Soil Physics and Land Management Group, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, the Netherlands; National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
Soil Physics and Land Management Group, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, the Netherlands; Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China.
Environ Res. 2022 Mar;204(Pt A):111938. doi: 10.1016/j.envres.2021.111938. Epub 2021 Aug 31.
Agricultural microplastic pollution has become a growing concern. Unfortunately, the impacts of microplastics (MPs) on agricultural soil carbon and nitrogen dynamics have not been sufficiently reported. In an attempt to remedy this, we conducted a 105-day out-door mesocosm experiment in a soil-plant system using sandy soils amended with two types of MPs, low-density polyethylene (LDPE-MPs) and biodegradable (Bio-MPs), at concentrations of 0.0% (control), 0.5%, 1.0%, 1.5%, 2.0% and 2.5% (w/w, weight ratio of microplastics to air-dry soil). Soil organic matter (SOM), dissolved organic carbon (DOC), permanganate oxidizable carbon (POXC), available nitrogen (AN) of N-NH and N-NO, and dissolved organic nitrogen (DON) were measured on day 46 (D46) and 105 (D105) of the experiment. SOM was also measured after microplastics were mixed into soils (D0). For LDPE-MPs treatments, SOM on D0, D46 and D105 showed no significant differences, while for Bio-MPs treatments, SOM significantly (p < 0.05) decreased from D0 to D46. Compared to the control, soil POXC was significantly (p = 0.001) lowered by 0.5%, 1.0% and 2.5% LDPE-MPs and ≥ 1.0% Bio-MPs on D105. LDPE-MPs showed no significant effects on soil DOC and nitrogen cycling. 2.0% and 2.5% Bio-MPs showed significantly higher (p < 0.001) DOC and DON (on D46 and D105) and ≥1.5% Bio-MPs showed significantly lower (p = 0.02) AN (on D46). Overall, Bio-MPs exerted stronger effects on the dynamics of soil carbon and nitrogen cycling. In conclusion, microplastics might pose serious threats to agroecosystems and further research is needed.
农业微塑料污染已成为一个日益严重的问题。不幸的是，微塑料（MPs）对农业土壤碳氮动态的影响尚未得到充分报道。为了弥补这一不足，我们在土壤-植物系统中进行了为期 105 天的室外中观实验，使用添加了两种类型的 MPs（低密度聚乙烯（LDPE-MPs）和可生物降解（Bio-MPs））的沙土，浓度为 0.0%（对照）、0.5%、1.0%、1.5%、2.0%和 2.5%（w/w，微塑料与风干土的重量比）。在实验的第 46 天（D46）和第 105 天（D105）测量了土壤有机质（SOM）、溶解有机碳（DOC）、高锰酸盐氧化碳（POXC）、有效氮（N-NH 和 N-NO）和溶解有机氮（DON）。在将微塑料混入土壤后（D0）还测量了 SOM。对于 LDPE-MPs 处理，D0、D46 和 D105 的 SOM 没有显著差异，而对于 Bio-MPs 处理，D0 到 D46 的 SOM 显著（p<0.05）下降。与对照相比，D105 时 0.5%、1.0%和 2.5%LDPE-MPs 和≥1.0%Bio-MPs 显著降低了土壤 POXC（p=0.001）。LDPE-MPs 对土壤 DOC 和氮循环没有显著影响。2.0%和 2.5%Bio-MPs 表现出显著更高的（p<0.001）DOC 和 DON（在 D46 和 D105），≥1.5%Bio-MPs 表现出显著更低的（p=0.02）AN（在 D46）。总体而言，Bio-MPs 对土壤碳氮循环动态的影响更强。总之，微塑料可能对农业生态系统构成严重威胁，需要进一步研究。
