Judul: Penerapan Bakteri sebagai Agen Bioremediasi dalam Mereduksi Limbah Organik Danau Ebony, Pantai Indah Kapuk, Jakarta Utara
Abstrak: Danau Ebony yang menerapkan polder system sebagai penampung air diindikasikan banyak menerima bahan organik yang dapat menyebabkan tingginya beban bahan organik perairan danau. Masuknya limbah organik ke perairan dalam jumlah berlebih akan menyebabkan meningkatnya beban nutrient ke perairan. Selain itu, juga akan memicu pertumbuhan mikroalga secara cepat yang dapat mengganggu keseimbangan ekosistem perairan. Bakteri dapat digunakan sebagai agen bioremediasi limbah organik Danau Ebony. Hasil penelitian menunjukkan bahwa penerapan bakteri tipe VannaPro dan Super PS mampu mereduksi limbah organik. Waktu efektif bakteri dalam mereduksi limbah organik adalah pada 6 hari pertama. Perlakuan yang paling efektif dalam mereduksi limbah organik adalah VannaPro. Perlakuan tersebut mampu menurunkan nilai COD mencapai 88,71% pada hari ke-6 dan meningkatkan jumlah koloni bakteri hingga 51,6 x 105 cfu/mL. Dosis bakteri yang efektif dalam mereduksi limbah organik Danau Ebony adalah VannaPro dua kali dosis anjuran.
Keyword: bakteri, bioremediasi, limbah organik

Judul: Laju Peluruhan Bahan Organik di Air Danau Ebony, Pantai Indah Kapuk, Jakarta Utara
Abstrak: Danau Ebony merupakan perairan buatan yang dimaksudkan sebagai danau hias di Cluster Ebony. Perairan yang dikelilingi oleh pemukiman berpotensi mengalami peningkatan bahan organik akibat aktivitas domestik. Kajian peluruhan bahan organik diperlukan karena terkait dengan kemampuan Danau Ebony dalam menampung bahan organik. Penelitian ini bertujuan untuk menganalisis proses peluruhan bahan organik di perairan Danau Ebony, Pantai Indah Kapuk, Jakarta Utara berdasarkan pada least square methods. Hasil penelitian menunjukkan bahwa laju peluruhan bahan organik pada air lapisan dekat dasar adalah 0,27 per hari; lebih cepat daripada air lapisan permukaan yaitu 0,20 per hari karena kelimpahan bakteri di air lapisan dekat dasar lebih tinggi. Secara umum, laju peluruhan bahan organik di air Danau Ebony termasuk kategori lambat, karena jenis bahan organiknya adalah non-biodegradable. Nilai UBOD pada lapisan dekat dasar yaitu 8,0272 mg/L sedangkan pada air lapisan permukaan adalah 8,0377 mg/L. Konsentrasi amonia, nitrat, nitrit, dan ortofosfat semakin meningkat.
Keyword: bahan organik, danau, dekomposisi, laju peluruhan

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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