Lead And Associated Heavy Metal Distribution In Ciudad Juarez, Mexico
Bibliographic record
Abstract
Concern over the extent and sources of heavy metals exposure has arisen worldwide since their significant effects have been discovered in the environment. There is general agreement that research is needed to examine the residual lead and its association to heavy metals contamination in soil and quantify the health hazards. This research was directed to quantify and document the geographic distribution of lead and associated heavy metals concentration in Ciudad Juarez, Mexico. Lead, cadmium, chromium, zinc, and copper were selected to analysis. The soil samples used in this research were collected during a previous Encountors Binational Community Lead Study (RO1ES 11367; 2001-2006. The composite surface soil samples were taken from municipal blocks around 50 strata that were randomly selected. Within each stratum, 10 blocks were randomly selected. The samples were prepared for analysis by X-ray fluorescence. The general procedures of EPA method 6200 for field portable XRF were followed for preparation of the samples, with slight modification. These included grinding, mixing, pressing, and homogenization. 496 soil samples were analyzed in this study. Statistical analyses were conducted to explore the relationship between lead and associated heavy metals. Additionally, geographic information system techniques (GIS) were used to create a detailed colored map of metals concentration. The soil lead concentration levels were recorded, ranging from 12.6 to 550.3 ppm, with the mean concentration values recorded for lead was 42.8 ppm. Soil chromium concentration levels recorded for chromium ranged from 1.8 to 75.6 ppm; with mean concentration values recorded for chromium was 32.1 ppm. Soil copper concentration levels recorded for Cu ranged from 6.3 to 547.3 ppm; with mean concentration values recorded for Cu was 22.3 ppm. Soil zinc concentration levels recorded for chromium ranged from 20.7 to 415.8 ppm; with mean concentration values recorded for chromium was 83.7 ppm. Soil cadmium concentration levels recorded for cadmium ranged from 0.1 to 6.2 ppm; with mean concentration values recorded for cadmium was 1.9 ppm. Soil antimony concentration levels recorded for antimony ranged from 2.7 to 28.8 ppm; with mean concentration values recorded for Sb was 5.8 ppm.
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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 | 0.002 | 0.002 |
| 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".