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A First Record of Metal Fractionation in Coastal Sediment from Ambon Bay, Moluccas, Indonesia
Get PDFFive metals in sediment samples at seven sites from the Ambon Bay were analyzed with BCR sequential extraction procedure to determine chemical fractionation of metals and to assess bioavailability of metals with Risk Assessment Code (RAC). The result showed that the percentages of cadmium (100%), lead (82.6-97.08%) and zinc (41.68-76.33%) were mostly accumulated in the non-residual (F1+F2+F3) fraction of the total concentrations. While the copper percentages (44.74-78.91%) and nickel (59.71-74.16%) were mostly accumulated in residual (F4) fraction of the total concentrations. The Risk Assessment Code (RAC) reveals that cadmium, copper, nickel and zinc at locations exist in acid soluble (exchangeable) fraction and therefore, they are in low until very high risk category meanwhile there is no Pb at locations exist in acid soluble (exchangeable) fraction.
Combined Multiple Attenuation Methods and Geological Interpretation : Seram Sea Case Study 2D Marine Seismic Data
Get PDFMultiple often and always appear in marine seismic data due to very high acoustic impedance contrasts. These events have undergone more than one reflection. This causes the signal to arrive back at the receiver at an erroneous time, which, in turn, causes false results and can result in data misinterpretation. Several types of multiple suppression have been studied in literature. Methods that attenuate multiples can be classified into three broad categories: deconvolution methods; filtering methods and wavefield prediction subtraction methods. The study area is situated on Seram Sea in between 131°15’E – 132°45’E and 3°0’S – 4°0’S, Seram Trough which is located beneath Seram Sea at northern part of the Banda-Arc – Australian collision zone and currently the site of contraction between Bird’s Head and Seram. This research uses predictive deconvolution and FK-filter to attenuate short period multiple from their move out, then continued by SRME method to predict multiple that cannot be attenuated from previous method, then followed by Radon transform to attenuate multiple that still left and cannot be attenuated by SRME method. The result of each method then compared to each other to see how well multiple attenuated. Predictive deconvolution and F-K filter could not give satisfactory result especially complex area where multiple in dipping event is not periodic, SRME method successfully attenuate multiple especially in near offset multiple without need subsurface information, while SRME method fails to attenuate long offset multiple, combination of SRME method and Radon transform can give satisfactory result with careful selection of the Radon transform parameters because it can obscure some primary reflectors. Based on geological interpretation, Seram Trough is built by dominant structural style of deposited fold and thrust belt. The deposited fold and thrust belt has a complexly fault geometry from western zone until eastern of seismic line
STRATIGRAFI SEISMIK CEKUNGAN ARU, PAPUA BARAT
Get PDFStudi rekaman seismik multi-kanal dari Cekungan Aru, Papua Barat yang diperoleh dengan menggunakan KR Geomarin III pada tahun 2016, bertujuan untuk menginventarisir dan memetakan aspek-aspek geologi serta untuk studi geo-tektonik dan sejarah geologi. Data seismik menunjukan bahwa urutan sedimen di Cekungan Aru ditandai oleh sedimen pra-ekstensi, sedimen sin-ekstensi, sedimen pos-ekstensi dan sedimen sin-inversi. Pengamatan mikroskopis inti sedimen permukaan dasar laut umumnya menunjukkan adanya fragmen cangkang kerang dan foraminifera, mineral mafik dan residu organik dari lignit berwarna coklat kehitaman. Kata kunci: Cekungan Aru, stratigrafi seismik, sedimen.Study on multi-channel seismic records from the Aru Basin, West Papua obtained using RV Geomarin III in 2016 were aimed to invent and map geological aspects and for geo-tectonic and geological history studies. Seismic data confirmed that sediment sequence in Aru Basin is characterized by pre-extension sediments, syn-extension sediments, syn-extension sediments and syn-inversion sediments. Microscopic observations of the core of surficial sediments generally show the presence of shell fragments and foraminiferas, mafic minerals and organic residuals of blackish-brownish lignite. Key words: Aru Basin, seismic stratigraphy, sediments
FORAMINIFERA BENTONIK SEBAGAI BIOINDIKATOR KUALITAS PERAIRAN TERUMBU KARANG DI PULAU TEGAL, TELUK LAMPUNG, LAMPUNG
Get PDFForaminifera telah banyak digunakan sebagai indikator kualitas perairan sekitar terumbu karang di Indonesia berdasarkan perbandingan kelompok foraminifera bentonik tertentu. Studi tersebut diterapkan di sekitar Pulau Tegal, Teluk Lampung yang merupakan salah satu destinasi wisata yang secara tidak langsung memberikan pengaruh terhadap ekosistem terumbu karang. Penelitian ini bertujuan untuk mengetahui struktur komunitas foraminifera bentonik kaitannya dengan kondisi perairan terumbu karang Pulau Tegal, Teluk Lampung. Penelitian ini dilakukan pada 16 stasiun penelitian di Pulau Tegal yang mewakili semua sisi pulau dengan variasi kedalaman dari 0 meter hingga 28 meter. Hasil dari penelitian ini ditemukan 6.918 spesimen foraminifera bentonik dengan keanekaragaman yang tergolong rendah. Genera Amphistegina dan Elphidium ditemukan sangat melimpah pada hampir seluruh stasiun. Nilai Indeks FORAM (FI) diatas 4 ditemukan pada 11 stasiun penelitian yang mengindikasikan bahwa sebagian besar perairan Pulau Tegal berada dalam kondisi yang sangat baik dan kondusif untuk pertumbuhan serta pemulihan terumbu karang. Hasil ini sejalan dengan melimpahnya kehadiran kelompok foraminifera yang berasosiasi dengan terumbu karang pada perairan Pulau Tegal.Kata Kunci: Bioindikator, Pulau Tegal, Indeks FORAM, Terumbu Karang, Komunitas.Foraminifera has been widely used as an indicator of the quality of the waters around coral reefs in Indonesia based on the comparison of certain groups of benthonic foraminifera. The study was implemented around Tegal Island, Lampung Bay, which is one of the tourist destinations that influence the coral reef ecosystem. This study aims to determine the structure of bentonic foraminifera communities related to the condition of the coral reef waters of Tegal Island, Lampung Bay. This research was conducted at 16 research stations in Tegal Island representing all sides of the island with variations in depth from 0 m to 28 m water depth. The results of this study found 6.918 specimens of bentonic foraminifera with relatively low diversity. The genera Amphistegina and Elphidium were found to be very abundant in almost all stations. The FORAM Index (FI) above 4 was found in 11 research stations which indicated that most of the waters of Tegal Island were in very good conditions and conducive to the growth and recovery of coral reefs. This result is in line with the abundance of the presence of foraminifera groups associated with coral reefs in the waters of Tegal Island. Keywords: Bioindicator, Tegal Island, FORAM Index, Coral Reef, Communit
Assessing Heavy Metals Contamination in Suspended Particulate Matter in Jakarta Bay, Indonesia
Get PDFSuspended Particulate Matter (SPM) is an important compartment within water column due to its capability in adsorbing pollutant like heavy metals. However, there was limited information regarding SPM and its heavy metals content in Jakarta Bay. Therefore, this study was proposed to understand the spatial distribution, source and to assess metal content in SPM in Jakarta Bay. The samples were collected from 24 stations in April 2011 and were then analyzed using acid digestion processes adopted from USEPA 3050b. The generated data were then modeled to determine the spatial distribution of metals in SPM. The result revealed that the concentration of Cd, Cu, Ni, Pb and Zn in SPM were as follow: 10-110; 21-472; 14-356; 7-107; 87-4255 mg.kg-1, respectively. Since Cd, Pb and Zn in SPM were majorly concentrated in the area closed to harboring activities, the activities was suspected in contributing of high input of those metals, meanwhile, Cu and Ni was mostly came from riverine runoff. The computation of Index of Geoaccumulation (Igeo) revealed that the major area in Jakarta Bay was unpolluted by Cu, Pb, Zn, and Ni in SPM however 96% of the selected area were strongly contaminated by Cd in SPM. Thus, this study emphasized that harbor area as a dominant source of metals in SPM in Jakarta Bay and required to be well managed.Keywords: Jakarta Bay, Suspended Particulate Matter, heavy metals, contamination.Materi Partikulat Tersuspensi (SPM) merupakan bagian penting dalam kolom air karena kemampuannya dalam menjerat polutan seperti logam berat. Akan tetapi, informasi mengenai SPM dan kandungan logam berat dalam SPM di Teluk Jakarta terbatas. Oleh karena itu, tujuan dari studi ini adalah untuk mengetahui distribusi spasial, dan sumber logam berat serta menilai kualitas lingkungan berdasar kandungan logam berat dalam SPM di Teluk Jakarta. Sampel SPM diambil dari 24 titik observasi pada bulan April 2011 kemudian dianalisis dengan proses digestif asam yang diadopsi dari USEPA 3050b. Data yang didapat kemudian dimodelkan untuk mengetahui distribusi spasial logam berat dalam SPM. Hasil analisis menunjukkan bahwa konsentrasi Cd, Cu, Ni, Pb dan Zn dalam SPM secara berurutan sebagai berikut: 10-110; 21-472; 14-356; 7-107; 87-4255 mg.kg-1. Cd, Pb dan Zn lebih ditengarai bersumber dari aktivitas pelabuhan karena konsentrasi Cd, Pb dan Zn di area tersebut tinggi sementara Cu dan Ni lebih banyak berasal dari limpasan sungai. Perhitungan Indeks Geoakumulasi (Igeo) menunjukkan bahwa sebagian besar area tidak tercemar oleh Cu, Pb, Zn dan Ni akan tetapi 96% area teramati tercemar Cd. Oleh karena itu, studi ini menyarankan untuk ditingkatkannya manajemen pembuangan limbah di pelabuhan sebagai sumber logam.Kata kunci: Teluk Jakarta, Materi Partikulat Tersuspensi, logam berat, pencemaran
DATA GEOLOGI DAN GEOFISIKA SELAT LEMBEH SEBAGAI PENDUKUNG PENGEMBANGAN INFRASTRUKTUR PELABUHAN
Get PDFSelat Lembeh sepanjang 16 km dengan lebar sekitar 1 km mempunyai kedalaman laut mencapai 380 m di bagian utaranya, memasuki selatnya mendangkal (20 m) dan ke arah selatannya mendalam (120 m). Dasar laut Selat Lembeh ditutupi oleh sedimen permukaan pasir kerikilan dan kerikil pasiran yang berkomposisi volkanoklastik dan bioklastik bersifat gampingan. Ke dua jenis sedimen ini relatif mempunyai kesesuaian dengan hasil interpretasi sidescan sonar dan seismik, masing-masing sebagai pasir dan sedimen berbutir sedang-kasar (Runtunan D). Daratannya, berdasarkan peta geologi Daerah Bitung dan sekitarnya didominasi oleh batuan gunungapi muda dengan kemiringan pantai antara 0-5o dan tidak ditemukan adanya indikasi sesar. Daerah penelitian mempunyai besaran kegempaan magnitudo kecil dan tsunami terlindung oleh Pulau Lembeh. Kawasan ini berdasarkan peta hidrogeologi termasuk kedalam akuifer setempat, produktif sampai produktif sedang penyebaran luas. Data dasar geologi dan geofisika ini sangat berperan dalam pengembangan Selat Lembeh terutama rencana pengembangan infrastruktur di kawasan Bitung dan sekitarnya. Kata kunci: Kedalaman laut, sedimen permukaan, batuan gunungapi muda, topografi, akuifer dan pengembangan Selat Lembeh.The Lembeh Strait with a length of 16 km and a width of about 1 km has a depth of 380 m in its northern part, entering the strait has a shallow depth of 20 m and to the south it has a depth of 120 m. The seabed of the Lembeh Strait is covered by surface sediment of gravelly sand and sandy gravel formed by volcanoclastic and bioclastic materials. The two types of sediments are relatively similar to the results of the side scan sonar and seismic interpretations, each of which is sand and medium-coarse grain sediments (Sequence D). In the mainland, based on the geological data of the Bitung Region and its surroundings, its lithology is dominated by young volcanic rocks with a slope on the coast between 0-5o and no indications of faults were found. This area is valued of seismicity relatively small magnitude and safe from tsunami waves because it is protected by Pulau Lembeh. This area based on hydrogeological data is classified into local aquifers, productive to medium productive with wide distribution. The basic data of the geological and geophysical aspects play a part in the development of the Lembeh Strait, especially the infrastructure development plan in the Bitung area and its surroundings.Keywords: Depth of sea, surface sediment, young volcanic rocks, topography, aquifers and development of Lembeh Strait
Characteristic of Shallow Subsurface Quaternary Sediment in Nongsa Isle, Part of Putri Islands, Batam, Based on Georadar Data Interpretation
Get PDFNongsa Isle belongs to Putri Islands in Batam, is the outermost island that need to be protected either from natural hazards and anthropogenic factor. Therefore, this study was conducted by performing Ground Penetrating Radar analysis, in order to understand the geological condition particularly sedimentology and its process. We used Sirveyor 20 GPR equipment type with MLF antenna frequency 40 Mhz and Radan 5 as processing software, which include time zero correction, spatial filter, deconvolution, migration and adjustment of amplitude and signal gain. Data interpretation was conducted based on radar facies methodology that describes georadar image/radargram. The study result showed differences of sedimentary facies based on three differences of radar facies units, with the first layer (unit 1) is the youngest unit has thicknesses ranging from 3.5 – 5 m that characterized by parallel, strong reflector, high amplitude and continuous reflector configurations, unit 2 from 5 – 11 meter of depth, indicates parallel reflector pattern with medium-high amplitude and continuous, and unit 3 which is the oldest unit with thickness until penetration limit (11 – 20 m), characterized by a configuration of sub parallel – hummocky reflectors that are undulating, low-medium amplitude reflectors. Based on radar facies characteristics such as reflector configuration, reflection amplitude, and reflection continuity, the differencies of depositional facies are changes from fluvial – coastal plain
POTENSI BAHAYA GEOLOGI DI PERAIRAN LHOKSEUMAWE ACEH
Get PDFPenelitian seismik pantul dangkal di perairan Lhoksemawe dilakukan untuk mengetahui kondisi geologi di bawah permukaan dasar laut. Adanya potensi bahaya geologi suatu daerah penelitian dapat diketahui dengan menganalisis kondisi geologinya. Hasil interpretasi rekaman seismik memperlihatkan struktur geologi sesar, pengangkatan, pelipatan dan intrusi. Sesar-sesar aktif yang terdapat di darat umumnya menerus hingga ke pantai dan lepas pantai. Untuk menentukan daerah yang mungkin dapat mengakibatkan terjadinya bahaya geologi maka dibuat zonasi berdasarkan morfologi dasar laut. Kewaspadaan terhadap bahaya geologi yang mungkin terjadi di laut terutama pada zona B dan zona C. Longsoran dapat terjadi di zona B karena morfologinya agak terjal, dan sesar aktif pada zona C dapat mengakibatkan gempa. Zona A dengan kedalaman antara 0 hingga 200 meter dapat dikatagorikan sebagai zona cukup aman. Pembangunan di daerah pantai hingga lepas pantai cukup aman pada kawasan kedalaman hingga 200 meter. Kata kunci: potensi, bahaya geologi, struktur geologi, LhokseumaweShallow seismic reflection research in the Lhokseumawe waters was conducted to determine the geological conditions beneath the seabed surface. The geological hazard potential of study area can be known to analyze its geological conditions. The results of seismic interpretation shows that geological structures as fault, up lift, fold and intrusion. Active faults on land are generally being up to the coast and offshore. To determine areas that may result in the geological hazards created zoning based on morphological seabed. Precautions against geological hazards that may occur in the sea, mainly in zones B and C.Landslide can be occured in B zone because the morphology rather steep, and the active fault on C zone can be resulted the earthquakes. The A zone with the depth between 0 to 200 meters can be considered safe zone. Development in coastal to offshore areas may be quite safe in the depth up to 200 meters.Keyword: Potency, geological hazard, geology structure, Lhokseumaw