Novel Endpoint Characterization Factors for Life Cycle Impact Assessment of Terrestrial Acidification
Bibliographic record
Abstract
• New terrestrial acidification characterization factors for vascular plants. • Combination of existing fate, updated soil response and effect factors, and GEP. • Aggregated impacts from NO x -/NH x -/SO x -emissions deposited anywhere in the world. • Harmonized methodology to allow cross-impact-category comparison of LCA results. Human activities involving combustion and agricultural practices, among others, lead to the release of acidifying compounds such as nitrogen oxides (NO x ), sulfur oxides (SO x ), and ammonia (NH 3 ). These substances are the main drivers of human-induced terrestrial acidification, a geochemical process resulting mainly in the decline of soil pH, causing ecosystem damage and biodiversity loss. A relevant tool to quantify impacts of human activities is Life Cycle Assessment where characterization factors are used to estimate the potential environmental impacts per unit of emission. These are derived from models of environmental processes occurring along the stressor’s impact pathway, connecting an emission to its potential environmental damage. Here, new ecosystem quality characterization factors for terrestrial acidification were developed, assessing the potential global loss of vascular plant species. The final values combine four elements: existing fate factors, updated soil response factors, recently revised effect factors, and the Global Extinction Probability. The latter allows to convert the local decline in species richness into a global species loss. The regionalized marginal characterization factors provided represent the aggregated global biodiversity impact in all the world’s ecoregions due to an acidifying emission (of NO x , NH x , or SO x ) from a specific country. The values cover five orders of magnitude (from 10 −16 to 10 −11 PDF global .yr.kg emitted −1 ), and the comparison to currently implemented values has helped both validate the calculation pathway and confirm the need for updated factors. Following current harmonization recommendations, terrestrial acidification impacts can now be compared to those from other stressors estimated in global Potential Disappeared Fraction of species.
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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 | 0.004 | 0.006 |
| Meta-epidemiology (narrow) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".