Assessing the Importance of Organic Matrix Materials in Biofilm Chemical Reactivity: Insights from Proton and Cadmium Adsorption onto the Commercially Available Biopolymer Alginate
Bibliographic record
Abstract
Biofilms coat the exterior of most water-exposed interfaces, from the surfaces of sediments and rocks to the interior walls of fluid transport systems and even medical and dental apparatus. Composed of a diverse assemblage of microbial species growing in a matrix of extracellular polymeric substances (EPS), biofilms are well-known for their ability to sorb metals and nucleate mineral phases. In this study, purified alginate, a major polysaccharide component of some algal and bacterial EPS, was studied to ascertain its chemical reactivity towards dissolved cadmium and protons, and thus better constrain its role in overall EPS reactivity. FTIR analysis and compositional constraints based on known molecular structure indicate that alginate’s geochemical behaviour is dominated by a single carboxyl functional group. Correspondingly, potentiometric titration data were best fit using a single functional group acidity constant (pKa) and site concentration of 3.98 ± 0.01 and 1.728 ± 0.02 mol/kg, respectively, which are in agreement with typical carboxyl acidity (pKa 3–6) and carboxyl functional group concentration based on alginate polymer composition. The logarithm of the Cd-carboxyl complexation constant (log K) was determined to be −0.52 ± 0.22, lower than carboxyl-Cd stability constants reported from independent studies of isolated microbes. Together, these results place important constraints on organic matrix contributions to overall biofilm reactivity.
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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 | 0.001 | 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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".