Editor: Yang Xiangyu Proofreading: Zhang Lu
Micro (nano) plastics refer to plastic particles , films, fragments, pellets and textile fibers with particle sizes ranging from tens of nanometers to several millimeters, which are dispersed in the environmental medium. It is often difficult to distinguish with the naked eye. In 2004, the article "Lost at Sea: Where Is All the Plastic? " published in the journal Science first proposed the concept of microplastics . In 2014, the first United Nations Environment Conference pointed out that special attention should be paid to environmental micro (nano) plastics. At the second United Nations Environment Conference in 2015, micro (nano) plastic pollution was listed as the second major scientific issue in the field of environmental and ecological research, becoming a major global issue alongside global climate change and ozone depletion. Environmental issues.
Constructed Wetlands are a sewage treatment system that simulates the water purification process of natural wetlands and also has the function of landscaping. Microorganisms are an important part of constructed wetlands, and the degradation and transformation of pollutants are mainly completed by microorganisms. The wetland system is considered an ideal barrier to intercept micro (nano) plastics from entering the water body - Micro (nano) plastics can be intercepted in the constructed wetland along with the sewage, reducing the pollution of the downstream water ecosystem. But what impact will long-term accumulation of micro (nano) plastics have on microorganisms in constructed wetlands? Under the continued influence of micro (nano) plastics, will the sewage treatment function of constructed wetlands change?
Recently, Ju Feng’s research group from the School of Engineering of West Lake University and Chen Yi’s research group from the School of Environment of Chongqing University conducted collaborative research, using a small test device of constructed wetlands to simulate the wetland water purification system, focusing on the wetland microbiome and the denitrification process of the system , using high-throughput sequencing and network analysis and other molecular ecology and bioinformatics methods have analyzed the dynamic changes in the microbial community structure during the accumulation of micro (nano) plastics of different particle sizes and concentrations in the wetland system. and the response of microbial nitrogen metabolism function. The research results of were published in the top international journal "Water Research" in the field of environment on May 19. The first authors are Yang Xiangyu, a visiting student of of West Lake University and a doctoral student in the School of Environment of Chongqing University, and Dr. Zhang Lu of West Lake University, Communications The authors of are Professor Ju Feng from the School of Engineering of West Lake University and Professor Chen Yi from the School of Environment of Chongqing University.
Wetland systems are an ideal barrier to intercept micro-nano plastics entering water bodies.
Constructed wetlands, as sewage treatment systems or riverbank buffers, are considered an important barrier to prevent pollutants from entering open waters. A large number of micro (nano) plastics that actually exist in various environmental media are continuously collected into the sewage system and surface runoff through sewage discharge and rainwater erosion. Finally, they will flow through the wetland system, be intercepted and purified, and then enter the downstream water body. Chongqing University Professor Chen Yi’s team has confirmed through preliminary research that constructed wetlands have good microplastics (96.7%-99.6%, DOI: 10.1016/j.watres.2022.118430) and nano-sized particles (83.8%-86.6%, DOI : 10.1016/j.jhazmat.2019.121376) interception capability.
Figure 1 Actual and schematic diagram of the constructed wetland experimental device
Ju Feng’s scientific research team and Professor Chen Yi’s team jointly carried out a study on nitrogen transformation and microbial community during the accumulation process of micro (nano) plastics in the constructed wetland system during the establishment of the inter-school cooperation framework. Exploring the response mechanism of dynamic succession and construction models in order to enhance the application potential of constructed wetlands in controlling micro (nano) plastic pollution in water bodies.
The impact of accumulation of micro-nano plastics on the denitrification efficiency of wetland systems
Denitrification is an important water purification process in constructed wetlands. It mainly uses functional microorganisms such as nitrification and denitrification to remove nitrogen in sewage to prevent water eutrophication. . The research team found that short-term accumulation of millimeter/micron-sized plastic particles can promote the nitrification process in the wetland system, but long-term accumulation will have a negative impact , and the degree of impact increases as the size of the plastic particles decreases; The accumulation of nano-sized plastic particles It always has an inhibitory effect on the nitrification process of the wetland system .And promotes the accumulation of millimeter/micron-sized plastic particles in the denitrification process, but nanoplastics will inhibit the denitrification process , causing the accumulation of (sub) nitrate . However, what is interesting is that this negative impact will Gradually disappear after adaptation to the wetland system. In response to the above-observed changes in wetland denitrification efficiency, the research team further explored the response mechanism of the wetland microbial community.
Figure 2 Changes in denitrification efficiency of constructed wetlands
Impact of micro-nano plastic accumulation on wetland microbiome
Through the sampling and analysis of microorganisms in the wetland system during the 300-day experiment, it was found that the microbial community structure changed significantly with the accumulation of micro (nano) plastics. Variety. Overall, long-term accumulation of micro (nano) plastics in wetland systems can lead to a decrease in microbial richness and diversity . Both plastic particle size and concentration will affect the degree of interference to the biofilm microbial community, with the particle size factor having a greater impact than the concentration factor.
Figure 3 Changes in the diversity of microbial communities in wetland systems
Based on co-occurrence network analysis of microbial communities, it was found that under plastic treatment conditions from micron to nanoscale, microbial symbiosis patterns (especially species separation) do not change randomly, but It is controlled by the particle size and concentration of plastic particles.. Micro (nano) plastics make the co-occurrence network model of microorganisms in the wetland system show the "small world" attribute; at the same time, the degree of co-occurrence of denitrification functional microorganisms and other microorganisms increases, that is, they may interact more closely, indicating that the denitrification function in the wetland system Under the interference of micro (nano) plastics, microorganisms may adapt to changes in their ecological niche through changes in interaction relationships.
Figure 4 The co-occurrence network of denitrifying microorganisms and other microorganisms in the wetland system
By analyzing the dynamic succession of bacterial communities in the wetland system, the research team found that nanoplastics are effective against most nitrifying bacteria (such as Nitrospira and Nitrosomonas). showed a significant inhibitory effect, but had no obvious effect on most denitrifying bacteria ; the abundance of most nitrifying bacteria (such as Nitrospira and Nitrosomonas) and denitrifying bacteria (such as Dechloromonas, Thauera and Zoogloea) in the millimeter and micron plastic treatment groups There is an upward trend in the later stages of plastic accumulation.
Figure 5 Dynamic succession of microorganisms in the wetland system
Finally, the research team conducted a functional prediction analysis of the nitrogen metabolism process based on the 16S ribosome RNA gene composition of the microbial community and found that the denitrification enzyme gene (EC 1.7.2.1, EC1.7.2.5, EC1.7.2.4) was significantly enriched in the micron particle size plastic treatment, which again shows that larger particle size plastics may promote the denitrification process. In addition, the abundance of key enzyme genes for the nitrogen fixation process and the dissimilation and reduction of nitrite to ammonia was reduced under the long-term cumulative influence of nanoplastics.
Figure 6 Prediction of microbial nitrogen metabolism function
The research experiment lasted for 300 days. Through long-term research, a comprehensive analysis of the efficiency and microbial community response of the engineering system simulating sewage treatment was conducted. The research results provide important evidence that plastic particles change the sewage treatment efficiency of constructed wetlands, and deeply reveal the microbial community response mechanism behind them , providing a basis for the management and optimization of constructed wetlands and other water treatment engineering systems affected by micro (nano) plastics. Provides important ideas.
Research Group Introduction and Recruitment Information
Environmental microbiomics studies all microorganisms in the environment and their genetic information . Its methodological basis and theoretical expansion and application are international academic frontiers and hot spots. Key scientific issues include: 1) How to comprehensively and efficiently quantify Identifying microbial communities? 2) How do communities build and determine their functions? 3) How can their functions be precisely designed and targeted? The research interests of the Environmental Microbiome and Biotechnology Laboratory (EMBLab) of West Lake University include: 1) Environmental biotechnology and synthetic microbiome; 2) Microbial community construction mechanism and functional principles; 3) Antibiotic resistance group Formation mechanism and risk prevention and control; 4) Degradation and transformation mechanism and health effects of new pollutants (plastics and drugs).The
laboratory is currently recruiting 3 postdoctoral fellows in any direction: plastic degradation, waste water recycling, microbiology, virology, and drug resistance. Scientific research assistant position: Microalgae water treatment, microbiology , bioinformatics, new pollutants, environment DNA direction. Welcome to contact us.
Contact email:
Introduction to the leader of the research group
Professor Ju Feng
Ju Feng, researcher, doctoral supervisor, Westlake University, head of Environmental Microbiome and Biotechnology Laboratory , deputy director of the Zhejiang Provincial Key Laboratory of Coastal Environment and Resources Research. He currently serves on the editorial board of SCI journals such as Engineering, Front Microbiol, and Eng Life Sci of the Chinese Academy of Engineering, and as a youth editorial board member of journals such as Crit Rev Environ Sci Technol, J Environ Sci, Environ Sci Ecotechnol, The Innovation, and iMeta. He once served as an international review expert for the Natural Sciences and Engineering Council of Canada (NSERC). Obtained a PhD in Engineering from the University of Hong Kong in 2015. From 2015 to 2018, he engaged in postdoctoral research on microbial ecology and antibiotic resistance at the Swiss Federal Institute of Water Science and Technology (EAWAG). From 2018 to now, he has served as a distinguished researcher at Westlake University. He has won the "Editorial Annual Contribution Award" of Engineering, a journal of the Chinese Academy of Engineering (2021), the "Shui Yuntian Microbial Ecology Youth Science and Technology Innovation Award-Special Award" of the Chinese Ecological Society (2018), the "Young Scientist Award" of the Hong Kong Science Society (2016), "Outstanding Postgraduate Award" of the University of Hong Kong (2015). In the past three years, he has hosted or participated in 4 national or provincial or ministerial level scientific research projects; he is currently co-editing 4 Chinese and English monographs, and has published more than 50 papers in well-known academic journals such as ISME J, Adv Sci, Microbiome, Environ Sci Technol, Water Res, etc. , cited more than 3,800 times. Introduction to
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