Judul: Deteksi penguraian herbisida glifosat oleh bakteri tanah
Abstrak: Glifosat (N-(phosphonomethyl) glycine) merupakan herbisida berspektrum luas, post-emergence, dan nonselektif. Glifosat di tanah secara kuat diikat oleh partikel tanah dan sebagian akan mengalar penguraian secara kimia dan hayati. Penelitian ini bertujuan mendapatkan isolat-isolat bakteri tanah yang diharapkan mampu menguraikan glifosat, diawali dengan isolasi bakteri dan penapisannya serta mengamati hasil penguraian glifosat oleh isolat bakteri terpilih menggunakan metode Kromatografi Lapis Tipis. Sampel tanah diambil dari Sukabumi dan Biotrop, Bogor yang gulmanya telah disemprot 1445 g monoamonium glifosat dalam 404 liter larutan per hektar tanah (larutan tersebut mengandung glifosat 2,67 mg/ml). Penapisan isolat dilakukan dengan konsentrasi glifosat bertingkat, yaitu 10,16 mg/ml, 20,32 mg/ml, dan 40,64 mg/ml. Tiga dari 19 isolat bakteri yang diperoleh toleran terhadap ketiga konsentrasi glifosat tersebut, dua isolat bakteri diantaranya diidentifikasi sebagai Leuconostoc sp. galur S30.1 dan Pseudomonas pseudoflava B25.1. Hasil Kromatografi Lapis Tipis menunjukkan bahwa kedua isolat bakteri terpilih dan Pseudomonas aeruginosa, sebagai kontrol positif, yang ditumbuhkan dalam kaldu nutrien mengandung glifosat 0,71 mg/ml dengan masa inkubasi enam hari tidak terdapat hasil penguraian glifosat. Hasil yang sama ditunjukkan juga pada P. pseudoflava B25.1 yang ditumbuhkan pada media yang sama dengan masa inkubasi 23 hari.
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Judul: Seleksi Bakteri Resisten Herbisida Glifosat
Abstrak: Dalam penelitian ini bakteri diisolasi dari tanah Sukabumi dan Bogor yang telah disemprot glifosat 1-1-15 gram dalam 404 liter larutan per hektar tanah (3.577 mglml) menggunakan media NA. Kemudian penapisan isolat dilakukan pada media Davis termodifikasi (MDT) dengan konsentrasi glifosat bertingkat (1,2,4, dan8 kali konsentrasi lapang) berdasarkan pertumbuhan koloninya. lsolatisolat tersebut diuji kemampuannya dalam menggunakan K,HPO.j dan KH,PO'j (fosfat anorganik) dan glifosat (fosfat organik). lsolat yang terpilih diidentifikasi dan diukur kandungan fosfat anorganiknya bcrdasarkan metode Ames selama 7 hari. Pseudomonas aeruginosa digunakan sebagai bakteri pembanding.
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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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