Ijen Research Articles

Forecasting Model for Tourist Numbers: A Case Study of Tamansari Banyuwangi Tourism Village

Developing a successful tourism village requires effective management, which includes forecasting tourist numbers. This study forecasts the number of visitors to Tamansari Banyuwangi Tourism Village, one of four tourist villages with independent status who had received national and international recognition. The Covid-19 pandemic from early 2020 to the end of 2022 had a considerable effect on tourist traffic around Tamansari Village’s popular destinations, including Kawah Ijen, Sendang Seruni, and Taman Gandung Terakota, as well as the management of Tamansari Tourism Village; specifically, BUMDesa Ijen Lestari. Time series forecasting was performed using the decomposition method and Holt-Winter exponential smoothing based on tourist data from 2016 to September 2023. Based on the smaller RMSE and MAPE values, the Holt- Winter forecasting model is better, with α = 0.05; β = 0.12; and γ = 0.35 as the utilized smoothing parameters. Additionally, the Holt-Winter method suggests an increasing trend for the following year’s forecasting results, with seasonal data being present in the July and December periods. Overall, it delivers more accurate information. The study’s findings can serve as a foundation for BUMDesa Ijen Lestari to create policies for the expansion of Tamansari Tourism Village and its surrounding destinations. Keywords: decomposition, Holt-Winter, Tamansari Banyuwangi tourism village, time series forecasting

Understanding zinc isotopic signatures in volcanic lakes

Magmatic activity can be monitored through the chemical variations of volcanic lakes. While those lakes can be influenced by direct magmatic input, water-rock interaction processes in hydrothermal system also have a large influence. Disentangling those effects is critical to use crater lakes for volcanic activity monitoring purposes. Zinc is a volatile metal that is easily degassed and can be incorporated into fluid circulation. During degassing, Zn isotopes can be fractionated and can thus be a potential tracer of magmatic input. Here we present a novel approach using stable Zn isotopic systems to understand how dissolution/precipitation processes affect isotopic compositions of volcanic lakes and if they can be used as tracers of magmatic activity. We investigate Zn isotopes expressed as δ66Zn for four volcanic lakes ranging from hyperacidic to neutral waters. Two of them, Kawah Ijen (Indonesia) and Santa Ana (El Salvador) volcanic lakes have been sampled from 2010 to 2012 and 2000–2002, respectively, and show a clear magmatic input with extremely low pH [0.1–1]. Taal (Philippines, pH ≈ 3) and Kelud (Indonesia, pH ≈ 6.5) volcanic lakes were sampled from 2017 to 2019 and 2003–2007 respectively, and are dominated by hydrothermal rather than magmatic inputs. Hyper-acidic lakes show minimal isotopic variation over the investigated time ranges, with δ66Zn values similar to their basalt-andesitic host rocks (0.26 ± 0.08 ‰). In contrast, we observe large δ66Zn fractionation for the Taal waters (0.4 ± 0.01 ‰) compared to their basalt-andesitic host rocks but no δ66Zn temporal variations. Kelud waters show significant δ66Zn (−0.08 ± 0.06 ‰ to 0.43 ± 0.06 ‰) temporal variation. This could be related to an evolution of the lake water chemistry as the sampling period occurred between two increases in lake temperature culminating into a lava dome eruption in 2007. For Taal and Kelud volcanic lakes, enrichment factors (EF) and PHREEQc modelling indicate that Zn is depleted and suggest that Zn could precipitate in the hydrothermal system, hence fractionating Zn isotopes during these precipitation processes. This contrasts to Zn elemental and isotope values from Kawah Ijen and Santa Ana with an EF ≈ 1 suggesting that Zn is derived from host rock dissolution, in agreement with their δ66Zn. These data are still limited and a longer observation is needed in the future to highlight significant geochemical changes in volcanic lakes and their relation to volcanic activity.

THE ANTECEDENTS OF ECOTOURISM INTENTION

Many people today need to pay more attention to the environment. In addition, more and more activities are making people unaware of how harmful their actions are to the environment. The aim is to examine the determinants influencing tourists' intentions to visit for ecotourism purposes. This study found a strong correlation between the three important factors determining tourists' interest in ecotourism sites. This is an environmental concern, the future time and eco-destination perspectives picture. This study also reports a strong relationship between eco-destination image, future time perspective, and environmental concern. This research is experimental research conducted in Indonesia. One hundred seventy-five respondents aged 20 to over 50 years were given a questionnaire to fill out to collect data. Purposive sampling was used as the sampling method in this study. The Structural Equation Model (SEM) approach assesses the research hypothesis. According to research, the contribution of time perspective to decision-making about visiting ecotourism sites is beneficial. Environmental concern also influences the intention to engage in ecotourism. It will increase ecological awareness if it has a positive reputation as an eco-friendly destination. If the image of an eco-friendly destination evokes pleasant emotions and attachments, the intention to visit ecotourism increases. Future research is expected to add more variables, such as loyalty. Further research can be carried out on other ecotourism destinations such as Tanjung Putting National Park, Kawah Ijen, Nusa Penida Island, etc.

Risk of low back pain among Indonesian volcano sulfur miners: a retrospective cohort study

Introduction. Kawah Ijen is the main volcano sulfur-producing in Indonesia. There is still a lot of conventional Sulfur mining going on there. Every day, Sulfur miners work walking about 8.5 km to transport Sulfur weighing 70-100 kilograms using simple transporters that are only held on one shoulder to the Sulfur collection site. The health problem that is the focus of this study is the incidence of low back pain (LBP) in volcano sulfur miners. Aims and objectives. This study aims to determine the magnitude of the risk of low back pain in sulfur miners to prevent occupational diseases.. Materials and methods. This research was carried out for three months. This study adopted a retrospective cohort study design. The research sample amounted to 140 respondents taken by simple random sampling. The data collection technique was carried out by interview and lasegue test and Patrick’s test to see the respondents’ positive or negative of low back pain. Data analysis was carried out using rank spearmen test. Results. The results showed a relationship between the incidence of low back pain in the community and work (p-value < 0.000). Indonesian volcano sulfur miners are 5,032 times more at risk of low back pain than other public workers. Conclusion. Volcano Sulfur Miners are more at risk of experiencing low back pain than other occupations.

The analysis of volcanic brines by freezing stage tandem LIBS-ICP-MS

Volcanic crater lakes pose unique hazards to the local population both during eruption and quiescence. The composition of crater lake fluids is therefore commonly monitored to aid hazard prediction and mitigation. Some of these fluids, such as at Kawah Ijen in Indonesia and Poas in Costa Rica, are hyper-acidic, concentrated brines (SO4–5 wt%, Cl - 2.5 wt%, Al - 5000 ppm). Analysis of such fluids requires extreme dilution due to the high total dissolved element load, which risks contamination and precipitate formation. To circumvent this undesired sample preparation and speed up the turn-around time on the analysis, we tested approaches which involved freezing the fluids to −30 °C and analysing them by simultaneous Laser Ablation-Inductively Coupled Plasma Quadrupole Mass Spectrometry (LA-ICP-QMS) and Laser-Induced Breakdown Spectroscopy (LIBS). LIBS is highly matrix sensitive, requiring matrix-matched reference materials. At the same time, LA-ICP-MS owes its success to being relatively insensitive to the matrix after accounting for differences in ablation yield. Analysing the fluids as a solid and sampling them by laser circumvents the usual dilution step. Fluid reference materials were prepared by adding the elements of interest to one of the crater lake fluid samples at known, but varying concentrations and by stepwise dilution of one of these fluids. Differences in ablation yield, resulting mainly from variations in the coupling of the laser with the sample, were accounted for by adding a known quantity of lithium as an internal standard. Working curves for both ICP-MS and LIBS were obtained for Al, Mg, Fe, Ca, K, Na, S and Cl, yielding relative trueness values for 4 crater lake samples of known composition of Al-7%, Ca-5%, Fe-1%, K < 1%, Mg-4%, Na-5%, S-3%, and Cl-6% for ICP-MS and Al-2%, Ca-9%, Fe-17%, K-10%, Mg-4%, Na < 1%, S-8%, and Cl-9% for LIBS. For these elements, ranging in concentration from around 400 mg/kg to 25 g/kg, LIBS yielded similar trueness results to ICP-MS. LIBS calibration without an internal standard produces acceptable results for Li only, allowing the cryo-LIBS to analyse the major elements while optimising the ICP-MS for trace-element analysis and obtaining a full suite of elements simultaneously without the need for sample dilution.

PERAN KLASTER PARIWISATA TERHADAP EKONOMI KREATIF KABUPATEN BANYUWANGI DI ERA INDUSTRI 4.0

Banyuwangi Regency is one city in Indonesia with a high potential in the tourism sector and is famous for its main attraction, Ijen Crater National Park or more known as Ijen Crater. In 2019, this destination was appointed as the center of the tourism cluster area by utilizing local potential to support regional economic growth. This research was conducted to determine the tourism clusters’ role in supporting the creative economy by applying technology 4.0 in Banyuwangi Regency. The result showed that the tourism cluster policy application positively encourages local communities to be more creative and innovate, like creating new SME featured products by utilizing the existing biodiversity and local wisdom nearby. Unfortunately, the development of the creative industry business in the Kawah Ijen cluster have some obstacles, caused by social, financial, and infrastructure factors. To overcome that obstacle, this research also tries to provide recommendation policy suggestions in the form of local community inventions that integrate local community institutions and technology 4.0 to overcome the negative impact. The related stakeholder can create a digital-based ecosystem to motivate local people to continue being innovative and creative.

Gypsum Precipitating From Volcanic Effluent as an Archive of Volcanic Activity

Records of volcanic activity are a key resource in volcano monitoring and hazard mitigation. The time period for which such records are available and the level of detail vary widely among volcanic centers and there is, therefore, a need for supplementary sources of this information. Here, we use growth-zoned gypsum as a mineral archive of the activity of Kawah Ijen volcano in East-Java, Indonesia. Gypsum precipitates where water seeps from the crater lake and hydrothermal system, and it has formed a 100 m long cascading plateau. A 19 cm plateau cross-section was analysed for minor and trace elements using laser-ablation ICP-MS. Absolute ages were assigned to this transect based on 210Pb dating. This 210Pb age model was corrected for variations in the 210Pb0 resulting from fluctuations in the volcanic radon flux by using 84Kr/36Ar and 132Xe/36Ar. The age model indicates that the transect covers a period from 1919 ± 12 to 2008 ± 0.2. Gypsum-fluid partition coefficients (D) permit the gypsum compositions to be converted to the concentrations in the fluid from which each growth zone grew. The D-values also show the compatibility of the elements in the gypsum structure, and identify the LREE, Sr, Pb, Tl, Ni, Co, Cu, Zn, Cd, Sb, Th, and Mo as least susceptible to contamination from rock fragment and mineral inclusions, and therefore as most reliable elements of the gypsum record. Compositional variability in the timeseries correlates with known element behavior in the Kawah Ijen system and shows three element groups: the LREE, Sr, and Pb that represent rock-leaching; Cu, Zn, and Cd, which have previously been linked to immiscible sulfide destabilization in a deep-seated basalt; and Sb, Tl, and As which point to a contribution from the shallow system and evolved magma. Moreover, the gypsum record shows that episodes of unrest and quiescence have a distinct compositional signature in Kawah Ijen seepage fluids, and can be distinguished. Thus, we show that gypsum is a sensitive recorder of volcanic activity and can provide detailed information on the state of the magmatic-hydrothermal system in the past.

Mobility of REE from a hyperacid brine to secondary minerals precipitated in a volcanic hydrothermal system: Kawah Ijen crater lake (Java, Indonesia)

Rare Earth Elements (REE; lanthanides and yttrium) are elements with high economic interest because they are critical elements for modern technologies. This study mainly focuses on the geochemical behavior of REE in hyperacid sulphate brines in volcanic-hydrothermal systems, where the precipitation of sulphate minerals occurs. Kawah Ijen lake, a hyperacid brine hosted in the Ijen caldera (Indonesia), was used as natural laboratory. ∑REE concentration in the lake water is high, ranging from 5.86 to 6.52 mg kg−1. The REE pattern of lake waters normalized to the average local volcanic rock is flat, suggesting isochemical dissolution. Minerals spontaneously precipitated in laboratory at 25 °C from water samples of Kawah Ijen were identified by XRD as gypsum. Microprobe analyses and the chemical composition of major constituents allow to identify possible other minerals precipitated: jarosite, Al-sulphate and Sr, Ba-sulphate. ∑REE concentration in minerals precipitated (mainly gypsum) range from 59.53 to 78.64 mg kg−1. The REE patterns of minerals precipitated normalized to the average local magmatic rock show enrichment in LREE. The REE distribution coefficient (KD), obtained from a ratio of its concentration in the minerals precipitated (mainly gypsum) and the lake water, shows higher values for LREE than HREE. KD-LREE/KD-HREE increases in the studied samples when the concentrations of BaO, MgO, Fe2O3, Al2O3, Na2O and the sum of total oxides (except SO3 and CaO) decrease in the solid phase. The presence of secondary minerals different than gypsum can be the cause of the distribution coefficient variations.High concentrations of REE in Kawah Ijen volcanic lake have to enhance the interest on these environments as possible REE reservoir, stimulating future investigations. The comparison of the KD calculated for REE after mineral precipitation (mainly gypsum) from Kawah Ijen and Poás hyperacid volcanic lakes allow to generalize that the gypsum precipitation removes the LREE from water.

Using the composition of fluid seepage from the magmatic-hydrothermal system of Kawah Ijen volcano, Indonesia, as a monitoring tool

The lake waters of Kawah Ijen volcano are concentrated hyperacidic brines that obtain their composition from volcanic gases and water-rock interaction. Lake water and hydrothermal fluids seep through the western flank of the volcano where they precipitate gypsum and form the hyperacid Banyu Pahit river. In this contribution, we present compositional data from bi-weekly samples taken from the Banyu Pahit between 2015 and 2018 to evaluate whether these fluids can be used to monitor the hydrothermal system, and compare the fluids to the record of variability documented by the precipitated gypsum. Understanding the causal links between variability of the Banyu Pahit and the magmatic-hydrothermal processes operating in the Kawah Ijen system, and establishing a baseline for quiescence are pre-requisites to using the river for monitoring. Fluid samples were analysed at the Ijen observatory for SO4/Cl ratio using BaSO4 turbidity and AgCl gravimetry, and subsequently sent for ICP-MS and ICP-OES analyses. The data shows a first order seasonal variation that can be explained by variable input of neutral groundwater, but is underlain by more subtle trends. Temporally, there is a shift in the system from 2015–2016 to 2017 when the fluid contains a higher proportion of elements derived from rock alteration. The shift occurs at the peak of the rainy season and coincides with a substantial rainfall increase in 2017 compared to 2015–2016. At the start of 2018 there is a marked increase in Cu, coinciding with a gas burst in March 2018. We suggest that an increased meteoric water input led to an increase in water-rock interaction and dissolution of a Cu-sulphide phase in the hydrothermal system. The variability of the fluids over the 3-year sampling period does not exceed that of the longer record preserved by the gypsum precipitates, indicating that it is typical for the current style of activity.

Sustainable development of sport tourism in Banyuwangi

This research has an aim to examine the role of Sport Tourism through the program of Banyuwangi festival (B-Fest) and the impact of local content and deciding sustainable strategy of Sport Tourism Development. This research uses descriptive associative research method with qualitative and quantitative approach. Data Collection method done by observation, direct interview, questionnaire and collect the data from related instance. The result of this analysis shows that: (1) Banyuwangi Festival Program (B-fest) successfully increase the number of visitor in Kawah Ijen and Pulau Merah within total contribution of 75.9%; (2) The effect of sport tourism toward the change of local community in Kawah Ijen, on economic aspect contribute 100%. On social aspect contribute 11.6%. Environmental aspect, edelweiss flower no longer to be seen, Javan lutung and deer are rarely to be seen. Social Aspect contribute 2.6% toward people prosperity, 0.2% toward local satisfaction, 12.7% toward people participation; (3) Development strategy on sustainable sport tourism using the model of Sport tourism Participation and oriented to tourism characteristic.

Oxygen isotope fractionation between gypsum and its formation waters: Implications for past chemistry of the Kawah Ijen volcanic lake, Indonesia

Abstract Gypsum (CaSO4·2H2O) provides an opportunity to obtain information from both the oxygen isotopic composition of the water and sulfate of its formation waters, where these components are commonly sourced from different reservoirs (e.g., meteoric vs. magmatic). Here, we present δ18O values for gypsum and parent spring waters fed by the Kawah Ijen crater lake in East Java, Indonesia, and from these natural samples derive gypsum-fluid oxygen isotope fractionation factors for water and sulfate group ions of 1.0027 ± 0.0003‰ and 0.999 ± 0.001‰, respectively. Applying these fractionation factors to a growth-zoned gypsum stalactite that records formation waters from 1980 to 2008 during a period of passive degassing, and gypsum cement extracted from the 1817 eruption tephra fall deposit, shows that these fluids were in water-sulfate oxygen isotopic equilibrium. However, the 1817 fluid was &amp;gt;5‰ lighter. This indicates that the 1817 pre-eruption lake was markedly different, and had either persisted for a much shorter duration or was more directly connected to the underlying magmatic-hydrothermal system. This exploratory study highlights the potential of gypsum to provide a historical record of both the δ18Owater and δ18Osulfate of its parental waters, and provides insights into the processes acting on volcanic crater lakes or any other environment that precipitates gypsum.

An Experimental Investigation of Interaction between Andesite and Hyperacidic Volcanic Lake Water

Alteration in magmatic-hydrothermal systems leads to distinct changes in rock texture and mineralogy, and a strong redistribution of elements between fluid and rock. Here, we experimentally interacted andesite scoria with hyperacidic, high-sulfidation style fluids from Kawah Ijen volcano (Indonesia) at 25 and 100 °C, seeking to reproduce the textures observed in natural samples from this volcano, and to understand the element fluxes that accompany alteration. The susceptibility to alteration in the experiments is Cu–Fe-sulphide &gt; calcic plagioclase &gt; pyroxene &gt; titano-magnetite &gt; sodic plagioclase, with complete preservation of glass. Silicate minerals alter to opaline silica, and gypsum, barite and a Zr-phase precipitate. The selective alteration of the phenocryst minerals results in a preferential release of compatible elements, as the glass is the main incompatible element host. The experiments reproduce the alteration textures of the natural samples, including the preservation of glass, but the predicted compatible over incompatible element enrichment in the alteration element flux is not observed in the natural setting. This suggests that alteration at Kawah Ijen is dominated by lithologies that lack abundant glass, in particular lava flows where the glass has devitrified, despite these lava flows having a lower surface area compared to scoria.

Growth-zoned gypsum stalactite from the Kawah Ijen volcanic lake, Indonesia, records a &gt;40-year record of volcanic activity

Volcanic crater lakes represent both a significant hazard and an opportunity to monitor the activity of their host volcano. Unfortunately monitoring efforts, especially of lake water composition, are commonly limited by the lack of a historical record. Here we report the results of a study on the Kawah Ijen crater lake in eastern Java, Indonesia that uses growth-zoned gypsum precipitated from lake water seepage as a proxy record of lake water chemistry. Absolute ages for gypsum growth zones were determined from 210Pb radionuclide dating with a newly developed Ar-Kr-Xe correction for variations in the volcanic flux. The resulting 40-year time series of gypsum composition shows that periods of unrest are recorded by large compositional variance, whereas quiescence is characterized by low concentrations and low variance. Gypsum associated with the 1817 phreato-magmatic eruption of Kawah Ijen is similar in most elements, but it has markedly higher ratios of Cu over Sb, As and Tl, which is interpreted to represent a volcanic gas signal. These results show that gypsum holds great promise to provide the missing historical record of lake chemistry and unrest at Kawah Ijen volcano, and this approach can be extended to other volcanoes hosting crater lakes where gypsum is present.

Change in seismic attenuation as a long-term precursor of gas-driven eruptions

Abstract A large fraction of volcanic eruptions do not expel magma at the Earth’s surface. Although less known than magmatic eruptions, gas-driven eruptions expel fragments of preexisting rocks, volcanic gases, and steam, causing substantial casualties. The destructive potential of these eruptions lies in the difficulty in identifying clear warning signals. Some gas-driven eruptions have been preceded by some physicochemical changes, but these were extremely short-term (from minutes to hours), and no long-term trends have been clearly evidenced so far. Here, we show that unheralded gas-driven eruptions can be forecast in the long term using seismic signals recorded at nearby active craters. In particular, we have found that the most recent gas-driven eruptions at Kawah Ijen (Indonesia) and Ruapehu and Tongariro (New Zealand) volcanoes were all preceded by a systematic relative increase in lower-frequency (4.5–8 Hz) seismic amplitude compared to higher frequencies (8–16 Hz) over time scales of months to years. We show that this precursory activity reflects significant increases in seismic attenuation affecting preferentially high-frequency travelling waves; this probably results from the accumulation of volatiles in the shallow crust, which increases pore pressure in small-scale rock heterogeneities and eventually leads to gas-driven eruptions. Our results highlight the feasibility of better constraining the onset and the end of an unrest episode, which is of paramount importance for agencies in charge of volcano monitoring.

Anatomy of phreatic eruptions

This study investigates phreatic eruptions at two similar volcanoes, Kawah Ijen (Indonesia) and White Island (New Zealand). By carefully processing broadband seismic signals, we reveal seismic signatures and characteristics of these eruptions. At both volcanoes, the phreatic eruptions are initiated by a very-long-period (VLP) seismic event located at shallow depths between 700 and 900 m below the crater region, and may be triggered by excitation of gas trapped behind a ductile magma carapace. The shallow hydrothermal systems respond in different ways. At Kawah Ijen, the stress change induced by VLPs directly triggers an eigenoscillation of the hyperacidic lake. This so-called seiche is characterized by long-lasting, long-period oscillations with frequencies governed by the dimensions of the crater lake. A progressive lateral rupture of a seal below the crater lake and/or fluids migrating toward the surface is seismically recorded sim 15 min later as high-frequency bursts superimposed to tilt signals. At White Island, the hydrothermal system later (sim 25 min) responds by radiating harmonic tremor at a fixed location that could be generated through eddy-shedding. These seismic signals shed light on several aspects of phreatic eruptions, their generation and timeline. They are mostly recorded at periods longer than tens of seconds further emphasizing the need to deploy broadband seismic equipment close to active volcanic activity.

Community Empowerment Based on Good Tourism Governance in the Development of Tourism Destination (Case Study of Kawah Ijen Tourism Buffer Zone "Kampung Kopi" Gombengsari Village, Kalipuro District, Banyuwangi Regency)

One form of the current trend in community empowerment is empowerment through tourism. Banyuwangi endeavor to develop the leading tourism attraction and tourism buffer. One of the buffer tourism developed in Ijen Crater Zone is Kampung Kopi (Coffee Village) Gombengsari Kalipuro District, Banyuwangi. This research used qualitative method with the type of research used a descriptive case study. In data collection, researchers used observation, interview, documentation and triangulation techniques. The analysis of case study data was carried out from reading transcripts/field notes, finding common findings and taking special findings, theoretical dialogue, triangulation of data and concluding the results of the study. The results of this study indicated that the empowerment program was conducted to change and increase community awareness, knowledge and skills in order to achieve local independence while utilizing existing local potential. The implementation of tourism management in Kampung Kopi Gombengsari is based on several principles described as follows: a) Engagement of all Stakeholders; the actors involved are classified into five actors (Government, private, community, academia, and media) or called as the Pentahelix Model, b) Continuous resource utilization and avoid the irreversible use of non-renewable resources, c) Advocating the value of local culture through the festival. Internal supporting factor for Kampung Kopi Gombengsari is various tourism potential. The external supporting factor is local government, NGOs, and other tourism actors’ support. The internal inhibiting factor is the level of education and the emergence of tourism business competition. External Inhibitors involved road infrastructure which requires improvement, bureaucratic structure and tendencies. Keywords : Community Empowerment, Good Tourism Governance, Tourism Destination Development.

Opal-A in Glassy Pumice, Acid Alteration, and the 1817 Phreatomagmatic Eruption at Kawah Ijen (Java), Indonesia

At Kawah Ijen (Indonesia), vigorous SO2 and HCl degassing sustains a hyperacid lake (pH ~0) and intensely alters the subsurface, producing widespread residual silica and advanced argillic alteration products. In 1817, a VEI 2 phreatomagmatic eruption evacuated the lake, depositing a widespread layer of muddy ash fall, and sending lahars down river drainages. We discovered multiple types of opaline silica in juvenile low-silica dacite pumice and in particles within co-erupted laharic sediments. Most spectacular are opal-replaced phenocrysts of plagioclase and pyroxene adjacent to pristine matrix glass and melt inclusions. Opal-bearing pumice has been found at numerous sites, including where post-eruption infiltration of acid water is unlikely. Through detailed analyses of an initial sampling of 1817 eruption products, we find evidence for multiple origins of opaline materials in pumice and laharic sediments. Evidently, magma encountered acid-altered materials in the subsurface and triggered phreatomagmatic eruptions. Syn-eruptive incorporation of opal-alunite clasts, layered opal, and fragment-filled vesicles of opal and glass, all suggest magma-rock interactions in concert with vesiculation, followed by cooling within minutes. Our experiments at magmatic temperature confirm that the opaline materials would show noticeable degradation in time periods longer than a few tens of minutes. Some glassy laharic sedimentary grains are more andesitic than the main pumice type and may represent older volcanic materials that were altered beneath the lake bottom and were forcefully ejected during the 1817 eruption. A post-eruptive origin remains likely for most of the opal-replaced phenocrysts in pumice. Experiments at 25°C and 100°C reveal that when fresh pumice is bathed in Kawah Ijen hyperacid fluid for six weeks, plagioclase is replaced without altering either matrix glass or melt inclusions. Moreover, lack of evidence for high-temperature annealing of the opal suggests that post-eruption alteration of pumice is more likely than pre-eruption envelopment of euhedral opal-replaced phenocrysts in dacitic melt. At Ijen and elsewhere, the ascent of magma into hydrous acid-altered mineral assemblages (e.g., opal, kaolinite, alunite) could induce rapid dehydration of hydrous minerals and amorphous materials, generating considerable steam and contributing to magmatic-hydrothermal and phreatomagmatic explosions.

PENGARUH TIPE KEPRIBADIAN KOMITMEN ORGANISASI MOTIVASI TERHADAP ORGANIZATION CITIZENSHIP BEHAVIOR (OCB) DAN KINERJA PETUGAS DI TAMAN WISATA ALAM KAWAH IJEN

Abstract: This study aims: (1) to analyze the influence of personality type to the Organization Citizenship Behavior (OCB) in Ijen Crater Natural Park; (2) to analyze the influence of the organization's commitment to the Organization Citizenship Behavior (OCB) in Ijen Crater Natural Park; (3) to analyze the influence of motivation to the Organization Citizenship Behavior (OCB) in Ijen Crater Natural Park; (4) to analyze the influence of personality type on the performance of officers in Ijen Crater Natural Park; (5) to analyze the effect of organizational commitment on performance of staff in Ijen Crater Natural Park; (6) to analyze the influence of motivation on the performance of officers in Ijen Crater Natural Park; (7) to analyze the Organization Citizenship Behavior (OCB) on the performance of officers in Ijen Crater Natural Park. The number of samples taken are 35 respondents (the employees of KSDA Sector Region III Jember, Conservation Section Region V Banyuwangi, Conservation Resort Region 18 Kawah Ijen).Result of the study indicates that (1) the officer's personality type has positive effect but not significant on the Organization Citizenship Behavior (OCB) in Ijen Crater Natural Park.; (2) organizational commitment has significant positive effect on the Organization Citizenship Behavior (OCB) in the Ijen Crater Natural Park. (3) officers motivation has positive effect but not significant on the Organization Citizenship Behavior (OCB) in Ijen Crater Natural Park.; (4) personality type has significant positive effect on the performance of officers in Ijen Crater Natural Park; (5) organizational commitment has significant positive effect on the performance of officers in Ijen Crater Natural Park; (6) motivation has positive effect but not significant on the performance of officers in Ijen Crater Natural Park; (7) Organization Citizenship Behavior (OCB) has positive and significant impact on the performance of officers in Ijen Crater Natural Park.&#x0D; Keywords: Ijen Crater Natural Park, Personality Type, Organization Commitment, Motivation, Organization Citizenship Behavior (OCB), Performance;

Experimental evaporation of hyperacid brines: Effects on chemical composition and chlorine isotope fractionation

Hyperacid brines from active volcanic lakes are some of the chemically most complex aqueous solutions on Earth. Their compositions provide valuable insights into processes of elemental transfer from a magma body to the surface and interactions with solid rocks and the atmosphere. This paper describes changes in chemical and δ37Cl signatures observed in a 1750 h isothermal evaporation experiment on hyperacid (pH 0.1) sulphate-chloride brine water from the active lake of Kawah Ijen volcano (Indonesia). Although gypsum was the only evaporite mineral identified in the evolving brine, decreasing Si concentrations may ultimately result in amorphous silica precipitation. Geochemical simulations predict the additional formation of elemental sulphur at lower water activities (aH2O ≤ 0.65) that were not reached in the experiment. Absence of other sulphates and halides despite the high load of dissolved elements (initial TDS ca. 100 g/kg) can be attributed to increased solubility of metals, promoted by extensive formation of complexes between the variety of cations and the major anions (HSO4−, Cl−, F−) present. Chlorine deviations from a conservative behaviour point to losses of gaseous hydrogen chloride (HCl(g)) and consequently an increase in Br/Cl ratios.Chlorine isotope fractionation that accompanied the escape of HCl(g) showed a marked change in sign and magnitude in the course of progressive evaporation of the brine. The calculated factor of fractionation between HCl(g) and dissolved Cl for the initial interval (before 500 h) is positive (1000lnαHCl(g)-Cldiss.=+1.55±0.49‰to+3.37±1.11‰), indicating that, at first, the escaping HCl(g) was isotopically heavier than the dissolved Cl remaining in the brine. Conversely, fractionation shifted to the opposite direction in the subsequent interval (1000lnαHCl(g)-Cldiss.=5.67±0.17‰to-5.64±0.08‰), in agreement with values reported in literature. It is proposed that Cl isotopic fractionation in highly acidic brines is controlled by the distribution of dissolved chlorine species, which changes from Cl− to HClo dominance with the progressive pH decline.The Kawah Ijen lake acquired its extreme composition through influx of sulphur and halogen-rich magmatic gas components and extensive rock dissolution. If hyperacid brines with comparable chemical composition existed on Mars, evaporation processes up to the extent reported here (aH2O=0.85), were likely accompanied by losses of gaseous HCl. The resulting changes in Cl isotope compositions, Br/Cl, S/Cl and other ratios in the residual brine might be potentially recorded in assemblages of halogen-bearing secondary evaporation minerals. Also, volcanic-hydrothermal brines as these would extend the stability of liquid water on the Martian surface down to a temperature of −90 °C.

Stratification at the Earth's largest hyperacidic lake and its consequences

Volcanic lakes provide windows into the interior of volcanoes as they integrate the heat flux discharged by a magma body and condense volcanic gases. Volcanic lake temperatures and geochemical compositions therefore typically serve as warnings for resumed unrest or prior to eruptions. If acidic and hot, these lakes are usually considered to be too convective to allow any stratification within their waters. Kawah Ijen volcano, featuring the largest hyperacidic lake on Earth (volume of 27 million m3), is less homogeneous than previously thought. Hourly temperature measurements reveal the development of a stagnant layer of cold waters (<30 °C), overlying warmer and denser water (generally above 30 °C and density ∼1.083 kg/m3). Examination of 20 yrs of historical records and temporary measurements show a systematic thermal stratification during rainy seasons. The yearly rupture of stratification at the end of the rainy season causes a sudden release of dissolved gases below the cold water layer which appears to generate a lake overturn, i.e. limnic eruption, and a resonance of the lake, i.e. a seiche, highlighting a new hazard for these extreme reservoirs. A minor non-volcanic event, such as a heavy rainfall or an earthquake, may act as a trigger. The density driven overturn requires specific salinity-temperature conditions for the colder and less saline top water layer to sink into the hot saline water. Spectacular degassing occurs when the dissolved gases, progressively stored during the rainy season due to a weakened diffusion of carbon dioxide in the top layer, are suddenly released. These findings challenge the homogenization assumption at acidic lakes and stress the need to develop appropriate monitoring setups.