Gao et al. 2023 - Kenaf and Sedum rotation for contaminated farmland phytoremediation

Gao and colleagues tested whether rotating kenaf with the Cd/Zn hyperaccumulator Sedum plumbizincicola could improve removal of cadmium, copper, lead, and zinc from contaminated farmland in Hunan, China. The source is primary field evidence for soil-remediation and supply-chain mitigation context, not food occurrence evidence: the measured plants were phytoremediation/industrial-biomass crops grown on land described as no longer suitable for food crops.

Key numbers

Contaminated field baseline

Table 1 reports the experimental soil as loamy clay with pH 5.70 and the following total metal concentrations:

The site was in Yonghe Town, Liuyang City, Hunan, in a former nonferrous-metal-resource area. The authors state that the farmland was seriously contaminated with Cd, Pb, Cu, and Zn.

Plant biomass and metal concentrations

Average biomass under combined contamination was 7700 kg/ha aerial and 1003 kg/ha root for S. plumbizincicola, compared with 19,256 kg/ha aerial and 3084 kg/ha root for kenaf. The conclusion summarizes aerial biomass as 7.5-7.9 Mg/ha for S. plumbizincicola and 17-21 Mg/ha for kenaf.

Figure 2 and the text report that Cd concentrations in S. plumbizincicola were >480 mg/kg in aerial parts and >330 mg/kg in roots, while both kenaf compartments were <6 mg/kg. Zn concentrations in S. plumbizincicola ranged from 13,296 to 13,993 mg/kg in aerial parts and 9830 to 10,573 mg/kg in roots; kenaf Zn concentrations were no more than 180 mg/kg. The authors state that Cd, Cu, Pb, and Zn concentrations in S. plumbizincicola were at least 100-, 2-, 8-, and 75-fold higher, respectively, than in kenaf.

S. plumbizincicola removed >3800 g/ha Cd, >720 g/ha Pb, and >104,347 g/ha Zn, at least 38-, 3-, and 27-fold higher than kenaf for those metals. Compared with S. plumbizincicola monoculture, the Sedum-kenaf rotation increased metal removal by 7.88% for Cd, 126% for Cu, 33.5% for Pb, and 4.39% for Zn.

Translocation and bioconcentration factors

Table 2 reports translocation factors (TF) and bioconcentration factors (BCF):

The authors conclude that both species performed better for Cd and Zn than for Cu and Pb, and that kenaf’s remediation ability is negligible for Cd and Zn compared with S. plumbizincicola despite kenaf’s much larger biomass.

Methods (brief)

The field trial used three treatments: S. plumbizincicola monoculture, kenaf monoculture, and S. plumbizincicola-kenaf rotation, each replicated four times in 4 m by 1.5 m plots. S. plumbizincicola was planted in November 2020; kenaf was sown in May 2021 after Sedum harvest in the rotation treatment. A compound N-P2O5-K2O fertilizer and urea were applied to each season; fertilizer brand names are omitted.

Soils were sampled before and after the experiment. Total soil metals were measured by ICP-OES after HF-HClO4-HNO3 digestion. Soil fractions were extracted with a modified BCR sequential extraction. Plant samples were collected at anthesis, separated into roots and aboveground biomass, oven-dried, ground, nitric-acid digested by microwave digestion, and analyzed by ICP-OES. The paper reports means of four plot replications and compares treatments using Duncan’s test at p ⇐ 0.05.

Implications

Certification: This paper should not contribute to edible-crop product pools. It supports supply-chain mitigation decisions for contaminated farmland: remediation cropping can remove substantial Cd and Zn, but the remediating biomass is heavily contaminated and must be kept out of food and feed channels.

Courses: Useful case study for the difference between phytoremediation crop success and food safety. A plant that removes metals efficiently is, by definition, a high-metal biomass stream requiring controlled disposal or industrial-only use.

App: Route as contaminated-farmland and phytoremediation context for Cd, Cu, Pb, and Zn. Do not route kenaf/Sedum plant-tissue concentrations to food ingredient pages.

Wiki pages this source may touch

• cadmium
• copper
• lead
• zinc
• soil-to-plant-transfer

Verification notes

The PDF has author attribution and DOI 10.3390/agronomy13051231; no DOI conflict was observed. This is a primary field study, but the matrices are contaminated soil and non-food phytoremediation biomass, not food, feed, or consumer-product matrices. No ingredients or products are listed in frontmatter for that reason. The source uses total elemental Cd, Cu, Pb, and Zn; no speciation issue arises. Values from Figures 1-4 are partly graphical; the page quotes exact numeric values only where the PDF text or Table 2 provides them directly.

2026-06-02 enhancement: replaced non-standard matrix slugs (contaminated-farmland-soil, phytoremediation-biomass, kenaf, sedum-plumbizincicola) with the recognized vocabulary entries agricultural-soil and plant-tissue. Both terms appear in the _no_route block of data/evidence/matrix-to-product-map.json, so the routing layer correctly ignores them rather than emitting false product routes. Plant-species identifiers (kenaf, Sedum plumbizincicola) are not matrix categories and have been dropped from frontmatter; the species names remain in the body where they belong.

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.