CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; University of the Chinese Academy of Sciences, Beijing, 100049, China.
CAS Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China; University of the Chinese Academy of Sciences, Beijing, 100049, China.
Environ Pollut. 2021 Mar 1;272:116028. doi: 10.1016/j.envpol.2020.116028. Epub 2020 Nov 9.
Microplastics occur widely in the terrestrial environment and they currently occur in organic fertilizers applied to agricultural land. However, there is little information available on the accumulation of microplastics in soils fertilized over the long term. Here, we investigate the characteristics of microplastics in both pig manure and soil following long-term manure application in an attempt to assess their accumulation and the potential risk to agricultural soils of repeated application of pig manure. Microplastics were separated from soil and pig manure samples using a sequential flow separation and flotation method. The abundances of microplastics were 16.4 ± 2.7 and 43.8 ± 16.2 particles kg in control plots (CK, no manure applied) and plots amended annually with pig manure for 22 years (PM), respectively. The microplastics (especially fragments) were significantly enriched in PM-amended soil compared with the control plots. The average annual abundance of microplastics was 1250 ± 640 particles kg in manure. Interestingly, the type and polymer composition of microplastics were very similar in the soil and manure. Differences in color and particle size indicate that microplastics sourced from pig manure may be gradually weathered and degraded after incorporation into the soil. The average accumulation rate of microplastics in the agricultural soil with long-term application of pig manure was estimated to be 3.50 ± 1.71 million particles ha a. The microplastics in the manured soil displayed complicated weathered surfaces. The presence of carbonyl groups suggests that the weathered microplastics in soil may have the potential to adsorb contaminants.
微塑料广泛存在于陆地环境中，目前存在于施用于农田的有机肥料中。然而，关于长期施肥后土壤中微塑料的积累情况，相关信息却很少。在这里，我们研究了长期施用猪粪后猪粪和土壤中微塑料的特征，试图评估其在土壤中的积累情况，以及重复施用猪粪对农业土壤的潜在风险。采用顺序流动分离和浮选法从土壤和猪粪样品中分离出微塑料。在未施有机肥的对照区（CK）和连续 22 年每年施用猪粪的试验区（PM）中，微塑料的丰度分别为 16.4±2.7 和 43.8±16.2 个颗粒/kg。与对照区相比，PM 处理区的土壤中微塑料（尤其是碎片）明显富集。有机肥中微塑料的年平均丰度为 1250±640 个颗粒/kg。有趣的是，土壤和有机肥中的微塑料类型和聚合物组成非常相似。颜色和粒径的差异表明，施入土壤后的猪粪来源的微塑料可能在逐渐风化和降解。长期施用猪粪的农业土壤中微塑料的平均积累速率估计为 3.50±1.71 百万个颗粒/公顷。施有机肥土壤中的微塑料表面呈现出复杂的风化特征。羰基基团的存在表明，土壤中风化的微塑料可能有吸附污染物的潜力。
