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: The Dynamics of Water Quality and Pollution Levels at the Planned Raw Water Intake in the Lower Cisadane River
Abstrak: Sungai Cisadane dimanfaatkan untuk industri, irigasi, dan kebutuhan sehari- hari oleh masyarakat sekitar. Berbagai aktivitas manusia dapat mempengaruhi kualitas air sungai. Penelitian ini bertujuan menganalisis pengaruh musim dan pasang surut terhadap dinamika kualitas air serta mengevaluasi tingkat pencemaran Sungai Cisadane. Pemantauan kualitas air dilakukan pada tahun 2017-2019 di Sungai Cisadane di sekitar rencana intake air baku. Kualitas air yang diamati adalah suhu, kekeruhan, TSS, salinitas, pH, DO, BOD5, COD, NH3, NO3, NO2, ortofosfat, fosfat total, H2S, Fe, Zn, As, Pb, Cd, Cu, Hg, Se, Cr6+, Mn, CN, detergen, dan total coliform. Dinamika kualitas air dianalisis secara deskriptif; dan tingkat pencemaran ditentukan dengan Indeks Pencemaran (IP) berdasarkan Keputusan Menteri Lingkungan Hidup No. 115 Tahun 2003. Berdasarkan hasil analisis, musim dan pasang surut sangat mempengaruhi kualitas air kecuali pH, Se, dan Cr6+. Suhu, salinitas, BOD5, COD, NH3, ortofosfat, fosfat total, Fe, Zn, Mn, dan total coliform cenderung lebih tinggi saat musim kemarau. Tingkat pencemaran Sungai Cisadane berdasarkan perhitungan IP adalah tercemar ringan sampai sedang pada tahun 2017-2019, kecuali tahun 2018 saat musim kemarau, yaitu tercemar berat.
Keyword: indeks pencemaran, kualitas air, musim, pasang surut, sungai Cisadane

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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