Plants, particularly their leaves, play a vital role in interacting with air pollutants through both physical and biological processes.
Plants absorb or remove pollutants primarily through their leaves via processes like adsorption and absorption. Additionally, microbes living on the leaf surface and within the leaves can further process certain pollutants.
Mechanisms of Pollutant Interaction
Plants utilize several methods to mitigate air pollutants. The most significant interactions occur at the leaf level.
- Adsorption: This is the process where gaseous or particulate pollutants stick to the outer surface of plant leaves. The rough or waxy cuticle of leaves provides a large surface area for pollutants to settle and adhere. Think of it like dust collecting on a surface.
- Absorption: Pollutants can also be taken into the plant tissues, primarily through stomata (tiny pores on the leaf surface used for gas exchange). Once absorbed, these pollutants can enter the plant's metabolic pathways or be stored in plant tissues. Gaseous pollutants like sulfur dioxide (SO2), nitrogen oxides (NOx), and ozone (O3) are commonly absorbed this way.
| Plant Part | Primary Interaction Type | Pollutant State | Notes |
|---|---|---|---|
| Leaves | Adsorption | Gaseous, Particulate | Pollutants stick to the surface. |
| Leaves | Absorption | Gaseous (primarily), Liquid | Pollutants enter plant tissue via stomata. |
The Role of Microbes
As highlighted in research, "Plant leaves are able to adsorb or absorb air pollutants, and habituated microbes on leaf surface and in leaves (endophytes) are reported to be able to biodegrade or transform pollutants into less or nontoxic molecules..."
This indicates that it's not just the plant itself but also the microbial communities associated with the leaves that contribute to pollutant reduction.
- Surface Microbes (Epiphytes): Bacteria and fungi living on the leaf surface can break down or change pollutants that have adsorbed onto the leaf.
- Internal Microbes (Endophytes): Microbes living within the leaf tissues can interact with pollutants that have been absorbed by the plant, transforming them into less harmful substances through biological processes called biodegradation or transformation.
While the potential of these microbes and the plants themselves for widespread air remediation is still being explored, the combination of physical adsorption/absorption by leaves and the biological action of associated microbes demonstrates multiple pathways through which plants interact with and reduce air pollutants.
