Judul: Kajian dampak reklamasi lahan tambang batubara terhadap komponen fungsi hidrologis dan ekologis DAS serta manfaat bagi masyarakat
Abstrak: This research was conducted at the PT Adaro Indonesia coal mining area in Negara watershed, sub-watershed of Barito, South Kalimantan Province. The aims of the study were: 1) to identify of the methods used for coal mined land reclamation; 2) to analyze the impacts of the reclamation on the hydrological and ecological functions of the watershed; and 3) to analyze the impact of the land reclamation activities on the involvements of and benefits for the communities. This study was carried out using survey method and field measurements in identifying the methods of reclamation. Analyzis of watershed hydrological function showed that reclamation activities significantly increased soil infiltration rate from 0.27 cm/hr to 1.01 cm/hr, decreased runoff coefficient from 49.04% to 13.97% and decreased erosion rate from 130.28 ton/ha to 7.64 ton/ha. Biodiversity analysis showed that there was no significant impact of reclamation activities on biodiversity at the early stage of reclamation trees up to 6 years of its development. However, after the reclamation trees were at the age of 15 years, the biodiversity indexes increased significantly; shurb index increased up to 1,10, seedlings 0.76, saplings 0.85, poles 0.53, and trees 0.23. Carbon sequestration analysis showed that the reclamation activities increased carbon sequestration significantly. At the area where the reclamation trees were at 15 years old the carbon stock reached 103.57 ton/ha, which consist of 95.94 ton/ha at trees, 4.12 ton/ha at undergrowth, and 3.51 ton/ha at the litter. Analysis of the impact of reclamation on social-economic of the local communities showed that the income of labor increased substantially up to Rp 36,000,000 per year, the income that have been greater than the income that can support life worthed living standard (Rp 24,000,000/year). This income was also already greather than income of South Kalimantan GDP (195%) and national GDP (117%). Multiple benefits gained by the local communities during the reclamation activities among others were the opportunities for supplier of food and housing, compost and plant seeds; the post-mining benefits from timber and non timber product of reclamation; as well as benefits from infrastructure/roads and recreation facilities.
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Judul: Quality Analysis of River Water Around and Soil in the Mining Area of PT Berau Coal Binungan Site, East Kalimantan Province
Abstrak: Salah satu hal terpenting dalam aktivitas penambangan batubara dengan sistem tambang terbuka adalah bagaimana melakukan reklamasi lahan dan mengembalikan agar kelestarian lingkungan tetap terjaga. Reklamasi lahan pasca tambang merupakan bagian dari perencanaan dan pelaksanaan kegiatan penambangan untuk memastikan agar upaya perbaikan lahan-lahan yang terganggu oleh kegiatan pertambangan dapat dilaksanakan secara efektif dan efisien dengan mempertimbangkan karakteristik kondisi fisik, kimia, dan biologi tanah. Sampai saat ini reklamasi yang telah dilakukan diduga belum ada yang berpihak pada pembangunan kawasan pasca tambang batubara yang berkelanjutan dengan menganut prinsip memanfaatkan, melindungi dan melestarikan lingkungan. Sementara itu, pelaksanaan reklamasi yang dilakukan sampai saat ini sifatnya sekedar memenuhi tuntutan prosedur yaitu hanya menjadikan reklamasi sebagai bagian dari persyaratan pelaksanaan pertambangan batubara yang kebanyakan belum memadai. Kegiatan reklamasi ini selain ditunjukan untuk memperbaiki sifat-sifat tanah, diharapkan juga akan memperbaiki kualitas air permukaan di sekitar areal reklamasi. Oleh karena itu perlu dilakukan penelitian untuk mengetahui kondisi air dan tanah di sekitar areal daerah tersebut. Dengan penelitian ini, diharapkan menjadi acuan dalam pelaksanaan reklamasi yang berkelanjutan., Coal mining activities without reclamation will lead to environmental degradation such as change of freshwater and soil qualities. Reclamation of post mining land is part of the planning and implementation of mining activities to ensure that repairing of lands affected by mining activities can be conducted effectively and efficiently by improving the post mined soil conditions. This research was aimed to analyze the qualities of river water around and soil in the mining area of PT Berau Coal Binungan Site. Samples of river water were taken as many as 10 locations, whereas soil samples were taken from soils of land after 0, 3, 6, and 9 years of reclamation and forest soil. The results showed that some of the parameters of water such as temperature, pH, DO, Fe, Mn, oils and fats, were below the grade I Quality Standard of Government Regulation No. 82/ 2001. However, COD was above Grade III, while BOD was above grade IV of the Quality Standard. These indicates that all the water sample were not qualified as standart drinking water (grade I). Results of soil analysis indicated that physical, chemical and biological of soil properties varied both due to the increase in reclamation age and the heterogeneous nature of the soil materials. Properties including BD, infiltration, aggregate stability, organic-C, and biological properties were improved with increasing the age of reclamation approaching the properties of forest soil. Other properties including pH, CEC, exchangeable bases, base saturation, available P, available micro elements, and total S were varied due also to the heterogeneous nature of the soil material.
Keyword: Coal mining, Water quality, Soil quality

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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