The response of some hyperaccumulating and excluding plants towards some selected radionuclides

Some heavy metals are also radionuclides (RN) that are characterized as an unstable form of chemical elements. Their concentration decreases after radioactive decay with emission of charged alpha and beta subatomic particles and high energetic gamma-rays. ²³⁸U, ⁹⁰Sr, ¹³⁷Cs occur as radioactive isotopes as well as stable elements (Sr, Cs). ²³⁸U, ⁹⁰Sr and ¹³⁷Cs are radiotoxic elements. ²³⁸U, however, has also a great risk of chemical toxicity; this may even surpass the radiological toxicity because of the large physical half-life time (4.5×109a for ²³⁸U).

Radionuclide emissions to the biosphere include: 1) fallout from atmospheric bomb tests of the 1950s and 1960s and major nuclear accidents, e.g. Chernobyl (important isotopes are ¹³⁷Cs and ⁹⁰Sr and, sad to say, recently Fukushima in Japan), 2) satellite re-entry, 3) routine emissions to the atmosphere from reprocessing plants and nuclear power stations (¹³⁷Cs, ⁹⁰S) and 4) waste disposal sites (²³⁸U), (Naito and Smith, 1998; Ould-Dada et al, 2001, Greger, 2004). The enrichment of RN in soil, water and air represent a great danger for health and environment.

Toxicity of ²³⁸U, ⁹⁰Sr and ¹³⁷Cs so far has only rarely been examined for plants but previous studies already described important toxicity effects of these RN on growth, development and plant nutrition. Some known stress reactions induced by accumulation of RN: chlorosis, macronutrient deficiency, accumulation of ROS and oxidative stress.

Only few species have evolved sophisticated mechanisms to control metal homeostasis at the level of uptake, distribution, sequestration, and export and to survive in toxic environments better than others ("metal-tolerant plants").

Most higher plants are so-called excluders; apoplastic barriers, exo-and endodermis, Casparian bands and suberin lamellae or binding by phytochelatines in their root systems block the entry of HM into the plant system (Seregin and Kozhevnikova, 2007).

Topics to be addressed:

1.    Availability of RN and their uptake into metal-tolerant and excluder plants
2.    Macroscopic effects of RN on plant photosynthetic perfomance, leaf and root size
3.    Deposition of RN in different plant parts and tissues

Publications

Burger, A., Weidinger, M., Baumann, N., Vesely, A., Lichtscheidl, I. (2019). The response of the accumulator plants Noccaea caerulescens, Noccaea goesingense and Plantago major towards the uranium. Submitted in: Journal of the Environmental Radioactivity

Burger, A., Weidinger, M., Adlassnig, W., Puschenreiter, M. & Lichtscheidl, I. (2019). Response of Arabidopsis halleri to cesium and strontium in hydroponics: Extraction potential and effects on morphology and physiology. Ecotoxicology and Environmental Safety 184, 109625.
doi.org/10.1016/j.ecoenv.2019.109625

Burger, A., Weidinger, M., Adlassnig, W., Puschenreiter, M. & Lichtscheidl, I. (2019). Response of Plantago major to cesium and strontium in hydroponics: Absorption and effects on morphology, physiology and photosynthesis. Environmental Pollution. 254, 113084.
doi.org/10.1016/j.envpol.2019.113084

Burger, A., Lichtscheidl, I. (2019): Strontium in the environment: Review about reactions of plants towards stable and radioactive strontium isotopes. Science of the Total Environment 653, 1458–1512.
Doi.org/10.1016/j.scitotenv.2018.10.312

Burger A, & Lichtscheidl I (2017). Stable and radioactive cesium: A review about distribution in the environment, uptake and translocation in plants, plant reactions and plants' potential for bioremediation. Science of the Total Environment, 618, 1459-1485. 
DOI: 10.1016/j.scitotenv.2017.09.298