Hydrogeochemistry of the upper Banyu Pahit River valley, Kawah Ijen volcano, Indonesia
Bibliographic record
Abstract
The largest naturally-occurring lake of hyperacid brine in the world is located in the crater of Kawah Ijen volcano in East Java, Indonesia. The hyperacid Banyu Pahit River flows down the side of Kawah Ijen and is a major source of regional natural pollution. Hydrothermal fluid, meteoric derived groundwater, seepage from the hyperacid crater lake, and water-rock interaction are the major sources and sinks of water and solutes from the volcano to the surrounding environment. The current research is focused on the upper Banyu Pahit River valley (within 3 km of the summit) which has been understudied to date. Detailed chemical analyses of the Banyu Pahit River, the crater lake, and all observed springs (neutral and acid) that contribute water to the river were made, including 46 major, minor and trace elements. The distinct chemical signature of each water source, as well as that of water-rock interaction, is determined. Several elements have been identified as conservative tracers of hydrologic sources and sinks as they enter the surface water system. Mass balance mixing analysis using the conservative tracers, combined with discharge measurements, is used to quantify the fluid and solute mass contribution of each source. The results of this analysis indicate that fluid from the deep hydrothermal system contributes the majority of the solute flux from Kawah Ijen, and that it also forms the headwaters of the Banyu Pahit River. The flux of crater lake seepage, which was previously assumed to be both the main source of acid water for the Kawah Ijen hydrologic system and the headwaters of the Banyu Pahit River, has now been determined to be a full order of magnitude lower than that of hydrothermal fluid (total calculated flux = 1.2 l/s crater lake seepage versus 15.4 l/s hydrothermal fluid).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".