School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China; Shanghai Engineering Research Center of Solid Waste Treatment and Resource, Shanghai 200240, China.
Water Res. 2022 Sep 1;223:119035. doi: 10.1016/j.watres.2022.119035. Epub 2022 Aug 30.
Landfills are the main plastic sinks and microplastics (MPs) sources in the anthropogenic terrestrial system. Understanding the dynamic process of generating MPs is a prerequisite to reducing their potential risk, which remains unexplored because of the complex stabilization process of landfills. In this study, we investigated the evolution process of MPs generated in a partitioned landfill, with well-recorded disposal ages of over 30 years. Considering the initial plastic proportions in fresh landfilled waste, the occurrence of MPs increased exponentially with the disposal age. A booming generation of MPs occurred from 71.3 ± 17.7 items/(g plastic) to 653.1 ± 191.5 items/(g plastic). The generation rates of MPs varied greatly depending on the individual polymer types, with polyethylene (PE) having the highest generation rate of 28.4 items/(g plastic) per year at 31 years, compared to that of polypropylene (PP) and polystyrene (PS) at 15.0 and 9.6 items/(g plastic) per year, respectively. The variation in the carbonyl index indicated that environmental oxidation might facilitate the fragmentation of plastic waste. The relative abundance of plastic-degrading microbes increased more than three times in the plastisphere after 30 years of landfilling, indicating that the potential biodegradation might be a nonnegligible driver for plastic fragmentation after long-term natural acclimatization. This study revealed the dynamic evolution process of MPs in landfills and predicted the booming stage, which might provide an important guideline for reducing the leakage risk of MPs during the reclamation of old landfills or dumping sites.
垃圾填埋场是人为陆地系统中塑料的主要汇和微塑料 (MPs) 来源。了解 MPs 生成的动态过程是降低其潜在风险的前提，但由于垃圾填埋场的复杂稳定过程，这一过程仍未得到探索。在这项研究中，我们研究了分隔式垃圾填埋场中产生的 MPs 的演化过程，这些垃圾填埋场的处置年龄超过 30 年，并有详细记录。考虑到新鲜填埋废物中初始塑料的比例，MPs 的出现呈指数增长，与处置年龄成正比。从 71.3 ± 17.7 个/(g 塑料)到 653.1 ± 191.5 个/(g 塑料)，MPs 的生成量呈爆炸式增长。MPs 的生成速率因聚合物类型而异，聚乙烯 (PE) 的生成速率最高，为 28.4 个/(g 塑料)，每年 31 年，而聚丙烯 (PP) 和聚苯乙烯 (PS) 分别为 15.0 和 9.6 个/(g 塑料)。羰基指数的变化表明，环境氧化可能促进了塑料废物的碎片化。在填埋 30 年后，塑料圈内的塑料降解微生物的相对丰度增加了三倍以上，这表明潜在的生物降解可能是长期自然驯化后塑料碎片形成的一个不可忽视的驱动因素。本研究揭示了垃圾填埋场中 MPs 的动态演化过程，并预测了其爆发阶段，这可能为减少旧垃圾填埋场或倾倒场复垦过程中 MPs 的泄漏风险提供重要指导。
