Microplastics Increase Cadmium Absorption and Hinder Growth in Red Amaranth

Jim Crocker
27th June, 2024

Microplastics Increase Cadmium Absorption and Hinder Growth in Red Amaranth

The addition of polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS) microplastics visibly impaired the overall growth and biomass of Amaranthus tricolor seedlings when compared to the microplastic-free controls.

Image adapted from: Roy et al. / CC BY (Source)

Key Findings

  • The study was conducted by Christian-Albrechts-Universität zu Kiel on the effects of microplastics (MPs) and cadmium (Cd) on red amaranth
  • Different types and concentrations of MPs did not negatively affect seed germination but increased phytotoxicity and decreased stress tolerance
  • Polystyrene (PS) MPs reduced phosphorus and potassium uptake while increasing cadmium uptake in red amaranth, raising food safety concerns
Microplastic (MP) pollution in terrestrial ecosystems is increasingly recognized as a significant environmental issue, yet its effects on leafy vegetables, particularly when combined with heavy metals, remain underexplored. A recent study by Christian-Albrechts-Universität zu Kiel[1] delves into this issue, focusing on the impact of three types of MPs—polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS)—at various concentrations, in conjunction with cadmium (Cd) and biochar (B), on red amaranth (Amaranthus tricolor L.). The study found that different MP types and concentrations did not negatively affect germination parameters such as germination rate, relative germination rate, germination vigor, relative germination vigor, and germination speed. However, MPs increased phytotoxicity and decreased stress tolerance compared to untreated controls. This aligns with previous research indicating that MPs can undergo weathering, altering their physicochemical properties and potentially affecting their interaction with environmental pollutants and organisms[2]. One of the significant findings was that PS, in particular, reduced phosphorus and potassium uptake while enhancing Cd uptake in red amaranth. For instance, treatments with PS and Cd (PS0.02CdB, PS0.05CdB, and PS0.1CdB) increased Cd content in the seedlings by 158%, 126%, and 44%, respectively, compared to the treatment with Cd and biochar alone (CK2). This suggests that MPs might act as carriers for heavy metal absorption in plants, a finding that raises concerns about food safety and crop contamination. The study also observed that MP contamination led to reduced plant height, leaf dry matter content, and fresh and dry weights, indicating adverse effects on plant growth. This is consistent with earlier findings that plastic residues in soil can inhibit the viability of seed germination and negatively impact plant growth parameters such as height, leaf area, and biomass[3]. The presence of MPs increased bioconcentration factors and translocation factors for Cd, further highlighting the potential for MPs to exacerbate heavy metal uptake in plants. On a positive note, the addition of biochar improved several root parameters, including root length, volume, surface area, and the number of root tips in the presence of MPs. This suggests that biochar could offer a mitigation strategy to counteract the negative effects of MPs and heavy metals on plant growth. Previous studies have highlighted the need for research into the long-term weathering of MPs and their interactions with environmental components such as natural organic matter and biofilm[2], and this study adds to that body of knowledge by exploring biochar's role in mitigating these interactions. In summary, the research conducted by Christian-Albrechts-Universität zu Kiel reveals that the combination of MPs and Cd reduces plant growth and increases the risk of heavy metal contamination in food crops. This underscores the need for further research to understand how different MP types and concentrations affect various plant species, which will aid in developing targeted mitigation strategies. Additionally, exploring the potential of biochar application in conjunction with other amendments could be key to addressing MP and heavy metal contamination in agricultural systems.

AgricultureEnvironmentPlant Science

References

Main Study

1) Microplastics increase cadmium absorption and impair nutrient uptake and growth in red amaranth (Amaranthus tricolor L.) in the presence of cadmium and biochar

Published 26th June, 2024

https://doi.org/10.1186/s12870-024-05312-0

Related Studies

2) Effect of weathering on environmental behavior of microplastics: Properties, sorption and potential risks.

https://doi.org/10.1016/j.chemosphere.2019.125193

3) Effects of plastic particles on germination and growth of soybean (Glycine max): A pot experiment under field condition.

https://doi.org/10.1016/j.envpol.2020.116418


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