Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Melbourne, VIC 3125, Australia.
Int J Environ Res Public Health. 2022 Oct 22;19(21):13752. doi: 10.3390/ijerph192113752.
The formation of plastisphere on plastics and their potential impact on freshwater ecosystems have drawn increasing attention. However, there is still limited information about the effects of plastisphere on the heavy metal adsorption capacity and the related mechanism of plastic debris in different freshwaters. Herein, the trace metal adsorption capacity, kinetics and adsorption mechanisms of virgin and biofilm-covered plastic debris were investigated. Polypropylene (PP) and polyethylene terephthalate (PET) plastic debris were placed in three freshwaters (Xuanwu Lake, Donghu Lake and the Qinhuai River) for 45 days to incubate biofilms. Batch adsorption experiments were performed to compare the adsorption processes of trace metal on virgin and biofilm-covered plastics. Results showed that biofilms increase the adsorption of metals on plastics, and the adsorption isotherms were well fitted by the Langmuir model. Furthermore, the adsorption capacities for lead (Pb(II)) were higher than that of cadmium (Cd(II)) and zinc (Zn(II)), with 256.21 and 277.38 μg/g (Pb(II)) adsorbed in biofilm-covered PP and PET, respectively, in Xuanwu Lake. The adsorption kinetics of metals on plastic debris were significantly affected by the biofilms, by switching the intraparticle diffusion for virgin plastic debris to film diffusion for the biofilm-covered plastic debris. Moreover, the complexation of functional groups within the biofilms might mainly contribute to the increases of metal adsorption, involving the participation of oxygen and nitrogen groups. Overall, these results suggested that biofilms reinforce the potential role of plastics as a carrier of trace metals in freshwaters.
塑料上的塑膜形成及其对淡水生态系统的潜在影响引起了越来越多的关注。然而，关于塑膜对不同淡水中塑料碎片重金属吸附能力的影响及其相关机制，仍缺乏相关信息。本研究考察了原始和生物膜覆盖的塑料碎片的痕量金属吸附能力、动力学和吸附机制。将聚丙烯（PP）和聚对苯二甲酸乙二醇酯（PET）塑料碎片分别放置在玄武湖、东湖和秦淮河三种淡水中 45 天以培养生物膜。进行批式吸附实验以比较痕量金属在原始和生物膜覆盖塑料上的吸附过程。结果表明，生物膜增加了金属在塑料上的吸附，吸附等温线很好地符合朗缪尔模型。此外，生物膜覆盖的 PP 和 PET 对铅（Pb（II））的吸附容量高于镉（Cd（II））和锌（Zn（II）），在玄武湖中分别吸附了 256.21 和 277.38μg/g（Pb（II））。金属在塑料碎片上的吸附动力学受到生物膜的显著影响，使原始塑料碎片的颗粒内扩散转变为生物膜覆盖塑料碎片的膜扩散。此外，生物膜内官能团的络合可能主要导致金属吸附的增加，涉及氧和氮基团的参与。总体而言，这些结果表明生物膜增强了塑料作为淡水中痕量金属载体的潜在作用。
