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: Heavy Metals Content (Pb, Hg, Cd) in Crescent Grunter (Terapon jarbua, Forsskål 1775) in Bacan Island Waters
Abstrak: Pulau Bacan memiliki potensi perikanan dan pariwisata yang tinggi. Kegiatan pariwisata dan kehidupan masyarakat sekitar berpotensi menjadi penyumbang cemaran logam berat ke lingkungan perairan tersebut. Salah satu potensi perikanan dengan nilai ekonomis penting yang terdapat di pulau ini adalah ikan kerong-kerong yang banyak dimanfaatkan sebagai bahan pangan baik dalam kondisi segar maupun olahan ikan asin-kering. Penelitian ini bertujuan menganalisis tingkat bioakumulasi logam berat Pb, Hg, dan Cd pada organ hati, insang, dan daging ikan kerong-kerong (Terapon jarbua, Forsskål 1775) di Perairan Pulau Bacan, Maluku Utara. Pengambilan sampel air, pengukuran kualitas air, serta pengambilan organ hati, insang, dan daging pada ikan kerong-kerong dilakukan pada bulan Februari 2022. Berdasarkan hasil anlisis, nilai kandungan logam berat Pb, Hg, dan Cd pada air telah melampaui baku mutu PP RI No. 22 tahun 2021 dan kandungan logam berat Pb pada hati ikan kerong-kerong ditemukan dalam konsentrasi tertinggi. Biokonsentrasi logam berat tergolong akumulasi rendah, kecuali Pb pada organ hati termasuk akumulasi sedang., Bacan Island has high fishery and tourism potential. Tourism activities and the life of the surrounding community have the potential to contribute to heavy metal contamination in the aquatic environment. One of the fishery potentials with important economic value found on this island is kerong-kerong fish which is widely used as a food ingredient both in fresh condition and processed salt-dried fish. This study aims to analyze the level of bioaccumulation of heavy metals Pb, Hg, and Cd in the liver, gills, and meat of crescent grunter (Terapon jarbua, Forsskål 1775) in Bacan Island waters, North Maluku. Sampling of water, measurement of water quality, as well as harvesting of liver, gills, and meat from crescent grunter was carried out in February 2022. Based on the results of the analysis, the values for the heavy metal content of Pb, Hg and Cd in water exceeded PP RI quality standards No. 22 of 2021 and the content of the heavy metal Pb in the liver of clam fish was found to be in the highest concentration. Bioconcentration of heavy metals is classified as low accumulation, except for Pb in the liver which is classified as moderate accumulation.
Keyword: Bacan Island, crescent grunter, heavy metals

Judul: Kajian frieze groups untuk klasifikasi dan konstruksi desain berdasarkan simetri pada pola
Abstrak: Frieze groups adalah konsep matematika untuk mengklasifikasikan desain pada dua dimensi permukaan yang berulang-ulang dalam satu arah berdasarkan simetri pada pola. Frieze groups merupakan grup yang mempertahankan bentuk pola. Pergerakan bentuk pola terdiri dari translasi, refleksi dan rotasi 180o. Tujuan dari karya ilmiah ini adalah mengkaji sifat Frieze group, mengkaji penggunaan Frieze group dalam mengklasifikasikan simetri pada pola dan mengkonstruksi pola dengan menggunakan software tesselmania. Hasil yang telah diperoleh, bahwa jenis Frieze groups merupakan subgroup dari grup pergerakan pola. Selain itu dapat dilihat dari sifat isomorfik berbagai jenis Frieze groups. Untuk mengkonstruksi sebuah bentuk pola dapat menggunakan salah satu software untuk membentuk sebuah pola bidang datar (dua dimensi) yaitu tesselmania.
Keyword: Frieze groups, Simetri, Pola