Sedimentation Rate Analysis in Dock C PT. Petrokimia Gresik, Indonesia

Dock C is one of the supporting facilities at PT. Petrokimia Gresik which functions as loading and unloading goods from ships to land and vice versa. Another benefit of the jetty is that it can significantly increase the company's production capacity. Dock C PT. Petrokimia Gresik. In the treatment of sedimentation in port it is necessary to analyze the current pattern and sedimentation rate early, because this is the first step to predict the amount of sedimentation contained in the port in a certain period of time. Several ways can be done to minimize the rate of sedimentation, one of which is the layout of Dock C to reduce the frequency of dredging. This study compares the sedimentation volume at the existing condition jetty and two alternative jetty that occur due to currents and waves, while modeling is done using Mike 21. The results of the existing jetty modeling show the sedimentation volume for 12 months was 20641.68 m3. Whereas the sedimentation volume from alternative jetty 1 and 2 produced for 12 months was 11293.56 m3 and 7426.2 m3. Modifications to the layout of the jetty provided were able to reduce the rate of sedimentation in Dock C, with the most optimal sedimentation volume for 12 months at 13215.48 m3

Anthropogenic and natural factors controlling the composition of bottom sediments of the Vaskovskoe Lake, Eastern Sihote-Alin, Primorye

Изучено вертикальное распределение Pb, Cd, Zn, Hg, Cu, Ni, Fe, Mn, Cорг, а также скорость осадконакопления, определенная по снижению 210Pb, в верхнем 50-сантиметровом слое донных отложений оз. Васьковского, расположенного на восточном макросклоне хр. Сихотэ-Алинь и находящегося под влиянием аэральных выбросов горно-рудных предприятий долины р. Рудная. Установлена скорость осадконакопления в центральной части озера 2.7±0.26 мм/год, что позволяет оценить изменение химического состава донных отложений за последние 160–180 лет. Верхний 8-сантиметровый слой, накопленный после 1983 г., обогащен Pb, Cd в 4.8–8.1 раза, а Zn, Cu, Mn и Hg – в 1.8–2.5 раза по сравнению с нижележащими отложениями, накопленными до 1960 г. В сочетании с данными по динамике добычи и переработки полиметаллических руд в долине р. Рудная это указывает на аэральное поступление техногенного газопылевого материала как на главный источник загрязнения верхнего слоя озерных донных отложений. Обнаружено, что даже при значительном, 2-кратном снижении объемов производства и выбросов в 90-х годах ХХ в., уровень загрязнения осадочного материала, накапливающегося в донных отложениях, остается высоким, и требуется дальнейший мониторинг для характеристики способности геосистем нижней части долины р. Рудная к самоочищению. Показано, что нормирование концентрации тяжелых металлов относительно Fe, учитывающее вариации гранулометрического состава и содержания гидроксидов Fe, позволяет отследить не только интенсификацию горнорудного производства в 70–80-х годах ХХ в., но и начало хозяйственной деятельности в конце ХIХ в. Установлено, что в отличие от тяжелых металлов, концентрация органического вещества (Сорг) в верхнем слое отложений отражает изменение природно-климатических условий на водосборе, соотношение автохтонных и аллохтонных источников Сорг и изменения трофического статуса водоема. The vertical distribution of Pb, Cd, Zn, Hg, Cu, Ni, Fe, Mn, Corg and the rate of sedimentation by 210Pb in the upper 50 cm layer of bottom sediments of the Vaskovskoe Lake has been studied. Vaskovskoe Lake is located on the eastern slope of Sihote-Alin range. It existed under the influence of the mining industry at the Rudnaya River Valley. The rate of sedimentation in the central part of the lake is set at 2.7±0.26 mm/year, which allows estimating the change in the chemical composition of bottom sediments over the last 160-180 years. The top 8 cm layer, accumulated after 1983, is enriched by Pb, Cd in 4.8-8.1 times, In the combination with data on the production and processing of polymetallic ores, it indicates the atmospheric deposition of technogenic dust material as the main source of pollution of the lake sediments. It has been found that even with a significant two-fold reduction in production and emissions in the 1990s, pollution levels of sediments remain high, and further monitoring is required to characterize the geosystem’s ability to self-purification. It is shown that the heavy metal concentration normalized by Fe, taking into account variations in the gran size composition and content of Fe hydroxides, allows us to track not only the intense mining production in the 70s and 80s of the twentieth century, but also the early beginning of economic activity at the Rudnaya R. valley at the end of the nineteenth century. It has been revealed that unlike heavy metals the concentration of organic matter (Corg) in the bottom sediments reflects the change in natural and climatic conditions at the catchment, the ratio of autochtonuos and allochtonuos sources of Corg and changes in the trophic status of the lake.

Evaluation of Aloe weloensis (Aloeacea) Mucilages as a Pharmaceutical Suspending Agent

Natural polymers, specifically mucilages, have been used as a suspending agent for a long period of time. Natural excipients can serve as an alternative to synthetic products since they are less expensive, less toxic, and devoid of environmental pollution. There are many species of Aloe found in Ethiopia which can be used as a source of mucilage. In this study, mucilage from Aloe weloensis, which is found in Wollo floristic region, was extracted and tested as a suspending agent at different suspending agent concentrations and compared with standard suspending agents (acacia and sodium carboxy methylcellulose (NaCMC)) by formulating zinc oxide suspension. The mucilage obtained from Aloe weloensis leaves has shown comparable suspending agent ability with acacia. The rate of sedimentation and viscosity was higher at 1% and 4% mucilage concentrations than acacia though the difference was not significant ( p > 0.05 ). The suspension was slightly basic and easily dispersible than NaCMC. Suspensions formulated from NaCMC were superior in terms of viscosity and sedimentation volume which was significantly different ( p < 0.05 ) accompanied by lower flow rates than suspensions formulated from acacia and Aloe weloensis mucilages. The results suggested that Aloe weloensis mucilage could be used as an alternative suspending agent.

A BATHYMETRY-BASED RESERVOIR SEDIMENTATION EVALUATION

Reservoir sedimentation is a serious problem that normally reduces the capacity of a dam (reservoir) for water storage over a given period of time. This can lead to insufficient availability of water for domestic uses, irrigation and hydropower. This study was conducted to determine the rate of sedimentation, sediment yield and the capacity of the University of Ilorin dam (Ilorin, Nigeria) between June 2007 and June 2014. Geographic Information System (GIS), Global Positioning System (GPS), canoe and lead-line techniques were used for the measurement of depth of the reservoir of the dam. Soil and Water Assessment Tool (SWAT) model was used to simulate the sediment yield. The initial capacity of the dam after construction in 2007 was 1.800 x 106 m3 but this capacity was reduced to 1.411 x 106 m3 in 2014 due to sedimentation. The sediment was found to be clay soil which covered 389,170 m3 of the reservoir and the mean bulk density of the clay soil sediment was 1139 kg/m3. The mean values of clay, silt and sand contents of the sediment yield were 46.5, 35.6 and 17.9 %, respectively. The annual sediment yield was high in the reservoir due to farming activities at the upstream end of the dam, annual rate of sedimentation was 12.78 m3/ha/yr and sediment yield was 14,557.14 kg/ha/yr. Farming activities should be prevented at the upstream of the dam and dredging should be done every 10 years when 30.87% of the storage capacity would be occupied by sediment.

Laju Sedimentasi di Dataran Banjir Sungai Ciujung Hulu Berdasarkan Profil Pb-210 Excess

Laju deposisi sedimen di dataran banjir merupakan salah satu komponen dalam budget sedimen daerah aliran sungai (DAS). Oleh karena itu, perlu dilakukan perhitungan estimasi laju deposisi sedimen di dua lokasi dataran banjir berdasarkan penanggalan umur sedimen dengan teknik Pb-210 excess. Core sedimen diambil di dataran banjir Sungai Ciujung Hulu tiap interval kedalaman 10 cm sampai kedalaman 120 cm. Sedimen yang didapat dikeringkan, diayak, ditimbang 150–300 gr, ditempatkan dalam wadah khusus dan ditutup rapat. Setelah sebulan dalam kondisi tertutup rapat, sampel diukur dengan spektrometer gamma Multichannel analyzer (MCA) untuk mengetahui aktivitas Pb-210 total dan Pb-210 supported. Berdasarkan data Pb-210 total dan Pb-210 supported, terdapat tiga cara berbeda untuk mendapatkan profil Pb-210 excess. Data Pb-210 excess yang diperoleh digunakan untuk menghitung umur sedimen berdasarkan metode constant of the rate of supply (CRS). Melalui umur tiap perlapisan sedimen ini, dapat diketahui adanya zona peralihan laju deposisi sedimen di kedua lokasi. Laju sedimentasi berkisar 1,028 cm/tahun dari tahun 1968 s/d 1987, dan naik menjadi sekitar 2,83 cm/tahun dari tahun 1987–2016 (28,95 tahun) di lokasi 1. Di lokasi 2, laju sedimentasi berkisar 0,676 cm/tahun dari tahun 1950–1993, dan naik menjadi kisaran 3,231 cm/tahun dari kurun waktu tahun 1993–2016 (23 tahun). The rate of deposition of sediment on the floodplain area is one of the constituent component of the sediment budget in watersheds. Therefore, the sedimentation rate estimation has been made in two locations of the floodplains based on the age sediment obtained using Pb-210 excess technique. Sediment cores were taken in the Ciujung Hulu River floodplain every 10 cm depth intervals up to a depth of 120 cm. Sediment was obtained then dried, disaggregated, sifted, weighing 150–300 gr, placed into the special containers and tightly closed. After a month in a sealed condition, samples were measured using gamma spectrometer Multichannel analyzer (MCA) to find out the activity of Pb-210 total and Pb-210 supported. Based on the data of Pb-210 total and Pb-210 supported, there are three different ways to get Pb-210 excess profiles. Obtained Pb-210 excess data is used to calculate the age of the sediments on the basis of the method of constant rate of supply (CRS). Through the age of sediment layers, can be recognized the existence of transitional zone of sediment deposition rate at both locations. The rate of sedimentation ranged from 1.028 cm/year from the years 1968–1987, and rose to about 2.83 cm/year from the years 1987–2016 (28.95 years) at location 1. While in location 2, the rate of sedimentation ranged 0.676 cm/year from the years 1950–1993, and rose to about 3.231 cm/year from the years 1993–2016 (2 years).

Silt content approximation of Neogene Surma group mudrocks, Sitakund anticline, Bengal basin

Petrography of the Neogene mudrocks in this study incorporates laser particle size analysis, thin sections and scanning electron microscopy (SEM). Ten representative mudrock samples were collected from outcrops of the Sitakund structure. From the studies, it is evident that mudrocks of Sitakund structure are characteristically silty. The silt content, as estimated by laser grain size analysis, of the mudrocks ranges from 39 to 77% with average of 58%. Significant amount of granular silt with the platy clay minerals is also evident from the SEM micrographs. The silts are mainly quartz, feldspar and micas. The high silt content in the Neogene mudrocks implies an enormous flux of silty sediments with a very high rate of sedimentation allowing little time for a more selective sorting. This supports the geologic history that the uplifting and erosion of Himalaya was at the peak during Miocene and the Ganges mega delta received highest rate of sedimentation and growth rendering shale consistently silty.Bangladesh J. Sci. Res. 30(1&2): 35-43, December-2017

The Effectiveness of Hybrid Structure in Overcoming Coastal Abration in Trimulyo, Genuk Subdistrict Semarang City

Trimulyo is one of coastal village in Genuk Subdistrict, Semarang City which now facing serious coastal abrasion. Such a thing has been causing loss of ponds and settlements. One of solution which currently carried is hybrid structure which combining permeable structure to break up the waves and trap sediment. The hybrid structure is designed as agitation dredging, which increase suspended sediment in sea water. The goals of this research were to studying the effectiveness of hybrid structure in handling coastal abration and to counting the volume of sedimentation during 20 months as well as rate of sedimentation. To reach the goals, high resolution satellite imagery year 2015 and 2016, scaled stick and sediment trap were applied to the study. Image processing was conducted by using Arc GIS 10.3 software. The effectiveness of hybrid structured was determined by series of field survey of existing condition. Rate of sedimentation measured during before and after hybrid structure built (20 months). The results showed that hybrid structure was effective to reduce coastal abrasion, it proven by a large amount of sediment was trapped behind the structure and coastline was upward along 170 meter since it was built. The volume of sediment during 20 months is 81.500 m3. If it assumed that the rate of sedimentation constantly, monthly rate of sedimentation is 4.075 m3/month or daily rate is 135,8 m3/day. The sediment that has formed highly recommended to use as mangrove conservation area in Semarang City.

THE RATE OF SEDIMENTATION ESTIMATION OF TANJUNG API-API ESTUARY SOUTH SUMATERA BY USING 210Pb PROFILE

Sedimentary processes occur intensively in Tanjung Api-Api area situated in the estuary of Musi Banyuasin river. A study on 210Pb isotopes of the sediments has been done to understand the rate of sedimentation. For that purpose, the Marine Geological Institute of Indonesia (MGI) has also conducted bathymetry and sediment distribution mappings. Two samples represent depths of 17-30 cm and 190-210 cm below sea floor give age of 11.54 and 22.45 years. The average of sedimentation rate is 2.03 cm/years (from 0 to 0.3 m below seafloor) and 8.9 cm/years (until 2.1 m depth below seafloor). The result shows, decreasing sedimentation rate upward, that indicates the surficial sediment less influenced by wave and surface current nowadays. Keywords : 210Pb isotope, rate sedimentation, Tanjung Api-Api Proses sedimentasi yang intensif terjadi di kawasan Tanjung Api-Api yang terletak di muara Sungai Banyuasin. Penelitian isotop sedimen 210Pb untuk mengetahui kecepatan sedimentasi telah dilakukan oleh Puslitbang Geologi Kelautan, selain itu dilakukan pula pemetaan batimetri dan sebaran sedimen permukaan dasar laut. Dua buah contoh sedimen mewakili kedalaman 17-30 cm dan 190-210 cm di bawah dasar laut memeperlihatkan umur 11,54 dan 22,45 tahun. Kecepatan sedimentasi rata-rata 2,03 cm/tahun (pada kedalaman 0-0,3 meter di bawah permukaan dasar laut) dan 8,9 cm/tahun (hingga kedalaman 2,1 meter di bawah dasar laut). Hasil tersebut menunjukkan penurunan kecepatan sedimentasi ke arah atas, yang mengindikasikan bahwa pada saat ini gelombang dan arus kurang berpengaruh terhadap proses sedimentasi. Kata kunci : isotop 210Pb, kecepatan sedimentasi, Tanjung Api-Api