The Lake St. Martin bolide has a big impact on groundwater fluoride concentrations
Bibliographic record
Abstract
Research Article| February 01, 2008 The Lake St. Martin bolide has a big impact on groundwater fluoride concentrations Matthew I. Leybourne; Matthew I. Leybourne 1GNS Science, P.O. Box 30-368, Lower Hutt, New Zealand Search for other works by this author on: GSW Google Scholar Jan M. Peter; Jan M. Peter 2Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar Karen H. Johannesson; Karen H. Johannesson 3Department of Earth and Environmental Sciences, Tulane University, New Orleans, Louisiana 70118, USA Search for other works by this author on: GSW Google Scholar Daniel R. Boyle Daniel R. Boyle 4Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar Geology (2008) 36 (2): 115–118. https://doi.org/10.1130/G24135A.1 Article history received: 31 May 2007 rev-recd: 21 Sep 2007 accepted: 01 Oct 2007 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Matthew I. Leybourne, Jan M. Peter, Karen H. Johannesson, Daniel R. Boyle; The Lake St. Martin bolide has a big impact on groundwater fluoride concentrations. Geology 2008;; 36 (2): 115–118. doi: https://doi.org/10.1130/G24135A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The majority of residents of Manitoba (Canada) outside of the capital, Winnipeg, rely on groundwater for their drinking water. Between lakes Winnipeg and Winnipegosis, most aquifers occur in Paleozoic carbonate lithologies. Proximal to the town of Gypsumville, however, lithologies associated with the Lake St. Martin impact structure and younger basin-filling red bed and evaporite (gypsum/anhydrite) sedimentary rocks complicate the hydrology and hydrochemistry. Here, domestic wells have elevated salinities (up to 8000 mg/L total dissolved solids), elevated sulfate (up to 4000 mg/L), and elevated fluoride concentrations that are in excess of health limits (F− up to 15.2 mg/L, with 20% over 1.5 mg/L). Groundwaters with elevated fluoride occur exclusively within the impact structure. The impact melt rocks and younger red beds consistently have the highest fluoride abundances, up to 2160 ppm. Groundwater pH values are alkaline, ranging up to 10.7, with highest groundwater pH from wells in the impact melt rocks. The spatial associations of impact melt rocks and red beds with elevated fluoride, strong positive correlations between fluoride and pH, sodium, chloride, sulfate, boron and lithium, greater Fe2O3 and Al2O3 concentrations of the host rocks, and cation exchange capacity (CEC) all indicate that fluoride concentrations in groundwaters are enhanced as a result of anion exchange wherein OH− and \(CO_{3}^{2{-}}\) displace F− adsorbed onto Fe- and Al-oxyhydroxide surfaces. Thus, the elevated fluoride contents of groundwaters at Gypsumville are a consequence of the composition of the impact melt rocks and enhanced permeability and grain-size reduction produced by bolide impact. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.000 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.032 | 0.003 |
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".