State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Sci Total Environ. 2019 Mar 1;654:576-582. doi: 10.1016/j.scitotenv.2018.11.123. Epub 2018 Nov 10.
Environmental contamination of plastics is becoming an issue of concern globally. Detection of plastics, particularly microplastics, has been increasingly reported in both marine environments and inland waters. Recent work has indicated that soil in terrestrial environments has also been contaminated by plastics. Research has also shown that plastics can have adverse effects on soil biota. However, the impact of plastics on soil physical properties is still unclear. In this work, effects of plastic film of different sizes at environmental relevant concentrations on water evaporation and desiccation cracking in two clay soils were studied. The results showed that the presence of plastics in soil significantly increased the rate of soil water evaporation by creating channels for water movement. The effect was more pronounced in soils treated with 2 mm plastics than in soils treated with 5 and 10 mm plastics, and increased with increasing plastic content. Desiccation cracking was observed on the surface of soil treated with 5 and 10 mm plastics likely due to the destruction of soil structural integrity. While 2 mm plastics increased the rate of desiccation shrinkage, the shrinkage ratio was reduced at the residual stage. Results from this work suggest that plastic contamination can alter the water cycle in soils, which may exacerbate soil water shortages and affect the vertical transport of pollutants. Further work is required to study the effects of plastics of other shapes, and laboratory observations should be tested at field scale.
塑料的环境污染正成为一个全球性关注的问题。在海洋环境和内陆水域中，越来越多的报道发现了塑料，尤其是微塑料的存在。最近的研究表明，土壤也受到了塑料的污染。研究还表明，塑料可能对土壤生物群产生不利影响。然而，塑料对土壤物理性质的影响仍不清楚。在这项工作中，研究了环境相关浓度下不同尺寸的塑料薄膜对两种粘性土中水分蒸发和干燥开裂的影响。结果表明，塑料的存在通过为水的运动创造通道，显著增加了土壤水分蒸发的速率。在处理 2mm 塑料的土壤中，这种效应比在处理 5mm 和 10mm 塑料的土壤中更为明显，并且随着塑料含量的增加而增加。在处理 5mm 和 10mm 塑料的土壤表面观察到干燥开裂，可能是由于土壤结构完整性的破坏。虽然 2mm 塑料增加了干燥收缩的速率，但在残余阶段，收缩率降低了。这项工作的结果表明，塑料污染可以改变土壤中的水循环，这可能会加剧土壤水分短缺，并影响污染物的垂直迁移。需要进一步研究其他形状的塑料的影响，并应在野外尺度上测试实验室观察结果。
