Judul: Komposisi dan Kelimpahan Makroplastik di Sungai Citarum (Sebelum dan Sesudah Waduk Saguling), Jawa Barat
Abstrak: Sungai Citarum merupakan sungai yang mengaliri tiga bendungan besar dan banyak dimanfaatkan oleh manusia dalam menjalankan aktivitasnya yang menghasilkan makroplastik sehingga terganggunya fungsi ekosistem. Tujuan penelitian ini untuk mengidentifikasi jenis dan jumlah makroplastik yang ada di Sungai Citarum, khususnya di lokasi sungai sebelum memasuki dan setelah outlet Waduk Saguling, berdasarkan perbedaan waktu, yaitu pagi, siang, dan sore. Pengambilan contoh dilakukan di Jembatan Nanjung, Desa Nanjung dan Jembatan Citarum Lama, Kecamatan Cipatat, pada bulan April hingga Juni 2021 dan bulan Agustus hingga November 2021. Sampel sampah plastik dianalisis kelimpahan dan komposisi jenis makroplastiknya. Uji statistik Kruskal Wallis, RLS, RLB, dan Korelasi digunakan untuk mengetahui beda nyata kelimpahan pada waktu pengamatan, dan pengaruh curah hujan terhadap kelimpahan. Hasil yang diperoleh menunjukkan kelimpahan makroplastik relatif sama antara waktu pengamatan, yaitu pagi, siang, dan sore hari. Curah hujan tidak berpengaruh terhadap kelimpahan makroplastik. Kelimpahan makroplastik paling tinggi ditemukan di Stasiun Nanjung pada sore hari. Sementara itu, komposisi jenis yang paling dominan ditemukan ialah kantung plastik bening, styrofoam, sachets, dan kemasan allumunium. Perbedaan kelimpahan pada kedua stasiun dipengaruhi oleh keberadaan Waduk Saguling di antara kedua stasiun., The Citarum River is a river that flows through three large dams and is widely used by humans in carrying out their activities that produce macroplastics so that ecosystem functions are disrupted. The purpose of this study was to identify the type and amount of macroplastic present in the Citarum River, especially at the location of the river before entering and after the outlet of the Saguling Reservoir, based on time differences, namely morning, afternoon, and evening. Sampling was carried out at Nanjung Bridge, Nanjung Village and Citarum Lama Bridge, Cipatat District, from April to June 2021 and August to November 2021. Plastic waste samples were analyzed for abundance and composition of macroplastic types. Kruskal Wallis, RLS, RLB, and Correlation statistical tests were used to determine the significant difference in abundance at the time of observation, and the effect of rainfall on abundance. The results obtained showed that the abundance of macroplastics was relatively the same between the time of observation, namely morning, afternoon, and evening. Rainfall has no effect on the abundance of macroplastics. The highest abundance of macroplastics was found at Nanjung Station in the afternoon. Meanwhile, the composition of the most dominant species found were clear plastic bags, Styrofoam, sachets, and aluminum packaging. The difference in abundance at the two stations is influenced by the presence of the Saguling Reservoir between the two stations.
Keyword: macroplastic, river, river discharge, species composition

Judul: Distribution of Microplastic in Water Column Citarum River, Jawa Barat Province.
Abstrak: Semakin meningkatnya asupan limbah dari berbagai macam kegiatan di sepanjang aliran sungai diduga juga menyebabkan meningkatnya limbah plastik, yang kemudian dapat berakumulasi sebagai mikroplastik baik di dalam tubuh biota maupun manusia. Penelitian ini bertujuan untuk membandingkan keberadaan mikroplastik pada air di bagian hulu, tengah, dan hilir Sungai Citarum, Jawa Barat berdasarkan tipe, warna dan kelimpahan mikroplastik. Analisis secara statistik menggunakan Uji Kruskal Wallis dan Uji Mann Whitney. Data dianalisis menggunakan perangkat lunak MS. Excel 2010 dan SPSS 15. Kelimpahan mikroplastik di Sungai Citarum pada Stasiun Hilir lebih tinggi dibandingkan dengan kelimpahan mikroplastik pada Stasiun Tengah dan Stasiun Hulu. Mikroplastik pada Stasiun Hulu, Stasiun Tengah, dan Stasiun Hilir didominasi oleh warna transparan. Kelimpahan mikroplastik pada Stasiun Hulu, Stasiun Tengah, dan Stasiun Hilir tertinggi yaitu tipe film., The increasing intake of waste from various activities along the river flow is also thought to have caused an increase in plastic waste, which can then accumulate as microplastics in both biota and human bodies. This research aims is to compare the presence of microplastics in the upstream, middle, and downstream of the Citarum River waters, West Java based on type, color and abundance of microplastics. Statistical analysis using Kruskal-Wallis test and Mann Whitney test. Data were analyzed using MS software Excel 2010 and SPSS 15. The abundance of microplastics in the Citarum River at the Downstream Station was higher than the abundance of microplastics at the Central Station and the Upstream Station. Microplastics at the Upstream Station, Middle Station, and Downstream Station are dominated by transparent colors. The highest abundance of microplastics at the Upstream Station, Middle Station, and Downstream Station was film type.
Keyword: itarum River, microplastic, waters

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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