辽宁地区农田土壤中微塑料丰度及其在团聚体中的分布特征

为了明确辽宁地区农田土壤微塑料污染情况，本研究以辽宁14个地区的农田土壤为研究对象，采用密度分离和氧化分解的方法，结合显微镜和红外光谱技术测定了土壤及各级团聚体中微塑料的丰度和分布特征。结果表明：辽宁地区农田土壤中微塑料丰度为3 605个·kg^-1，主要包括纤维状、颗粒状、块状和薄膜状4种形状，其中纤维状最多(42.11%)，颗粒状和块状次之(29.10%和22.32%)，薄膜状最少(6.47%)。纤维状微塑料的主要成分是尼龙，颗粒状微塑料的主要成分是聚对苯二甲酸乙二酯，块状和薄膜状微塑料的主要成分是聚乙烯。辽宁14个地区农田土壤中微塑料丰度及其形状组成各不相同，其中辽阳、朝阳、本溪、营口地区土壤中微塑料丰度显著高于其他地区。土壤中69.14%的微塑料以与团聚体结合的方式存在，尤其与小团聚体结合的最多，另外30.86%的微塑料以分散态存在。不同形状微塑料在团聚体中的分布也不同，纤维状和颗粒状微塑料主要存在于小团聚体中，薄膜状微塑料主要存在于大团聚体中，而块状微塑料在各级团聚体中的分布没有显著差异。研究表明，辽宁地区农田土壤中普遍存在微塑料污染，但是在空间上分布不均...

Abundance of microplastics in farmland soil and its distribution in soil aggregate fractions in the Liaoning area

To clarify microplastic pollution in farmland soil in the Liaoning area, the abundance and distribution of microplastics in the soil and aggregate fractions were determined using density separation, and oxidative decomposition combined with a microscope and Fourier infrared spectrometer. The farmland soils from 14 regions in Liaoning were collected as tested samples. The results showed that the abundance of microplastics in the farmland soil of the Liaoning area was 3 605 items·kg^-1. There were four main shapes of microplastics in the soil, including fibers, granules, flakes, and films. Of the microplastics analyzed, fibers were found to be the most prevalent in the soil, with a ratio of 42.11%, followed by granules and flakes, with a ratio of 29.10% and 22.32%, respectively, while films accounted for the smallest ratio of 6.47%. The main component of fibers was nylon, the main component of granules was polyethylene terephthalate, and the main component of flakes and films was polyethylene. The abundance and shape composition of the microplastics in the farmland soil of the 14 regions of Liaoning were various. The abundance of microplastics in the soil of Liaoyang, Chaoyang, Benxi, and Yingkou was significantly higher than that of other regions. Additionally, 69.14% of the microplastics in the soil were associated with soil aggregates, especially micro-aggregates, and 30.86% of the microplastics were dispersed. The distribution of various shapes of microplastics in the aggregate fractions was also different. The fibers and granules were mainly in micro-aggregates, and the films were mainly in macroaggregates; there were no obvious differences in the distribution of flakes in the various aggregate fractions. In conclusion, microplastics were widely present in the farmland soils of the Liaoning area, but their spatial distribution was uneven in the different areas. The microplastics in the soil were mainly fibers, which were composed of nylon. Most of the microplastics were associated with aggregates, but some were dispersed, exhibiting a potential risk of leaching into deeper soil and groundwater under irrigation or rainfall conditions.