Judul: Assessment Of Benthic Amphipod Grandidierella Bonnieroides Stephenson 1948 As A Test Organism For Metal Contaminated Sediment Bioassay
Abstrak: To date the evaluation of contaminated sediment using sediment toxicity testing approaches and bioavailable metal, which is a phase that is harmful to aquatic life, is the best approach. Sediment toxicity tests i.e. measuring directly biological effects of sediment contamination and account for additive, synergistic, and antagonistic effects between chemicals, relatively inexpensive and account for all routes of contaminant exposure to the test organism. Amphipod is the most sensitive taxa among benthic organisms that widely used in sediment bioassay. The procedures of using this amphipod as test species are well established in many countries, while in Indonesia, it has not established yet. The recent study aimed to determine benthic amphipod Grandidierella bonnieroides collected from Kramat Kebo estuary, Tangerang, Banten, as test organism for sediment bioassay through various sensitivity tests. These include sensitivity test to particle size and ammonia, cadmium, the salinity tolerance, and the response to field contaminated sediment. Cd, Pb, Cu and Zn content in sediment of Jakarta Bay were used to determine the response of the amphipod to field contaminated sediment. These tests were performed individually using different batch of amphipod collection. Amphipod used in all tests was 7 days laboratory cultured larvae production, and the size was 2.5-3.5 mm. Effect of sediment particle size on survival of benthic amphipod Grandidierella bonnieroides Stephensen 1948 was conducted in relation to the development of a standard test protocol for measuring sediment toxicity. The association of test species with sediment substrates is one of the essential factors in a sediment bioassay. The unfed amphipod was exposed to four different sediment substrates: sand (82% of particles were in the range of 63 μm-2 mm), muddy sand (57% of particle size in the range of 63 μm-2 mm and 43% of particle in the range of <63 μm), sieved mud (sieved through 63 μm pore size), and natural mud for 10 days. Survival of G. bonnieroides was well associated with all sediment types. Survival of the amphipod was significantly reduced (p< 0.05) in sand substrate compared with that in muddy sand and sieved sediments, suggested that survival of the amphipod was strongly related to finer sediment that contained more total organic matter as food source. The result showed that G. bonnieoides is suitable for the toxicity assessment of contaminated sediments with high proportion of mud. Ammonia toxicity was tested by using benthic amphipods Grandidierella bonnieroides to describe its role as a confounding factor in sediment quality assessment. High ammonia content in the pore water sediment can be potentially toxic to benthic biota that will interfere the results of sediment toxicity tests. The results showed that ammonia has a relatively low toxicity to amphipod and does not act as a confounding factor in sediment toxicity tests. This is because the content of ammonia in the sediment does not cause a significant impact on the 6 survival of amphipod if not exceeded its LC50 value (65.5 mg/L). Thus, the amphipod has potential as test organisms in sediment bioassay to assess contaminated sediment. Grandidierella bonnieroides was exposed to cadmium to determine its potential as test species for sediment
Keyword: amphipod, Grandidierella bonnieroides, sediment, bioassay, metals

Judul: Distribution and Bioaccumulation of Heavy Metals Related to Methionine, Cystine in Gonggong Conch (Laevistrombus canarium) in Coastal Waters of Bangka Island
Abstrak: Industry and the community have carried out tin mineral exploration on Bangka Island for a long time. Industrial mining has been going on for 200 years, while community mining has been carried out illegally (Unconventional Mining/UM). UM has increased since the period of regional autonomy in 2008. UM is carried out using the land opening method. It has a significant impact on the damage to the tailing’s expanse. The land becomes nutrient-poor, and many basins are formed (kolong). Tailings (fine grain) are suspected of containing heavy metals because, naturally, heavy metals are contained in soil minerals. Several studies have indicated the contamination of heavy metals in marine waters and their accumulation in aquatic resources. One of the commercial resources is the gonggong conch (Laevistrombus canarium). This study reveals the level of heavy metal contamination and the biological aspects of the gonggong conch resource related to the presence of tin mining exploration. The study was conducted by purposive sampling: areas affected by mining and far from mining activities. The samples used were sediment, seagrass and L. canarium. Sediment samples were taken at twelve points around Bangka Island. This sample describes the distribution of heavy metals on Bangka Island. L. canarium and seagrass data were collected using a quadratic transect (1 x 1m) in six L. canarium habitats. The research variables included measurements of heavy metal concentrations (Zn, Cu, Pb, Cd, Sn) in sediments and L. canarium (gills and meat), methionine and cystine in L. canarium (gills, meat) and hepatopancreas histology of L. canarium. The total heavy metals were measured according to APHA (2012) by Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-EOS). Amino acid preparation and measurement with modified AOAC (2005) method using Liquid chromatography-mass spectrometry (LC-MS). Statistical approach (Kruskal – Wallis and Pairwise Comparison test) was used to explain the effect of heavy metals due to mining activities on the habitat of L. canarium, the relationship between environmental conditions and the growth/health of L. canarium (population and structure/age group, amino acid content of methionine, cystine, and histology). The analysis reveals that almost all sediment samples are contaminated with heavy metals (Zn, Cu, Pb, Cd, and Sn). Concentrations of Zn, Cu, and Pb consistently show relatively high values in the environs of Teluk Kelabat and Tanah Merah Beach, as locations around mining activities. Based on the Enrichment Factor (EF) category, Zn and Cu contamination in the research area was still relatively small (EF < 2), except for Pb, which had undergone high enrichment (EF 5-20). The high Pb still requires further research to find the cause. Is it related to the soil geology of the Bangka area as an indication of tailings waste or anthropogenic impact?. The presence of heavy metals in these sediments can still be classified as relatively safe when referring to quality standards such as CCME or ANZECC/ARMCANZ. L. canarium is relatively low, with a density range of 6-8 ind/m2. The organism's condition also showed poor growth as indicated by the negative allometric growth form (b<3), and the body condition was classified as thin. A negative allometric is a growth
Keyword: Gonggong conch (Laevistrombus canarium), hepatopancreas, negative allometric, tin mining

Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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