Serrano et al. 2024 - phosphorus-loaded biochar-assisted phytoremediation

Serrano and colleagues tested whether phosphorus-loaded biochars made from coffee husk or sugar-cane leaf residues could assist Lolium perenne phytoremediation of Cd-, Cr-, and Pb-contaminated soils. This is mitigation evidence, not occurrence evidence: the metals were deliberately added to soil and measured through soil bioavailability and plant-organ retention. The source belongs in remediation and metal pages while leaving product and ingredient occurrence pools empty.

Key numbers

The experimental design used three separately contaminated soils, each spiked at 10 mg/kg for Cd, Cr, or Pb. Each contaminated soil received either no biochar or 1% of one of four phosphorus-loaded biochar amendments: activated coffee husk biochar (BAC), nonactivated coffee husk biochar (BSAC), activated sugar-cane leaf biochar (BAA), or nonactivated sugar-cane leaf biochar (BSAA). The experiments were run in triplicate and followed for 45 days.

Across soils amended with 1% biochar, pH increased by 13.9% compared with non-biochar controls. Activated coffee-husk and activated sugar-cane-leaf biochars had stronger effects: BAC and BAA increased pH by 19.29% and 15.77%, respectively, compared with the other samples. Biochar-amended soils also showed a 40.57% increase in electrical conductivity, with BAC producing a 2.31-fold increase relative to the other biochar tests.

For metal bioavailability, the authors report that Cr bioavailability stayed below 0.1 mg/kg on all monitoring days, while Pb bioavailability decreased over time in the order day 15 > day 30 > day 45. They concluded that Cd and Pb had absent or low bioavailability by the end of follow-up, consistent with precipitation, complexation, redox reactions, and plant uptake mechanisms.

Plant-organ results showed root-dominant retention. Figure 11 and the accompanying text report root concentrations higher than stem concentrations by 83.00% for Cr, 91.02% for Cd, and 94.98% for Pb. Plant organs in biochar-amended soils retained 11.6% more heavy metals than plant organs in non-biochar controls. Pb was the most retained metal in roots, followed by Cr and then Cd.

The authors flag a Cr-specific caution: phosphorus-loaded biochar can compete with Cr for binding sites because phosphate is a Cr analog in this system, and Cr bioavailability increased at day 45 in some treatments even though concentrations remained low.

Methods (brief)

Soil was collected from the north side of Universidad de Los Andes in Bogota, Colombia, sieved to 2 mm, characterized for pH, electrical conductivity, water-holding capacity, organic matter, nitrogen, cation exchange capacity, available phosphorus, and moisture, then split into three spiked metal soils. Biochar feedstocks were coffee husks and sugar-cane leaves pyrolyzed at 500 C; half of each material was activated with KOH, and all four biochars were phosphorus loaded with potassium phosphate.

Bioavailable Cd, Cr, and Pb were extracted with 0.01 M CaCl2 and measured by ICP-OES after microwave digestion using EPA 3051A and ICP-OES readings using EPA 6010D. Lolium perenne seedlings were grown in rhizoboxes and harvested at day 45, with stems and roots separated for metal analysis.

Implications

Certification: Do not use the source’s spiked-soil or plant-retention values in product occurrence pools. It supports mitigation evidence for soil immobilization and phytoremediation workflows.

Courses: The paper is useful for supplier and agricultural mitigation training because it compares coffee-husk and sugar-cane-leaf biochar amendments and documents a Cr caveat for phosphorus loading.

App: Context only. The source can inform mitigation explanations but does not estimate heavy metals in coffee, food, or consumer products.

Wiki pages this source may touch

• remediation-evidence
• agronomic
• cadmium
• chromium
• lead

Verification notes

• DOI, title, authors, journal, license, and year were taken from the ACS Omega PDF first page.
• Products and ingredients are intentionally empty because the study uses spiked soil and remediation matrices; the coffee-husk feedstock does not make this coffee occurrence evidence.
• The source reports total Cr in the remediation experiment. It does not establish Cr-VI occurrence in any product matrix.
• sample_n: 15 reflects Table 4’s enumeration of 15 experimental units (three metal groups × five treatments per group: one nonbiochar blank plus four P-loaded biochar amendments). Section 4.3 of the paper states “12 samples were obtained as shown in Table 4,” which is an internal text/table inconsistency in the source; the wiki adopts the Table 4 count because that is the per-unit experimental enumeration and matches the 3 × 5 design described in Section 4.1.
• mitigation/supply-chain-screening was not included as a touched page: that category covers sourcing-side interventions (geographic risk segmentation, pre-purchase soil testing, incoming-batch screening) on natural-contamination distributions, whereas this paper is bench-scale post-hoc remediation of deliberately spiked soil.

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.