Research Center for cultural Landscape Protection and Ecological Restoration, China-Portugal Belt and Road Cooperation Laboratory of Cultural Heritage Conservation Science, Gold Mantis School of Architecture, Soochow University, Suzhou 215006, China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China.
College of Civil and Architecture Engineering, Chuzhou University, Chuzhou 239000, China.
J Hazard Mater. 2024 Oct 5;478:135528. doi: 10.1016/j.jhazmat.2024.135528. Epub 2024 Aug 15.
Microplastics (MPs) in agricultural plastic film mulching system changes microbial functions and nutrient dynamics in soils. However, how biodegradable MPs impact the soil gross nitrogen (N) transformations and crop N uptake remain significantly unknown. In this study, we conducted a paired labeling N tracer experiment and microbial N-cycling gene analysis to investigate the dynamics and mechanisms of soil gross N transformation processes in soils amended with conventional (polyethylene, PE) and biodegradable (polybutylene adipate co-terephthalate, PBAT) MPs at concentrations of 0 %, 0.5 %, and 2 % (w/w). The biodegradable MPs-amended soils showed higher gross N mineralization rates (0.5-16 times) and plant N uptake rates (16-32 %) than soils without MPs (CK) and with conventional MPs. The MPs (both PE and PBAT) with high concentration (2 %) increased gross N mineralization rates compared to low concentration (0.5 %). Compare to CK, MPs decreased the soil gross nitrification rates, except for PBAT with 2 % concentration; while PE with 0.5 % concentration and PBAT with 2 % concentration increased but PBAT with 0.5 % concentration decreased the gross N immobilization rates significantly. The results indicated that there were both a concentration effect and a material effect of MPs on soil gross N transformations. Biodegradable MPs increased N-cycling gene abundance by 60-103 %; while there was no difference in the abundance of total N-cycling genes between soils without MPs and with conventional MPs. In summary, biodegradable MPs increased N cycling gene abundance by providing enriched nutrient substrates and enhancing microbial biomass, thereby promoting gross N transformation processes and maize N uptake in short-term. These findings provide insights into the potential consequences associated with the exposure of biodegradable MPs, particularly their impact on soil N cycling processes.
农田塑料薄膜覆盖系统中的微塑料（MPs）改变了土壤中的微生物功能和养分动态。然而，可生物降解的 MPs 如何影响土壤总氮（N）转化和作物 N 吸收仍然知之甚少。在这项研究中，我们进行了配对标记 N 示踪实验和微生物 N 循环基因分析，以研究在浓度为 0%、0.5%和 2%（w/w）的常规（聚乙烯，PE）和可生物降解（聚丁二酸丁二醇酯共对苯二甲酸酯，PBAT） MPs 处理的土壤中土壤总 N 转化过程的动态和机制。可生物降解的 MPs 处理的土壤表现出更高的总 N 矿化速率（0.5-16 倍）和植物 N 吸收速率（16-32%），高于无 MPs（CK）和含常规 MPs 的土壤。高浓度（2%）的 MPs（PE 和 PBAT 两者）与低浓度（0.5%）相比，增加了总 N 矿化速率。与 CK 相比，除了 2%浓度的 PBAT 外， MPs 降低了土壤总硝化速率；而 0.5%浓度的 PE 和 2%浓度的 PBAT 显著增加了总氮固定速率，而 0.5%浓度的 PBAT 则降低了总氮固定速率。结果表明， MPs 对土壤总 N 转化既有浓度效应又有材料效应。可生物降解的 MPs 通过提供丰富的养分底物和增强微生物生物量来增加 N 循环基因的丰度，从而在短期内促进总 N 转化过程和玉米 N 吸收。这些发现为与可生物降解 MPs 暴露相关的潜在后果提供了深入了解，特别是它们对土壤 N 循环过程的影响。
