Bocci Valerio, De Vivo Martina, Alfano Sara, Rossetti Simona, Di Pippo Francesca, Pietrelli Loris, Martinelli Andrea
Water Research Institute, CNR-IRSA, National Research Council, Monterotondo, 00015 Rome, Italy.
PhD Program in Evolutionary Biology and Ecology, Department of Biology, University of Rome 'Tor Vergata', 00133 Rome, Italy.
Polymers (Basel). 2025 Aug 17;17(16):2236. doi: 10.3390/polym17162236.
Plastic pollution in freshwater ecosystems is an increasing environmental concern, prompting the search for biodegradable polymer (BP) alternatives. However, their degradation in natural aquatic environments remains poorly investigated and understood. This four-month in situ study compared the degradation in a lentic freshwater ecosystem of two compostable items, Mater-Bi shopping bag and disposable dish, with their respective pure polymer matrices, poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA). Additionally, biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and oil-based polypropylene (PP) were also tested. Changes in morphology, chemical composition and thermal and mechanical properties, as well as microbial colonization, were analyzed over time. A validated cleaning protocol was employed to ensure accurate surface analysis. Results showed detectable but limited degradation of pure polymers and their matrices in commercial products after 120 days of immersion with variations observed among polymer materials. Compostable materials exhibited significant leaching of fillers (starch, inorganic particles), leading to morphological changes and fragmentation. PHBV showed the fastest degradation among tested polyesters. PP exhibited only minor surface changes. Microbial colonization varied with polymer structure and degradability, but long-term degradation was limited by polymer properties and the gradual development of the plastisphere. This study highlights that standard laboratory tests may overestimate the environmental degradability of BPs and emphasizes the importance of in situ assessments, careful cleaning procedures and property characterizations to accurately assess polymer degradation in freshwater systems.
淡水生态系统中的塑料污染日益引起环境关注，促使人们寻找可生物降解聚合物（BP）替代品。然而，它们在天然水生环境中的降解情况仍未得到充分研究和理解。这项为期四个月的原位研究比较了两种可堆肥物品——麦秸生物购物袋和一次性餐具，及其各自的纯聚合物基质聚（己二酸丁二醇酯-co-对苯二甲酸丁二醇酯）（PBAT）和聚乳酸（PLA）在静水淡水生态系统中的降解情况。此外，还测试了可生物降解的聚（3-羟基丁酸酯-co-3-羟基戊酸酯）（PHBV）和油基聚丙烯（PP）。随着时间的推移，分析了形态、化学成分、热性能和机械性能的变化以及微生物定殖情况。采用了经过验证的清洁方案以确保准确的表面分析。结果表明，在浸泡120天后，商业产品中的纯聚合物及其基质有可检测到但有限的降解，不同聚合物材料之间存在差异。可堆肥材料表现出填料（淀粉、无机颗粒）的大量浸出，导致形态变化和破碎。在测试的聚酯中，PHBV降解最快。PP仅表现出轻微的表面变化。微生物定殖随聚合物结构和降解性而变化，但长期降解受到聚合物性能和塑料球的逐渐形成的限制。这项研究强调，标准实验室测试可能高估了可生物降解聚合物的环境降解性，并强调了原位评估、仔细的清洁程序和性能表征对于准确评估淡水系统中聚合物降解的重要性。
