Chlorine‐36 in Ground Water Containing Low Chloride Concentrations
Bibliographic record
Abstract
Abstract Analyses of ground water from wells and springs in the United States indicate a broad regional trend in preanthropogenic ( 36 Cl/total Cl) ×10 15 ratios in potable water. Coastal areas influenced by marine chloride have ratios less than 100. These ratios increase inland and reach a maximum of about 1400 in the central and northern Rocky Mountains. However, the magnitude of these regional variations is greatly exceeded at a local level if water samples are considered regardless of age or origin. Most local departures from regional trends can be attributed to mixing of ground water recharge with either 36 Cl from nuclear fusion tests to produce higher ratios or mixing with sources of old chloride such as from evaporite minerals to produce lower ratios. A useful interpretation of 36 Cl data is difficult unless the origin of the chloride is understood. The interpretation is an unusually difficult problem for water having low chloride concentrations. The assumption that low concentrations originate primarily from wet and dry atmospheric deposition can be questioned even for some dilute waters with less than 2.0 mg/L chloride. Chloride/bromide ratios in ground water can help decipher the origin of the chloride. The presence of nonatmospheric chloride can be identified in part by its association with chloride/bromide mass ratios greater than about 200 in coastal areas and 100 in inland areas. Accurate chloride and bromide analyses are recommended for virtually all studies of 36 Cl in natural waters, and particularly those with low concentrations of chloride.
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How this classification was reachedexpand
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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.029 | 0.004 |
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; both teacher heads agree on what is shown here.
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".