Judul: The Characteristics of Types of Plastic Packaging Waste in the Upstream Segment of the Citarum River, Bandung, West Java
Abstrak: Sungai Citarum merupakan salah satu sungai terbesar di Jawa Barat yang memiliki banyak fungsi, namun memiliki permasalahan baik dalam kualitas air, pencemaran logam berat, juga pencemaran sampah. Tujuan penelitian ini untuk mengidentifikasi dan menganalisis karakteristik jenis sampah plastik kemasan di segmen hulu Sungai Citarum (hilir Sungai Cikapundung dan Nanjung), Bandung, Jawa Barat serta dampaknya ke perairan. Pengambilan contoh dilakukan di hilir Sungai Cikapundung, Kecamatan Bojongsoang dan Jembatan Nanjung, Desa Nanjung, pada bulan April hingga November 2021. Sampel sampah plastik kemasan dianalisis berdasarkan bobot dan kelimpahannya berdasarkan jenis plastiknya. Uji statistik Mann-Whitney digunakan untuk mengetahui beda nyata sampah kemasan yang ditemukan antara kedua stasiun dan Uji Kruskal Wallis untuk mengetahui pengaruh waktu pengambilan contoh. Hasil yang diperoleh menunjukkan jenis sampah plastik kemasan pada kedua stasiun didominasi oleh jenis PP (Polypropylene) dan jenis lainnya. Selain itu, jenis PET (Polyethylene Terephthalate) juga dominan ditemukan pada Stasiun Cikapundung, serta jenis PS (Polystyrene) pada Stasiun Nanjung. Sampah plastik tersebut bersifat toksik dan karsinogenik yang akan menurunkan kualitas perairan serta berbahaya bagi biota perairan., Citarum River is one of the largest rivers in West Java which has many functions, but has problems both in water quality, heavy metal pollution, and garbage pollution. The purpose of this study was to identify and analyze the characteristics of the types of plastic packaging waste in the upstream segment of the Citarum River (downstream of the Cikapundung and Nanjung Rivers), Bandung, West Java and their impact on the waters. Sampling was carried out in the downstream of the Cikapundung River, Bojongsoang District and Nanjung Bridge, Nanjung Village, from April to November 2021. Samples of plastic packaging waste were analyzed based on their weight and abundance based on the type of plastic. The Mann-Whitney statistical test was used to determine the significant difference in packaging waste found between the two stations and the Kruskal Wallis test to determine the effect of sampling time. The results obtained show that the type of plastic packaging waste at both stations is dominated by PP (Polypropylene) other types. Furthermore, the type of PET (Polyethylene Terephthalate) is also dominantly found at Cikapundung Station, and PS (Polystyrene) at Nanjung Station. The plastic waste is toxic and carcinogenic which will reduce water quality and be harmful to aquatic biota.
Keyword: plastic packaging waste, rivers pollution, toxic compounds, types of plastic

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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