Abstract:

Microplastics are becoming one of the important emerging pollutants that threatens the safety of the global water ecosystem. Microplastics have attracted great attention from countries all over the world. When microplastics enter the freshwater environment, they are not only easy to form biofilms on the surface, but also easy to contact with the existing biofilms in the water. However, there is still a lack of research foundation for the study of the interaction between microplastics and biofilms in freshwater. In this paper, the distribution of microplastics in freshwater, the effects of biofilm on the migration and transformation of microplastics, and the effects of microplastics on the microbial community structure of biofilms were systematically reviewed. The effects and potential mechanisms of microplastics on ecological functions such as carbon and nitrogen cycling of biofilms were revealed. Microplastics are widely distributed in freshwater rivers and lakes. The interaction between biofilms and microplastics could significantly alter the properties of microplastics, thereby affecting their environmental behavior and fate in aquatic ecosystems. Biofilms could enrich microplastic particles, increase the speed and depth of microplastic sedimentation, and accelerate the degradation of microplastics. Microplastics in the environment not only have toxic effects on biofilms, leading to negative effects such as slow growth, but also alter the microbial community, enzyme activity and functional gene abundance of biofilms. Microplastics could enhance the carbon cycling function of biofilms by acting as the carrier and carbon source of biofilms, but they also cause biofilms to be damaged and weaken its carbon cycling function. Microplastics could change the living environment of biofilms, the total amount of biofilms, and the enzyme activity and gene abundance related to nitrogen metabolism, thereby affecting the nitrogen cycling function of biofilms. This study proposes that it is necessary to carry out in-depth research on the kinetic process of biofilm adsorption and degradation of microplastics, the internal mechanism of “water-sediment-organism” migration and transformation of microplastics influenced by biofilms, and microbial community structure and function during carbon and nitrogen cycling of biofilms influenced by microplastics under real aquatic ecological conditions. This paper aims to deeply evaluate the potential impacts and risks of microplastic pollution in freshwater ecosystems.

Key words: microplastics, biofilms, pollution status, migration transformation, microbial community, ecological effects

摘要：

环境中微塑料正成为威胁全球水生态系统安全的重要新兴污染物之一，受到世界各国的高度重视。微塑料进入淡水环境中，不但表面容易形成生物膜，而且容易与水体中已存在生物膜发生接触。但目前针对淡水中微塑料与生物膜的相互作用及影响研究尚缺乏坚实基础。文章系统综述了淡水中微塑料分布状况、生物膜对微塑料迁移转化的影响、微塑料对生物膜微生物群落结构的影响，揭示了微塑料对生物膜碳氮循环等生态功能的影响与潜在作用机理。微塑料广泛分布在淡水河流湖泊中，生物膜和微塑料之间的相互作用可以显著改变微塑料的性质，进而影响微塑料在水生态系统中的环境行为和归趋。生物膜可以富集微塑料颗粒，增加微塑料沉降的速度和深度，加快微塑料的降解。环境中的微塑料，不但对生物膜起到毒害作用，导致生物膜出现生长减缓等负面影响，还会改变生物膜微生物群落结构，影响微生物酶活性和功能基因丰度等。微塑料可以通过作为生物膜的载体和碳源等途径增强生物膜碳循环功能，但也会导致生物膜因受损而减弱其介导的碳循环功能。微塑料还可以改变生物膜的生存环境、生物膜总量以及氮代谢相关的酶活性和基因丰度，进而影响生物膜氮循环功能。该文提出需在真实水生态条件下，开展生物膜对微塑料吸附、降解的动力学过程及其影响微塑料的“水-沉积物-生物体”迁移转化的内在机理、微塑料对生物膜碳氮循环功能微生物群落结构与功能的深入研究，以深入评估微塑料污染对淡水生态系统的潜在影响及风险。

关键词: 微塑料, 生物膜, 污染现状, 迁移转化, 微生物群落, 生态效应