Judul: Evaluasi kadar ambien logam berat Cu dan Zn dalam tanah berbahan induk batuan volkanik/plutinik dan batuan sedimen
Abstrak: Hingga saat ini, kriteria baku kerusakan tanah akibat pencemaran logam berat belum diatur di Indonesia. Hal ini antara lain disebabkan oleh keterbatasan data kadar ambien (background concentration) logam-logam berat pada berbagai jenis tanah di Indonesia. Penelitian ini dilakukan dengan tujuan menginventarisasi dan mengevaluasi kadar ambien fogam berat Cu dan Zn serta interaksinya dengan sifat kimia, fisik dan mineralogi tanah yang berkembang dari batuan andesitik/ basaltik, granitik serta sedimen batuliat, batupasir dan tuf volkan intermedier. Contoh tanah diambil secara komposit pada kedalaman 0-30 dan 30-60 cm di sekitar Jawa barat, Banten dan Lampung yang mewakili kelima tipe batuan bahan induk. Analisis tanah dilakukan terhadap pH (H₂O dan KCI 1:1), C-organik, kation basa-basa, KTK, tekstur, kadar total Cu dan Zn (Aqua Regia: HNO3 dan HCI 1:3; AAS), kadar fraksi Cu dan Zn mudah tersedia (NH₄OAc EDTA pH 4.65; AAS), serta analisis mineral fraksi pasir dan liat. Kadar total dan fraksi mudah tersedia kation logam berat dalam tanah dipengaruhi faktor geogenik maupun antropogenik yang ditunjukkan oleh penggunaan lahan, sifat kimia dan mineralogi tanah, terutama pH dan kadar C-organik serta jenis dan kadar mineral. Kadar Cu total pada kedalaman 0-30 cm pada tanah dari sedimen batuliat > batupasir tuf volkan intermedier > andesitik/basaltik granitik, sedangkan pada kedalaman 30-60 cm dari batuliat > tuf volkan intermedier > andesitik/basaltik > granitik > batupasir. Kadar Cu total dalam tanah dari batuan andesitik/basaltik, granitik, batuliat dan tuf volkan intermedier pada kedalaman 0-30 dan 30-60 cm relatif sama, sedangkan pada tanah dari sedimen batupasir lebih tinggi pada kedalaman 0-30 cm. ...
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Judul: Evaluasi Kadar Ambien Logam Berat Nikel (Ni) dau Timbal (Pb) dalam Tauah sebagai Dasar Penyempurnaau Kriteria Baku Mutu Tauah di Indonesia
Abstrak: "Peraturan Pemerintah" No. 150 in Years 2000 about Soil Degradation Control for Biomass Production does not include the criteria of soil degradation caused by heavy metals contamination. It was probably due to the lack of data of heavy metals background concentration in Indonesian soils. Such criteria are already available and used in some developed countries, but they could not be directly adopted in Indonesia, since Indonesian soils have different type of parent material and processes. The aim of this research is to measure and evaluate Ni and Pb metal ambient content in soils of different parent materials including soils derived ii-om andesiticroasaltic igneous rock, clay and sand sediments, and volcanic tuff in Indonesia. The total and the bioavailable fraction contents of Ni and Pb in some soil samples of 0-30 cm and 30-60 cm depth from West Java, Banten and Lampung have been measured as well as the composition of clay minerals and sand fraction minerals, texture, pH, organic matter content, bases and CEC. The result showed that the highest Ni total content was found in the soils from andesitic/basaltic igneous rock, mean while the highest Pb total content found in the soils from granitic igneous rock. The range of total Ni in the soils from andesitic/basaltic igneous rock at 0-30 cm and 30-60 cm depth are 14.95-30.48 mg/kg and 17.01-32.49 mg/kg, and the range of Pb in these soils are 32.66-34.44 mg/kg and 31.42-37.96 mg/kg. The range of total Ni in the soils from granitic igneons rock are 0.90-10.06 mg/kg and 0.91-11.09 mg/kg, and the range of total Pb in these soils are 57.39-62.86 mg/kg and 67.60-76.66 mg/kg. The highest Ni available content was found in the soils from sand sediment and the highest Pb available content found in the soils from granitic igneous rock. The range of available Ni in the soils from granitic igneous rock at 0-30 em and 30-60 cm depth are 0.08-1.07 mg/kg and 0.05-0.69 mg/kg, and the range of available Pb in these soils are 6.81-14.60 mg/kg and 9.70-14.05 mg/kg. The range of available Ni in the soils from sand sediment are 1.38 mg/kg and 2.18 mg/kg, and the range of available Pb in these soils are 3.16 mg/kg and 3.4 7 mg/kg. In general, total contents of Ni and Pb in the soils did not reflect high Ni and Pb available content, since the availability was influenced by soil properties such as CEC, organic matter content, pH, clay content and clay mineral type. However, specific correlation of Ni and Pb available contents in soil from each the parent material type with these soil properties could not be traced yet.
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Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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