Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300 RA Leiden, the Netherlands.
Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland.
Sci Total Environ. 2024 Jul 20;935:173265. doi: 10.1016/j.scitotenv.2024.173265. Epub 2024 May 15.
Agricultural lands have been identified as plastic sinks. One source is plastic mulches, which are a source of micro- and nano-sized plastics in agricultural soils. Because of their persistence, there is now a push towards developing biodegradable plastics, which are designed to undergo (partial) breakdown after entering the environment. Yet, limited research has investigated the impacts of both conventional and biodegradable plastics on distinct plants. Moreover, comparisons among studies are difficult due to differences in experimental design. This study directly compares the effects of artificially weathered conventional polyethylene (PE) and starch-based biodegradable polybutylene adipate terephthalate (PBAT) on four food crops, including two monocots (barley, Hordeum vulgare, and wheat, Triticum aestivum L.) and two dicots (carrot, Daucus carota, and lettuce, Lactuca sativa L.). We investigated the effects of environmentally relevant low, medium, and high (0.01 %, 0.1 %, 1 % w/w) concentrations of PE and starch-PBAT blend on seed germination (acute toxicity), and subsequently on plant growth and chlorophyll through a pot-plant experiment (chronic toxicity). Germination of all species was not affected by both plastics. However, root length was reduced for lettuce and wheat seedlings. No other effects were recorded on monocots. We observed a reduction in shoot length and bud wet weight of carrot seedlings for the highest concentration of PE and starch-PBAT blend. Chronic exposure resulted in a significant decrease in shoot biomass of barley and lettuce. Additionally, a positive increase in the number of leaves of lettuce was observed for both plastics. Chlorophyll content was increased in lettuce when exposed to PE and starch-PBAT blend. Overall, adverse effects in dicots were more abundant than in monocots. Importantly, we found that the biodegradable plastic caused more commonly adverse effects on plants compared to conventional plastic, which was confirmed by a mini-review of studies directly comparing the impact of conventional and biodegradable microplastics.
农田已被确定为塑料汇。其中一个来源是塑料覆盖物，它们是农业土壤中微塑料和纳米塑料的来源。由于其持久性，现在人们正在推动开发可生物降解塑料，这些塑料旨在进入环境后（部分）分解。然而，有限的研究调查了传统塑料和可生物降解塑料对不同植物的影响。此外，由于实验设计的差异，研究之间的比较比较困难。本研究直接比较了人工风化的传统聚乙烯（PE）和淀粉基可生物降解聚对苯二甲酸丁二醇酯（PBAT）对四种粮食作物（包括两种单子叶植物（大麦、Hordeum vulgare 和小麦、Triticum aestivum L.）和两种双子叶植物（胡萝卜、Daucus carota 和生菜、Lactuca sativa L.）的影响。我们研究了低、中、高（0.01%、0.1%、1%w/w）浓度的 PE 和淀粉-PBAT 混合物对种子发芽（急性毒性）的影响，随后通过盆栽植物实验（慢性毒性）对植物生长和叶绿素进行了研究。两种塑料都没有影响所有物种的发芽。然而，生菜和小麦幼苗的根长减少。单子叶植物没有其他影响。我们观察到胡萝卜幼苗在最高浓度的 PE 和淀粉-PBAT 混合物下，茎长和芽湿重减少。慢性暴露导致大麦和生菜的地上生物量显著减少。此外，两种塑料都观察到生菜叶片数量增加。暴露于 PE 和淀粉-PBAT 混合物时，生菜的叶绿素含量增加。总的来说，双子叶植物的不良影响比单子叶植物更普遍。重要的是，我们发现可生物降解塑料对植物的不良影响比传统塑料更常见，这一点通过直接比较传统和可生物降解微塑料影响的研究综述得到了证实。
