Investigating the sustainability of agricultural plastic products, combined influence of polymer characteristics and environmental conditions on microplastics aging
Investigating the sustainability of agricultural plastic products, combined influence of polymer characteristics and environmental conditions on microplastics aging
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DOI：
10.1016/j.scitotenv.2022.156385
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发表时间：
2022-06-06
影响因子：
9.8
通讯作者：
Herath, Amali
中科院分区：
文献类型：
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作者：
Bonyadinejad, Gholamreza;Salehi, Maryam;Herath, Amali
塑料产品在农业实践中的加速使用引起了全球对其对土壤健康的负面影响的关注。本研究旨在更好地了解聚合物特性和环境条件对农业土壤系统中微塑料光降解的综合影响。为此，通过加速UVA辐射实验，研究了低密度聚乙烯（LDPE）微塑料在两种不同相对湿度（RH10和RH70）和土壤沉积条件下的光降解行为。利用衰减全反射-傅里叶变换红外光谱（ATR-FTIR）、x射线光电子能谱（XPS）和场发射扫描电镜（FE-SEM）研究了加速光降解对塑料表面物理化学的影响。利用ATR-FTIR信息计算羰基指数和乙烯基指数，比较微塑料的光降解程度。使用差示扫描量热法（DSC）和凝胶渗透色谱法（GPC）检测塑料的体积特性，包括结晶度百分比和分子量分布。此外，通过测定光谱量子产率，研究了UVA光与微塑料相互作用的程度。结果表明，较低分子量（Mw = 233 kD）的新型LDPE微塑料比较大分子量（Mw = 515 kD）的微塑料更易被光降解。较高的相对湿度（RH70）限制了微塑料的光氧化过程，从而减少了表面化学变化。土壤颗粒相对于塑料颗粒的沉积影响了光降解行为。被土壤颗粒覆盖的微塑料没有被降解，不像那些沉积在土壤颗粒旁边的塑料。通过这项研究获得的知识可以鼓励农民和农业利益相关者采用更有效的做法来清除收获后的塑料残留物，并进行适当的塑料处理做法，以保护土壤健康。
The accelerated use of plastic products for agricultural practices has raised global concern regarding their negative impacts on soil health. This study aims to better understand the combined influence of polymer characteristics and environmental conditions on microplastic photodegradation within the agricultural soil system. For this purpose, the photodegradation behavior of low density polyethylene (LDPE) microplastics was studied through accelerated UVA radiation experiments under two different relative humidity (RH10 and RH70) and soil deposition conditions. The variations of plastics' surface physiochemistry due to the accelerated photodegradation were studied using Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS), and Field Emission Scanning Electron Microscopy (FE-SEM). The carbonyl and vinyl indices were calculated using the ATR-FTIR information to compare the degree of microplastics' photodegradation. The plastics' bulk characteristics, including the percentage of crystallinity and molecular weight distributions, were examined using the Differential Scanning Calorimetry (DSC) and Gel Permeation Chromatography (GPC). Furthermore, the extent of UVA light interaction with the microplastics was studied by determining spectral quantum yield. The results demonstrated that new LDPE microplastics with a lower molecular weight (Mw = 233 kD) were subjected to a greater extent of photodegradation than those with greater molecular weight (Mw = 515 kD). Elevated relative humidity (RH70) limited the photooxidation process of microplastics and consequently reduced the surface chemistry alterations. Deposition of soil particles with respect to the plastic particles impacted the photodegradation behavior. The microplastics covered by soil particles were not degraded, unlike those deposited next to the soil particles. The knowledge developed through this study could encourage the farmers and agricultural stakeholders to apply more efficient practices to remove plastic residuals after harvesting and conduct proper plastic disposal practices to protect soil health.