Influence Of Beggiatoa Bacterial Mats On Chemistry Of Sediment From Hood Canal, Washington
Bibliographic record
Abstract
Recent fish kills have highlighted the need to better understand the factors that contribute to development of large hypoxic zones in Hood Canal. Among the important questions are whether hypoxic events have occurred in the past and, if so, whether the current events are more extensive, more frequent, or more sustained. The goal of this study is to look for a geochemical signature in sediment cores that could be used to identify whether anoxic conditions existed in the past. In particular we have focused on trace metals in sediment beneath mats of Beggiatoa, sulfide-metabolizing bacteria, that are abundant on the bottom of low-oxygen areas of the canal. Gravity cores were collected from two sites at the southern end of the canal (47 degrees 24'10.96" N, 122 degrees 55'13.22" W and 47 degrees 24'46.07 degrees N, 122 degrees 53'48.44" W), one from a site inside a Beggiatoa mat, the other from a site without Beggiatoa. In the core taken from the Beggiatoa location, the upper 15-25 cm of sediment are noticeably darker in color than the lower layers; no such color change is observed in the other core. ICP-OES analyses of sediment from the Beggiatoa core indicate significant changes in chemical composition within the upper 15-25 cm. Organic content (by LOI), Fe, and Al levels are more variable in this upper section (LOI=11-16%, Fe=13.7-17.0 ppt, Al=8.0-10.1 ppt at the top, and LOI=11-12%, Fe=15.2-16.0 ppt, Al=8.3-8.9 ppt at the bottom), and heavy metals are notably enriched (Zn=24 ppm, Pb=12 ppm in the top, and Zn=2 ppm, Pb=1 ppm in the bottom). These changes in sediment chemistry may reflect variations in sediment input or differences in redox conditions associated with Beggiatoa mats. By comparing the chemistry of the cores from inside and outside Beggiatoa locations we hope to distinguish the relative importance of these factors.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".