长期施用有机肥对土壤微塑料赋存及迁移特征的影响

为探明设施土壤中微塑料的赋存特征与施肥模式、种植年限及土壤深度之间的响应关系，通过现场采样、显微镜观察、傅里叶变换红外光谱（FTIR）和扫描电子显微镜（SEM）等方法，对长期施用有机肥土壤中微塑料丰度、形状、粒径、颜色、种类和表面形貌特征及有机肥中微塑料的丰度、粒径和种类进行分析.结果表明，设施土壤中不同种植年限下（2016～2021年）表层土壤中微塑料的平均丰度随着种植年限的升高而升高，化肥（CF）、有机肥（OF）和生物炭+有机肥（BOF）处理中微塑料丰度不同，其中每年OF处理微塑料的丰度最高，2021年长期施用OF的表层土壤微塑料丰度最高，为543.33 n·kg-1.3种施肥处理土壤中微塑料平均年增长速率分别为11.16%、12.61%和9.17%.微塑料丰度在不同深度土层中表现为随土层深度的增加而显著降低，且BOF处理中微塑料向深层土壤迁移效率最高.微塑料形状主要为纤维状、碎片状、颗粒状和薄膜状，在0～40 cm深度土壤中，纤维状微塑料在3种施肥类型土壤中均占主导地位.在40～60 cm土壤中CF处理无纤维状和薄膜状微塑料，颗粒状微塑料占比最高（57.14%）;OF处理无薄膜状...

Effects of Long-term Application of Organic Fertilizer on the Occurrence and Migration Characteristics of Soil Microplastics

To explore the response relationship between the occurrence characteristics of microplastics in the facility soil （fertilization mode, planting years, and soil depth）, the abundance, shape, particle size, color, type, and surface morphology characteristics of microplastics in the soil with long-term application of organic fertilizer, as well as the abundance, particle size, and type of microplastics in organic fertilizer, were analyzed through on-site sampling, microscopic observation, Fourier transform infrared spectroscopy （FTIR）, and scanning electron microscopy （SEM）. The results showed that the average abundance of microplastics in the surface soil under different planting years （2016-2021） increased with the increase in planting years, and the abundance of microplastics in the chemical fertilizer （CF）, organic fertilizer （OF）, and biochar organic fertilizer （BOF） treatments differed, among which the abundance of microplastics in the OF treatment was the highest per year, and the highest abundance of microplastics in the topsoil with long-term application of OF in 2021 was 543.33 n·kg^-1. The average annual growth rates of microplastics in the soil treated by the three fertilization treatments were 11.16%, 12.61%, and 9.17%, respectively. The abundance of microplastics decreased significantly with the increase in soil depth in different soil layers, and the migration efficiency of microplastics to deep soils was the highest in the BOF treatment. The shapes of the microplastics were mainly fibrous, fragmentary, particle, and film, and in the soil at a depth of 0-40 cm, fibrous microplastics were dominant in the soil of all three fertilization types. In 40-60 cm soil, CF-treated fibrous and thin-film microplastics were not detected, and particle microplastics accounted for the highest proportion （57.14%）. The OF treatment did not have the presence of film microplastics, and particle microplastics and fibrous microplastics accounted for the highest proportion （36.00%）. The highest proportion in the BOF treatment was particle microplastics （41.18%）, and the lowest proportion was that of film microplastics （5.88%）. The proportion of small-size （<0.5 mm） microplastics in the three fertilization-treated soils was the highest, and PE was the main microplastic species in the three treated soils of CF, OF, and BOF； additionally, the characteristics of porous, torn, cracked, and worn on the surface of microplastics were all presented. The average abundance of microplastics in organic fertilizer was as high as 577.78 n·kg^-1. The abundance of microplastics in the soil of facilities for the long-term application of organic fertilizers was closely related to organic fertilizers, and the migration of microplastics was also closely related to the types of fertilizers applied. It is of great significance to clarify the distribution characteristics and migration of microplastics in facility soils under different long-term fertilization modes.