scholarly journals Prediksi Laju Sedimentasi di Perairan Teluk Benoa Menggunakan Pemodelan Numerik

2018 ◽  
Vol 5 (1) ◽  
pp. 44 ◽  
Author(s):  
I Putu Ranu Fajar Maharta ◽  
I Gede Hendrawan ◽  
Yulianto Suteja
Keyword(s):  
Numerical Modeling ◽  
Sedimentation Rate ◽  
Mangrove Ecosystem ◽  
Scientific Study ◽  
Sedimentation Rates ◽  
Minimum Value ◽  
Shallow Estuary ◽  
High Sedimentation ◽  
Hydrodynamic Processes

Benoa Bay is one of the unique ecosystems on the island of Bali because it is a shallow estuary area and has an ecosystem that is important for the waters of the mangrove ecosystem and seagrass. In recent years, Benoa Bay has been reported to have undergone siltation due to sedimentation. However, there has not been much scientific study of the sedimentation rate occurring in Benoa Bay. The study of sedimentation will provide an overview of the rate of sedimetation in the study area. Numerical modeling is one of the most commonly used methods to describe hydrodynamic processes in waters, which are the main drivers of the process of movement of pollutants in waters such as waste, sediment, and others. Thus, the study of sedimentation rate, either spatially or temporally, needs to be done in the waters of Benoa Bay using numerical modeling. The results of this study show that sedimentation rates in Benoa Bay have a minimum value of 1.08x10-6 and a maximum of 24.88 kg/m2/day with an average of 0.57 kg/m2/day. High sedimentation rates occur in the western part of the bay, on the river route, and in the northern part of the bay, between Serangan Island and Mertasari beach. Areas that potentially experience silting in Benoa Bay include the southern port of Benoa Harbor which reaches 0.23 m/year, the waters north of Serangan Island reaching 0.008 m/year, and the area close to the estuary which reaches 0.35 m/year.

scholarly journals Semi-automated counting of complex varves through image autocorrelation

2021 ◽  
pp. 1-12
Author(s):  
Maximillian Van Wyk de Vries ◽  
Emi Ito ◽  
Mark Shapley ◽  
Guido Brignone
Keyword(s):  
Sedimentation Rate ◽  
Sliding Window ◽  
Sedimentation Rates ◽  
Sedimentary Sequences ◽  
High Sedimentation ◽  
History Of ◽  
History Of Use ◽  
Sediment Layers ◽  
Annual Resolution ◽  
Varve Counting

Abstract Annual resolution sediment layers, known as varves, can provide continuous and high-resolution chronologies of sedimentary sequences. In addition, varve counting is not burdened with the high laboratory costs of geochronological analyses. Despite a more than 100-year history of use, many existing varve counting techniques are time consuming and difficult to reproduce. We present countMYvarves, a varve counting toolbox which uses sliding-window autocorrelation to count the number of repeated patterns in core scans or outcrop photos. The toolbox is used to build an annually-resolved record of sedimentation rates, which are depth-integrated to provide ages. We validate the model with repeated manual counts of a high sedimentation rate lake with biogenic varves (Herd Lake, USA) and a low sedimentation rate glacial lake (Lago Argentino, Argentina). In both cases, countMYvarves is consistent with manual counts and provides additional sedimentation rate data. The toolbox performs multiple simultaneous varve counts, enabling uncertainty to be quantified and propagated into the resulting age-depth model. The toolbox also includes modules to automatically exclude non-varved portions of sediment and interpolate over missing or disrupted sediment. CountMYvarves is open source, runs through a graphical user interface, and is available online for download for use on Windows, macOS or Linux at https://doi.org/10.5281/zenodo.4031811.

Paleoecology of mangroves along the Sibun River, Belize

2011 ◽  
Vol 76 (2) ◽  
pp. 220-228 ◽  
Author(s):  
Natalie M. Monacci ◽  
Ursula Meier-Grünhagen ◽  
Bruce P. Finney ◽  
Hermann Behling ◽  
Matthew J. Wooller
Keyword(s):  
Sea Level ◽  
Sedimentation Rate ◽  
Drainage Basin ◽  
Marked Change ◽  
Mangrove Ecosystem ◽  
Sedimentation Rates ◽  
Radiocarbon Dates ◽  
Elemental Ratios ◽  
Red Mangrove ◽  
Mangrove Ecosystems

AbstractThis study examines a sediment core (SR-63) from a mangrove ecosystem along the Sibun River in Belize, which is subject to both changes in sea-level and in the characteristics of the river's drainage basin. Radiocarbon dates from the core show a decreased sedimentation rate from ~ 6 ka to 1 cal ka BP and a marked change in lithology from primarily mangrove peat to fluvial-derived material at ~ 2.5 cal ka BP. Changes in the sedimentation rates observed in mangrove ecosystems offshore have previously been attributed to changes in relative sea-level and the rate of sea-level rise. Pollen analyses show a decreased abundance of Rhizophora (red mangrove) pollen and an increased abundance of Avicennia (black mangrove) pollen and non-mangrove pollen coeval with the decreased sedimentation rates. Elemental ratios ([N:C]a) and stable isotope analyses (δ15N and δ13C) show that changes in the composition of the organic material are also coeval with the change in lithology. The decrease in sedimentation rate at the site of core SR-63 and at offshore sites supports the idea that regional changes in hydrology occurred during the Holocene in Belize, influencing both mainland and offshore mangrove ecosystems.

Varve Studies at Hector Lake, Alberta, Canada, and the Relationship Between Glacial Activity and Sedimentation

1986 ◽  
Vol 25 (2) ◽  
pp. 199-214 ◽  
Author(s):  
Eric M. Leonard
Keyword(s):  
Sedimentation Rate ◽  
General Pattern ◽  
Sedimentation Rates ◽  
Sedimentary Records ◽  
Banff National Park ◽  
High Sedimentation ◽  
Lake Bottom ◽  
Lake Bottom Sediments ◽  
The Relationship ◽  
Very High

Glacial lake sedimentary records from Hector Lake in Banff National Park, Alberta, are examined with the aim of clarifying the relationship between glacial activity and outwash sedimentation. Rhythmic couplets in lake bottom sediments provide a method for accurate documentation and dating of recent sedimentation chronology, as analysis of 137Cs content indicates that the couplets are of annual periodicity (i.e., varves). A comparison of sedimentation rate records with recent regional glacial history indicates that high sedimentation rates of one to a few decades duration occur either during and immediately following periods of moraine deposition (ie, maximum ice stands) or during periods of rapid ice recession. Comparison of sedimentary records with somewhat longer term glacial and vegetation records indicates that sedimentation rate variations of several centuries duration closely parallel changes in upvalley ice extent. Over this time scale, high sedimentation rates occur during periods of relatively increased ice extent, low rates during periods of reduced ice extent. Within this general pattern, however, sedimentation rates may remain very high for nearly a century following maximum ice stands, due to the exposure of unstable glaciogenic deposits to fluvial reworking during ice recession.

New Devonian microconchids (Tentaculita) from the Holy Cross Mountains, Poland

2011 ◽  
Vol 85 (4) ◽  
pp. 757-769 ◽  
Author(s):  
Michał Zatoń ◽  
Wojciech Krawczyński
Keyword(s):  
Sedimentation Rate ◽  
Distal Portion ◽  
Taxonomic Composition ◽  
Soft Bottom ◽  
Holy Cross Mountains ◽  
Competition For Space ◽  
High Sedimentation ◽  
New Material ◽  
Three New Species ◽  
Hard Substrates

Tentaculitoid microconchid tubeworms from Devonian (uppermost Emsian-upper Givetian) deposits of the Holy Cross Mountains, Poland, include three new species from stratigraphically well-constrained lithological units:Polonoconchus skalensisn. gen. n. sp.,Palaeoconchus sanctacrucensisn. sp. andMicroconchus vinnin. sp. The microconchids inhabited fully marine environments during transgressive pulses, as is evidenced from facies and associated fossils.Polonoconchus skalensisn. gen. n. sp. andPalaeoconchus sanctacrucensisn. sp. inhabited secondary firm- to hard-substrates in deeper-water, soft-bottom environments. They developed planispiral, completely substrate-cemented tubes and planispiral tubes with elevated apertures, which is indicative of environments where sedimentation rate is low but competition for space (by overgrowth) may be high.Microconchus vinnin. sp., on the other hand, developed a helically coiled distal portion of the tube as a response to a high sedimentation rate. As the taxonomic composition of Devonian microconchids is poorly recognized at both regional and global scales, this new material contributes significantly to our understanding of the diversity of these extinct tube-dwelling encrusters.

The determination of sedimentation rates in Lake Ontario using the 210Pb dating method

1978 ◽  
Vol 15 (3) ◽  
pp. 431-437 ◽  
Author(s):  
John G. Farmer
Keyword(s):  
Sedimentation Rate ◽  
Lake Ontario ◽  
Sedimentary Basins ◽  
210Pb Dating ◽  
Sedimentation Rates ◽  
Surface Mixing ◽  
Dating Method ◽  
210Pb Dating Method

The 210Pb dating method has been applied successfully to the determination of recent sedimentation rates at four sites distributed among the three major sedimentary basins (Niagara, Mississauga and Rochester) of Lake Ontario. Following correction for effects due to compaction of the sediments, mean sedimentation rates ranging from 0.02 cm/year at the periphery of the Mississauga basin to 0.11 cm/year in the Niagara and Rochester basins were determined. Allowance for compaction reduced the non-compaction-corrected sedimentation rates by 20–35%. Neither 210Pb nor fallout 137Cs profiles indicated surface mixing of sediment sufficient to noticeably affect the calculated sedimentation rates. At all four sites, the sedimentation rate seems to have remained constant during the last 100–150 years.

scholarly journals Ventilation changes in the western North Pacific since the last glacial period

2011 ◽  
Vol 7 (4) ◽  
pp. 2719-2739 ◽  
Author(s):  
Y. Okazaki ◽  
T. Sagawa ◽  
H. Asahi ◽  
K. Horikawa ◽  
J. Onodera
Keyword(s):  
Sedimentation Rate ◽  
North Pacific ◽  
Western North Pacific ◽  
Glacial Period ◽  
High Quality ◽  
Last Glacial Period ◽  
The Past ◽  
High Sedimentation ◽  
The Last Glacial

Abstract. We reconstructed the ventilation record of deep water at 2100 m depth in the mid-latitude western North Pacific over the past 25 kyr from radiocarbon measurements of coexisting planktic and benthic foraminiferal shells in sediment with a high sedimentation rate. The 14C data on fragile and robust planktic foraminiferal shells were concordant with each other, ensuring high quality of the reconstructed ventilation record. The radiocarbon activity changes were consistent with the atmospheric record, suggesting that no massive mixing of old carbon from the abyssal reservoir occurred throughout the glacial to deglacial periods.

scholarly journals Lithium carbonate sedimentation using flocculants with different ionic bases

2021 ◽  
pp. 20-20
Author(s):  
Yam Morales ◽  
Nelson Herrera ◽  
Kevin Pérez
Keyword(s):  
Sedimentation Rate ◽  
Rapid Growth ◽  
Crystallization Process ◽  
Lithium Carbonate ◽  
Rechargeable Batteries ◽  
Point Of View ◽  
Sedimentation Rates ◽  
Economic Point ◽  
Carbonate Sedimentation ◽  
Cationic Flocculant

Lithium has become a metal of enormous interest worldwide. The extensive use of rechargeable batteries for a range of applications has pushed for rapid growth in demand for lithium carbonate. This compound is produced by crystallization, by reaction with lithium chloride (in solution) and by adding sodium carbonate. Low sedimentation rates in the evaporation pools present a problem in the crystallization process. For this reason, in this work, mineral sedimentation tests were carried out with the use of two flocculant types with different ionic charges. The tests were carried out at a laboratory level using different dosages for each flocculant and measurements were performed to obtain the increase in the content of solids in the sediment. The anionic flocculant had better performance as compared to that of the cationic flocculant, increasing the sedimentation rate of lithium carbonate by up to 6.5. However, similar solids contents were obtained with the use of the cationic flocculant at 3.5 times lower dosage making it the flocculant of choice regarding the economic point of view.

Taphonomy and paleoecology of the bivalve trace fossil Protovirgularia in deltaic heterolithic facies of the Miocene Chenque Formation, Patagonia, Argentina

2010 ◽  
Vol 84 (4) ◽  
pp. 730-738 ◽  
Author(s):  
Noelia B. Carmona ◽  
María Gabriela Mángano ◽  
Luis A. Buatois ◽  
Juan José Ponce
Keyword(s):  
Sedimentation Rate ◽  
Oxygen Depletion ◽  
Sedimentation Rates ◽  
Low Friction ◽  
Delta Front ◽  
Plastic Substrates ◽  
Marine Deposits ◽  
Median Axis ◽  
Nearshore Environments ◽  
Biogenic Structures

Lower Miocene tide-influenced deltaic deposits from the Chenque Formation, Patagonia, Argentina, contain abundant and well-preserved biogenic structures attributed to locomotion of deposit-feeder protobranch bivalves. These trace fossils, assigned to the ichnogenus Protovirgularia, consist of delicate, inclined-to-horizontal, chevronate structures, mostly symmetrical with respect to a median axis. Identification of Protovirgularia at sandstone sole beds (hypichnion) is quite straightforward. Endichnial, exichnial and epichnial preservation in heterolithic facies, however, provides a wide variety of forms that depart from the archetypal Protovirgularia and challenges ichnotaxonomic classification. Specimens in prodelta and delta-front facies display morphologic features controlled by substrate fluidity, toponomy, and sedimentation rate. Most specimens show sharp, closely spaced chevrons and occur along sandstone/mudstone interfaces of the proximal prodelta and distal delta-front deposits. These forms reflect how tracemakers experienced significant friction while advancing through the sediment, which resulted in relatively smaller increments of movements. In contrast, variants of Protovirgularia formed in muddier beds, such as in prodeltaic facies, show irregular, poorly defined and unevenly spaced chevrons, and are locally asymmetric in relation to the axis, reflecting softer, water-rich, and plastic substrates. This sediment offered relatively low friction but poor anchorage for the foot. These occurrences of Protovirgularia in tide-influenced, marginal-marine deposits suggests that protobranchs were tolerant of fluctuations in salinity, sedimentation rates, turbidity, and oxygen depletion, displaying opportunistic strategies in stressed nearshore environments. Our evaluation of taphonomic controls and appropriate identification of Protovirgularia can provide valuable information for expanding our knowledge of the ethology and paleoecology of protobranch bivalves.

Late Quaternary history of the Lake O'Hara region, British Columbia – an evaluation of sedimentation rates and bulk amino acid ratios in lacustrine records

1988 ◽  
Vol 25 (7) ◽  
pp. 1037-1048 ◽  
Author(s):  
Mel A. Reasoner ◽  
Nathaniel W. Rutter
Keyword(s):  
Amino Acid ◽  
Aspartic Acid ◽  
Sedimentation Rate ◽  
River Sediments ◽  
Sedimentation Rates ◽  
Rate Data ◽  
Radiocarbon Dates ◽  
Clastic Sediments ◽  
Lake Cores ◽  
Total Sedimentation

Lake O'Hara (subalpine) and Opabin Lake (alpine) are situated directly adjacent to a high section of the Continental Divide in the central Canadian Rocky Mountains. Core samples recovered from the lakes show a consistent stratigraphy comprising gyttja and underlying inorganic clastic sediments. The gyttja contains Bridge River (2350 years BP) and Mazama (6800 years BP) tephras and is separated from the lower clastic sediments by a sharp, conformable contact. Radiocarbon dates obtained from conifer needles, extracted from directly above the contact, indicate that deglaciation had proceeded upvalley from the O'Hara basin priorto ca. 10 100 years BP. Preliminary palaeobotanical and macrofossil data suggest that a Pinus–Abies forest with lesser Picea was established in the vicinity of Lake O'Hara by this time. Consequently, the minimum age of moraine systems situated downvalley from Lake O'Hara is Late Wisconsinan.Mean annual sedimentation rates were derived from sediment thickness data from 14 Lake O'Hara and 2 Opabin Lake cores. Averaged total sedimentation rate values from the Lake O'Hara cores are 0.13 mm/year (post-Bridge River), 0.13 mm/year (Mazama – Bridge River) and 0.05 mm/year (11 000 years BP – Mazama). Averaged total sedimentation rate values from the Opabin Lake cores are 0.19 mm/year (post-Bridge River), 0.07 mm/year (Mazama – Bridge River), and 0.06 mm/year (8530 years BP – Mazama). Higher total sedimentation rates in post-Bridge River sediments of Opabin Lake are presumably related to climatic conditions associated with more extensive upvalley ice during the last ca. 2300 years. Highly variable sedimentation rate data obtained from the Lake O'Hara cores suggest that the use of sedimentation rate data as a proxy record of upvalley glacial activity is inappropriate in the Lake O'Hara setting where inflowing glacial stream systems are interrupted by upvalley lake basins.Aspartic acid D/L ratios were derived from bulk gyttja samples of known age from seven Lake O'Hara and one Opabin Lake core. In all but two cases, aspartic acid D/L ratios increase consistently with respect to sediment age. The increasing downcore trends in the aspartic acid D/L ratios suggest the possibility of using amino acid data from bulk gyttja samples as a check for reworking in cases where chronostratigraphic markers are absent.

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