Judul: Daya Tampung Beban Nitrogen di Waduk Jatigede, Jawa Barat
Abstrak: Waduk Jatigede terletak dekat dengan daerah pemukiman dan kegiatan pertanian, sehingga berpotensi menerima buangan limbah. Limbah tersebut dapat mengandung bahan pencemar seperti nitrogen. Peningkatan kadar nitrogen yang tidak terkontrol dalam perairan dapat memberikan dampak buruk, seperti menurunnya kualitas air dan memicu terjadinya eutrofikasi. Penelitian ini bertujuan menganalisis daya tampung beban nitrogen di Waduk Jatigede, Jawa Barat. Pengambilan contoh air dilakukan pada bulan Februari hingga April 2021 di perairan Waduk Jatigede pada enam stasiun pengamatan dan dua sungai utama inlet Waduk Jatigede. Analisis data yang digunakan meliputi penentuan beban nitrogen dari sungai (inlet), pendugaan beban nitrogen dalam waduk, sedimentasi nitrogen, daya tampung beban nitrogen, dan uji perbedaan konsentrasi nitrogen total pada lapisan epilimnion dan hipolimnion. Beban nitrogen di Waduk Jatigede selama pengamatan adalah 24.374 ton. Hal ini menunjukkan bahwa beban nitrogen tersebut telah melebihi batas maksimum menurut baku mutu perairan sebesar 1.739 ton. Kesimpulan dari penelitian ini adalah Waduk Jatigede sudah tidak mampu lagi menampung beban nitrogen yang masuk ke dalam waduk. Namun, daya tampung beban nitrogen masih dapat diestimasi berdasarkan nilai baku mutu perairan. Daya tampung beban nitrogen maksimal sesuai dengan baku mutu perairan di Waduk Jatigede adalah 595 ton/tahun., Jatigede Reservoir is situated close to residential areas and agricultural activities, making Jatigede Reservoir has the potential to receive waste disposal. The waste may contain pollutants, one of which is nitrogen. Uncontrolled increases in nitrogen levels can cause negative impacts, such as water quality deterioration which may lead to eutrophication. The purpose of this study is to analyze the nitrogen load capacity in Jatigede Reservoir, West Java. Water samples were taken from February to April 2021 at six sampling points in the reservoir and two locations in the main inlet rivers. Data analysis consisted of nitrogen load from the river (inlet), nitrogen load in the reservoir, nitrogen sedimentation, nitrogen load capacity, and the test of difference in total nitrogen concentration at the epilimnion and hypolimnion layers. The nitrogen load in Jatigede Reservoir during the observation was 24,374 tons. It shows that the nitrogen load has exceeded the maximum limit according to the water quality standard, which is 1,739 tons. In conclusion, Jatigede Reservoir is no longer able to accommodate the nitrogen load to enter the reservoir. However, the nitrogen load capacity can still be estimated based on water quality standards. Based on water quality standards, the maximum nitrogen load capacity of Jatigede Reservoir was 595 tons N per year.
Keyword: nitrogen load, nitrogen load capacity, Jatigede Reservoir

Judul: Spatial Distribution of Nitrogen in the Waters of Jatigede Reservoir, Sumedang, West Java
Abstrak: Materi yang masuk ke dalam perairan dapat berupa bahan organik dan anorganik yang bermuatan nitrogen. Sumber masukan nitrogen yang beragam dapat memengaruhi pola penyebaran nitrogen di Waduk. Penelitian ini bertujuan untuk menganalisis distribusi nitrogen secara spasial di perairan Waduk Jatigede, Sumedang, Jawa Barat. Penelitian dilaksanakan pada bulan Februari-April 2021. Analisis data yang digunakan berupa uji signifikansi antara lapisan dan antarawaktu, penentuan musim, kesamaan karakteristik stasiun berdasarkan kualitas air, pemetaan sebaran spasial nitrogen, dan analisis korelasi nitrogen dengan parameter kualitas air. Waduk Jatigede terdiri dari tiga zona, yaitu Zona Riverin, transisi, dan lakustrin. Konsentrasi nitrat, nitrit, dan nitrogen total tinggi di Zona Riverin pada lapisan epilimnion dan di Zona Transisi pada lapisan hipolimnion. Konsentrasi amonia tertinggi di Zona Lakustrin pada lapisan epilimnion dan hipolimnion. Terdapat hubungan antaraa nitrogen dengan parameter kualitas air seperti COD, kekeruhan, TSS, dan DO. Konsentrasi tertinggi nitrogen terjadi pada lapisan hipolimnion. Nitrogen tersebar dengan konsentrasi bervariasi secara vertikal dan cenderung seragam secara horizontal. Nitrogen memiliki tingkat konsentrasi dengan kecenderungan lebih tinggi di Zona Riverin secara horizontal dan di lapisan hipolimnion secara vertikal. Secara spasial, tingkat konsentrasi nitrogen dipengaruhi oleh COD, kekeruhan, TSS, dan DO di perairan., Materials enter waters can be form of organic and inorganic containing nitrogen. Various sources of nitrogen input which can affect nitrogen distribution pattern. This study aims to analyze the nitrogen spatial distribution in Jatigede Reservoir, Sumedang, West Java. Research carried out in February-April 2021. Analysis of data used are test of significance between layers and over time, season determination, similarity of station characteristics based on water quality, mapping of nitrogen spatial distribution, and nitrogen correlation analysis with water quality parameters. Jatigede Reservoir consists of three zones, namely riverine, transition, and lacustrine zones. Concentrations of nitrate, nitrite, and total nitrogen were high in riverine in epilimnion and in transition in hypolimnion. The highest amonia concentration was in lacustrine in epilimnion and hypolimnion. There is relationship between nitrogen and water quality parameters such as COD, turbidity, TSS, and DO. The highest nitrogen concentration occurs in hypolimnion. Nitrogen is dispered with varying concentrations vertically and tends to be uniform horizontally. Nitrogen has a concentration tend to be higher in riverine horizontally and in hypolymnion vertically. Spatially, nitrogen concentration is influenced by COD, turbidity, TSS, and DO in waters.
Keyword: distribution, Jatigede Reservoir, nitrogen

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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