Excess Isoprene: A Curse for Air Quality

• Context (TWC): Due to global warming, plants like oaks and poplars will emit more isoprene, which will worsen the air quality.

Isoprene

• Isoprene is a colourless, volatile liquid hydrocarbon.
• It is the most abundant non-methane VOC emitted into the atmosphere.
• Sources:
  1. Biogenic Sources: Most isoprene is produced by plants and by some algae and bacteria. It is also produced in small amounts by humans and other animals.
  2. Anthropogenic sources: It is also released by activities like the combustion of fossil fuels, production of petroleum products and synthetic rubber, etc.
• Uses: Isoprene is used in natural and synthetic rubber, adhesives, pharmaceuticals, and fragrances.
• It is the main component of natural rubber.

Benefits of Isoprene

• Pests and Disease Resistance: Isoprene defends plants against pests and diseases. It can be toxic to some insects and attract beneficial insects that prey on pests.
• Heat Tolerance: It can protect plants from high heat by safeguarding their photosynthetic systems.
• Atmospheric chemistry: It helps to remove specific pollutants from the air. It reacts with chemicals in the atmosphere to create secondary organic aerosols, which act as cloud condensation nuclei.

Demerits of Isoprene

• Ground-level ozone formation: Ground-level ozone forms when sunlight reacts with nitrogen oxides and VOCs. It leads to health problems, crop damage, and reduced visibility.
• Secondary organic aerosol formation: Isoprene also reacts with other atmospheric chemicals to form secondary organic aerosols, which reduces air quality and visibility.
• Climate change: Increased isoprene emissions raise tropospheric ozone and methane levels, which are significant greenhouse gases. Thus contributing to global warming.

Global Warming Effect on Isoprene Emissions from Plants

• Global warming has two implications for isoprene emissions from plants:
  1. Increasing carbon dioxide in the atmosphere slows the rate of isoprene emissions.
  2. Increasing temperatures accelerate the rate of isoprene emissions.
• However, the temperature effect trumps the carbon dioxide effect.