Pollution affects plant growth in many harmful ways, depending on the type and level of pollutants present in the air, water, or soil. Here’s how different kinds of pollution can impact plants:
1. Air Pollution:
- Sulfur dioxide (SO₂), nitrogen oxides (NOₓ), and ozone (O₃) damage leaves by entering through the stomata. They can cause yellowing, browning, or necrosis (dead spots) on leaves.
- Ozone especially harms the photosynthetic machinery, reducing the plant’s ability to make food.
- Particulate matter (dust, soot, smoke) can block sunlight and clog stomata, reducing photosynthesis and respiration.
- Prolonged exposure to polluted air weakens plants, making them more vulnerable to diseases and pests.
2. Water Pollution:
- Polluted water containing industrial chemicals, heavy metals (like lead, mercury, and cadmium), or acidic runoff can poison plants and inhibit root growth.
- Excess fertilizers or sewage in water cause eutrophication, leading to oxygen deficiency and the accumulation of toxic substances in soil and plants.
- Salinity from polluted irrigation water interferes with water absorption, leading to wilting and stunted growth.
3. Soil Pollution:
- When soil contains toxic chemicals, pesticides, or heavy metals, plants absorb them through their roots. These substances interfere with nutrient uptake and can cause deformation, reduced germination, or even death.
- Pollutants disturb the activity of soil microbes, including beneficial organisms like mycorrhizal fungi, reducing soil fertility.
4. Acid Rain:
- Acid rain (caused by SO₂ and NOₓ) lowers soil pH, washing away essential nutrients like calcium and magnesium.
- It damages leaf surfaces, reducing photosynthesis and causing nutrient imbalance.
5. Reduced Photosynthesis and Growth:
- Pollution often damages chlorophyll, reducing a plant’s ability to produce food.
- As a result, plants grow slower, produce fewer flowers and fruits, and have weaker resistance to stress.
In summary:
Pollution harms plants by damaging leaves, contaminating soil and water, blocking photosynthesis, and disturbing nutrient uptake. Over time, this leads to reduced growth, lower yields, and sometimes plant death.