Judul: Water Quality of the Downstream Cisadane River and Its Feasibility as a Source of Clean Water and Dringking Water for Residential Areas
Abstrak: Sungai Cisadane memiliki fungsi dan nilai yang sangat tinggi bagi kehidupan manusia. Namun, kegiatan manusia di DAS Cisadane dan di Sungai Cisadane dapat mengancam fungsi dan pemanfaatan perairan karena dapat menurunkan kualitas air Sungai Cisadane. Penelitian ini bertujuan untuk menentukan kelayakan kualitas air Sungai Cisadane untuk air baku air minum terkait dengan dinamika akibat pasang-surut dan musim. Pemantauan di lakukan selama tahun 2020 di Sungai Cisadane bagian hilir. Parameter kualitas air yang diamati meliputi TSS, warna, kekeruhan, bau, BOD, COD, amonia, nitrat, nitrit, fosfat, total P, sulfida, Zn, Fe, As, Pb, Cd, Cu, Hg, Se, Cr6+, Mn, sianida, deterjen, dan Total Coliform. Analisis dilakukan secara deskriptif, dan dengan penentuan Indeks Pencemaran (IP). Hasil analisis menunjukan bahwa kondisi musim, musim hujan dan musim kemarau, dan kondisi ketinggian muka air yang dipengaruhi oleh pasang surut laut berpengaruh pada beberapa parameter kualitas air. Kecuali NO3, PO4, H2S, Ar, Cd, Se, Cr6+, sianida dan deterjen. Berdasarkan Indeks Pencemaran (IP) perairan bagian hilir S. Cisadane telah tercemar ringan sampai berat, sehingga air tidak dapat digunakan sebagai sumber baku air minum tanpa melalui pengolahan terlebih dahulu., The Cisadane River has a very high function and value for human life. However, human activities in the Cisadane watershed and in the Cisadane River can threaten the function and utilization of the waters because they can reduce the water quality of the Cisadane River. This study aims to determine the appropriateness of the water quality of the Cisadane River for drinking water related to the dynamics due to tides and seasons. Monitoring was carried out during 2020 in the lower reaches of the Cisadane River. Water quality parameters observed included TSS, color, turbidity, odor, BOD, COD, ammonia, nitrate, nitrite, phosphate, total P, sulfide, Zn, Fe, As, Pb, Cd, Cu, Hg, Se, Cr6+, Mn , cyanide, detergent, and Total Coliform. The analysis was carried out descriptively, and by determining the Pollution Index (IP). The results of the analysis show that seasonal conditions, rainy and dry seasons, and water level conditions which are affected by sea tides affect several water quality parameters. Except NO3, PO4, H2S, Ar, Cd, Se, Cr6+, cyanide and detergents. Based on the Pollution Index (IP) the downstream waters of Cisadane river have been lightly to heavily polluted, so that the water cannot be used as a raw source of drinking water without going through treatment first.
Keyword: Pollution index, seasons, tides, water quality

Judul: Water Quality Fluctuations in the Lower Cisadane River, Tangerang Regency, Banten
Abstrak: Sungai Cisadane merupakan sungai yang bersumber dari Gunung Salak dan Gunung Gede Pangrango, Kabupaten Bogor dan bermuara di Tanjung Burung, Kabupaten Tangerang. Hilir Sungai Cisadane yang dekat dengan kawasan Pantai Indah Kapuk 2 (PIK 2) menjadikannya sebagai sumber masukan air bersih bagi kawasan PIK 2. Penelitian ini bertujuan menganalisis keterkaitan pasang surut atau tinggi muka air terhadap fluktuasi beberapa parameter kualitas air di bagian hilir Sungai Cisadane. Data yang digunakan merupakan data hasil pemantauan 3 x 24 jam setiap bulan, periode tahun 2020. Pengamatan dilakukan pada satu titik dengan pengukuran in situ pada permukaan dan kolom perairan (vertikal). Keterkaitan data kualitas air berupa salinitas, DHL, TDS, suhu, DO, pH dan data pasang surut dianalisis menggunakan analisis deskriptif dan analisis regresi linier sederhana. Berdasarkan hasil analisis, pasang surut pada musim kemarau memberikan pengaruh yang signifikan pada semua parameter yaitu salinitas, DHL, TDS, suhu, DO, dan pH. Selain itu, air dari Sungai Cisadane bagian hilir yang akan digunakan sebagai sumber air bersih dan air minum di kawasan Pantai Indah Kapuk (PIK 2) tidak memenuhi baku mutu air sungai kelas 1 berdasarkan PPRI No. 22 tahun 2022. Oleh karena itu, air tersebut perlu pengelolaan lebih lanjut., Cisadane River originates from Mount Salak and Mount Gede Pangrango in Bogor Regency and ends in Tanjung Burung in Tangerang Regency. The downstream of the Cisadane River, which is close to the Pantai Indah Kapuk 2 (PIK 2) area, makes it a source of clean water input for the PIK 2 area. This study aims to analyze the relationship between tides or water levels to fluctuations in several water quality parameters in the downstream of the Cisadane River. The data used were the results of 3 x 24 hours from monthly monitoring in 2020. Observations were conducted at one site with in situ measurements on the surface and water column (vertical). The relationship between water quality data (salinity, DHL, TDS, temperature, DO, pH) and tidal data was analyzed using descriptive and simple linear regression analyses. Based on the results, tides in the dry season have a significant influence on all parameters, salinity, DHL, TDS, temperature, DO, and pH. Furthermore, water from the Cisadane River downstream, which will be used as source of clean water and drinking water in the PIK 2 residential area, does not meet the river water quality standards of class I based on PPRI No. 22 of 2021. Therefore, the water requires further management.
Keyword: Cisadane River, seasons, tides, water quality

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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