Globally significant yields of dissolved organic carbon from small watersheds of the Pacific coastal temperate rainforest
Bibliographic record
Abstract
Abstract. The perhumid region of the Pacific coastal temperate rainforest of North America (PCTR) is one of the wettest places on Earth and contains numerous small catchments that discharge freshwater and high concentrations of dissolved organic carbon (DOC) directly to the coastal ocean. However, empirical data on the flux and composition of DOC exported from these watersheds is scarce. We established monitoring stations at the outlets of seven catchments on Calvert and Hecate Islands, British Columbia, which represent the rain dominated outer-coast region of the PCTR. Over several years, we measured stream discharge, stream water DOC concentration, and stream water dissolved organic matter (DOM) composition. Discharge and DOC concentrations were used to calculate DOC fluxes and yields, and DOM composition was examined using absorbance and fluorescence spectroscopy, including parallel factor analysis (PARAFAC). The areal estimate of annual DOC yield in water year 2015 was 33.3 Mg C km−2 yr−1, with individual watersheds ranging from an average of 24.1–37.7 Mg C km−2 yr−1. This represents some of the highest DOC yields in the world exported to the ocean. We observed strong seasonality in the quantity and composition of exports, with the majority of DOC export occurring during the extended wet period of the year (September–April). Stream flow from catchments reacted quickly to rain inputs, resulting in rapid flushing of relatively fresh, highly terrestrial-like DOM. DOC concentration and measures of DOM composition were correlated with watershed attributes, including the extent of lakes and wetlands, and thickness of organic and mineral soils. Our discovery of high DOC yields from these small catchments on the outer-coast of the temperate rainforest is especially compelling as they represent the delivery of relatively fresh, highly terrestrial organic matter directly to the coastal ocean. This suggests that this coastal margin may play an important role in the global processing of carbon and in linking terrestrial carbon to marine ecosystems.
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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 | 0.001 |
| 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".