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%)

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%)

Mixing and its effects on biogeochemistry in the persistently stratified, deep, tropical Lake Matano, Indonesia

This is the publisher's version, also available electronically from http://www.aslo.orgIn the > 590-m deep, tropical Lake Matano (Indonesia), stratification is characterized by weak thermal gradients (< 2°C per 500 m) and weak salinity gradients (< 0.14% per 500 m). These gradients persist over seasons, decades, and possibly centuries. Under these nearly steady-state conditions, vertical eddy diffusion coefficients (Kz) cannot be estimated by conventional methods that rely on time derivatives of temperature distributions. We use and compare several alternative methods: one-dimensional k-ε modeling, three-dimensional hydrodynamic modeling, correlation with the size of Thorpe instabilities, and correlation with the stability frequency. In the thermocline region, at 100-m depth, the Kz is ~ 5 × 10-6 m2 s-1, but, below 300 m, the small density gradient results in large (20 m) vertical eddies and high mixing rates (Kz ~ 10-2 m2 s-1). The estimated timescale of water renewal in the monimolimnion is several hundred years. Intense evaporation depletes the surface mixed layer of 16O and 1H isotopes, making it isotopically heavier. The lake waters become progressively isotopically lighter with depth, and the isotopic composition in the deep waters is close to those of the ground and tributary waters. The vertical distribution of Kz is used in a biogeochemical reaction-transport model. We show that, outside of a narrow thermocline region, the vertical distributions of dissolved oxygen, iron, methane, and phosphorus are shaped by vertical variations in transport rates, rather than by sources or sinks

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

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

Formation of diagenetic siderite in modern ferruginous sediments

Ferruginous conditions prevailed in the world’s deep oceans during the Archean and Proterozoic Eons. Sedimentary iron formations deposited at that time may provide an important record of environmental conditions, yet linking the chemistry and mineralogy of these sedimentary rocks to depositional conditions remains a challenge due to a dearth of information about the processes by which minerals form in analogous modern environments. We identified siderites in ferruginous Lake Towuti, Indonesia, which we characterized using high-resolution microscopic and spectroscopic imaging combined with microchemical and geochemical analyses. We infer early diagenetic growth of siderite crystals as a response to sedimentary organic carbon degradation and the accumulation of dissolved inorganic carbon in pore waters. We suggest that siderite formation proceeds through syntaxial growth on preexisting siderite crystals, or possibly through aging of precursor carbonate green rust. Crystal growth ultimately leads to spar-sized (>50 μm) mosaic single siderite crystals that form twins, bundles, and spheroidal aggregates during burial. Early-formed carbonate was detectable through microchemical zonation and the possible presence of residual phases trapped in siderite interstices. This suggests that such microchemical zonation and mineral inclusions may be used to infer siderite growth histories in ancient sedimentary rocks including sedimentary iron formations

The Towuti Drilling Project:paleoenvironments, biological evolution, and geomicrobiology of a tropical Pacific lake

The Towuti Drilling Project (TDP) is an international research program, whose goal is to understand long-term environmental and climatic change in the tropical western Pacific, the impacts of geological and environmental changes on the biological evolution of aquatic taxa, and the geomicrobiology and biogeochemistry of metal-rich, ultramafic-hosted lake sediments through the scientific drilling of Lake Towuti, southern Sulawesi, Indonesia. Lake Towuti is a large tectonic lake at the downstream end of the Malili lake system, a chain of five highly biodiverse lakes that are among the oldest lakes in Southeast Asia. In 2015 we carried out a scientific drilling program on Lake Towuti using the International Continental Scientific Drilling Program (ICDP) Deep Lakes Drilling System (DLDS). We recovered a total of  ∼ 1018 m of core from 11 drilling sites with water depths ranging from 156 to 200 m. Recovery averaged 91.7 %, and the maximum drilling depth was 175 m below the lake floor, penetrating the entire sedimentary infill of the basin. Initial data from core and borehole logging indicate that these cores record the evolution of a highly dynamic tectonic and limnological system, with clear indications of orbital-scale climate variability during the mid- to late Pleistocene