Plants are more photosynthetic “productive” on weekends due to cleaner air

New research shows that plants in Europe photosynthesize more on weekends because there is less pollution in the air. The related paper was published in the Proceedings of the National Academy of Sciences (PNAS) of the United States on November 20. Photosynthesis, the chemical reaction by which plants obtain energy from the sun and convert carbon dioxide and water into sugar, represents the "productivity" of an ecosystem. As air pollution becomes increasingly serious, LiyinHe and her colleagues at the Carnegie Institution for Science wanted to understand the impact of air quality on photosynthesis.

The researchers analyzed satellite measurements between 2018 and 2021 of the amount of light emitted by chlorophyll in plant leaves in Europe, which represents the amount of photosynthesis occurring. By comparing it with satellite measurements of air pollution over the same period, they found that photosynthesis rates increased when aerosol levels were lower.

Aerosols are a type of pollution that includes dust and smoke from wildfires and human activity. Aerosols prevent sunlight from reaching the Earth's surface, affecting plants' ability to photosynthesize. When there is less aerosol pollution in the atmosphere, more sunlight can reach plant leaves.

Aerosol pollution from road vehicles can limit the photosynthetic capacity of plants. Source: Aleksei Gorodenkov/Alamy

The researchers found that photosynthesis rates were higher on weekends in 64% of Europe. "There is less traffic and industrial activity on weekends, and the air is cleaner than during the week, so we see a strong 'weekly cycle,'" He said.

Additionally, aerosol pollution was significantly reduced in 2020 compared to other years due to the covid-19 pandemic, so during this year, plants were "productive" throughout the week.

Research shows that reducing aerosol levels, especially those generated during transportation or industrial processes, could allow plants to capture and store more carbon.

"Improving air quality is not only good for people's health, but it's also very good for ecosystem productivity," He said.