Judul: Persebaran Fosfor Secara Spasial Di Perairan Waduk Jatigede, Kabupaten Sumedang, Jawa Barat
Abstrak: Akumulasi bahan organik yang tinggi ke dalam ekosistem perairan waduk akan meningkatkan ketersediaan nutrien salah satunya fosfor. Penelitian ini bertujuan menganalisis persebaran fosfor secara spasial dan faktor-faktor yang mempengaruhi keberadaan fosfor di Waduk Jatigede. Pengambilan contoh dilakukan pada bulan Februari hingga April 2021 pada enam stasiun pengamatan. Analisis data terdiri atas sebaran spasial horizontal dengan ArcMap 10.5, sebaran vertikal dengan Ocean Data View, analisis klaster, analisis komponen utama dan korelasi Pearson dengan perangkat lunak R Studio. Zona Waduk Jatigede terdiri dari Zona Riverine, Zona Transisi, dan Zona Lakustrin. Konsentrasi fosfor total berkisar antara 0,075˗0,130 mg L-1, sedangkan ortofosfat berkisar antara 0,004˗0,023 mg L-1. Sebaran fosfor total dan ortofosfat di lapisan epilimnion memiliki sebaran yang tertinggi di Zona Riverine. Sebaran fosfor total di lapisan hipolimnion dan sedimen memiliki sebaran yang tertinggi di Zona Lakustrin. Fosfor tersebar dengan merata, baik secara horizontal maupun vertikal dengan kecenderungan lebih tinggi di Zona Riverine dan lapisan epilimnion. Sebaran fosfor dipengaruhi parameter fisika dan kimia perairan yang terdiri atas parameter suhu, kekeruhan, pH, dan oksigen terlarut., The accumulation of high organic matter into the reservoir water ecosystem will increase the availability of nutrients, one of which is phosphorus. This study aims to analyze the spatial distribution of phosphorus and the factors that influence the presence of phosphorus in the Jatigede Reservoir. Sampling was carried out from February to April 2021 at six observation stations. Data analysis consisted of horizontal spatial distribution using ArcMap 10.5, vertical distribution using Ocean Data View, cluster analysis, principal component analysis and Pearson correlation with R Studio software. The Jatigede Reservoir Zone consists of the Riverine Zone, Transition Zone, and Lacustrin Zone. The total phosphorus concentration ranged from 0.075˗0.130 mg L-1, while orthophosphate ranged from 0.004˗0.023 mg L-1. The distribution of total phosphorus and orthophosphate in the epilimnion layer has the highest distribution in the Riverine Zone. The distribution of total phosphorus in the hypolimnion and sediment layers has the highest distribution in the Lacustrin Zone. Phosphorus is evenly distributed, both horizontally and vertically with the tendency to be higher in the Riverine Zone and the epilimnion layer. The distribution of phosphorus is influenced by physical and chemical parameters of the waters which consist of parameters of temperature, turbidity, pH, and dissolved oxygen
Keyword: fosfor, sebaran spasial, Waduk Jatigede, Zona Riverine

Judul: Daya Tampung Beban Fosfor di Perairan Waduk Jatigede, Kabupaten Sumedang, Jawa Barat
Abstrak: Kegiatan pertanian dan pemukiman yang berada di sekitar waduk dapat menjadi sumber masukan fosfor, sehingga akan memengaruhi kualitas air waduk. Penelitian ini bertujuan menghitung daya tampung beban nutrien fosfor (P) berdasarkan lapisan kedalaman di perairan Waduk Jatigede. Pengambilan contoh air dilakukan setiap bulan dari bulan Februari hingga April 2021 pada inlet Waduk Jatigede dan perairan Waduk Jatigede. Seluruh stasiun pengamatan di perairan waduk terbagi menjadi lapisan epilimnion dan hipolimnion. Konsentrasi fosfor (total dan terlarut) tertinggi pada zona riverin di lapisan epilimnion. Terdapat 11 sungai yang masuk ke Waduk Jatigede, namun masukan beban fosfor yang utama adalah dari Sungai Cimanuk dan Sungai Cinambo. Daya tampung beban fosfor berdasarkan lapisan kedalaman di perairan Waduk Jatigede adalah 3285 kg tahun-1 untuk lapisan epilimnion dan 1593 kg tahun-1 untuk lapisan hipolimnion. Daya tampung beban fosfor untuk seluruh volume waduk adalah 4878 kg tahun-1., Agricultural and residential activities around the reservoir can be a source of phosphorus input, which will affect the water quality of the reservoir. This study aims to calculate the load capacity of phosphorus (P) based on the stratification of water in Jatigede Reservoir. Water samples were taken every month from February to April 2021 at rivers inlet and Jatigede Reservoir. All observation stations in the reservoir are divided into epilimnion and hypolimnion layers. The concentration of phosphorus (total and dissolved) were highest in the riverine zone at the epilimnion layer. There are 11 rivers that enter the Jatigede Reservoir, but the main phosphorus load input is from the Cimanuk River and Cinambo River. The load capacity of phosphorus in the Jatigede Reservoir are about 3285 kg year-1 for epilimnion layer and 1593 kg year-1 for hypolimnion layer. The load capacity of phosphorus for the entire volume of the reservoir is about 4878 kg year-1.
Keyword: Beban Fosfor, Lapisan Perairan, Waduk Jatigede

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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