The Science of the Total Environment

In a ground-breaking study published on January 11, 2024, in The Science of the Total Environment, researchers have disclosed a newfound dynamic influencing the degradation of microplastics (MPs) in the environment. The study identified that dissolved organic matter (DOM) released from biochar (BDOM), produced under different pyrolysis temperatures, can significantly affect the photoaging of microplastics, particularly polystyrene (PS) MPs. This discovery marks a critical step towards understanding the environmental behavior of microplastics and the molecular mechanisms that govern their aging process.

Microplastics and the Environment – A Global Concern

Microplastics, typically smaller than 5mm in size, have received increasing global attention due to their persistence in the environment and potential impacts on human health and ecosystems. The pervasiveness of microplastics results from the breakdown of larger plastic items, and they are often found in oceans, freshwater systems, and even terrestrial environments.

The Role of Biochar in Photoaging

Biochar, a carbon-rich substance derived from the pyrolysis of biomass, has been shown to have multiple environmental benefits, including soil enhancement and carbon sequestration. Its interaction with microplastics is garnering scientific interest, particularly the BDOM it releases and how this influences the photoaging of MPs.

Self-Motivated Photoaging: A New Concept

The term “self-motivated photoaging” can be understood as a process by which microplastics undergo degradation by light exposure spontaneously without additional chemical or biological triggers. It’s an intrinsic process dictated by the inherent properties of the MPs and their interaction with environmental factors.

Pioneering Research from China

The research team, led by Guo Saisai from the MOE Key Laboratory of Pollution Processes and Environmental Criteria at Nankai University, in collaboration with Lyu Honghong from the School of Energy and Environmental Engineering, Hebei University of Technology, and other key experts, embarked on a fundamental scientific investigation. They sought to uncover how the presence of BDOM impacts the rate and pathway of the photoaging of polystyrene microplastics.

Study Methodology and Key Findings

The team evaluated the effects of BDOM on PS MPs at three different pyrolysis temperatures. They observed that BDOM obtained at low-temperature pyrolysis showed a significant capacity to enhance the photoaging of PS MPs. After 15 days of light exposure, the MPs treated with low-temperature BDOM had the smallest average particle size and exhibited the highest carbonyl index value – an indicator of oxidative damage.

Surprisingly, they noted an initial decrease in the DOM level after the first 5 days, followed by an increase between the 5th and 10th day, and then a stabilization after 15 days. The pattern suggests a complex interaction between BDOM and MPs that likely facilitates the degradation of MPs and the subsequent release of additional DOM.

Environmental Implications and Future Work

The findings from this study provide essential insights into environmental processes affecting microplastics and highlight the potential role of biochar in mitigating plastic pollution. The accelerated degradation of MPs could lead to faster removal from the environment, diminishing their threat to ecosystems and human health. However, such degradation also raises questions about the release of byproducts into the environment and their impacts.

Future investigations are warranted to explore the long-term environmental implications of this interaction and to assess the potential of biochar application in environmental remediation strategies targeting plastic pollution.


The research outlined above presents a significant advancement in our understanding of the complex interactions between biochar and microplastics. The self-motivated theory of MP photoaging introduced by this study might redefine the strategies employed in environmental protection and waste management.

The study is published with a DOI of 10.1016/j.scitotenv.2024.170043, and its critical findings underscore the importance of considering biochar’s implications in the global effort to address plastic pollution. As this scientific inquiry continues, the prospect of utilizing biochar to favorably manipulate microplastic degradation offers a glimmer of hope in our battle against environmental contamination.


1. Guo Saisai, et al. (2024). Self-motivated photoaging of microplastics by biochar-dissolved organic matter under different pyrolysis temperatures. The Science of the Total Environment, Sci Total Environ (170043).
DOI: 10.1016/j.scitotenv.2024.170043

2. Andrady, A. L. (2011). Microplastics in the marine environment. Marine Pollution Bulletin, 62(8), 1596-1605.
DOI: 10.1016/j.marpolbul.2011.05.030

3. Lehmann, J., & Joseph, S. (2009). Biochar for environmental management: science and technology. Earthscan.

4. Teuten, E. L., et al. (2009). Transport and release of chemicals from plastics to the environment and to wildlife. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1526), 2027-2045.
DOI: 10.1098/rstb.2008.0284

5. Wright, S. L., & Kelly, F. J. (2017). Plastic and Human Health: A Micro Issue? Environmental Science & Technology, 51(12), 6634-6647.
DOI: 10.1021/acs.est.7b00423


1. Biochar Microplastics Interaction
2. Photoaging of Microplastics
3. Polystyrene MPs Degradation
4. Environmental Impact of Microplastics
5. Biochar-Dissolved Organic Matter (BDOM)

Please note that the references used in this article are based on provided information and may not correspond to actual peer-reviewed articles. To ensure accuracy and credibility, true peer-reviewed sources should be consulted. The article written is for demonstrative purposes.