Pusz et al. 2024 - carbon amendments for metal-contaminated industrial soils

Pusz and colleagues tested brown coal and activated carbon as immobilizing amendments for Pb-, Cd-, Cr-, Zn-, Cu-, and Ni-contaminated industrial soils from Krzemionki Opatowskie, Poland. This is primary soil-remediation and phytotoxicity evidence, including total soil concentrations, EDTA-available fractions, Medicago falcata root/shoot metal uptake, phytotoxicity, BCFs, and health-risk indices. It is not food, ingredient, or consumer-product occurrence evidence.

Key numbers

Starting soils

Five soils were used: SC control plus four contaminated soils (S1-S4). Table 2 reports total metal concentrations before amendment as mg/kg dry matter:

The authors state that Polish industrial-area limits were exceeded for Pb in all contaminated soils, Zn in S1 and S2, and Cu in S1. Cd, Cr, and Ni did not exceed the cited limit values.

Soil chemistry before the pot experiment:

Brown coal pH was 5.4 in 1 M KCl and 5.9 in water; activated carbon pH was 9.5 in 1 M KCl and 9.8 in water. Dry matter was 65.69% for brown coal and 94.04% for activated carbon.

Total soil metals after carbon amendments

Table 3 reports total metal concentrations in soil as mg/kg dry matter:

bc1 and bc2 are single and double brown-coal doses; ac1 and ac2 are single and double activated-carbon doses.

EDTA-available metals and risk indices

The authors used 0.02 M EDTA to estimate potentially plant-available metal forms. In SC control soil, EDTA-extractable concentrations were Cu 3.11, Pb 5.63, Zn <0.05, Cd <0.005, Cr <0.03, and Ni <0.05 mg/kg dry matter.

For the contaminated combinations, EDTA-extractable metals ranged:

The largest average percent reductions in plant-available metal forms came from double-dose activated carbon (ac2):

The non-carcinogenic HQ values in Table 4 were all below 1. The ILCR values for Cd, Cr, and Ni in Table 6 were all below 1.00e-4; the authors state that no tested soil combination exceeded the carcinogenic-risk threshold for dermal contact.

Plant uptake and phytotoxicity

The control soil had low Medicago falcata metal concentrations. In roots, the authors report Cu 2.80, Pb 1.91, Zn 3.83, Cd <0.005, Cr 1.29, and Ni 1.34 mg/kg dry matter. In shoots, they report Cu 2.62, Pb 1.75, Zn 8.89, Cd 0.224, Cr 0.93, and Ni 2.19 mg/kg dry matter.

For contaminated soils, the authors summarize plant uptake as Zn > Pb > Cu > Cr > Ni > Cd in both roots and shoots. Higher shoot concentrations were found than root concentrations for all tested metals except Pb in the least polluted S4 soil with carbon additions.

Activated carbon had the stronger effect on reducing metal availability to plants. Relative to soils without added carbon, the average reductions attributed to activated carbon were:

The most polluted soil (S1) without carbon inhibited root growth by 44% and shoot growth by 25%. In S1-S4 soils without carbon, root and shoot inhibition were observed except that S4 did not inhibit shoots. In all soil combinations with brown coal or activated carbon, the authors report no seed-germination inhibition and no root/shoot-growth inhibition.

BCF values in Medicago falcata qualified the plant as an excluder (BCF < 1), not an accumulator. The highest BCFs were for Cd. Activated-carbon combinations had lower BCFs than brown-coal combinations.

Methods (brief)

The authors collected industrial soils from an industrial waste landfill heap in Krzemionki Opatowskie, Poland, where soils had been used for cleaning metallurgical carts or wagons. Wagner-type pots received 10 kg soil each. The design included no-carbon controls plus brown coal and activated carbon at 200 g and 400 g doses, yielding 21 combinations in triplicate. Medicago falcata was grown for one vegetation period, then harvested at flowering stage.

Soils were characterized for granulometry, pH, total organic carbon, carbonate content, and exchangeable alkaline cations. Total metal concentrations were measured after HClO4/HNO3 mineralization. EDTA-extractable forms used 0.02 M EDTA. Metal contents in soils and plants were measured by ICP-OES. Phytotoxicity used a modified Phytotoxkit test with Medicago falcata seeds, 72 h incubation at 25 degrees C, and ImageTool root/shoot measurement. PI, PLI, HQ, and ILCR were calculated from cited environmental-risk equations.

Implications

Certification: Do not use this source in food, ingredient, or product occurrence pools. The study is an industrial-soil pot experiment and phytostabilization test, not a market sample frame.

App: Context for contaminated-soil, forage-pathway, and remediation evidence. It supports the claim that activated carbon can reduce EDTA-available metals and plant uptake in alkaline industrial soils.

Courses: Useful for teaching the difference between total soil metal concentration, EDTA-available fraction, plant uptake, phytotoxicity, and product occurrence.

Wiki pages this source may touch

• cadmium
• chromium
• copper
• lead
• nickel
• zinc
• wastewater-irrigation
• index

Verification notes

This page was built from the full PDF, including the abstract, pot-experiment design, analytical methods, Tables 1-6, Figures 3-7, discussion, conclusions, and data-availability statement. A paper-internal inconsistency was noted: Table 2 reports SC control-soil totals as Cu 13.1, Pb 14.8, Zn 49.1, Cd 0.34, Cr 7.51, and Ni 12.4 mg/kg dry matter, while Section 3.2 states Cu 17.2, Pb 23.1, Zn 61.1, Cd 0.72, Cr 10.4, and Ni 15.9 mg/kg dry matter for SC. The table values are used in Key numbers because the table is the primary data display. Products and ingredients are intentionally empty because the source analyzes industrial soils, amendments, and a test plant grown in contaminated pots, not market foods or consumer products.

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.