerosols is calculated within DRYDEP, whereas SEDI deals with aerosol particle sedimentation. Dry deposition velocities depend on the near-surface turbulence and the physical and chemical properties of the surface cover (e.g. the roughness length, soil pH or leaf stomatal exchange). The dry deposition algorithm used in DRYDEP is based on the big leaf approach and is described in detail within this Technical Note. The sedimentation submodel SEDI contains two sedimentation schemes: a simple upwind zeroth order scheme and a first order approach.

APA, Harvard, Vancouver, ISO, and other styles

8

Brynn, David J., and John C. Clausen. "Postharvest Assessment of Vermont's Acceptable Silvicultural Management Practices and Water Quality Impacts." Northern Journal of Applied Forestry 8, no. 4 (December 1, 1991): 140–44. http://dx.doi.org/10.1093/njaf/8.4.140.

Full text

Abstract:

Abstract Seventy-eight recently completed timber harvesting operations in Vermont were evaluated for Acceptable Management Practice (AMP) compliance, soil erosion extent, and water quality impacts using a systematic, one-day examination of each site. Evaluations of water quality impacts and soil erosion were conducted on the portions of the transportation network and streams that could be most heavily affected by the timber harvesting operation. Increased stream sedimentation was observed on 46% of the operations with streams. Woody debris impacts occurred on 65% of the operations with streams. AMP compliance was over 90% for protective strip maintenance and stream avoidance, but soil erosion control practices on truck roads and skid trails commonly failed to meet AMP recommendations. Soil erosion was very limited on truck roads, skid trails, and log landings. Although the Vermont operations often only partially complied with the AMPs, minimal soil erosion and water quality impacts were observed. North. J. Appl. For. 8(4):140-144.

APA, Harvard, Vancouver, ISO, and other styles

9

YU, C. P., B. ASGHARIAN, and B. M. YEN. "Impaction and Sedimentation Deposition of Fibers in Airways." American Industrial Hygiene Association Journal 47, no. 2 (February 1986): 72–77. http://dx.doi.org/10.1080/15298668691389388.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Campos, Jody, Iran Eduardo Lima Neto, Ticiana Marinho Studart, and José Nilson Beserra Campos. "Influence of sediment distribution on the relationships among reservoir yield, spill, and evaporation losses." Engenharia Sanitaria e Ambiental 23, no. 5 (October 2018): 849–56. http://dx.doi.org/10.1590/s1413-41522018177058.

Full text

Abstract:

ABSTRACT This study shows how the sedimentation process in reservoirs affects the yield-spill-evaporation losses in reservoirs of Ceará State, Brazilian Northeast. Reservoirs are assumed to have, initially, inverted conical shape. Three forms of sedimentation were investigated: type 1, with deposition occurring parallel to the wetted perimeter; type 2, deposition distributed proportionally to the water depth; and, type 3, deposition concentrated in the reservoir bottom. These sedimentation patterns were found in many reservoirs in Ceará, with capacity ranging from about 0.5 to 100 hm3. Nevertheless, type 2 pattern was the most frequent. In this paper, five large reservoirs, over 100 hm3, were studied using Monte Carlo approach, and considering the silting over the time horizon. It was found that sediment distribution can significantly affect the yield-spill-evaporation trade-off on large reservoirs. Type 1 results have the lowest impact on reservoir yield, followed by type 2 and type 3. For Cedro reservoir, the yield would go to zero in 2115, assuming a type 3 deposition pattern. These results reinforce the need for monitoring sedimentation in large reservoirs in the Brazilian semiarid region. In addition, this study provides a relatively simple methodology to predict the impact of siltation on reservoir yield-spill-evaporation relationships, for the three most found patterns of sedimentation.

APA, Harvard, Vancouver, ISO, and other styles

11

Huang, Shu You, Zhi Gang Yin, Jin Guang Zhang, Yu Shan Ren, and Jing Hai Zhou. "Research the Problem about the Silted Deposition of the Broken Model." Applied Mechanics and Materials 204-208 (October 2012): 279–83. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.279.

Full text

Abstract:

On the foundation of the item that the residence flood controlled technique and standard tested and the analysis according to the formation of the sediment and the regulation of the sedimentation in the actual river. In the process of the studied item, design a kind of a new sedimentation basin in order to lower the sand carrying capacity of the down water in the limited distance and the biggest limit. Through the model experiment of this kind of the sedimentation basin and find out the result of the sink the sand under the different discharge, in order to guide the actual engineering application.

APA, Harvard, Vancouver, ISO, and other styles

12

Ren, Zhihui, Ting Wang, Yuanjian Wang, and Shaojun Qu. "A study on the characteristics and influencing factors of reservoir sedimentation in Wanjiazhai Reservoir." MATEC Web of Conferences 246 (2018): 01046. http://dx.doi.org/10.1051/matecconf/201824601046.

Full text

Abstract:

Based on measured data of the Wanjiazhai Reservoir in different periods, the characteristics of the spatial and temporal distribution of sedimentation in the reservoir area were preliminarily analyzed and the impact of reservoir operation on this distribution was discussed. Primary conclusions are as followed: in terms of temporal distribution, sedimentation continuously accumulated over the period from 2000 to 2017, with the sediment deposition ratio dramatically decreasing between 2011 and 2017; in terms of spatial distribution, the sedimentation in the reservoir area was mainly concentrated downstream of the WD54 section, with the highest concentration being downstream of the WD23 section. The characteristics of sedimentation distribution in the reservoir area were closely related to inflow and sediment conditions and reservoir operation water level. When the water level was lower than 952 m, the sediment deposition ratio was lower than 0. To further improve the sediment deposition form in the reservoir area, lowering water level and ejecting the sediment are recommended in a timely manner.

APA, Harvard, Vancouver, ISO, and other styles

13

Jennings, Karen L., Paul R. Bierman, and John Southon. "Timing and style of deposition on humid-temperate fans, Vermont, United States." Geological Society of America Bulletin 115 (February 2003): 182–99. http://dx.doi.org/10.1130/0016-7606(2003)115<0182:tasodo>2.0.co;2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Reath, Mark, James Brannen, Paul Bakeman, and Richard Lebel. "Use of Residual Gas Analysis in Low-Pressure Semiconductor Process Reactors." Journal of the IEST 37, no. 2 (March 1, 1994): 57–60. http://dx.doi.org/10.17764/jiet.2.37.2.0q1489887h1x0780.

Full text

Abstract:

Residual gas analysis (RGA) was used for troubleshooting tetra (ethoxyorthosilicate) (TEOS) and tungsten silicide chemical vapor deposition processes. In each process, RGA identified reactor impurity sources later proven to be the root cause of film defects and foreign material deposition. RGA verified the effectiveness of modified reactor hardware and operating procedures. This paper describes two case studies that represent RGA contributions to the 0.5-μ process development at the IBM semiconductor manufacturing facility in Essex Junction, Vermont.

APA, Harvard, Vancouver, ISO, and other styles

15

Lee, H. N., and J. K. Shi. "An alternative approach for atmospheric plume deposition and sedimentation." International Journal of Environmental Studies 25, no. 1-2 (June 1985): 109–26. http://dx.doi.org/10.1080/00207238508710214.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Ismayilova, F. B. "Formation of sedimentation in oil mixing." Azerbaijan Oil Industry, no. 12 (December 15, 2020): 36–38. http://dx.doi.org/10.37474/0365-8554/2020-12-36-38.

Full text

Abstract:

As a result of the studies on the impact of the mixing of various sorts of Azerbaijani oils on their quality parameters, it was defined that in some correlations oil mixing is impossible as both rheological and physico-chemical parameters of these oils after mixing abnormally change. In the context of the oils from Bulla and Garachukhur fields it was specified that in 58:42 ratio percentage correspondingly, abnormal phenomenon is observed in parameter change. Moreover, various ballast deposition occurs due to the mixing. The paper studies the kinetics of deposition of different ballasts (resin, asphaltene and paraffins, as well as water, salt and mechanical impurities) in the mixture of incompatible oils. It was defined that the main mass of all ballasts is deposited during 8–10 hours. The studies justified that depending on the chemical composition of the oils, the incompatibility in the mixture may also be occured in intensive seperation of various ballasts.

APA, Harvard, Vancouver, ISO, and other styles

17

Markova, Irina, and Yuliya Bryanskaya. "Restrained fall velocity of suspended solids particles sedimentation in still water." E3S Web of Conferences 91 (2019): 07004. http://dx.doi.org/10.1051/e3sconf/20199107004.

Full text

Abstract:

The deposition rate is sufficiently studied in the case of single particles or in conditions of low concentrations of suspended matter, in which the precipitating particles do not affect each other. In the article, the method of calculation of the rate of the constrained deposition is offered, comparative calculations of the rate of the free and constrained deposition of particles are executed, the settlement results reflecting essential difference of the speed of the constrained and free deposition of particles are presented. The factors influencing the rate of confined deposition, among which the main one is the concentration of suspended matter in water, are considered. The experimental data confirming the reduction of speed of the constrained deposition of more than 3 times in a five-fold increase in the concentration of suspended solids is given. The dependence of the strained deposition rate of particles on the concentration of the suspension is obtained.

APA, Harvard, Vancouver, ISO, and other styles

18

Feng, Xiao Xiang, Zhe Liu, and Xing Kui Wang. "Application Comparison about Sediment Deposition in Outer Channel by Three-Layer Mode and Analog Analysis Mode." Applied Mechanics and Materials 130-134 (October 2011): 1638–44. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1638.

Full text

Abstract:

Sudden sedimentation is an important subject for building ports in silt-sandy coast. It elaborates calculation methods detailed about three-layer deposition mode and analogy analysis mode. And they are used to predict the deposition in outer channel of Binzhou Port. Comparative results show that they are basically same on the distribution of sudden sedimentation, deposition thickness and volume along the channel. And it is larger from three-layer deposition mode than analogy analysis mode. The formal mode is propitious to project security. By analyzing the characteristics and applicability about two methods, basic law is obtained for sediment movement and predicting methods under strong wind in the outer channel of silt-sandy coast.

APA, Harvard, Vancouver, ISO, and other styles

19

Koster, Kay, Jan Stafleu, Peter C. Vos, and Michiel J. van der Meulen. "Can we elevate the subsiding coastal plain of the Netherlands with controlled sedimentation?" Proceedings of the International Association of Hydrological Sciences 382 (April 22, 2020): 767–73. http://dx.doi.org/10.5194/piahs-382-767-2020.

Full text

Abstract:

Abstract. Half the surface area of the coastal plain of the Netherlands has been subsiding below mean sea-level as a result of peatland drainage. At present, the low elevation is sustained, because sedimentation necessary to aggrade the coastal plain back to natural elevations is hampered by engineering structures. Alternatively, controlled sedimentation is a discussed method to elevate the coastal plain. This can either be achieved by allowing water courses to deliver sediments to designated areas, or by anthropogenic deposition. Here, we assess the possibilities of this strategy by determining whether natural systems or anthropogenic deposition are sufficient to elevate the surface to mean high water (MHW), taking into account IPCC projected minimum and maximum forecasted sea-level rise (RCP2.6 and RCP8.5), and predicted future subsidence. We use the 3D geological subsurface model GeoTOP to quantify sediments; i.e. clay and sand that were naturally delivered to the coastal plain by series of tidal inlets and the Rhine river system. Furthermore, we quantify the amount of anthropogenic deposition, and analyze documented supplies. Finally, we discuss the implications of controlled sedimentation in designated areas by providing examples of past embankment breaches. We quantify that 16.98 km3 of sediments are required to elevate the surface to MHW, and between 22.41 and 29.29 km3 at the end of the 21st century. We estimate that 45.30 km3 of sediments were delivered by the tidal systems during 3000 years (52 % sand), 20.18 km3 by the Rhine river system during 8000 years (29 % sand), and 3.59 km3 of anthropogenic deposition. We conclude that the coastal plain of the Netherlands cannot be elevated to more safe levels with controlled sedimentation. Exceptions are areas proximal to tidal systems with high sediment yields. Anthropogenic deposition, combining natural sedimentation with supplied sediments, or allowing peat growth in inundated areas could be viable alternatives as well as.

APA, Harvard, Vancouver, ISO, and other styles

20

Pavlenko, Ivan, Marek Ochowiak, Praveen Agarwal, Radosław Olszewski, Bernard Michałek, and Andżelika Krupińska. "Improvement of Mathematical Model for Sedimentation Process." Energies 14, no. 15 (July 28, 2021): 4561. http://dx.doi.org/10.3390/en14154561.

Full text

Abstract:

In this article, the fractional-order differential equation of particle sedimentation was obtained. It considers the Basset force’s fractional origin and contains the Riemann–Liouville fractional integral rewritten as a Grunwald–Letnikov derivative. As a result, the general solution of the proposed fractional-order differential equation was found analytically. The belonging of this solution to the real range of values was strictly theoretically proven. The obtained solution was validated on a particular analytical case study. In addition, it was proven numerically with the approach based on the S-approximation method using the block-pulse operational matrix. The proposed mathematical model can be applied for modeling the processes of fine particles sedimentation in liquids, aerosol deposition in gas flows, and particle deposition in gas-dispersed systems.

APA, Harvard, Vancouver, ISO, and other styles

21

Wang, Jianfu, Xin Kang, and Chunyin Peng. "Modelling and Experimental Investigation on the Settling Rate of Kaolinite Particles in Non-Ideal Sedimentation Stage under Constant Gravity." Materials 13, no. 17 (August 27, 2020): 3785. http://dx.doi.org/10.3390/ma13173785.

Full text

Abstract:

We compared the catalytic effects of two polymers (soluble starch and apple pectin) on the flocculation of kaolinite suspension. Moreover, the relationship between the zeta potential value and the time when kaolin particle sedimentation occurred was verified, and the mechanism of flocculation was analyzed. Additionally, a constitutive model was proposed to simulate the non-ideal sedimentation of clay particles in an aqueous system under constant gravity. This model not only considers the inhomogeneity of the solute but also simulates the change in clay concentration with time during the deposition process. This model proposes a decay constant (α) and sedimentation coefficient (s). The model can also be used to calculate the instantaneous sedimentation rate of the clay suspensions at any time and any depth for the settling cylinder. These sedimentary characteristics were simulated by adopting the established deposition model. The results show that the model is capable of predicting the time required for the complete sedimentation of particles in the aqueous system, suggesting the feasibility of engineering wastewater treatment, site dredging, etc.

APA, Harvard, Vancouver, ISO, and other styles

22

Castro, Clovis Barreira e., Bárbara Segal, Fábio Negrão, and Emiliano Nicolas Calderon. "Four-year monthly sediment deposition on turbid southwestern Atlantic coral reefs, with a comparison of benthic assemblages." Brazilian Journal of Oceanography 60, no. 1 (March 2012): 49–63. http://dx.doi.org/10.1590/s1679-87592012000100006.

Full text

Abstract:

High sedimentation is often related to stress in coral reef communities. Most southwestern Atlantic reefs are characterized by high sedimentation. However, there are no temporal series of sediment deposition rates. We evaluated sediment deposition, the sediment carbonate composition and coral and zoanthid covers on six reefs in Brazil over four-years. Sediment deposition rates varied from near zero to 233 mg cm-2 day-1, with peaks between August and December, and yearly averages ranging from nine to 104 mg cm-2 day-1. Deposition rates presented site-specific correlations with wind, indicating that resuspension must be a major factor. The presence of carbonates varied from 38% to 90%, with two sites showing seasonal differences. Benthic communities were fairly similar among sites, but the analyses suggested particular frequencies at each site. There was no significant correlation between sediment and benthic communities. However, Palythoa caribaeorum usually occur in high sediment deposition areas. Our results did not corroborate previous data that suggested that a 10 mg cm-2 day-1 would be a "critical limit for coral survival". Some coral reefs may be associated with high sedimentation environments including carbonatic fractions, but which does not per se hinder the development of southwestern Atlantic coral reef communities.

APA, Harvard, Vancouver, ISO, and other styles

23

Lee, S. S., and J. E. Penner. "Aerosol effects on ice clouds: can the traditional concept of aerosol indirect effects be applied to aerosol-cloud interactions in cirrus clouds?" Atmospheric Chemistry and Physics Discussions 10, no. 4 (April 21, 2010): 10429–62. http://dx.doi.org/10.5194/acpd-10-10429-2010.

Full text

Abstract:

Abstract. Cirrus clouds cover approximately 20–25% of the globe and thus play an important role in the Earth's radiation budget. This indicates that aerosol effects on cirrus clouds can have a substantial impact on the variation of global radiative forcing if the ice-water path (IWP) changes. This study examines the aerosol indirect effect (AIE) through changes in the IWP for a cirrus cloud case. We use a cloud-system resolving model (CSRM) coupled with a double-moment representation of cloud microphysics. Intensified interactions among the cloud ice number concentration (CINC), deposition and dynamics play a critical role in the IWP increases due to aerosol increases. Increased aerosols lead to increased CINC, providing increased surface area for water vapor deposition. The increased deposition causes depositional heating which produces stronger updrafts, and leads to the increased IWP. The conversion of ice crystals to aggregates through autoconversion and accretion plays a negligible role in the IWP responses to aerosols, as the sedimentation of aggregates. The sedimentation of ice crystals plays a more important role in the IWP response to aerosol increases than the sedimentation of aggregates, but, not more important than the interactions among the CINC, deposition and dynamics.

APA, Harvard, Vancouver, ISO, and other styles

24

Dun, Hongchao, Guowei Xin, Ning Huang, Guangtian Shi, and Jie Zhang. "Wind-Tunnel Studies on Sand Sedimentation Around Wind-Break Walls of Lanxin High-Speed Railway II and Its Prevention." Applied Sciences 11, no. 13 (June 27, 2021): 5989. http://dx.doi.org/10.3390/app11135989.

Full text

Abstract:

Wind-break walls along Lanxin High-Speed Railway II were studied and approved as effective measures to reduce strong wind damage to the high-speed trains. The results show that sand sedimentation on the leeward sides of wind-break walls along the railway within Gobi Desert could significantly threaten the operation safety of running trains. Different from the current sand sedimentation prevention measures without adequate consideration of the deposition process of airborne sand particles, this study revealed the mechanism of sand sedimentation on the leeward sides of three wind-break walls within different terrains. A series of wind-tunnel experiments were carried out to measure the horizontal velocity, number density, transport flux, and deposition rate of sand particles, and it was found that the horizontal speed of sand particles was first increased and then decreased on the railway track, and the peak speed over the concave subgrade was much smaller than those over convex and flat subgrades. The number density and horizontal sand flux were largest over the concave subgrade, and were the smallest over the convex subgrade. The sand particle deposition rate and distribution were also the largest within the concave subgrade, and some measures were also proposed to prevent sand sedimentation on the leeward sides of wind-break walls.

APA, Harvard, Vancouver, ISO, and other styles

25

Theol, Shaimaa A., Bert Jagers, F. X. Suryadi, and Charlotte de Fraiture. "The Role of Gate Operation in Reducing Problems with Cohesive and Non-Cohesive Sediments in Irrigation Canals." Water 11, no. 12 (December 6, 2019): 2572. http://dx.doi.org/10.3390/w11122572.

Full text

Abstract:

Sediments cause serious problems in irrigation systems, adversely affecting canal performance, driving up maintenance costs and, in extreme cases, threatening system sustainability. Multiple studies were done on the deposition of non-cohesive sediment and implications for canal design, the use of canal operation in handling sedimentation problems is relatively under-studied, particularly for cohesive sediments. In this manuscript, several scenarios regarding weirs and gate operation were tested, using the Delft3D model, applied to a case study from the Gezira scheme in Sudan. Findings show that weirs play a modest role in sedimentation patterns, where their location influences their effectiveness. On the contrary, gate operation plays a significant role in sedimentation patterns. Reduced gate openings may cause canal blockage while intermittently fully opening and closing of gates can reduce sediment deposition in the canal by 54% even under conditions of heavy sediment load. Proper location of weirs and proper adjusting of the branch canal’s gate can substantially reduce sedimentation problems while ensuring sufficient water delivery to crops. The use of 2D/3D models provides useful insights into spatial and temporal patterns of deposition and erosion but has challenges related to running time imposing a rather coarse modelling resolution to keep running times acceptable.

APA, Harvard, Vancouver, ISO, and other styles

26

Saraiva, L. B., C. G. Ribeiro Meneses, H. N. de Souza Melo, A. L. Calado Araújo, and H. Pearson. "Determination of the sedimentation constants for total suspended solids and the algal component in a full-scale primary facultative pond operating at high wind velocities under tropical conditions." Water Science and Technology 51, no. 12 (June 1, 2005): 213–16. http://dx.doi.org/10.2166/wst.2005.0465.

Full text

Abstract:

This study evaluated the amount, distribution and sedimentation constant of solids in a full-scale primary facultative pond operating mostly under high wind conditions and the contribution made by the algal biomass. Solids deposition rates were measured using sedimentation traps placed in the inlet and outlet zones of the pond. Most sludge accumulation occurred, not surprisingly, in the inlet zone A1 with a sludge volume of 9072 m3 accumulating over an operating time of approximately 3 years. However, sludge deposition within this zone was uneven and affected by wind action. Mean proportionality constant (K) values for solids sedimentation were 3.02 and 5.70 for depths of 50 cm and 100 cm respectively for A1. In contrast in zone A3, (the outlet zone), reduced K values of 1.38 and 3.22 were obtained for depths of 50 cm and 100 cm respectively. The algal sedimentation constant varied from 0.8 d−1 in zone A1 to 0.02 d−1 in A3. These data suggest that in this large facultative pond the wind, blowing predominantly from the direction of the outlets towards the pond inlets, had a greater influence on solids deposition than the bulk hydraulic flow and also kept the pond completely mixed for most of the time.

APA, Harvard, Vancouver, ISO, and other styles

27

Friedland, Andrew J., Arthur H. Johnson, and Thomas G. Siccama. "Coniferous litter decomposition on Camels Hump, Vermont: a review." Canadian Journal of Botany 64, no. 7 (July 1, 1986): 1349–54. http://dx.doi.org/10.1139/b86-186.

Full text

Abstract:

The high-elevation forests of the northeastern United States receive relatively large quantities of atmospheric pollutants, including trace metals, in rain, fog, snow, and dry deposition. Measurements of forest floor thickness and trace metal and organic matter concentrations on Camels Hump, Vermont, taken between 1965 and 1983 show that while trace metal and organic matter concentrations have increased substantially during that time period, forest floor thicknesses have not shown a consistent pattern of change. Based on previously published decomposition experiments, it does not appear that the current metal concentrations present in the forest floor on Camels Hump are capable of significantly reducing decomposition of organic matter. It is possible that trace metal accumulations over the next century (or more) may be consequential to biological processes in the forest floor.

APA, Harvard, Vancouver, ISO, and other styles

28

Darquenne, C., K. L. Zeman, R. C. Sá, T. K. Cooper, J. M. Fine, W. D. Bennett, and G. K. Prisk. "Removal of sedimentation decreases relative deposition of coarse particles in the lung periphery." Journal of Applied Physiology 115, no. 4 (August 15, 2013): 546–55. http://dx.doi.org/10.1152/japplphysiol.01520.2012.

Full text

Abstract:

Lung deposition of >0.5-μm particles is strongly influenced by gravitational sedimentation, with deposition being reduced in microgravity (μG) compared with normal gravity (1G). Gravity not only affects total deposition, but may also alter regional deposition. Using gamma scintigraphy, we measured the distribution of regional deposition and retention of radiolabeled particles (99mTc-labeled sulfur colloid, 5-μm diameter) in five healthy volunteers. Particles were inhaled in a controlled fashion (0.5 l/s, 15 breaths/min) during multiple periods of μG aboard the National Aeronautics and Space Administration Microgravity Research Aircraft and in 1G. In both cases, deposition scans were obtained immediately postinhalation and at 1 h 30 min, 4 h, and 22 h postinhalation. Regional deposition was characterized by the central-to-peripheral ratio and by the skew of the distribution of deposited particles on scans acquired directly postinhalation. Relative distribution of deposition between the airways and the alveolar region was derived from data acquired at the various time points. Compared with inhalation in 1G, subjects show an increase in central-to-peripheral ratio ( P = 0.043), skew ( P = 0.043), and tracheobronchial deposition ( P < 0.001) when particles were inhaled in μG. The absence of gravity caused fewer particles to deposit in the lung periphery than in the central region where deposition occurred mainly in the airways in μG. Furthermore, the increased skew observed in μG likely illustrates the presence of localized areas of deposition, i.e., “hot spots”, resulting from inertial impaction. In conclusion, gravity has a significant effect on deposition patterns of coarse particles, with most of deposition occurring in the alveolar region in 1G but in the large airways in μG.

APA, Harvard, Vancouver, ISO, and other styles

29

Liverman, David G. E. "Sedimentation in ice-dammed Hazard Lake, Yukon." Canadian Journal of Earth Sciences 24, no. 9 (September 1, 1987): 1797–806. http://dx.doi.org/10.1139/e87-171.

Full text

Abstract:

"Hazard Lake," located in Kluane National Park, the Yukon, is an ice-dammed lake formed in 1966 by the surge of the Steele Glacier. Since 1975 it has drained annually by means of a subglacial tunnel. During July 1979, observations were made of lake processes before drainage and of sections described in the lake bottom after drainage. Three facies associations are believed to represent prelake, stable lake, and annual draining phases. Gravel commonly found at the base of sections represents deposition in a braided fluvial system prior to 1966. Lake sediments deposited between 1966 and 1975 are dominantly graded laminated silt deposited by turbid underflow from the major inflow stream. Lamination is probably caused by diurnal underflow events or daily variation in strength of underflow. No "winter" clay component of varved sediments is observed. During drainage a regressive sequence is deposited as the lake level drops, with sand-dominated sediments overlapping laminated silt where the main inflow stream enters the lake. This is followed by local fluvial deposition along the course of the reestablished stream. During filling a transgressive sequence is deposited as the lake level rises. Sand-dominated deltaic sedimentation is followed by deposition from underflow, resulting in laminated and massive silt and clay. These fine-grained facies separate sand facies and demark individual filling events but are easily eroded. Thus it is not possible to identify the effects of each individual drainage–filling cycle in the sediments. After drainage the lake remains empty until the next melt season, during which time a braided stream is established in the lake basin, depositing sands and gravels and eroding lake sediments.

APA, Harvard, Vancouver, ISO, and other styles

30

Stratmann, Frank, Heinz Fissan, and Thomas Peterson. "Particle Deposition Onto a Flat Surface from a Point Particle Source." Journal of the IEST 31, no. 6 (November 1, 1988): 39–41. http://dx.doi.org/10.17764/jiet.1.31.6.n65256516m648901.

Full text

Abstract:

A series of two-dimensional calculations are performed to determine particle fluxes to wafers in a stagnation flow configuration. Mechanisms that influenced particle deposition included convection, diffusion, sedimentation, and thermophoresis. Particle deposition patterns resulting from a uniform freestream concentration are compared with deposition patterns from a narrow particle beam.

APA, Harvard, Vancouver, ISO, and other styles

31

Kadko, David. "Late Cenozoic sedimentation and metal deposition in the North Pacific." Geochimica et Cosmochimica Acta 49, no. 3 (March 1985): 651–61. http://dx.doi.org/10.1016/0016-7037(85)90160-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Maina, Caroline W., Joseph K. Sang, Benedict M. Mutua, and James M. Raude. "A review of radiometric analysis on soil erosion and deposition studies in Africa." Geochronometria 45, no. 1 (January 24, 2018): 10–19. http://dx.doi.org/10.1515/geochr-2015-0085.

Full text

Abstract:

Abstract Soil erosion is one of the main soil degradation phenomena that threaten sustainable use of soil productivity thus affecting food security. In addition, it leads to reservoir storage capacity loss because of sedimentation. This not only affects water quantity but also water quality. Worldwide, annual loss in reservoir storage capacity due to sedimentation is 0.5 to 1%. Similarly, about 27% of land in Africa is largely degraded by erosion. As a result, there is need to minimize soil erosion and deposition through site specific estimation of soil erosion and deposition rates in the reservoirs. To achieve this, Fallout RadioNuclides (FRNs) are some of the methods in use. The most common radionuclides include; 137Cs, 210Pb and 7Be. Only few countries in Africa have exploited these FRNs. In these countries, 137Cs has been largely exploited but in some regions, it has been reported to be below minimum detection limit. Using 137Cs and 210Pb, maximum reference inventory in Africa is found to be 1450 and 2602 Bq/m2, respectively. However, there is minimal application of 7Be within the continent. Also, very little has been done in Africa to assess chronology and sedimentation rates of reservoirs using FRNs measured from sediment cores. In conclusion, a gap still exists on FRNs application in Africa in assessing soil erosion, deposition and reservoir sedimentation.

APA, Harvard, Vancouver, ISO, and other styles

33

Hoque, Ashabul, Dipankar Kumar, Anip Kumar Paul, Masudar Rahman, Gour Chandra Paul, and Shin Ichi Aoki. "Sedimentation in Dune Forests, Mangrove Forests and CC Block System and Associated Topographic Changes." Journal of Bangladesh Academy of Sciences 43, no. 1 (July 16, 2019): 67–78. http://dx.doi.org/10.3329/jbas.v43i1.42235.

Full text

Abstract:

This paper is concerned with the deposition of sediment due to dune forests (Nakatajima dune, Japan) and CC block system on a riverbank (Padma, Bangladesh). Measurements of sediment deposition were carried out at Nakatajima dune, Japan and at Padma riverbank, Rajshahi, Bangladesh using Global Positioning System (GPS). 2442 m3 sediment migrates each year to the East side of Nakatajima dune by wind and the edge of the dune develops about 6-7 m/year due to the existence of forests. Sedimentation rate is also greater in shallower mangrove areas. The trapped sediment height varies from 8.0 to 10.0 cm in the mangrove-lined bank. Mangrove forests help to trap 25% more sedimentation at low tide than at high tide. On the other hand, only for setting up the CC block and groynes along the bank, the sedimentation rate is observed almost twice than that of the previous year. An analysis shows that there is a similarity of sedimentation among dune, beach forests, mangrove forests and CC blocks. Journal of Bangladesh Academy of Sciences, Vol. 43, No. 1, 67-78, 2019

APA, Harvard, Vancouver, ISO, and other styles

34

Cuddington, K., and P. R. Leavitt. "An individual-based model of pigment flux in lakes: implications for organic biogeochemistry and paleoecology." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 10 (October 1, 1999): 1964–77. http://dx.doi.org/10.1139/f99-108.

Full text

Abstract:

Vertical fluxes of pigments are used in limnology to monitor phytoplankton abundance, herbivore grazing, ecosystem efficiency, and historical changes in production. However, significant pigment degradation can occur during algal sedimentation. We used an individual-based model of pigment flux to quantify the relative importance of production and degradation as controls of pigment sedimentation. Pigment deposition increased with production, sinking rate, and phytoplankton depth and declined as lake depth and the depth of oxygen penetration increased. Unexpectedly, pigment sedimentation rate was not sensitive to variation in photooxidation rates, even though bleaching accounted for the second greatest amount of pigment loss. Digestion by zooplankton caused the most pigment degradation, but grazing increased pigment deposition when digestive losses were less than those due to oxidation of pigments in ungrazed cells. The model suggests that algal production may be underestimated in sedimentation studies that do not consider variability in water column depth. Further, comparisons with paleoecological analyses suggest that some inferred increases in production during lake ontogeny may arise from changes in regulation of pigment fluxes rather than from increased algal production.

APA, Harvard, Vancouver, ISO, and other styles

35

Guo, Shuai Jie, Bao Tian Wang, Fu Hai Zhang, and Liang Chen. "Settlement and Consolidation Mechanism of Cohesive Sedimentation in Estuarine Environment." Advanced Materials Research 261-263 (May 2011): 1454–58. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1454.

Full text

Abstract:

Estuarine area is the intersection zone of river estuary, coastal and land-phase. Cohesive sediment deposition for mutation affects estuary channel transport and brings great challenges to dredging project. Consolidation indicators are closely related to sedimentation and dredging, and there are apparent errors in application of Terzaghi theory in cohesive sediment consolidation evaluation for large stain characteristics. Then it is necessary to modify some consolidation parameters to extend Terzaghi theory in cohesive sediment consolidation. Considering a whole process of sedimentation and consolidation, a unified equation can be established based on sediment deposition and consolidation theory. Equation parameters can be determined by the simulation test (settlement column experiment). According to the settlement curves and volume fraction distribution curves by simulation experiment, modified consolidation coefficient and the trends can be determined, and modified consolidation coefficient can apply in dredging and deposition project.

APA, Harvard, Vancouver, ISO, and other styles

36

Roushangar, Kiyoumars, and Roghayeh Ghasempour. "Prediction of non-cohesive sediment transport in circular channels in deposition and limit of deposition states using SVM." Water Supply 17, no. 2 (September 23, 2016): 537–51. http://dx.doi.org/10.2166/ws.2016.153.

Full text

Abstract:

Sedimentation in sewer pipes has a negative impact on the performance of sewerage systems. However, due to the complex nature of sedimentation, determining the governing equations is difficult and the results of the available classic models for computing bedload transport rate often differ from each other. This paper focuses on the capability of a support vector machine (SVM) as a meta-model approach for predicting bedload transport in pipes. The method was applied for the deposition and limit of deposition states of sediment transport. Two different scenarios were proposed: in Scenario 1, the input combinations were prepared using only hydraulic characteristics, on the other hand, Scenario 2 was built using both hydraulic and sediment characteristics as model inputs of bedload transport. A comparison between the SVM and the employed classic approaches in predicting sediment transport indicated the supreme performance of the SVM, in which more accurate results were obtained. Also it was found that for estimation of bedload transport in pipes, Scenario 2 led to a more valid outcome than Scenario 1. Based on the sensitivity analysis, parameters Frm and d50/y in the limit of deposition state and Frm in the deposition state had the more dominant role in prediction of bedload discharge in pipes than other parameters.

APA, Harvard, Vancouver, ISO, and other styles

37

Hasthi, Saputra, Lilin Budiati, and Rukuh Setiadi. "IDENTIFIKASI KONDISI EKSISTING DAN DAMPAK SEDIMENTASI PADA SUNGAI KREO DAN KALIGARANG KOTA SEMARANG." saintifika 24, no. 2 (January 12, 2023): 95. http://dx.doi.org/10.25037/saintifika.v24i2.133.

Full text

Abstract:

The Garang watershed which includes the Kreo River and the Kaligarang River is an ecosystem unit that is limited by topographical separators and functions as a collector, storage, and distributor of water, nutrients, and sediment through the river's hydrological system. Garang watershed plays an important role in achieving Sustainable Development Goals (SDGs) 6 related to clean water, namely supplying drinking water raw materials in the city of Semarang experiencing environmental damage due to sedimentation common in river systems in Indonesia. Sedimentation occurs due to the deposition of fragmental material by water caused by erosion. Erosion consists of three phases, namely the release of soil particles and then transport by erosion agents (wind and water). Sediment deposition occurs which is influenced by natural and anthropogenic factors. The impact of sedimentation causes siltation which affects the decreasing capacity of river flow and decreases river water quality. This study aims to identify and analyze the existing conditions of the Kreo River and Kaligarang River related to the impact of sedimentation with qualitative descriptive methods and literature studies of previous studies. The Kreo River and Kaligarang River experience sedimentation due to suspended solids in the form of soil and sand mixed with household waste, resulting in decreased river flow and water quality. This is in line with the results of literature studies from previous studies, in 2008 sedimentation in the Kaligarang River was 124.944.13 tons/year with an erosion rate of 1,064.260.08 tons/ha/year. In 2009-2014 sedimentation in the Kreo River increased from 2,781 to 4,083 tons/year with an erosion rate of 17,827 - 26,171 tons. It can be concluded that the Kaligarang River and the Kreo River are currently experiencing increased sedimentation, so they are threatened with silting and damage to the river's natural functions.

APA, Harvard, Vancouver, ISO, and other styles

38

Marysyk, S. V. "DETERMINATION OF HYDRAULIC GRAIN SIZE OF NATURAL AND ARTIFICIAL SORBENTS FOR SIMULATION OF SETTLE FACILITY." Міжвідомчий тематичний науковий збірник "Меліорація і водне господарство", no. 2 (December 21, 2022): 94–99. http://dx.doi.org/10.31073/mivg202202-346.

Full text

Abstract:

In the conditions of progressive contamination of surface sources of water supply and inefficient wastewater treatment when using existing water treatment technologies, the research problem and the justification of the use of sorption materials for the retention of specific pollutants, in particular heavy metal ions and radionuclides, is urgent. The parameters that determine the efficiency of sorbents are indicators of their sedimentation rate. The purpose of the experiments was to determine the sedimentation rate indicators for bentonite and copper ferrocyanide, build sorbent sedimentation graphs, and establish the estimated sedimentation rate of sorbents in the sedimentation tank based on the studied data considering temperature regime. Deposition of the sorbent in settling tanks occurs with the non-stop movement of water at a low speed in the direction from the inlet to the outlet. The experiments are aimed at substantiating the efficiency and criteria of a universal facility, which is able to work equally effectively with sorbents in different aggregate states. The process of sorbent sedimentation in water is characterized by the kinetics of sorbent flakes conglomerates sedimentation. These processes are displayed in the form of deposition kinetics graphs. The experiment used powdered bentonite and a solution of copper ferrocyanide, consisting of yellow blood salt and copper sulphate in a given proportional ratio. In the course of the study the following parameters were determined: the hydraulic grain size of bentonite powdery clay, the dependence of the sedimentation rate on the temperature regime. The liquid layer was divided into layers that show changes in the amount of suspended substances depending on the depth, which made it possible to determine the dimensions of the settling tank, the height of the liquid overflow, which, in turn, made it possible to conduct simulation experiments on virtual machines with a full-scale clarifier-absorber in accordance to geometric parameters.

APA, Harvard, Vancouver, ISO, and other styles

39

Lee, S. S., and J. E. Penner. "Aerosol effects on ice clouds: can the traditional concept of aerosol indirect effects be applied to aerosol-cloud interactions in cirrus clouds?" Atmospheric Chemistry and Physics 10, no. 21 (November 4, 2010): 10345–58. http://dx.doi.org/10.5194/acp-10-10345-2010.

Full text

Abstract:

Abstract. Cirrus clouds cover approximately 20–25% of the globe and thus play an important role in the Earth's radiation budget. Therefore the effect of aerosols on cirrus clouds can have a substantial impact on global radiative forcing if either the ice-water path (IWP) and/or the cloud ice number concentration (CINC) changes. This study examines the aerosol indirect effect (AIE) through changes in the CINC and IWP for a cirrus cloud case. We use a cloud-system resolving model (CSRM) coupled with a double-moment representation of cloud microphysics. Intensified interactions among CINC, deposition and dynamics play a critical role in increasing the IWP as aerosols increase. Increased IWP leads to a smaller change in the outgoing LW radiation relative to that for the SW radiation for increasing aerosols. Increased aerosols lead to increased CINC, providing increased surface area for water vapor deposition. The increased deposition causes depositional heating which produces stronger updrafts, and leads to the increased IWP. The conversion of ice crystals to aggregates through autoconversion and accretion plays a negligible role in the IWP response to aerosols, and the sedimentation of aggregates is negligible. The sedimentation of ice crystals plays a more important role in the IWP response to aerosol increases than the sedimentation of aggregates, but not more than the interactions among the CINC, deposition and dynamics.

APA, Harvard, Vancouver, ISO, and other styles

40

Apak, S. N., W. J. Stuart, and N. M. Lemon. "COMPRESSIONAL CONTROL ON SEDIMENT AND FACIES DISTRIBUTION SW NAPPAMERRI SYNCLINE AND ADJACENT MURTEREE HIGH, COOPER BASIN." APPEA Journal 35, no. 1 (1995): 190. http://dx.doi.org/10.1071/aj94013.

Full text

Abstract:

The northeast-trending Nappamerri Syncline and its flanking high to the southeast, the Murteree-Nappacoongee (NM) Trend, show structural development throughout the deposition of the Permo-Triassic Cooper Basin sequences. Pre-existing topography, such as around Moomba, influenced early depositional patterns within the area. Rates of sedimentation were influenced by the rate of uplift of source areas around the basin, largely as a consequence of buckling. Periods of active tectonism resulted in non-deposition and stripping of sediments from uplifted blocks while deposition continued in deeper areas. Hangingwall blocks, pushed up along reverse faults, strongly influenced the areas of sedimentation and the facies being deposited. This is particularly evident along the NM Trend. Phases of uplift were immediately followed by increased sedimentation where fluvial deposition dominated. The effect of displacement along the northwest-trending basement lineaments was to subdivide the northeast trends into compartments which contain similar facies within each time slice. Adjacent compartments may display different facies and different tectonic histories. An inversion episode, particularly evident in the Big Lake/Moomba area, resulted in a reversal of the depocentre and was related to phases of Sakmarian compression.Facies distribution and sandstone percentage maps of the chronostratigraphic units of the Patchawarra Formation suggest that a northeast-trending major channel system entered this part of basin along the NW edge of the Murteree area.

APA, Harvard, Vancouver, ISO, and other styles

41

Tsuda, A., J. P. Butler, and J. J. Fredberg. "Effects of alveolated duct structure on aerosol kinetics. II. Gravitational sedimentation and inertial impaction." Journal of Applied Physiology 76, no. 6 (June 1, 1994): 2510–16. http://dx.doi.org/10.1152/jappl.1994.76.6.2510.

Full text

Abstract:

We studied the effects of alveolated duct structure on deposition processes for particle diameters > or = 1 micron. For such large particles, Brownian motion is insignificant but gravity and inertial forces play an important role. A Lagrangian description of particle dynamics in an alveolated duct flow was developed, and computational analysis was performed over the physiologically relevant range. At low flow rates gravity caused deposition. Gravitational cross-streamline motion depended on the coupled effects of curvature of gas streamlines and duct orientation relative to gravity. The detailed convective flow pattern was an important factor in determining deposition. At higher flow rates, inertial impaction contributed markedly to deposition. The curved nature of streamlines again played a major role on deposition, but duct orientation had little effect. In the medium range of flow rates, both gravitational and inertial forces simultaneously influenced particle motion. Particle inertia, per se, did not cause deposition but substantially suppressed gravitational deposition. The deposition mechanism was complex; contrary to what is often assumed in past analyses, the interaction between gravitational and inertial effects could not be described in a simple additive fashion. We conclude that the structure of the alveolar duct has an important role in gravitational sedimentation and inertial impaction in the lung acinus.

APA, Harvard, Vancouver, ISO, and other styles

42

Petticrew, Ellen L., and Jacob Kalff. "Water Flow and Clay Retention in Submerged Macrophyte Beds." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 12 (December 1, 1992): 2483–89. http://dx.doi.org/10.1139/f92-274.

Full text

Abstract:

The effect of aboveground plant structure on near-bottom water flow and surficial sediment composition was evaluated in Lake Memphremagog (Quebec–Vermont) at 34 nearshore sites within three mixed-species macrophyte beds. Plant surface area accounted for 70% of the variance in flow reduction when the effect of changing water depth was removed. Relationships between plant surface area and surficial sediment clay content were evident within each of the three multispecies beds. The equations predicting within-bed clay concentrations were not significantly different from a general among-bed model (r2 = 0.74) developed at 25 sites of high biomass from other nearshore locations in Lake Memphremagog. The study provides quantitative evidence for the importance of macrophytes as sites of sedimentation of fine particles and their associated nutrients and contaminants.

APA, Harvard, Vancouver, ISO, and other styles

43

Li, Yuhao, Bruce R. Sutherland, Murray K. Gingras, George W. Owttrim, and Kurt O. Konhauser. "A novel approach to investigate the deposition of (bio)chemical sediments: The sedimentation velocity of cyanobacteria–ferrihydrite aggregates." Journal of Sedimentary Research 91, no. 4 (April 22, 2021): 390–98. http://dx.doi.org/10.2110/jsr.2020.114.

Full text

Abstract:

ABSTRACT Sedimentation velocities of various chemical sediments are typically calculated using Stokes's law. However, applying it to chemical sediments that form in situ in the water column is not ideal because the particle properties do not fulfill many of the assumptions underpinning the applicability of Stokes' law. As a consequence, it has been difficult to predict the sedimentation rate of ancient chemical sediments, such as Precambrian banded iron formations (BIF), because their primary sediments likely comprised aggregates of ferric hydroxides, such as ferrihydrite [Fe(OH)3], and marine bacterial biomass, including cyanobacteria. In this work we use a new experimental method to address the mechanisms by which primary BIF sediment, formed by the oxidation of dissolved Fe(II) by O2 and simultaneously incubated with cyanobacterium Synechococcus sp., were deposited to the Archean ocean. Specifically, we formed the aggregates in situ over a wide range of initial pH and Fe(II) concentrations, continuously recorded the entire settling processes of aggregates under each condition, and then processed the data in MATLAB according to different settling mechanisms. Our results demonstrate that ferrihydrite–cyanobacteria aggregates settled to the ocean floor either through the formation of uniformly descending concentration fronts or through convective plumes. The sedimentation mechanism depended on both initial Fe(II) concentration and the pH. Correspondingly, two algorithms were developed to characterize the sedimentation velocity. These algorithms tracked the alteration of light intensity from low to high as sediments descended from an initially homogeneous state through a water tank, and as well calculated the average light intensity over time, from which vertical time series were constructed allowing calculation of the sedimentation velocity. Our method not only provides an accurate estimation of the in situ sedimentation velocity of cell–mineral aggregates, but also provides new insights into the physical mechanisms by which the primary sediments composing BIF were deposited.

APA, Harvard, Vancouver, ISO, and other styles

44

Isdarmanto, Isdarmanto, and Oentoeng Soebyanto. "ANALISIS POTENSI PANTAI GLAGAH SEBAGAI EKOWISATA UNGGULAN DI KABUPATEN KULONPROGO." Kepariwisataan: Jurnal Ilmiah 12, no. 02 (May 31, 2018): 1–12. http://dx.doi.org/10.47256/kepariwisataan.v12i02.82.

Full text

Abstract:

Glagah Beach is one of the most potential beaches and has the uniqueness as the charm and excellence of other southern seas. Glagah Beach located in Kulon Progo Regency is the only beach in Java that has a breakwater and has a lagoon on the edge of the sea separated by the sea so that large waves do not reach the lagoon. According to the typology of Glagah beach it self can be included in the classification of marine deposition coast. This is because the beach is formed due to the deposition deposition of river sedimentation material to the sea. This condition can be indicated by the emergence of a barrier coast emerging due to sedimentation from the river that empties into the location, then subject to marine effects that result in the formation of the lagoon. The process of sedimentation that occurs due to the flow and sedimentation of the river mouth that causes sedimentation in the coastal area. Qualitative research methods used with data collection techniques in the form of observation, interviews, documents, and various sources of data so it can be more clearly known geographical aspects of Glagah Beach, tourism profile, tourist visit conditions, tourism potential Glagah Beach, and to know the constraints which faced Glagah Beach tourism object and how the development strategy of Glagah Beach tourist attraction area in the future. Glagah Beach is a natural attraction that has the privilege and excellence compared to other beaches in Yogyakarta that need to keep the sustainability and need to be managed more effectively by the community and the local government as a policy holder so Glagah Beach became one of the leading ecotourism object which is interesting in Kulon Progo Regency Yogyakarta. Keywords: Glagah Beach; Sea Lagoon; Barrier Coast

APA, Harvard, Vancouver, ISO, and other styles

45

Dobson, Evan P., and Gerald L. Mackie. "Increased deposition of organic matter, polychlorinated biphenyls, and cadmium by zebra mussels (Dreissena polymorpha) in western Lake Erie." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 5 (May 1, 1998): 1131–39. http://dx.doi.org/10.1139/f97-321.

Full text

Abstract:

Biodeposition of organic matter, polychlorinated biphenyls (PCBs), and cadmium (Cd) by zebra mussels (Dreissena polymorpha) was investigated at five stations in the western basin of Lake Erie during the summer of 1992. Biodeposition rates at the five stations were determined by using sediment traps and converted to per unit area values to facilitate comparisons with natural sedimentation rates. Biodeposition of suspended material by zebra mussels was up to 8 times greater than sedimentation in the traps. Concentrations of organic matter, PCBs, and Cd were determined for the biodeposits and the sedimented material. There were no significant differences in concentration of organic matter, PCBs, or Cd between the two types of material. Biodeposition rates per unit area of organic matter, PCBs, and Cd were 8-10 times greater than corresponding values for natural sedimentation; therefore, the natural sedimentation processes of these factors appear to be greatly accelerated in the presence of zebra mussels. Results support the possibility that zebra mussels are altering contaminant movement in western Lake Erie, as well as clarifying the water column by removing suspended material.

APA, Harvard, Vancouver, ISO, and other styles

46

Kusumgar, Sheela, D. P. Agrawal, and Prabhakar Sharma. "Radiocarbon Chronology and Magnetic Susceptibility Variation in Kumaon Lake Sediments." Radiocarbon 31, no. 03 (1989): 957–64. http://dx.doi.org/10.1017/s0033822200012583.

Full text

Abstract:

This study was carried out to determine time controls of erosion and sedimentation in the catchment area and lakes of the Naini Tal district in the Kumaon Himalayas. We present here our preliminary data from five lakes, Beon Tal, Garud Tal, Sukha Tal, Bhim Tal and Kamal Tal (Naukuchia Tal). A number of 14C dates are now available to estimate the sedimentation rate of the five lakes and magnetic susceptibility (xL; xfd) variation to determine the signature of sediment source. High xfd values indicate a higher proportion of soil component generally characterized by a slower rate of deposition, and low xfd values with a higher rate of sedimentation indicate rock-debris-derived sediment. A 14C chronology enables us to estimate the mean sedimentation rate whereas rock magnetic properties help us to characterize the type of source responsible for sedimentation.

APA, Harvard, Vancouver, ISO, and other styles

47

Darquenne, Chantal, John B. West, and G. Kim Prisk. "Dispersion of 0.5- to 2-μm aerosol in μG and hypergravity as a probe of convective inhomogeneity in the lung." Journal of Applied Physiology 86, no. 4 (April 1, 1999): 1402–9. http://dx.doi.org/10.1152/jappl.1999.86.4.1402.

Full text

Abstract:

We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (μG) and hypergravity (∼1.6 G). Boluses of 0.5-, 1-, and 2-μm-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-μm-diameter particles for which sedimentation velocity is low, the differences between dispersion in μG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between μG and 1 G.

APA, Harvard, Vancouver, ISO, and other styles

48

Sehsah, E. M. E. "SPRAY SPECTRA, DEPOSITION AND SEDIMENTATION CHARACTERISTICS FOR LOW PRESSURE LIQUID ATOMIZERS." Misr Journal of Agricultural Engineering 27, no. 3 (July 1, 2010): 839–62. http://dx.doi.org/10.21608/mjae.2010.105748.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Markelonis, Andrew R., Joanna S. Wang, Bruno Ullrich, Chien M. Wai, and Gail J. Brown. "Nanoparticle film deposition using a simple and fast centrifuge sedimentation method." Applied Nanoscience 5, no. 4 (July 25, 2014): 457–68. http://dx.doi.org/10.1007/s13204-014-0338-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Ghorbani, Mohammad, and Milad Roushanafshar. "Electrophoretic Deposition of Titania Nanopowders." Key Engineering Materials 412 (June 2009): 77–82. http://dx.doi.org/10.4028/www.scientific.net/kem.412.77.

Full text

Abstract:

Titania Nanopowders were successfully deposited on stainless steel sheet by means of electrophoretic deposition method from titania suspension in which isopropanol was employed as a solvent and Triethanolamine as a dispersant. The effect of TEA addition on the stability of nanopowders in suspensions was examined by sedimentation test; in addition, Malvern zeta sizer was employed for determination their particle size. Electrophoretic Deposition was done at different deposition conditions of voltage (5-20 volts) and time (5-60 sec) and the scanning electron microscopy (SEM) was used to investigate the effect of suspension composition and deposition parameters on the microstructure of coatings. Furthermore, the effect of deposition parameters on the consistencies of different coatings was analyzed by Scanning Probe Microscope (SPM).

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Sedimentation and deposition – Vermont'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles