Transport and transformations of groundwater-borne carbon discharging through a sandy beach to a coastal ocean
Bibliographic record
Abstract
Submarine groundwater discharge (SGD) is now recognized as an important coastal process affecting local and regional sources of solutes to coastal oceans.The objective of this study was to compare SGD estimates through Martinique Beach (les-de-la-Madeleine, QC, Canada) using different sampling techniques in order to quantify SGD fluxes of dissolved organic and inorganic carbon (DOC, DIC) exported to a coastal embayment.These fluxes were estimated using hydrogeological and geochemical methods, including direct measurement via seepage meters and hydrogeological estimation using Darcy's law.Darcy estimates led to a fresh SGD flow ranging from 0.020 m 3 /s at the shoreline to 0.030 m 3 /s at the beach face.Direct measurements by seepage meters revealed higher SGD flows, with a mean value of 0.090 m 3 /s.These SGD flows were mainly composed of recirculating seawater flushing by the falling tide.The unconfined aquifer of Martinique Beach is a biogeochemically reactive zone, where DOC and DIC are nonconservative.The groundwater residence time (~32 days), low oxygen conditions (~20%) and high DOC concentrations (~2 mmol/L) represent a suitable environment for biogeochemical reactions to occur, and subsequently alter groundwater-borne carbon concentrations.We calculated a fresh-groundwater carbon load of 147 kg/d of DIC and 27 kg/d of DOC at the beach face.Even though recirculating seawater dominated the volume of total SGD, fresh SGD was an important carbon pathway, accounting for 12 and 20% of total DIC and DOC, respectively.This site-specific study is the first attempt to estimate volumetric and chemical groundwater fluxes to a coastal Canadian ocean, and demonstrates the strong interaction between fresh groundwater and coastal systems.Les dcharges d'eau souterraine (SGD pour submarine groundwater discharge) sont courantes en milieu ctier et sont maintenant reconnues comme des sources locales et rgionales de soluts l'ocan ctiers.L'objectif de cette tude tait de comparer diffrentes techniques pour estimer les SGD travers la plage de la Martinique (les-de-la-Madeleine, QC, Canada) et ainsi pouvoir valuer les flux de carbone organique et inorganique dissous (DOC et DIC) exports la cte.Des donnes aussi bien hydrogologiques que gochimiques ont t utilises pour valuer ces flux, en utilisant notamment des mesures directes avec des chambres d'exfiltration (seepage meter) et des mesures hydrogologiques en se basant sur la loi des coulements de Darcy.Les estimations faites partir de Darcy donnent des flux d'eau douce entre 0,020 m 3 /s la ligne de rivage et 0,030 m 3 /s dans la zone de dcharge de la plage.Les mesures directes donnent des valeurs plus leves, autour de 0,090 m 3 /s mais ces flux incluent l'eau de mer de recirculation advecte par la pompe tidale.L'aquifre non confin de la plage est aussi une zone biogochimiquement active o le DOC et DIC montrent un comportement non-conservatif.Le temps de rsidence de l'eau douce (autour de 32 jours), les faibles concentrations en oxygne dissous (DO ~20% de saturation) et les fortes concentrations en DOC (~2 mmol/L) permettent le dveloppement de conditions idales aux processus de respiration et la transformation du carbone apport par les coulements souterrains.Ces transformations mnent des flux souterrains de 147 kg DOC/j et 27 kg DIC/j dans la zone de dcharge.Et mme si l'eau de mer de recirculation domine le volume total de SGD dans ce site, l'coulement d'eau douce est une importante voie de transport de carbone l'ocan et reprsente respectivement 12 et 20% des apports en DIC et DOC.Bien que ces rsultats soient spcifiques au site d'tude, ils reprsentent la premire tentative d'estimation des flux, qu'ils soient volumtriques ou chimiques, dans l'ocan ctier canadien et soulignent la forte interaction entre les eaux souterraines et les milieux ctiers.
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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 | 0.001 | 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) | 0.000 | 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 teacher head, 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".