Thirty-Year Manuring and Fertilization Effects on Heavy Metals in Black Soil and Soil Aggregates in Northeastern China
Bibliographic record
Abstract
To evaluate the effects of thirty years of manure and chemical fertilizer applications on metal accumulations in soil and soil aggregates, fresh soils were separated by wet sieving into four aggregate fractions and heavy-metal concentrations in soil and aggregates were determined. The soil organic carbon (SOC) concentration in microaggregates ranged from 20.2 to 39.6 g carbon (C) kg−1, which was significantly greater than those in the other fractions. The proportion of heavy metals in small macroaggregates and the silt + clay fraction accounted for 45.5 ± 10.6% and 35.8 ± 14.1% of the total amount in soil, respectively, which might be due primarily to their greater mass percentages in soil. Both chemical fertilizer and manure significantly stimulated iron (Fe) and zinc (Zn) accumulation; horse manure also increased copper (Cu), lead (Pb), and chromium (Cr) concentration in bulk soils as compared with the control. The results also indicated that heavy-metal distribution in aggregates was not controlled by SOC but possibly by soil clay.
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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 | 0.000 |
| Science and technology studies | 0.001 | 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) | 0.000 | 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".