Phytoextraction
Phytoextraction (phytoremediation, фитоэкстракция) is an attempt to remove contaminants from soil by growing plants that accumulate these contaminants in their tissues.
For radioactive contamination, phytoextraction is often promoted as an “environmentally friendly” method of soil purification. However, published scientific data indicate that for most radionuclides the efficiency of phytoextraction is extremely low, usually lower than or comparable to natural radioactive decay. Therefore, in many practical cases, large phytoextraction programs serve primarily administrative, political, or economic goals rather than scientific ones.
Scientific background
Phytoextraction is based on three measurable quantities:
- BCF (Bioconcentration Factor):
the ratio of contaminant concentration in plant tissue to that in soil.
- TF (Translocation Factor):
the ratio of concentration in shoots to concentration in roots.
- E (Extraction efficiency per growing season):
the percentage of total soil inventory removed per cycle; depends on biomass × concentration.
In realistic outdoor conditions, E rarely exceeds a few percent per year, and often is below 1%.
Decay vs phytoextraction
Many dangerous radionuclides decay faster than plants can remove them:
| Isotope | Half-life | Typical extraction per year | Which is faster? |
|---|---|---|---|
| I-131 | 8 days | irrelevant | decay |
| Cs-137 | 30 years | 0.5–2% | decay |
| Sr-90 | 29 years | 1–5% (optimistic) | similar or decay |
| Pu-239 | 24,000 years | ~0% | none |
| Am-241 | 432 years | ~0% | none |
Thus, phytoextraction rarely accelerates decontamination of radioactive soil.
Case 1: Cesium (Cs-137)
Cesium behaves chemically like potassium. Most terrestrial plants actively exclude excess Cs from transport tissues.
Typical field numbers:
| Quantity | Value | Comments |
|---|---|---|
| Soil concentration (contaminated field) | 200–1000 Bq/kg | Fukushima, Belarus, Ukraine |
| BCF (shoot/soil) | 0.05–0.3 | very low |
| Extraction per season (E) | 0.5–2% | field results |
| Cycles needed for x10 reduction | 50–200 years | slower than decay |
Conclusion: Phytoextraction is scientifically ineffective for Cs-137.
Case 2: Strontium (Sr-90)
Strontium behaves chemically like calcium. Many plants absorb it somewhat more readily than cesium.
| Quantity | Value | Comments |
|---|---|---|
| BCF (shoot/soil) | 0.5–2 | better than Cs |
| Extraction per season | 1–5% | optimistic upper range |
| x10 reduction time (no decay) | 40–60 cycles | too slow for agriculture |
| Is half-life similar? | 29 years | yes |
Thus, even for Sr-90—which is the *best case* among major fission products— phytoextraction removes the contaminant **no faster than natural decay**.
Case 3: Uranium, Plutonium, Americium (actinides)
These radionuclides dominate environmental contamination after 100+ years.
| Isotope | Half-life | BCF | Extraction efficiency | Feasibility |
|---|---|---|---|---|
| U-238 | 4.5×10^9 y | 0.001–0.1 | <0.1%/yr | no practical extraction |
| Pu-239 | 24,000 y | <0.01 | <0.01%/yr | no |
| Am-241 | 432 y | <0.01 | <0.01%/yr | no |
Actinides bind strongly to soil particles and are biologically excluded. Thus, phytoextraction is effectively impossible.
Example: Scientific presentation (Strontium)
A fictional but realistic example illustrating scientific reasoning.
Speaker: “Five field plots were contaminated with Sr-90 at 310–330 Bq/kg. After one sunflower cycle (140 days), the control plots decreased to 300–305 Bq/kg, consistent with leaching and redistribution. The treatment plots decreased to 285–295 Bq/kg. Thus, the net removal due to phytoextraction is approximately 3% per cycle.”
Audience member: “What was the strontium concentration in the dried plant biomass?”
Speaker: “Between 650 and 1100 Bq/kg, depending on plot. This is consistent with BCF ≈ 1–1.5.”
Moderator: “How many cycles would be needed to reach 20 Bq/kg?”
Speaker: “Assuming 3% removal per cycle, roughly 50–60 years.”
Farmer: “I cannot grow unsellable sunflowers for sixty years.”
Speaker: “Yes, the method is scientifically valid but too slow to be practical.”
Non-scientific and fraudulent uses
Phytoextraction becomes pseudoscience when:
- no measurements of soil and plant concentrations are reported;
- extraction rates are not quantified;
- predictions exceed biological constraints;
- disposal of radioactive biomass is ignored;
- the program continues even when decay is faster than extraction.
In such cases, large phytoextraction projects are easily used for administrative theatrics or money laundering.
Warnings
- Phytoextraction often produces large volumes of concentrates (biomass) that are hotter than the original soil.
- Disposal of contaminated biomass is rarely addressed in public reports.
- Without quantification of BCF and extraction efficiency, “phytoextraction” is not a scientific activity.
Notes by Editor
The first complete version of this article has been generated with ChatGPT.
The later versions may significantly deviate from the original.
References
https://en.wikipedia.org/wiki/Phytoextraction_process Redirected from Phytoextraction) .. Phytoextraction is a subprocess of phytoremediation in which plants remove dangerous elements or compounds from soil or water, most usually heavy metals, metals that have a high density and may be toxic to organisms even at relatively low concentrations.[1] The heavy metals that plants extract are toxic to the plants as well, and the plants used for phytoextraction are known hyperaccumulators that sequester extremely large amounts of heavy metals in their tissues. [[Phytoextraction[[ can also be performed by plants that uptake lower levels of pollutants, but due to their high growth rate and biomass production, may remove a considerable amount of contaminants from the soil. ..
2014.01.01. https://link.springer.com/chapter/10.1007/978-3-319-07665-2_9 S. Mehdi Borghei, Reza Arjmandi, Roxana Moogouei. Bioaccumulation of Radionuclide Metals in Plants: A Case Study of Cesium. Chapter. First Online: 01 January 2014
2014.02.18. https://link.springer.com/article/10.1007/s12665-014-3111-2 Anika Kötschau, Georg Büchel, Jürgen W. Einax, Wolf von Tümpling & Dirk Merten1. Sunflower (Helianthus annuus): phytoextraction capacity for heavy metals on a mining-influenced area in Thuringia, Germany Original Article Published: 18 February 2014 Volume 72, pages 2023–2031, (2014) // Abstract // On an uranium-mining-influenced area, sunflowers (Helianthus annuus) were grown on a small-scaled plot. Subsamples of sunflowers were harvested 34, 66, 96, 108, 140, and 170 days after sowing. Contents of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Th, U, Zn, and rare earth elements (REEs, La–Lu) were determined in the sunflower shoots, as well as total and bioavailable contents of these 25 elements in the soil taken on the day of sowing and after the last harvest. Shoot contents alone were not sufficient to evaluate the extraction capacity of the sunflowers. Instead total extracted masses (product of biomass and element content) had to be calculated. The total extracted mass increased for most of the elements until 140 days after sowing. Bioconcentration factors (BCFs) as ratio between element content in shoot and soil, were calculated for this time to evaluate the phytoextraction efficiency. BCFs ≥1 (relating total soil contents) and thus a very effective extraction was calculated for Cd. The BCFs, based on mobile soil contents, were ≥1 for all elements, except for U and REEs (La–Lu). Consequently, the sunflower is able to extract many elements effectively from the direct harmful soil fraction. To reduce the contents of Cd and Ni down to levels, where the mining-influenced area could be classified as arable land would require 55 and 207 sunflower growth cycles. Although this is quite a long time, the uranium-mining-influenced area could be successively remediated, while growing biofuel crops, without interfering with food production.
2019.10.21. https://www.tandfonline.com/doi/abs/10.1080/15226514.2019.1566878 Yu Zhang & Gui-Jian Liu. Uptake, accumulation and phytoextraction efficiency of cesium in Gypsophila paniculata. International Journal of Phytoremediation Volume 21, 2019 - Issue 13 Original Articles // Pages 1290-1295 | Published online: 21 Oct 2019 Cite this article https://doi.org/10.1080/15226514.2019.1566878 To evaluate the phytoextraction efficiency of Gypsophila paniculata from Cs-contaminated soils and analyze the mechanism of Cs accumulation in G. paniculata, we analyzed the characteristics of Cs bioaccumulation and subcellular distribution, in addition to its chemical forms in the plant under hydroponic conditions. The results showed that total Cs content in the aboveground parts and the entire plant were as high as 6137.32 mg·kg−1 dry weight and 7338.49 mg·kg−1 dry weight, respectively, after 17 days in the 50 mg·L−1 Cs treatment. The BCF was between 2.35 and 3.38. The TF was between 1.00 and 2.46 in G. paniculata. Subcellular distribution of Cs in the plant was as follows: soluble fraction > cell wall > organelles. Inorganic Cs (F-ethanol) and water-soluble Cs (F-dH2O) were the main types of Cs in G. paniculata. Further studies show that the phytoextraction efficiency can reach 10.30–11.91% planting a season of G. paniculata under potted conditions. The results suggested that G. paniculata, a perennial, drought-tolerant herb, was a high-accumulator of Cs, which may have potential uses in phytoremediation of Cs-contaminated soil.
2020.08.01. https://www.sciencedirect.com/science/article/pii/S0959652620315389 Phytoremediation of uranium and cadmium contaminated soils by sunflower (Helianthus annuus L.) enhanced with biodegradable chelating agents Li Chen, Jin-yan Yang, Dan Wang. Journal of Cleaner Production Volume 263, 1 August 2020, 121491 Applying biodegradable chelating agents to assist in phytoremediation is a promising method to increase the remove efficiency of metal pollutants from contaminated soils. The effects of biodegradable chelating agents on improving the phytoremediation capacity in uranium (U) and cadmium (Cd) contaminated soil was investigated using sunflowers, which were grown in pots containing soil with U and Cd added at 15 mg/kg. After 2 months of growth, citric acid (CA), oxalic acid (OA) and ethylenediamine disuccinate (EDDS) at various concentrations (0, 2.5, 5.0 and 7.5 mmol/kg) were applied. The results showed that plant biomass decreased by 12.12% for shoot and 15.74% for root under U and Cd combined stress. Meanwhile, chelating agent treatments, especially with EDDS, enhanced U and Cd stress in plants by decreasing biomass, inhibiting photosynthesis, and increasing malondialdehyde and H2O2 levels. The U uptake of plants after CA addition was significantly greater than that after OA and EDDS addition. Nevertheless, EDDS addition has better effects on Cd uptake than CA and OA addition. U and Cd remove efficiencies reached the maximum following the application of 5.0 mmol/kg CA and 5.0 mmol/kg EDDS, which were 177.48% and 181.51% higher than that of the control, respectively. Furthermore, the bioavailable U content in soils treated with CA were higher than that in soils treated with EDDS, whereas bioavailable Cd content significantly increased due to EDDS addition. These results suggest that biodegradable chelating agents have significant effects on improving the U and Cd phytoremediation potential of sunflowers.
2025.11.17. https://www.tandfonline.com/doi/abs/10.1080/15226514.2025.2586803 Sun, M., Chen, X., Yang, C. H., Wen, Y. han, Fan, Y. meng, Feng, M. qin, … Li, Q. (2025). Phytoremediation of strontium by different sunflower cultivars (He$ Phytoremediation of strontium by different sunflower cultivars (Helianthus annuus L.): insights from accumulation traits and subcellular distribution. International Journal of Phytoremediation Published online: 17 Nov 2025
Keywords
«ChatGPT», «Chernobyl disaster», «Cesium», «Fukushima disaster», «Nuclear waste», «Phytoextraction», «Plutonium», «Polonium», «Strontium», «Uranium»