Hydrochemistry of a coastal sedimentary basin: evidence from the Lower Kutai Basin, Indonesia
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Bibliographic record
Abstract
Groundwater is a vital freshwater resource in coastal regions, where 38 % of the global population currently resides. The hydrochemistry of abstracted groundwater in low-lying deltaic regions can pose a risk to human health, especially where monitoring of groundwater quality is limited. This study investigates new evidence of the hydrochemistry of shallow (depths of <250 m) groundwater in the Lower Kutai Basin (LKB) where Indonesia's new capital, Nusantara, is situated. Shallow groundwater is predominantly (67 out of 73 samples) fresh with a median total dissolved solids of 197 mg/L and hydrochemical facies are dominated by the bicarbonate anion. In this coastal sedimentary basin, high concentrations of iron (median = 5.4 mg/L) and manganese (median = 138 μg/L) that exceed WHO drinking-water guidelines reflect widespread reducing conditions in shallow groundwater, promoted by sluggish flow under low hydraulic gradients (primarily <0.002). Stable isotope ratios (δ 18 O, δ 2 H) indicate that inland fresh groundwater, traced to heavy rainfall, becomes isotopically heavier and more saline toward the coast. Although the hydrochemical conditions favoring arsenic mobilization mirror those of Asian megadeltas, arsenic concentrations in the shallow groundwater of the LKB are generally low (median = 0.5 μg/L).
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 it