Ion Selective Electrode (ISE) method overview and variations in implementation descriptions for the determination of sulfide in marine sediment samples
Bibliographic record
Abstract
This document is part of a Canadian Science Advisory Secretariat (CSAS) process to give Fisheries and Oceans Canada (DFO) science advice pertaining to the sulfide ion selective electrode (ISE) method. This method is currently the only approved regulatory tool within Canada used to determine the oxic state of the benthos as a result of organic loading from finfish aquaculture activities. ISE is an easily operated and highly cost-effective technique compared to other high level instrumental methods. However, due to its manual nature, methodological steps can be prone to subjective interpretation by the analyst resulting in inconsistent execution by different individuals and/or laboratories. In terms of sulfide monitoring, this can potentially lead to the generation of variable, and inaccurate data with ramifications to regulatory decision making. The sulfide ISE method was initially evaluated by Wildish et al. (1999) and subsequently adopted for use by New Brunswick, Nova Scotia, and nationally as part of the Aquaculture Activities Regulations (DFO 2018a), which British Columbia follows as part of Annex 8 of the Aquaculture Activities Regulations guidance document. In their environmental monitoring standard operating procedures (SOPs), New Brunswick (NB DELG 2018), Nova Scotia (NS DFA 2021), and British Columbia (DFO 2018b) all refer to Wildish et al. (1999) for measurement of sulfide in collected sediment samples. However, they deviate in certain aspects from Wildish et al. (1999), and also amongst themselves, e.g., the number of standards used to calibrate the ISE, the time from sample collection to analysis, etc. In this paper, we list the necessary steps required for the determination of sulfide in sediment samples, and also document deviations from Wildish et al. (1999) by the aforementioned regulators, along with procedural differences between one another. A proposed methodological procedure for determination of sulfide in sediment samples is also presented, which could lead the way for development of a revised and more prescriptive SOP that can be adopted nationally.
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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 | 0.009 | 0.011 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.006 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.013 | 0.015 |
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".