摘要

塑料颗粒广泛存在于自然环境中并且很可能与细菌（自然环境中普遍存在的微生物）相互作用，这可能影响细菌在多孔介质中的运输和沉积。在这项研究中，纳米级到微米级（0.02-2μm）的塑料颗粒对细菌（大肠杆菌）在石英砂中的运输和沉积行为的重要性在环境相关条件下在NaCl和CaCl2溶液中在pH下进行了检测6.结果表明，不同大小的塑料颗粒的存在不会影响低离子强度（10 mM NaCl和1 mM CaCl2）下的细菌转运行为，而在高离子强度条件下（50 mM NaCl和5 mM CaCl2） ），塑料颗粒增加了石英砂中的细菌运输。在低离子强度条件下，塑料颗粒和细菌的迁移率都很高，这可能会导致塑料颗粒对细菌运输行为的影响微乎其微。对于不同尺寸的塑料颗粒，在高离子强度下驱动增强的细胞运输的机制是不同的。具体地，对于0.02μm的纳米塑料颗粒，塑料颗粒在细胞表面上的吸附和由悬浮的塑料颗粒引起的排斥效应有助于增加细胞运输。对于0.2μm微塑料（MP），悬浮塑料颗粒诱导排斥效应有助于增加细胞运输，而对于2μmMPs，塑料颗粒的竞争沉积位点是增加细胞运输的贡献者。

Plastic particles are widely present in the natural environment and are highly likely to interact with bacteria (the ubiquitous microbes in the natural environment), which might affect the transport and deposition of bacteria in porous media. In this study, the significance of plastic particles from nanoscale to micrometer-scale (0.02-2 μm) on the transport and deposition behaviors of bacteria ( Escherichia coli) in quartz sand was examined under environmentally relevant conditions in both NaCl and CaCl2 solutions at pH 6. The results showed that the presence of different-sized plastic particles did not affect bacterial transport behaviors at low ionic strength (10 mM NaCl and 1 mM CaCl2), whereas, at high ionic strength conditions (50 mM NaCl and 5 mM in CaCl2), plastic particles increased bacterial transport in quartz sand. At low ionic strength conditions, the mobility of both plastic particles and bacteria was high, which might drive the negligible effects of plastic particles on bacterial transport behaviors. The mechanisms driving the enhanced cell transport at high ionic strength were different for different-sized plastic particles. Specifically, for 0.02 μm nanoplastic particles, the adsorption of plastic particles onto cell surfaces and the repel effect induced by suspended plastic particles contributed to the increased cell transport. As for 0.2 μm microplastics (MPs), the suspended plastic particles induced  repel effect contributed to the increased cell transport, whereas, for 2 μm MPs, the competition deposition sites by the plastic particles were the contributor to the increased cell transport.

https://www.ncbi.nlm.nih.gov/pubmed/30204419