Evaluating dissolved organic matter loads in tropical alpine rivers using FDOM measurements
Bibliographic record
Abstract
Peru is home to about 70% of the world’s tropical glaciers. However, due to climate change mainly, they have lost 40% of their surface area since the 1970s. This retreat has been decreasing the meltwater contribution to the streams especially in the dry season, which increases the concentration of contaminants. Dissolved organic matter (DOM) is an indicator of water quality as it is influenced by natural as well as by anthropogenic activities. Quantifying and characterizing DOM is challenging because of its complexity. Recent technological development allows us to quantify and/or qualify fluorescent dissolved organic matter (FDOM), the fraction of DOM that has fluorescence properties, by employing portable fluorometers or benchtop measurements of fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC). The objective of this research was to evaluate the evolution of FDOM measurements throughout two glacierized tropical alpine watersheds in Peru: the Shullcas and the Upper-Santa. Using a portable fluorometer equipped with a CDOM/FDOM sensor and a portable multimeter, 38 on-site measurements of FDOM, pH and turbidity were completed. Simultaneously 38 samples were taken to be analyzed with fluorescence spectroscopy followed by parallel factor analysis. FDOM results performances were compared with Dissolved Organic Carbon (DOC) measurements using high-temperature catalytic oxidation used as a reference method. Our results show that the portable fluorometer readings are limited to the portion of fluorescent dissolved organic matter that corresponds to humiclike substances due to the narrow bandwidth of the sensor used. The fluorescence spectroscopy coupled with PARAFAC was the only method able to both differentiate between potential sources of DOM and estimate relative concentrations of different organic substances types. The ability of the method to provide accurate estimations of the total FDOM load at the watershed scale remains, however, to be proven. Among others, this study shows cities have a strong impact on the water quality of studied catchments, mainly due to the absence of proper sewage systems.
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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 | 0.001 | 0.001 |
| 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) | 0.001 | 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".