Ash et al. 2016 - shredded-card soil-washing filter
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.
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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.
Page history
The five most recent substantive edits to this page. 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.