微塑料对假单胞菌(Pseudomonas sp.) J-1参与下辉锑矿释放的影响

Microplastics affect the stibnite dissolution with participation of Pseudomonas sp. J-1

摘要:

微塑料是一种新型污染物，在海洋、土壤和大气环境中广泛存在，可通过物理、化学或生物作用影响污染物的迁移转化过程。矿业开采活动导致锑矿区周边水土环境的污染程度逐年升高，然而，目前针对矿区环境中微塑料对锑迁移转化影响的研究却鲜有报道。目的 了解微塑料的种类、粒径以及浓度对微生物介导辉锑矿释放的影响。方法 以具有高浓度锑耐性且能够促进辉锑矿释放的假单胞菌(Pseudomonas sp.) J-1，以及使用较广泛的聚丙烯、聚氯乙烯、聚苯乙烯3种微塑料为研究对象，通过对菌种生长过程中pH、氧化还原电位和菌落生物量变化进行分析，并定期监测锑释放量，结合不同pH下微塑料对锑的吸附实验以及激光共聚焦显微镜(confocal laser scanning microscopy, CLSM)和扫描电子显微镜-能量色散X射线光谱仪(scanning electron microscope-energy dispersive X-ray spectroscopy, SEM-EDS)等表征手段，进一步揭示微塑料对锑的生物地球化学循环的影响机理。结果 粒径为13 μm、高浓度的聚丙烯对Pseudomonas sp. J-1参与下辉锑矿释放的抑制作用最强。微塑料通过抑制菌群生长从而导致对辉锑矿释放的促进效果减弱，高浓度的微塑料甚至可使Pseudomonas sp. J-1的生长被完全抑制。微塑料能够吸附锑，但其吸附能力与溶液pH无关。结论 微塑料的种类、粒径与浓度是影响Pseudomonas sp. J-1介导辉锑矿释放的关键因素，主要是通过影响微生物生长从而间接影响辉锑矿的释放。

Abstract:

Microplastics are novel pollutants that are widespread in the oceans, soil, and atmosphere, affecting the process of pollutant transport and transformation through physical, chemical or biological interactions. The heavy metal pollution caused by mining activities in the soil and water environment around antimony mining regions is increasing year by year. However, the effect of microplastics on the biogeochemical transformation of heavy metal contaminants in the mining regions has been rarely reported.Objective To understand the effects of microplastic type, size and concentration on microbially mediated antimony release from stibnite.Methods We took Pseudomonas sp. J-1 with strong antimony tolerance and promoting antimony release and widely used polypropylene, polyvinyl chloride, and polystyrene as the objects of the study. The changes in pH, redox potential (ORP), microbial biomass, and antimony concentration were analyzed. Furthermore, microplastic adsorption of antimony under different pH values was studied, and confocal laser scanning microscopy (CLSM) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) were employed to reveal the mechanism by which microplastics affected the biogeochemical cycle of antimony.Results Polypropylene with a particle size of 13 μm and a high concentration had the strongest inhibitory effect on stibnite dissolution with the participation of Pseudomonas sp. J-1. Microplastics inhibited the growth of the bacterial colony, which led to weakened promoting effect on the release of antimony, and the growth of Pseudomonas sp. J-1 was even completely inhibited by the high concentration of microplastics. Microplastics were able to adsorb antimony, while the adsorption capacity was independent of solution pH.Conclusion The type, particle size, and concentration of microplastics are the key factors affecting the stibnite dissolution mediated by Pseudomonas sp. J-1 and they indirectly affect stibnite dissolution mainly by influencing microbial growth.