School of Life and Environment Sciences, Guilin University of Electronic Technology, Guilin 541004, People's Republic of China.
Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin 541006, People's Republic of China.
Environ Sci Technol. 2020 Apr 7;54(7):4248-4255. doi: 10.1021/acs.est.9b07905. Epub 2020 Mar 11.
The widespread application of sewage sludge produced from wastewater treatment plants for agricultural use has been regarded as a primary source of microplastics (MPs) into soils. However, little is known regarding MPs in sludge-based fertilizers and their relevant fate in soils as being applied in agriculture. We comprehensively investigated the abundance, polymer size, type, and morphology of MPs in dewatered sludge, sewage sludge composts, sludge-based fertilizer-amended soils, and earthworms by stereoscopy and micro Fourier transform infrared (μ-FTIR) spectrometry methods. The results clearly showed that the quantity of MPs in soils exhibited a close correlation with the application rate of sludge-based fertilizers. The total abundances of MPs were 545.9 and 87.6 items/kg in soils after annual amendment with 30 (field A) and 15 t/ha (field B) of sludge composts, which is significantly higher than that without compost application (field C, 5.0 items/kg). Correspondingly, MPs were found in earthworms with low quantities of 1.8 and 0.4 items/individual in fields A and B, respectively, while no MP was detected in field C. We speculate that sludge composts may act as a vehicle of MPs into soils and then enter soil biota and in turn influence the spread of MPs in the environment.
污水处理厂产生的污水污泥广泛应用于农业，被认为是土壤中微塑料（MPs）的主要来源。然而，对于污泥基肥料中的 MPs 及其在农业应用中相关的土壤归宿知之甚少。我们通过体视学和微傅里叶变换红外（μ-FTIR）光谱法全面研究了脱水污泥、污水污泥堆肥、污泥基肥料改良土壤和蚯蚓中 MPs 的丰度、聚合物尺寸、类型和形态。结果清楚地表明，土壤中 MPs 的数量与污泥基肥料的施用量密切相关。每年施用 30 吨/公顷（A 田）和 15 吨/公顷（B 田）污泥堆肥后，土壤中 MPs 的总丰度分别为 545.9 和 87.6 个/千克，明显高于不施堆肥的土壤（C 田，5.0 个/千克）。相应地，在 A 田和 B 田的蚯蚓中分别发现了低含量的 1.8 和 0.4 个/个体的 MPs，而在 C 田则未检测到 MPs。我们推测污泥堆肥可能是 MPs 进入土壤的载体，然后进入土壤生物群，并反过来影响 MPs 在环境中的传播。
