Judul: Composition and Density of Marine Debris in the Mangrove Ecosystems on Tidung Besar Island, Kepulauan Seribu
Abstrak: Pulau Tidung Besar merupakan pulau pemukiman yang dekat dengan wilayah konservasi Pulau Tidung Kecil memiliki aktivitas penduduk, wisatawan, dan aktivitas penangkapan yang tinggi sehingga dapat menghasilkan sampah laut dengan jumlah besar dan berdampak pada ekosistem mangrove. Penelitian ini bertujuan menganalisis komposisi dan densitas marine debris yang berada di ekosistem mangrove di Pulau Tidung Besar. Survey lapang meliputi pengamatan kerapatan jenis mangrove, parameter fisika kimia perairan, pengambilan sampel sampah laut (marine debris), dan sedimen untuk mikroplastik pada 3 stasiun di Pulau Tidung Besar. Pada lokasi pengamatan ditemukan 1 spesies mangrove yaitu Rhizophora stylosa dengan kerapatan 1-9 ind/m2. Makrodebris yang ditemukan memiliki 5 kategori yaitu, plastik, karet, tekstil, B3, dan logam dengan kepadatan makrodebris setiap jenis berkisar 0,84-28,32 gr/m2. Sedangkan mikroplastik yang ditemukan terdiri dari jenis fiber, film, fragmen, foam, dan palet dengan kelimpahan 7-4280 partikel/kg. Kesimpulannya, marine debris yang diamati pada ekosistem mangrove Pulau Tidung Besar didominasi oleh kategori plastik pada makrodebris dan jenis fiber pada mikroplastik. Kepadatan makrodebris kategori plastik memiliki nilai kedekatan yang cukup akurat sehingga berbanding lurus dengan banyaknya kelimpahan mikroplastik pada jenis fiber, fragmen, film, dan palet pada mangrove kategori semai dan anakan pada setiap stasiun.
Keyword: Pulau Tidung Besar, Sampah Laut, Mangrove, Mikroplastik, Ekosistem Mangrove

Judul: Komposisi dan Densitas Marine Debris di Pantai Pulau Tidung Besar, Kepulauan Seribu
Abstrak: Pulau Tidung Besar sebagai salah satu dari wilayah pesisir dan pulau kecil tidak terlepas dari permasalahan marine debris. Penelitian ini bertujuan mengetahui komposisi, densitas, dan keterkaitan antara jenis-jenis marine debris serta menganalisis perbedaan densitas marine debris dari tiga stasiun di Pulau Tidung Besar, Kepulauan Seribu. Hasil menunjukkan plastik merupakan jenis makro debris yang paling banyak ditemukan dengan rata-rata komposisi 89,35%. Fiber merupakan jenis mikroplastik yang paling mendominasi di antara jenis mikroplastik lainnya baik pada sedimen maupun gastropoda dengan nilai rata-rata komposisi 51,67% untuk mikroplastik pada sedimen dan 44,31% untuk mikroplastik pada gastropoda. Uji non-Metric Multidimensional Scaling menunjukkan kepadatan makro debris dari jenis plastik memiliki asosiasi dengan kelimpahan mikroplastik jenis fiber, fragment, dan pellet pada sedimen dan kelimpahan mikroplastik jenis fiber dan pellet pada gastropoda. Terdapat perbedaan densitas marine debris antar stasiun pengamatan secara statistik menggunakan Uji Kruskal-Wallis dengan stasiun pengamatan kesatu (area wisata) merupakan area dengan densitas marine debris tertinggi di Pantai Pulau Tidung Besar., Tidung Besar Island, as one of the coastal and small island areas, is not exempt from marine debris issues. This research aimed to know the composition, density, and interrelationships among various types of marine debris, and to analyze differences among three stations Tidung Besar Island, Seribu Archipelago. The results indicated that plastic is the most commonly found type of macro debris, with an average composition of 89,35%. Fiber is the predominant type of microplastic among others, observesed in sediment and gastropods, with average compositions of 51,67% and 44,31% respectively. Non-Metric Multidimensional Scaling analysis showed that the density of plastic macro debris is associated with the abundance of microplastics such as fibers, fragments, and pellets in sediment, as well as fibers and pellets in gastropods. Marine debris density showed significant difference among stations. The first observation station (tourist area) exhibited the highest marine debris density on the beaches of Tidung Besar Island.
Keyword: abundance, density, gastropods, microplastics, sedimen

Judul: Effects of Particle Shapes on Temperature Distribution under Static Ohmic Heating.
Abstrak: The ohmic heating is defined as a process wherein an alternating electrical current is passed through materials resulting in the heat generation inside the product. The excellence of ohmic heating in comparison with other thermal processing is its energy efficiency and ohmic heating could keeping nutritional as well quality attribute of food via blanching, sterilization, pasteurization, extraction, fermentation, and evaporation. Nevertheless, in ohmic heating process, the electrical conductivity of product is a key parameter. The worst case in the ohmic heating of multiphase product could be occurred when the solid phase has very lower or very high electrical conductivity than the liquid. This study aims to reveal the temperature distribution and the heating rate properties of solid and liquid phase as affected by particle shape and its orientation to the electric field. Experiments were conducted with salt solution 1% and carrot that blanched in salt solution 6%. Blanching process was conducted in order to increase the electrical conductivity of carrot close to the salt solution 1%. Ohmic heating was applied to the sample using static cell (4.90 cm diameter and 6.00 cm in length of sample area) at constant voltage gradient (40 V). Each experiment was conducted in triplicate. It was observed that the different particle shape and orientation provide the different heating rate properties. The slice particle had the fastest heating rate. Moreover the perpendicular orientation was heated faster than parallel orientation. The parallel cylindrical shape provides the slowest heating rate. This shape possibly induced the worst-case condition and could be used as sufficiency heat parameter. The heating pattern of each solid and liquid were simulated using COMSOL modeling software. The predicted temperature values were in good agreement with the experimental data with the maximum prediction error of 3 °C.
Keyword: particle orientation, particle shape, electrical conductivity, ohmic heating