Overview
Malyshevska evaluated the phytotoxicity of sludge from mechanical processing and washing of mixed polymer waste, then measured lead (Pb), Cu, cadmium (Cd), Zn, and nickel (Ni) in growth substrates and plant material. This is not soy-product occurrence evidence: it is upstream soil-amendment and plant-uptake evidence showing how lead in a waste-derived growth substrate can migrate into plants.
Key numbers
The tested sludge consisted of 0.5 to 2.7 mm particles. Polymer particles accounted for 87.3 to 92.6% of the total amount, and paper-label residues accounted for 7.4 to 12.6%.
The growth-substrate treatments were control substrate, sludge, and control substrate amended with 10 g/kg, 100 g/kg, 500 g/kg, or 1000 g/kg sludge. Six plant species were tested: watercress, mustard, wheat, corn, soy, and barley. Table 1 reports 30 seeds per condition.
Seed germination was 100% for watercress, mustard, and corn in all tested samples. Soy germination on sludge was 29 of 30 seeds, or 96.7%, with a 3.33% difference from control and phytotoxicity rated permissible. Barley germination was 29 of 30 seeds, or 96.7%, in the control and in the 100 g/kg sludge-amended growth substrate; the 100 g/kg condition was rated permissible. Wheat germination ranged from 28 of 30 seeds, or 93.3%, to 29 of 30 seeds, or 96.7%, with 3.33% to 6.67% differences and permissible phytotoxicity ratings.
Table 2 reports the strongest stem/root phytotoxicity responses for watercress and mustard when grown on 100% sludge. Watercress on sludge had stem length 2,7 +/- 0,32 mm, a -33,61% change rated medium phytotoxicity, and root length 1,37 +/- 0,23 mm, a -42,92% change rated medium phytotoxicity. Mustard on sludge had stem length 5,03 +/- 0,23 mm, a -12,98% change rated weak phytotoxicity, and root length 2,7 +/- 0,27 mm, a -29,50% change rated weak phytotoxicity.
Table 2 reports no phytotoxic effect on vegetative growth of corn, wheat, barley, and soy. Soy stem length increased from 1,23 +/- 0,37 mm in the control substrate to 3,92 +/- 0,37 mm at 1000 g/kg sludge, a +218,7% change; soy root length remained rated permissible across sludge-amended substrates.
Table 3 reports mobile forms of heavy metals in averaged growth-substrate samples, in mg/kg:
| Substrate | Pb | Cu | Ni | Cd | Zn |
|---|---|---|---|---|---|
| Control | 0,333 +/- 0,054 | 0,254 +/- 0,045 | 0,283 +/- 0,075 | 0,085 +/- 0,053 | 1,782 +/- 0,048 |
| Conditionally clean soil | 0,732 +/- 0,062 | 0,293 +/- 0,024 | 0,261 +/- 0,067 | 0,284 +/- 0,057 | 2,172 +/- 0,065 |
| Sludge | 0,863 +/- 0,073 | 0,462 +/- 0,035 | 0,373 +/- 0,064 | 0,343 +/- 0,082 | 1,681 +/- 0,076 |
| Permissible concentration of mobile forms in soil | 6,0 | 3,0 | 4,0 | 0,7 | 23,0 |
| SanPiN 42-123-4089-86 comparator for food raw materials and food products | 1,0 | 25,0 | 4,0 | 0,05 | 50,0 |
The English abstract and discussion report that heavy metals in plant material were insignificant across the studied sludge-content samples. Pb in plant material grown on sludge was 1.83 times higher than in control samples, 2.13 times higher than in conditionally clean soil samples, and 14% lower than the SanPiN 42-123-4089-86 comparator cited by the source. The conclusions state that mobile forms of Pb migrated from the studied growth substrates and sludge into plants and accumulated in them, while migration of bound Cu, Ni, Cd, and Zn forms was not established.
Methods (brief)
The study used vegetative phytotoxicity methods following ISO 17402-2008, ISO 17126-2005a, ISO 22030:2005b, ISO 11269-1:2012a, and Ukrainian/Russian methodological guidance for waste hazard-class justification by phytotoxicity. Growth substrates included washed sand control substrate, conditionally clean soil from Halych National Park, the polymer-waste sludge, and sludge-amended growth substrates at 10, 100, 500, and 1000 g/kg.
Pb, Cu, Cd, Zn, and Ni were measured by atomic absorption spectrophotometry on a CAS-120.1 spectrophotometer with electrothermal atomization after HNO3 extraction. Plant material was prepared by dry ashing in a muffle furnace followed by nitric-acid treatment. The paper reports total elemental heavy metals and mobile/bound forms in substrates and plants; it does not report arsenic, mercury, chromium, inorganic arsenic, methylmercury, or Cr(VI).
Related evidence
- Irrigation water and soil amendments as anthropogenic inputs to cropland
- Soil-to-plant transfer of heavy metals
- Lead
- Cadmium
- Nickel
- Copper
- Zinc
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.