Phytoextraction and recovery of rare earth elements using willow (Salix spp.)

Muhammad Mohsin; Mir Md Abdus Salam; Nicole Nawrot; Erik Kaipiainen; Daniel J Lane; Ewa Wojciechowska; Niko Kinnunen; Mikko Heimonen; Arja Tervahauta; Sirpa Peräniemi; Olli Sippula; Ari Pappinen; Suvi Kuittinen

doi:10.1016/j.scitotenv.2021.152209

Phytoextraction and recovery of rare earth elements using willow (Salix spp.)

Sci Total Environ. 2022 Feb 25:809:152209. doi: 10.1016/j.scitotenv.2021.152209. Epub 2021 Dec 7.

Authors

Affiliations

¹ School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, P.O. Box 111, 80100 Joensuu, Finland.
² Gdansk University of Technology, Faculty of Civil and Environmental Engineering, Narutowicza 11/12, 80-233 Gdansk, Poland.
³ Department of Environmental and Life Sciences, University of Eastern Finland, Yliopistonranta 1E, P.O. Box 1627, 70211 Kuopio, Finland; Mineral Resources, Commonwealth Scientific and Industrial Research Organization (CSIRO), Queensland Centre for Advanced Technologies (QCAT), 1 Technology Court, Pullenvale, QLD 4069, PO Box 883, Kenmore, Australia.
⁴ Department of Chemistry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland.
⁵ Department of Environmental and Life Sciences, University of Eastern Finland, Yliopistonranta 1E, P.O. Box 1627, 70211 Kuopio, Finland.
⁶ School of Pharmacy, Biocenter Kuopio, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland.
⁷ Department of Environmental and Life Sciences, University of Eastern Finland, Yliopistonranta 1E, P.O. Box 1627, 70211 Kuopio, Finland; Department of Chemistry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland.
⁸ School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, P.O. Box 111, 80100 Joensuu, Finland. Electronic address: suvi.kuittinen@uef.fi.

PMID: 34883169
DOI: 10.1016/j.scitotenv.2021.152209

Abstract

Soil and water contaminations are caused by rare earth elements (REEs) due to mining and industrial activities, that threaten the ecosystem and human health. Therefore, phytoremediation methods need to be developed to overcome this problem. To date, little research has been conducted concerning the phytoremediation potential of Salix for REEs. In this study, two Salix species (Salix myrsinifolia and Salix schwerinii) and two Salix cultivars (Klara and Karin) were hydroponically exposed to different concentrations of six-REE for 4 weeks. The treatments were: T1 (Control: tap water), T2 (La: 50 mg/L) and T3 (La 11.50 + Y 11 + Nd 10.50 + Dy 10 + Ce 12 and Tb 11.50 in mg L^-1). The effects of the REE on Salix growth indicators (height, biomass, shoot diameter and root length), concentrations of REE in the produced biomass, and accumulation of REE in different parts of the Salix (stem, root, and leaf) tissues, were determined. In addition, the retention of REE in ashes following Salix combustion (800 and 1000 °C) was determined. The result indicates that with La and REE exposure, the height growth, dry biomass, shoot diameter and root length of all Salix remained equivalent to the control treatment excluding Klara, which displayed relatively higher growth in all parameters. Further, among the REE studied, the highest La concentration (8404 μg g^-1 DW) and La accumulation (10,548 μg plant^-1) were observed in Karin and Klara root respectively. Translocations and bioconcentration factors were discovered at <1 for all Salix, which indicates their phytostabilization potential. The total REE concentrations in bottom ashes varied between 7 and 8% with retention rates between 85 and 89%. This study demonstrates that Salix are suitable candidates for REE phytostabilization and the remediation of wastewater sites to limit metals percolating to the water layers in the ecosystem.

Keywords: Hydroponics; Metal recovery; Phytoremediation; Rare earth elements; Salix; Wastewater.

MeSH terms

Biodegradation, Environmental
Ecosystem
Humans
Metals, Rare Earth*
Salix*
Soil Pollutants* / analysis

Substances

Metals, Rare Earth
Soil Pollutants