Microplastics Impair Photosynthesis in Freshwater, Marine, and Terrestrial Ecosystems

A research team from the Institute of Soil Science of the Chinese Academy of Sciences, in cooperation with Nanjing University, identified the negative effects of microplastic pollution on photosynthesis.

The study was led by Prof. Fei Dang from the Institute of Soil Science of the Chinese Academy of Sciences, in collaboration with Prof. Huan Zhong from Nanjing University.

The research provides a comprehensive evaluation of the impact of microplastic exposure on photosynthesis across freshwater, marine, and terrestrial ecosystems.

Microplastics, which are plastic particles smaller than 5 mm, are present in environments ranging from alpine glaciers to deep-sea sediments. Despite growing awareness of environmental threats, the effects of microplastics on photosynthesis at the ecosystem level have not been well understood.

Previous studies have produced inconsistent or fragmented results, due to the complexity of the environment, differences among the impacted photoautotrophs (such as plants and algae), and the heterogeneous nature of microplastics. This information gap presents a challenge to global efforts to achieve the United Nations’ Sustainable Development Goals (SDGs), particularly the Goals of Zero Hunger (#2), Good Health and Well-Being (#3), Responsible Consumption and Production (#12), and Life Below Water (#14).

The researchers quantified the global reduction in photosynthesis caused by microplastic exposure by analyzing 3,286 records through meta-analysis and machine learning techniques. The study found that microplastics decrease the photosynthetic efficiency of freshwater algae, marine algae, and terrestrial plants by 7.05–12.12 %. This corresponds to estimated global yearly losses of 4.11–13.52 % (109.73–360.87 MT·yr^-1) for major staple crops such as rice, wheat, and maize.

In addition, seafood production is expected to decrease by 1.05 to 24.33 MT·yr^-1, due to net primary productivity (NPP) losses of 0.31 to 7.24 %(147.52 to 3,415.11 MT C·yr^-1) caused by microplastic-induced suppression of photosynthesis in aquatic ecosystems. These figures underline the subtle but significant risk that microplastic contamination poses to global food security.

However, the study also offers a path toward mitigation. The researchers suggest that reducing environmental microplastic levels by 13 % could prevent global losses of 22.15–115.73 MT·yr^-1 in key crops and 0.32–7.39 MT·yr^-1 in seafood production, with an estimated 30 % reduction in photosynthetic losses.

The findings underscore the importance of addressing microplastic contamination, as it significantly impacts global primary productivity. The study stresses the need to integrate plastic pollution reduction methods into broader sustainability and food security initiatives. Furthermore, it calls for future field research to gather additional data on the scope and causes of microplastic-induced disturbances to photosynthesis.

With more high-quality field data and advances in remote sensing technologies, researchers can deepen their understanding of this emerging threat. This could provide valuable insights for supporting the UN SDGs and informing international plastic treaty discussions.

Journal Reference:

Zhu, R., et al. (2025) A global estimate of multi-ecosystem photosynthesis losses under microplastic pollution. PNAS. doi.org/10.1073/pnas.2423957122