KARAKTERISASI DAN KOMPOSISI BIODIESEL DARI MINYAK JARAK PAGAR (jatropha curcas L.)

Biodiesel was the process of esterification and transesterification of jatropha oil has a yield of 50% of dry jatropha seeds. Physicochemical characteristics of biodieselfrom jatropha curcas L.), among others, specific gravity (0.89 g/L), acid number (0.549 mg KOH/g), iod number (65.79 gI2/100g), and hydroxy numbers entered into theIndonesian Biodiesel Quality Standards, except for viscosity (9,7 cSt). Characteristics of Fourier Transformation Infrared spectra showed that the absence of the intensity of the OH group show has been a process of methylation of castor oil fatty acids. The composition of fatty acid methyl esters of biodiesel was dominated by the acid that has a double chain of oleic and linoleic acid. These compounds were dominated by oleic acid (39.33%), linoleic (27%), palmitic acid (11.14%) and stearic acid (5.11%)

Authigenic minerals reflect microbial control on pore waters in a ferruginous analogue

Ferruginous conditions prevailed in the oceans through much of Earth's history. However, minerals recording these conditions remain difficult to interpret in terms of biogeochemical processes prior to lithification. In Lake Towuti, Indonesia, ferruginous sediments are deposited under anoxic sulfate-poor conditions similar to the Proterozoic oceans, allowing the study of mineralogical (trans)formations during microbial diagenesis. Comprehensive pore water geochemistry, high resolution geochemical core profiles, and electron microscopy of authigenic minerals revealed in situ formation of magnetite, millerite, and abundant siderite and vivianite along a 100 m long sequence. Framboidal magnetites represent primary pelagic precipitates, whereas millerite, a sulfide mineral often overlooked under sulfate-poor conditions, shows acicular aggregates entangled with siderite and vivianite resulting from saturated pore waters and continuous growth during burial. These phases act as biosignatures of microbial iron and sulfate reduction, fermentation and methanogenesis, processes clearly traceable in pore water profiles. Variability in metal and organic substrates attests to environment driven processes, differentially sustaining microbial processes along the stratigraphy. Geochemical profiles resulting from microbial activity over 200 kyr after deposition provide constraints on the depth and age of mineral formation within ferruginous records

KARAKTERISASI DAN KOMPOSISI BIODIESEL DARI MINYAK JARAK PAGAR (jatropha curcas L.)

Biodiesel was the process of esterification and transesterification of jatropha oil has a yield of 50% of dry jatropha seeds. Physicochemical characteristics of biodieselfrom jatropha curcas L.), among others, specific gravity (0.89 g/L), acid number (0.549 mg KOH/g), iod number (65.79 gI2/100g), and hydroxy numbers entered into theIndonesian Biodiesel Quality Standards, except for viscosity (9,7 cSt). Characteristics of Fourier Transformation Infrared spectra showed that the absence of the intensity of the OH group show has been a process of methylation of castor oil fatty acids. The composition of fatty acid methyl esters of biodiesel was dominated by the acid that has a double chain of oleic and linoleic acid. These compounds were dominated by oleic acid (39.33%), linoleic (27%), palmitic acid (11.14%) and stearic acid (5.11%)

KARAKTERISASI DAN KOMPOSISI BIODIESEL DARI MINYAK JARAK PAGAR (jatropha curcas L.)

Biodiesel was the process of esterification and transesterification of jatropha oil has a yield of 50% of dry jatropha seeds. Physicochemical characteristics of biodieselfrom jatropha curcas L.), among others, specific gravity (0.89 g/L), acid number (0.549 mg KOH/g), iod number (65.79 gI2/100g), and hydroxy numbers entered into theIndonesian Biodiesel Quality Standards, except for viscosity (9,7 cSt). Characteristics of Fourier Transformation Infrared spectra showed that the absence of the intensity of the OH group show has been a process of methylation of castor oil fatty acids. The composition of fatty acid methyl esters of biodiesel was dominated by the acid that has a double chain of oleic and linoleic acid. These compounds were dominated by oleic acid (39.33%), linoleic (27%), palmitic acid (11.14%) and stearic acid (5.11%)

An application of Bayesian Belief Networks to assess management scenarios for aquaculture in a complex tropical lake system in Indonesia

A Bayesian Belief Network, validated using past observational data, is applied to conceptualize the ecological response of Lake Maninjau, a tropical lake ecosystem in Indonesia, to tilapia cage farms operating on the lake and to quantify its impacts to assist decision making. The model captures ecosystem services trade-offs between cage farming and native fish loss. It is used to appraise options for lake management related to the minimization of the impacts of the cage farms. The constructed model overcomes difficulties with limited data availability to illustrate the complex physical and biogeochemical interactions contributing to triggering mass fish kills due to upwelling and the loss in the production of native fish related to the operation of cage farming. The model highlights existing information gaps in the research related to the management of the farms in the study area, which is applicable to other tropical lakes in general. Model results suggest that internal phosphorous loading (IPL) should be recognized as one of the primary targets of the deep eutrophic tropical lake restoration efforts. Theoretical and practical contributions of the model and model expansions are discussed. Short- and longer-term actions to contribute to a more sustainable management are recommended and include epilimnion aeration and sediment capping

Economic valuation of ecosystem services trade-offs of tilapia cage culture farm and native capture fisheries in Lake Maninjau, Indonesia

Research on the effects of cage aquaculture on native fish populations has revealed its negative and positive impacts. However, a separate analysis of its ecological and economic effects creates incomplete information for the decision-makers. Moreover, the inadequacy of time series data has caused challenges to knowledge-based decision-making in establishing new cage aquaculture sites, especially in low-middle income countries. We use the ecosystem services (ES) framework to analyse the synergy and trade-off of cage aquaculture to a native fish species, Gobiopterus sp. in Lake Maninjau, Indonesia, as an effort to provide comprehensive information to support local decision-makers and to fill the information gap. We engaged some modelling techniques such as the Maximum Entropy Model (MaxEnt) validated with field survey data, Bayesian Networks (BN), and Monte Carlo Simulation (MCS) in this research. The results show that cage aquaculture provides habitat services for the species and temporary forgone fish production due to the accelerated sulfur upwelling. The economic value of habitat provision reached 74,500 IDR per year per cage or 1,128 million IDR per year in 2017. Further, the average value of the forgone benefit of fish production in the current cage aquaculture business extends from more than 550 million IDR per year in the dry season to almost 600 million IDR per year in the rainy season. The results indicate that the negative impacts of cage aquaculture on the native fish population outweigh its benefit. The recommendation for management actions includes applying alternative aquaculture techniques and other technological interventions.</p

KONDISI KUALITAS AIR PADA DAERAH PEMELIHARAAN IKAN KERAMBA JARING APUNG DI DANAU MANINJAU

Danau Maninjau di Sumatera Barat adalah danau dengan tingkat pemanfaatan sangat tinggi di wilayah daratan maupun perairannya. Di daerah perairan pemeliharaan ikan di keramba jaring apung (KJA) merupakan salah satu kegiatan utamanya. Bahwa kegiatan tersebut telah menyebabkan pertambahan jumlah keramba jaring apung yang signifikan sehingga menyebabkan penurunan kualitas air dan kematian massal ikan yang dipelihara di keramba jaring apung. Pemantauan kualitas air dilakukan pada level permukaaan di perairan Sungai Batang, Sungai Tampang, Maninjau, Intake PLTA pada bulan November 2013 dan September 2015. Hasil riset menunjukan bahwa jumlah KJA pada tahun 2013 adalah 16.120 petak dengan parameter kualitas air adalah kecerahan rata-rata 1,75±0,15 m, total N 1,25±0,48 mg/L, total P 0,47±0,12 mg/L, Ortofospat 0,30±0,04 mg/L, nitrat 1,26±0,3 mg/L dan khlorophyl 1320 mg/m3. Pada bulan September 2015 jumlah KJA sebanyak 21.651 petak dengan kecerahan air rata-rata 1,50±0,26 m, total N 1,71±0,62 mg/L, total P 0,51±0.17mg/L, Ortofospat 0,20±0,05 mg/L, nitrat 1,36 ± 0,8 mg/L dan khlorophyl 1364,1 mg/m3. Rasio kadar TP dan TN pada permukaaan Danau Maninjau bulan November 2013 dan September 2015 masing-masing adalah 4,47 dan 3,51.Berdasarkan kadar TN, TP, khlorophyl dan kecerahan perairan, maka Danau Maninjau berdasarkan indeks status trofik (Carlson’s,1977) tergolong eutrofik berat. Kata Kunci : Danau Maninjau, keramba jaring apung, kualitas air, status trofik

Biogeochemistry of manganese in ferruginous Lake Matano, Indonesia

This study explores Mn biogeochemistry in a stratified, ferruginous lake, a modern analogue to ferruginous oceans. Intense Mn cycling occurs in the chemocline where Mn is recycled at least 15 times before sedimentation. The product of biologically catalyzed Mn oxidation in Lake Matano is birnessite. Although there is evidence for abiotic Mn reduction with Fe(II), Mn reduction likely occurs through a variety of pathways. The flux of Fe(II) is insufficient to balance the reduction of Mn at 125 m depth in the water column, and Mn reduction could be a significant contributor to CH&lt;sub&gt;4&lt;/sub&gt; oxidation. By combining results from synchrotron-based X-ray fluorescence and X-ray spectroscopy, extractions of sinking particles, and reaction transport modeling, we find the kinetics of Mn reduction in the lake's reducing waters are sufficiently rapid to preclude the deposition of Mn oxides from the water column to the sediments underlying ferruginous water. This has strong implications for the interpretation of the sedimentary Mn record

Sulfate was a trace constituent of Archean seawater

In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water column of Lake Matano, Indonesia, a low-sulfate analog for the Archean ocean, we find large (>20 per mil) sulfur isotope fractionations between sulfate and sulfide, but the underlying sediment sulfides preserve a muted range of δ^(34)S values. Using models informed by sulfur cycling in Lake Matano, we infer Archean seawater sulfate concentrations of less than 2.5 micromolar. At these low concentrations, marine sulfate residence times were likely 10^3 to 10^4 years, and sulfate scarcity would have shaped early global biogeochemical cycles, possibly restricting biological productivity in Archean oceans