Judul: Keterkaitan Revegetasi dengan Karakteristik Sifat Tanah pada Lahan Pascatambang Tembaga di Nusa Tenggara Barat
Abstrak: Sumberdaya mineral dan batu bara di Indonesia sebagian besar terdapat pada lapisan bumi yang dekat permukaan tanah, oleh karena itu penambangannya banyak dilakukan dengan cara terbuka (open pit mine methode). Salah satu perusahaan pertambangan yang masih aktif beroperasi di Indonesia adalah PT Amman Mineral Nusa Tenggara (PT AMNT). PT AMNT mengelola kegiatan penambangan di Batu Hijau, Nusa Tenggara Barat, dengan produk utama berupa konsentrat tembaga yang kemudian menghasilkan produk sampingan berupa emas. Selain memberikan devisa, aktivitas pertambangan dapat memberikan dampak yang merugikan bagi lingkungan antara lain berupa kerusakan lahan. Untuk mengatasi kerusakan lahan bekas tambang perlu dilakukan reklamasi. Reklamasi adalah kegiatan yang dilakukan sepanjang tahapan usaha pertambangan untuk menata, memulihkan, dan memperbaiki kualitas lingkungan dan ekosistem agar dapat berfungsi kembali sesuai peruntukannya. Salah satu bentuk usaha reklamasi adalah revegetasi, yaitu proses pengembalian fungsi tanah setelah penggalian selesai, paling sering dicapai dengan membangun vegetasi. Penelitian ini bertujuan untuk mempelajari karakteristik sifat fisik dan kimia tanah dari lahan pasca reklamasi tambang PT. Amman Mineral Nusa Tenggara dalam periode waktu 8 tahun dan membandingkannya dengan tanah pada hutan alami. Penelitian dilakukan meliputi studi pustaka serta analisis dan interpretasi data. Setelah penanaman vegetasi berhasil dilakukan, proses pembentukan tanah dimulai. Berdasarkan hasil penelitian terjadi pembentukan agregat tanah dengan struktur pori baru. Secara kimia dapat ditunjukkan bahwa proses pelapukan overburden masih dalam tahap awal ditunjukkan oleh antara lain nilai kejenuhan basa berkisar antara 82,59% hingga 93,64%, dan Ca berkisar antara 10,77% hingga 19,26%. Proses tanah penting lain yang terjadi di dalam tanah bekas tambang yang diteliti adalah akumulasi bahan organik. Hal ini berkaitan dengan pengaruh revegetasi yang ditunjukkan oleh peningkatan kadar C-organik dan N total pada lapisan atas walaupun masih lebih rendah dari pada hutan alami., Most of the mineral and coal resources in Indonesia are found in the earth's layers which are near the ground surface, therefore mining activities are mostly done with open pit mine methode. One mining company that is still actively operating in Indonesia is PT Amman Mineral Nusa Tenggara (PT AMNT). PT AMNT manages mining activities in Batu Hijau, West Nusa Tenggara, with the main product in the form of copper concentrate which then produces a by-product in the form of gold. Apart from providing foreign exchange, mining activities can have a disadvantageous impact on the environment, including land damage. To overcome the damage to ex-mining land, it is necessary to do reclamation. Reclamation is an activity carried out throughout the stages of the mining business to organize, restore and improve the quality of the environment and ecosystem so that they can function again according to their designation. One form of reclamation efforts is revegetation The purpose of this research is to learn the soil chemical and physical characteristics from post-mining reclamation land of PT Amman Mineral Nusa Tenggara in 8 years of period and compare it to soil in natural forest. This research was carried out covering literature studies as well as data analysis and interpretation. After successful planting of vegetation, the process of forming ex-mining soil begins to occur. Based on the research results, there was the formation of soil aggregates
Keyword: overburden, post-mining land, reclamation, revegetation, nature forest

Judul: Vegetation and Environmental Characteristics in Land Ecosystems Results from Revegetation on Post-Coal Mining Lands PT. Pesona Khatulistiwa Nusantara
Abstrak: Pertambangan batu bara mengakibatkan hilangnya vegetasi yang berada di atas permukaan tanah, mengubah struktur, dan tekstur tanah. Kegiatan revegetasi dilakukan untuk memulihkan kembali kondisi lingkungan. Penelitian ini bertujuan untuk menganalisis karakteristik vegetasi dan lingkungan pada areal revegetasi lahan pascatambang batu bara. Metode penelitian menggunakan analisis vegetasi dan analisis biofisik lingkungan (edafis dan klimatis). Hasil penelitian menunjukkan bahwa hutan alam (ekosistem referensi) memiliki jenis vegetasi yang lebih banyak. Lahan revegetasi yang diamati hanya didominasi oleh satu jenis saja, yaitu sengon laut (Falcataria moluccana), sehingga nilai indeks keanekaragaman jenis, indeks kekayaan jenis, dan indeks kemerataan jenis hutan alam lebih tinggi daripada lahan revegetasi. Nilai indeks kesamaan tergolong tinggi hanya ditemukan pada lokasi lahan revegetasi umur 10 tahun dan 2 tahun pada tingkat pancang dan tiang. Lahan revegetasi umur 10 tahun memiliki total biomassa dan simpanan karbon lebih tinggi dibandingkan lahan revegetasi umur 2 tahun. Karakteristik kesuburan tanah lahan revegetasi umur 2 tahun memiliki nilai rendah daripada kedua lokasi lainnya, karena memiliki pH masam, C-organik sangat rendah, kapasitas tukar kation (KTK) rendah, dan kejenuhan basa (KB) yang sedang., Coal mining results in the loss of aboveground vegetation, changing the structure and texture of the soil. Revegetation activities are carried out to restore environmental conditions. This study aims to analyze the characteristics of vegetation and the environment in the revegetation area of post-coal mining land. The research method used vegetation analysis and biophysical analysis of the environment (edaphic and climatic). The results showed that natural forest (reference ecosystem) has more vegetation types. The revegetated land is only dominated by sengon laut (Falcataria moluccana), so the value of the species diversity index, species richness, and species evenness of natural forest is higher than the revegetated land. High similarity index values were only found in the second location of revegetated land at the sapling and pole levels. The 10-year-old revegetated land had higher total biomass and carbon storage than the 2-year-old revegetated land. Soil fertility characteristics of 2-year-old revegetated land have low values than the two locations, because they have acidic pH, very low C-organic, low cation exchange capacity (CEC), and medium base saturation.
Keyword: coal, post-mining, revegetation, soil, vegetation

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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