Abstract：
Biodegradable microplastics (BMPs) and cadmium (Cd) are posing threats to agro-systems especially to plants and current studies mostly used virgin BMPs to explore their ecological effects. However, effects of naturally aged BMPs and their combined effects with Cd on pakchoi are yet to be unraveled. Therefore, this study incubated naturally aged polylactic acid (PLA) MPs through soil aging process and investigated the single and combined effects of Cd and PLA MPs (virgin and aged) on pakchoi (Brassica rapa subsp. chinensis) morphology, antioxidant systems and soil microbial activities. Our results found that after being deposited in soil for six months, aged PLA (PLAa) MPs formed with a fractured surface, demonstrating more detrimental effects on pakchoi than virgin ones. PLA/PLAa MPs and Cd stunted pakchoi growth, caused oxidative stress and altered the biophysical environment in soil, separately. Moreover, co-existence of PLA/PLAa MPs and Cd caused greater damages to pakchoi than applied alone. The co-presence of PLAa MPs and Cd inhibited pakchoi biomass accumulation rate by 92.2 % compared with the no-addition group. The results unraveled here emphasized BMPs, especially aged BMPs, could trigger negative effects on agro-systems with heavy metals. These findings will give reference to future holistic assessments of BMPs\' ecological effects.
摘要：
可生物降解的微塑料（BMPs）和镉（Cd）对农业系统尤其是植物构成威胁，目前的研究主要使用原始BMPs来探索其生态效应。然而,自然老化BMP的作用及其与Cd对小白菜的综合作用尚未阐明。因此,这项研究通过土壤老化过程孵育了自然老化的聚乳酸（PLA）MPs，并研究了Cd和PLAMPs（原始和老化）对小白菜（Brassicarapa亚种。中国）形态学，抗氧化系统和土壤微生物活性。我们的结果发现，在土壤中沉积六个月后，老化的PLA(PLAa)MPs形成有断裂表面，对小白菜的影响比处女更大。PLA/PLAaMPs和Cd阻碍了小白菜的生长，引起了氧化应激并改变了土壤中的生物物理环境，分开。此外，PLA/PLAaMPs和Cd共存对小白菜造成的损害比单独使用更大。与不添加组相比，PLAaMPs和Cd的共存抑制了小白菜生物量积累率92.2％。这里公布的结果强调了BMPs，尤其是老年BMP，可能会引发重金属对农业系统的负面影响。这些发现将为未来BMPs生态效应的整体评估提供参考。
