scholarly journals Morfologia e Sedimentação em Praias Oceânicas da Amazônia Oriental durante a Variação Anual de Chuvas

2020 ◽  
Vol 13 (5) ◽  
pp. 2086
Author(s):  
LEILANHE ALMEIDA RANIERI ◽  
Maâmar El-Robrini

Este artigo buscou analisar os efeitos dinâmicos da sazonalidade climática sobre a morfologia e sedimentação de praias oceânicas da Amazônia durante as estações chuvosa e menos chuvosa. A importância deste estudo foi demonstrar um comportamento deposicional de sedimentos nestas praias de uma estação climática à outra. A metodologia consistiu em perfilagem topográfica nas praias dos setores: oeste (Corvina e Maçarico), central (Farol Velho) e leste (Atalaia) de Salinópolis (PA), amostragem de sedimentos, análise granulométrica com aplicação de parâmetros estatísticos e medições de altura e período de ondas. O diâmetro médio dos sedimentos consistiu predominantemente de areia fina (2,6 a 2,8 phi), muito bem a bem selecionada (0,2 a 0,5). A assimetria variou, principalmente, entre positiva (0,10 a 0,30) e aproximadamente simétrica (-0,10 a 0,10). O grau de curtose entre muito platicúrtica (<0,67) a muito leptocúrtica (1,50 a 3,00). As alturas de ondas foram mais elevadas no setor leste (máximo de 1,05 m) e períodos de ondas foram mais curtos (< 4,5 s) no setor oeste. As praias apresentaram declives suaves (< 1,5°) e grandes variações na largura entre as estações do ano (9,6 a 88,4 m). Predominou o estado morfodinâmico dissipativo (Ω>5,5), mas com ocorrência do estado de banco e calha longitudinais (4,7<Ω<5,5) no setor oeste. Foi observada acreção sedimentar da estação chuvosa a menos chuvosa em todas as praias. O transporte transversal de sedimentos foi elevado, especialmente no sentido onshore (máximo: 11x10-3 kg/s/m, setor leste). No setor central foi baixo (mínimo: 0,72x10-3 kg/s/m), favorecendo tendências erosivas neste local. Morphology and Sedimentation in Ocean Beaches in the Eastern Amazon during the Annual Rain Variation A B S T R A C TThis paper aimed to analyze the dynamic effects of climatic seasonality on the morphology and sedimentation of oceanic beaches in the Amazon during the rainy and less rainy seasons. The importance of this study was to demonstrate a depositional behavior of sediments on these beaches from one climatic season to another. The methodology consisted of topographic profiling on the beaches of the sectors: west (Corvina and Maçarico), central (Farol Velho) and east (Atalaia) of Salinópolis (PA), sediment sampling, grain-size analysis with application of statistical parameters and measurements of height and wave period. The mean diameter of the sediments consisted predominantly of fine sand (2.6 to 2.8 phi), well sorted and very well sorted (0.2 to 0.5). The asymmetry varied, mainly, between positive (0.10 to 0.30) and nearly symmetrical (-0.10 to 0.10). The degree of kurtosis between very platykurtic (<0.67) to very leptokurtic (1.50 to 3.00). The wave heights were higher on the eastern sector (maximum 1.05 m) and wave periods were shorter (<4.5 s) on the western sector. The beaches presented smooth slopes (<1.5°) and great variations in width between the seasons (9.6 to 88.4 m). The dissipative morphodynamic state (Ω > 5.5) predominated, but with the occurrence of the longshore bar and trough (4.7 < Ω <5.5) in the western sector. Sedimentary accretion from the rainy to less rainy season was observed on all beaches. Cross-shore sediment transport was high, especially in the onshore (maximum: 11x10-3 kg.s-1.m-1, east sector). In the central sector it was low (minimum: 0.72x10-3 kg.s-1.m-1), favoring erosive trends in this location.Keywords: Beach, Morphodynamic, Grain-Size, Amazon.

2018 ◽  
Vol 47 ◽  
pp. 02008
Author(s):  
Risandi Dwirama Putra ◽  
Tri Apriadi ◽  
Ani Suryanti ◽  
Henky Irawan ◽  
Tengku Said Raja'I ◽  
...  

Bauxite production and exploration give negative impact environmental modification and increasing concern pollution of heavy metals. One of an alternative to reduce the negative impact of bauxite post-mining production is by re-utilizing the abandoned bauxite land and necessary exploratory study to obtain the current environmental conditions primarily related to heavy metals in bauxite mining area. Soil and water quality samples from 5 (five) sites based on post-mining activities were used to determine concentration heavy metals of As, Cd, Pb, Zn, Cr, Cu from different soil level. They were also collected for grain size analysis including those of sand and mud percentages along with the mean, and sorting analysis. The mean grain size post-mining bauxite ranged between very fine sand to medium sand and had heterogeneous texture. The coarse grain size percentage increased towards the bottom of the soil. Total heavy metal contents for post-mining bauxite soils are 0,081 ppm, 0,245 to 0,471 ppm and 0,007 ppm for As, Pb and Cd respectively. Heavy metals for Cd, uniformly at every depth from soil level. On the other hand, Pb showed significance pattern, it was indicated every depth from soil level, the concentration of Pb was different.


2021 ◽  
pp. 57-93
Author(s):  
Noor Al-Dousari ◽  
Modi Ahmed ◽  
Ali Al-Dousari ◽  
Musaad Al-Daihani ◽  
Murahib Al-Elaj

AbstractGrain ‘size’ can be specified and measured in several different ways. All methods of grain size determination have blemishes, and the choice of the most appropriate method is governed by the nature of the sample and the use to which the data are placed. Four main methods are currently used for size analysis of sands: (a) sieving; (b) settling tube analysis; (c) electro-optical methods, including Coulter Counter analysis and laser granulometry; and (d) computerized image analysis. The classification of the particle size distribution of Kuwait dust was mapped according to the parameters proposed by Folk And Ward (1957) which were widely used for quantitative comparisons between natural grain size distribution and the lognormal distribution that shows better sorted sediments have lower values of σ1. Maps of the distribution of dust in Kuwait were obtained that included: fine sand (F.S.), Coarse sand (C.S), Medium Sand (M.S), Very Fine Sane (V.F.S), Very Coarse Silt (V.C.Silt), Coarse Silt (C.Silt), Medium Silt (M.Silt), Fine Silt (F.Silt), Very Fine Silt (V.F.Silt), in addition to that, the deposition percentage of Clay, Sand, mud (silt plus clay) and silt were provided.


2013 ◽  
Vol 404 ◽  
pp. 67-71 ◽  
Author(s):  
Zaliman Sauli ◽  
Vithyacharan Retnasamy ◽  
Fairul Afzal Ahmad Fuad ◽  
Phaklen Ehkan ◽  
Moganraj Palianysamy ◽  
...  

Reactive Ion Etch (RIE) has been an important process in the world of microelectronic fabrication. Focus of this preliminary study is on how RIE affects the grain size of aluminum film which is fabricated on substrates. RIE parameters are varied to obtain 16 different recipes which are done using Design of Experiment. Grain size of the samples is recorded for all 16 samples before and after RIE treatment. This produces results that can be compared to obtain the effect of RIE on the aluminum film. Results show that RIE affects the mean grain size of the aluminum film as it increases after RIE treatment.


2016 ◽  
Vol 27 (2) ◽  
pp. 55
Author(s):  
Yudhicara Yudhicara ◽  
Andrian Ibrahim

Post tsunami survey of the October 25, 2010, Mentawai tsunami, has been carried out by a collaboration team of Indonesian-German scientists from 20 to 28 November 2010. One activity of the researches were investigation on tsunami deposits along the coast following the event that devastated the islands of Sipora, North Pagai and South Pagai. Sedimentological properties of Mentawai tsunami deposit were explained by this study, from both megascopic and laboratory result. In general, beaches along the study area are underlying by a stretch of reef limestone, sediments mostly composed of white sand while grey sand was found only at Malakopa. Tsunami sediments were taken from 20 locations, start from Betumonga at Sipora Island until Sibaru-baru Island at the southern tip of the study area. The thickness of tsunami deposits are ranged between 1.5 and 22 cm, which are generally composed of fine to coarse sand in irregular boundaries with the underlying soil. Based on grain size analysis, variation of sedimentological properties of tsunami deposits range between phi=-0,5793 and phi=3,3180 or very coarse to very fine sand. Tsunami deposits mostly have multiple layers which described their transport processes, run up at the bottom and back wash at the top. Structural sediments such as graded bedding of fining upward, parallel lamination and soil clast were found. The grain size distribution curves show two types of mode peak, unimodal and multimodal which are indication of different sorting condition representing the source materials. While segment grain size accumulative plot generally shows domination of dilatation and traction transport mechanism rather than suspension. In general, very rare fossils were found from Mentawai tsunami deposit, but those findings gave information on how depth tsunami start to scour the seafloor and transport it landward, such as an abundance of Sponge spicule was found which indicate shallow water environments (20-100 m seafloor depth). Keywords: 2010 Mentawai tsunami, tsunami deposit, grain size analysis, fossils identification. Survei pasca-tsunami Mentawai 25 Oktober 2010, telah dilakukan oleh Tim gabungan Indonesia-Jerman pada tanggal 20 - 28 November 2010. Salah satunya adalah melakukan identifikasi endapan tsunami yang ditemukan di sepanjang pantai yang terlanda tsunami di Pulau Sipora, Pagai Utara dan Pagai Selatan. Berdasarkan hasil penelitian baik megaskopik maupun analisis laboratorium, dalam tulisan ini dapat dijelaskan mengenai sifat-sifat sedimentologi dari endapan tsunami Mentawai. Secara umum litologi penyusun pantai di daerah penelitian disusun oleh hamparan batugamping terumbu, sebagian disusun oleh pasir berwarna putih, sedangkan di Malakopa tersusun oleh endapan pasir pantai berwarna abu-abu. Berdasarkan hasil analisis laboratorium, diperoleh variasi sifat sedimentologi, seperti kisaran ukuran butir endapan tsunami antara -0,5793 phi dan 3,3180 phi, yaitu pasir sangat kasar hingga sangat halus. Endapan tsunami umumnya memiliki beberapa lapis yang menunjukkan adanya proses transportasi, seperti saat air naik (run up) di lapisan bagian bawah dan surut di bagian atas, yang ditunjukkan dengan adanya perbedaan ukuran butir. Struktur sedimen ditemukan seperti adanya perubahan besar butir secara berangsur menghalus ke bagian atas, perlapisan sejajar dan fragmen tanah yang terperangkap dalam sedimen. Kurva distribusi ukuran butir memperlihatkan dua jenis model puncak, yaitu unimodal dan multimodal yang memperlihatkan kondisi pemilahan yang berbeda yang menunjukkan kondisi sumber material endapan tsunami, sedangkan grafik akumulasi ukuran butir umumnya memperlihatkan dominasi mekanisme transportasi dilatasi dan traksi daripada suspensi. Secara umum fosil yang terkandung dalam endapan tsunami Mentawai sangat jarang, namun sedikit banyak telah memberikan informasi seberapa dalam gelombang tsunami mulai menggerus lantai samudera dan memindahkannya ke darat, misalnya dengan ditemukannya fosil bentonik Sponge spicule yang melimpah, menunjukkan asal lingkungan laut dangkal dengan kedalaman laut 20-100 m. Kata kunci: Tsunami Mentawai 2010, endapan tsunami, analisis besar butir, identifikasi fosil.


2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Deny Setiady ◽  
Asep Permana

Berdasarkan hasil analisis besar butir sebanyak 36 percontoh sedimen permukaan dasar laut di Perairan Cirebon, didapatkan 4 jenis sedimen: lanau, lanau pasiran, pasir lanauan dan pasir. Sedimen lanau, lanau pasiran, dan pasir, tersebar di lepas pantai Cirebon dan muara Sungai Kalijaga, sedangkan pasir lanauan di muara sungai Sukalila. Dari Peta Batimetri terlihat daerah dangkal di sekitar muara Sungai Kalijaga. Sedimen paling tebal terdapat di sekitar muara Sungai Kalijaga dan Sungai Sukalila. Sedimen tersebut tersebar ke arah lepas pantai dan ke daerah rencana lokasi pelabuhan. Di muara Sungai Kalijaga sedimennya berupa pasir. Berdasarkan plot pada grafik antara ukuran besar butir terhadap persen frekuensi, didapatkan hasil sedimen dengan persen frekuensi yang tinggi antara 2.25 phi - 2.75 phi atau pasir sedang sampai pasir halus. Berdasarkan grafik frekuensi kumulatif terhadap besar butir terdapat 2 cara transpor yaitu traksi untuk butiran pasir sedang dan saltasi untuk kisaran butiran lanau sampai pasir halus. Kata Kunci : S. Kalijaga, S. Sukalila, Cirebon, besar butir, sedimen Based on grain size analysis of 36 seafloor surficial sediment samples from Cirebon Water; there are 4 types of sediments silt, sandy silt, silty sand and sand. Silt, sandy silt and sand are distributed offshore of Cirebon and in the river mouth of Kalijaga, while silty sand is in the river mouth of Sukalila. From the bathymetric map the shallow water can be observed in Kalijaga river mouth. The thicker sediments are found in Kalijaga mouth and Sukalila river. These sediments have been transported to the offshore and to the proposed Harbour location. Sediment in Kalijaga river mouth is sand. Based on graphic presentation between grain size and percent frequencies, it indicates that the percentage of higher frequencies ranges between 2.25 TO 2.75 phi. Based on the cumulative frequency to grain size graphic, there are two transport modes: traction for medium size sand and saltation for grain size range silt to fine sand. Keywords : Kalijaga River, Sukalila River, Cirebon, grain size, sediment


Author(s):  
Fernando Alvim VEIGA ◽  
Rodolfo José ANGULO ◽  
Eduardo MARONE ◽  
Frederico Pereira BRANDINI

O objetivo deste trabalho é caracterizar os sedimentos da plataforma continental interna paranaense entre as profundidades de 5 a 15 m entre os estuários de Guaratuba, ao sul e Paranaguá, ao norte da área de estudo. Informações batimétricas, análises granulométricas e determinação de teores de carbonato e matéria orgânica de amostras de sedimentos de fundo permitiram a geração dos mapas temáticos. Observou-se uma grande predominância de areia fina, porém a média granulométrica dos sedimentos varia do silte grosso até a areia grossa. Foram identificados cinco padrões distintos de sedimentos na área estudada: i) as areias fina e muito fina do delta de maré vazante associado à desembocadura sul do Complexo Estuarino de Paranaguá; ii) as areias muito finas bimodais, com teores de finos entre 10 e 40 %, localizadas próximas à costa, iii) as areias média e grossa unimodais; iv) as areias finas na faixa dos 10 a 15 m de profundidade, unimodais menos selecionadas que as areias finas do delta de maré vazante; v) as areias finas a muito finas das barras do início da zona de arrebentação. SHOREFACE SEDIMENTOLOGY AT PARANÁ MIDDLE COAST Abstract The aim of this work aims at knowing the shallow inner continental shelf between 5 and 15 m water depths of the State of Paraná between the Guaratuba (south) and Paranaguá (north) estuaries. Bathymetric data, grain size analysis and carbonate and organic matter rates of bottom sediments samples allowed to make thematic charts of this deposicional environment. The predominance of fine sand is quite large; despite the mean grain size of the samples varies (coarse silt to coarse sand). It was identified five different sediment patterns at the study area: i) fine and very fine sands of the Paranaguá Estuarine Complex south mouth tide delta; ii) bimodal very fine sand with 10 to 40% rates of silt and clay that occurs near the coastline between 5 and 10 m water depths; iii) unimodal medium and coarse sand sediments; iv) fine sand sediments between 10 and 15 m water depths, unimodal but different from the delta fine sands because the distributions in more Ø intervals; v) fine and very fine sands of the beach braking bars zone.


2020 ◽  
Vol 12 (1) ◽  
pp. 1512-1532
Author(s):  
Temitope Love Baiyegunhi ◽  
Kuiwu Liu ◽  
Oswald Gwavava ◽  
Christopher Baiyegunhi

AbstractA total of 92 representative sandstone samples of the Bredasdorp Basin in boreholes E-AH1, E-AJ1, E-BA1, E-BB1 and E-D3 have been investigated for their grain size characteristics. Grain size textural parameters and their cross plots, linear discriminate functions (LDFs), C–M (C = first percentile and M = median) diagram and log–probability plots were calculated and interpreted to understand the mode of transportation and hydrodynamic conditions and also to unravel the depositional environments of the sediments. The grain size textural parameters revealed that the Bredasdorp sandstones are unimodal, predominantly fine-grained, moderately well-sorted, mesokurtic and near symmetrical. The bivariate plots of grain size textural parameters indicate that the depositional environments had been influenced mainly by river/beach/coastal dune conditions. The LDF plots show that the sediments are turbidity current deposits in a shallow marine environment. The C–M diagram revealed that the studied sandstones were mainly deposited by traction currents and beach process. In addition, the grain size log–probability curves and C–M diagram show the predominance of suspension and saltation modes of sediment transportation. Based on the inter-relationship of the various statistical parameters, it is deduced that the Bredasdorp Basin are mainly shallow marine deposits with signature of beach and coastal river processes.


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