Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)?
In soil with extremely high contents of Cd (101.87), Pb (26,526.44), and Zn (17,652.63 mg kg<sup>−1</sup>), we aimed to test the phytostabilization capacity of purslane (<i>Portulaca oleracea</i>) with the use of various soil improvers, both organic (biochar, compost, insect...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-11-01
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| Series: | Agronomy |
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| Online Access: | https://www.mdpi.com/2073-4395/13/11/2827 |
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| author | Giorgos Thalassinos Efi Levizou Vasileios Antoniadis |
| author_facet | Giorgos Thalassinos Efi Levizou Vasileios Antoniadis |
| author_sort | Giorgos Thalassinos |
| collection | DOAJ |
| description | In soil with extremely high contents of Cd (101.87), Pb (26,526.44), and Zn (17,652.63 mg kg<sup>−1</sup>), we aimed to test the phytostabilization capacity of purslane (<i>Portulaca oleracea</i>) with the use of various soil improvers, both organic (biochar, compost, insect frass) and inorganic (lime and zeolite). Thus, in a 60-day pot experiment, we amended this heavily contaminated soil with the five materials at two rates, 2% and 4%, resulting in 11 treatments (control plus five materials × two rates) replicated 10 times. We found that soil extractions of Cd with DTPA (diethylenetriaminepentaacetic acid) were not affected by any of the amendments, as there was no recorded significant reduction in soil Cd. In the case of Pb, there were even significant increases in its extractability with added biochar, and so was the case for compost at 4%. The reason may be the formation of organometallic complexes with organic substances of low molecular weight eluted by the organic amendments. Similarly, Zn extractability increased significantly compared to the control in the compost and frass treatments. As for purslane shoots, Cd decreased from 61 μg kg<sup>−1</sup> fresh weight (FW) at control to 39 at biochar 4%, but the reduction was non-significant. As for Pb, it decreased with biochar but not significantly, while it exhibited a significant decrease in all other treatments. However, in all cases the content of Pb in purslane was well above the European regulation limit of 0.100 mg kg<sup>−1</sup> FW (fresh weight) for vegetables and fresh herbs, while Cd fell below the regulation limit of 50 μg kg<sup>−1</sup> FW at biochar 4%, compost 4%, and frass 2% and 4% (with control being 62.5 μg kg<sup>−1</sup> FW). We conclude that in heavily contaminated soils, although biochar, along with compost and frass, was not entirely unsuccessful, the tested amendments did not reduce satisfactorily toxic elements to sufficiently low levels both in soil and in the test plant (here, purslane) in order to achieve phytostabilization. However, further research is necessary to identify exact mechanisms and to elucidate the role of different biochars. |
| first_indexed | 2024-03-09T17:05:26Z |
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| id | doaj.art-6a22939a299c4b149a5f78b2356d8e1a |
| institution | Directory Open Access Journal |
| issn | 2073-4395 |
| language | English |
| last_indexed | 2024-03-09T17:05:26Z |
| publishDate | 2023-11-01 |
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| spelling | doaj.art-6a22939a299c4b149a5f78b2356d8e1a2023-11-24T14:24:11ZengMDPI AGAgronomy2073-43952023-11-011311282710.3390/agronomy13112827Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)?Giorgos Thalassinos0Efi Levizou1Vasileios Antoniadis2Department of Agriculture Crop Production and Rural Environment, University of Thessaly, GR-384 46 Volos, GreeceDepartment of Agriculture Crop Production and Rural Environment, University of Thessaly, GR-384 46 Volos, GreeceDepartment of Agriculture Crop Production and Rural Environment, University of Thessaly, GR-384 46 Volos, GreeceIn soil with extremely high contents of Cd (101.87), Pb (26,526.44), and Zn (17,652.63 mg kg<sup>−1</sup>), we aimed to test the phytostabilization capacity of purslane (<i>Portulaca oleracea</i>) with the use of various soil improvers, both organic (biochar, compost, insect frass) and inorganic (lime and zeolite). Thus, in a 60-day pot experiment, we amended this heavily contaminated soil with the five materials at two rates, 2% and 4%, resulting in 11 treatments (control plus five materials × two rates) replicated 10 times. We found that soil extractions of Cd with DTPA (diethylenetriaminepentaacetic acid) were not affected by any of the amendments, as there was no recorded significant reduction in soil Cd. In the case of Pb, there were even significant increases in its extractability with added biochar, and so was the case for compost at 4%. The reason may be the formation of organometallic complexes with organic substances of low molecular weight eluted by the organic amendments. Similarly, Zn extractability increased significantly compared to the control in the compost and frass treatments. As for purslane shoots, Cd decreased from 61 μg kg<sup>−1</sup> fresh weight (FW) at control to 39 at biochar 4%, but the reduction was non-significant. As for Pb, it decreased with biochar but not significantly, while it exhibited a significant decrease in all other treatments. However, in all cases the content of Pb in purslane was well above the European regulation limit of 0.100 mg kg<sup>−1</sup> FW (fresh weight) for vegetables and fresh herbs, while Cd fell below the regulation limit of 50 μg kg<sup>−1</sup> FW at biochar 4%, compost 4%, and frass 2% and 4% (with control being 62.5 μg kg<sup>−1</sup> FW). We conclude that in heavily contaminated soils, although biochar, along with compost and frass, was not entirely unsuccessful, the tested amendments did not reduce satisfactorily toxic elements to sufficiently low levels both in soil and in the test plant (here, purslane) in order to achieve phytostabilization. However, further research is necessary to identify exact mechanisms and to elucidate the role of different biochars.https://www.mdpi.com/2073-4395/13/11/2827heavy metalsphytomanagementsoil pollutiontoxic elements |
| spellingShingle | Giorgos Thalassinos Efi Levizou Vasileios Antoniadis Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)? Agronomy heavy metals phytomanagement soil pollution toxic elements |
| title | Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)? |
| title_full | Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)? |
| title_fullStr | Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)? |
| title_full_unstemmed | Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)? |
| title_short | Can Soil Improvers (Biochar, Compost, Insect Frass, Lime, and Zeolite) Achieve Phytostabilization of Potentially Toxic Elements in Heavily Contaminated Soil with the Use of Purslane (<i>Portulaca oleracea</i>)? |
| title_sort | can soil improvers biochar compost insect frass lime and zeolite achieve phytostabilization of potentially toxic elements in heavily contaminated soil with the use of purslane i portulaca oleracea i |
| topic | heavy metals phytomanagement soil pollution toxic elements |
| url | https://www.mdpi.com/2073-4395/13/11/2827 |
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