Overview
Ash and colleagues tested shredded card as a post-soil-washing filter for As, Cd, and Pb mobilized from contaminated Czech forest soil by organic acid, salt, and water leachates. This is mitigation evidence, not mineral-water or product occurrence evidence: all reported values are contaminated-soil, leachate, shredded-card sorption, or desorption endpoints.
Key numbers
Table 1 reports total PTE content in mg/kg. Soil O contained As 266 +/- 16.6, Cd 14.4 +/- 0.05, and Pb 24962 +/- 1401. Soil AB contained As 327 +/- 20.0, Cd 5.86 +/- 0.24, and Pb 5046 +/- 255. The shredded-card material before leaching contained As 0.42 +/- 0.36, Cd 0.14 +/- 0.02, and Pb 7.06 +/- 5.40.
The leaching columns used 5 g of soil and 5 g of shredded card, ran continuously for 24 hrs, and used a peristaltic pump set to 100 mL/hr, giving an hourly solution:soil ratio of 20:1 (v:w). The tested leachates were oxalic acid, formic acid, CaCl2, and deionized water.
Table 3 reports the ratio of PTE in solution without shredded card to solution with shredded card. In soil O, oxalic-acid ratios were As 12.9, Cd 9.86, and Pb 33.0; formic-acid ratios were As 1.41, Cd 4.93, and Pb 248.1; CaCl2 ratios were As 28.7, Cd 1.15, and Pb 1.66; and deionized-water ratios were As 1.13, Cd 1.48, and Pb 164.9. In soil AB, oxalic-acid ratios were As 25.6, Cd 15.3, and Pb 58.4; formic-acid ratios were As 3.05, Cd 7.93, and Pb 219.2; CaCl2 ratios were As below determination limit with shredded card, Cd 1.32, and Pb 3.90; and deionized-water ratios were As 1.39, Cd 2.21, and Pb 191.8.
Table 4 reports PTE content retained on shredded card after leaching as Aa-Ab in mg/kg. For soil O, oxalic acid retained As 58.1, Cd 3.18, and Pb 2459; formic acid retained As 7.35, Cd 2.98, and Pb 456; CaCl2 retained As 6.17, Cd 0.32, and Pb 1415; and deionized water retained As 0.80, Cd 0.25, and Pb 25.2. For soil AB, oxalic acid retained As 43.7, Cd 1.32, and Pb 647; formic acid retained As 3.69, Cd 1.11, and Pb 700; CaCl2 retained As 14.4, Cd 0.16, and Pb 484; and deionized water retained As 1.07, Cd 0.31, and Pb 14.3.
Table 4 also reports shredded-card-to-solution sorption ratios. The largest Pb ratios were 169 for soil O in formic acid and 103 for soil AB in formic acid. The largest As ratios were 11.1 for soil O in CaCl2 and 14.0 for soil AB in CaCl2. The largest Cd ratios were 5.15 for soil O in oxalic acid and 3.59 for soil AB in formic acid.
The abstract reports that solution pH increased by as much as +4.49 with shredded card present. It also states that low As sorption from water was followed by fast release, with 70% As released from shredded card, that Cd sorption from organic acid solutions was followed by about 12% Cd desorption, and that shredded card retained Pb after water sorption with later losses of about 8.5% of total bound Pb.
Methods (brief)
Soils were collected from a forested area near Pribram, Czech Republic, affected by atmospheric deposition of Cd, Pb, and As. The authors leached soil O and soil AB columns with oxalic acid, formic acid, CaCl2, or deionized water, with or without a shredded-card layer, then measured target elements in filtered leachates and digested soil/card fractions by ICP-OES. Desorption experiments used 1 g of dried shredded card and acidified deionized water at pH 3.4. The paper reports total elemental As, Cd, and Pb after digestion or solution analysis; it does not speciate inorganic arsenic.
Implications
Certification: Do not use the soil, leachate, sorption, or desorption values as product occurrence data. They are remediation-performance endpoints for soil-washing extract treatment.
Courses: Useful for teaching mitigation evidence because it separates contaminated-soil source material, mobilizing leachates, sorbent retention, and later desorption under acidic water.
App: Context only. The paper can support upstream remediation and source-pathway explanations, not consumer-product contamination estimates.
Wiki pages this source may touch
- Remediation evidence — drivers and interventions
- Supply-chain screening
- Atmospheric deposition of heavy metals
- Arsenic, Total
- Cadmium
- Lead
Verification notes
Recovered from skip:not-food-occurrence under the 2026-06-10 inclusion-by-default rule. The old skip treated a soil-washing/filter paper as out of scope because it did not measure a finished product, but the source is in-scope a2 mitigation/remediation evidence.
Numbers were checked against the extracted PDF text, especially the abstract, Table 1, Table 3, Table 4, Table 5, the leaching-method paragraph, and the desorption discussion. Units are preserved as reported. Arsenic is treated as total As (tAs) because the paper reports As by total elemental analysis rather than inorganic-arsenic speciation.
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.