Salt‐Induced Flocculation of Dissolved Organic Matter and Iron Is Controlled by Their Concentration and Ratio in Boreal Coastal Systems
Bibliographic record
Abstract
Abstract Rivers and estuaries are important conduits and reactors for organic matter (OM). Despite the substantial export of terrestrial OM by rivers, only a small proportion of this material reaches the open ocean. One potentially important mechanism contributing to the removal of terrestrial dissolved OM (DOM) is flocculation; a process that transforms DOM into larger size fractions that can settle into sediment pools. Here we investigate the role of flocculation in adjacent boreal coastal systems over three consecutive seasons. Flocculation experiments, which include the artificial salting of freshwater DOM to mid (12 psu) and high salinity (25 psu), and a 1:1 mixture of freshwater DOM with their respective saline endmember, highlight a potentially important source of particulate carbon (PC) in boreal estuaries. Along with a 3.5% ± 1.0% removal of dissolved organic carbon (DOC) and 44% ± 16% dissolved iron (DFe), the potential for flocculation of these constituents significantly increased with increasing salinity from 12 to 25 psu. The particulate matter (PM) produced by salt‐induced flocculation was comparable to in situ PC concentrations (in situ PC = 27.5 μmol L −1 and flocculated PC = 15.0 μmol L −1 ) and stable carbon isotopic signatures (in situ PM = −28.8‰ and flocculated PM = −28.3‰). DFe:DOC and S r were the only parameters that could significantly explain the degree of carbon and iron flocculation. This demonstrates the importance of DOC, DFe, and optical properties, and the predictive value of DFe:DOC for understanding DOM susceptibility to flocculation and its relevance and contribution to regional and global carbon budgets.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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".