摘要
微塑料影响土壤对重金属的吸附,改变重金属在土壤中的迁移转化。该文采用批量实验研究了3种粒径(13、48、150μm)聚乙烯微塑料(PE-MPs)存在时土壤对Cd的吸附解吸行为,同时借助扫描电子显微镜-X射线能谱、X射线衍射、X射线光电子能谱和傅里叶变换红外光谱等测试方法探究了相关机理。结果表明,PE-MPs对土壤吸附Cd^(2+)的影响表现为:抑制Cd^(2+)的吸附,促进Cd^(2+)的解吸,且当PE-MPs剂量较高或粒径较大时,这种影响更明显。无论是否存在PE-MPs,土壤对Cd^(2+)的吸附过程均更符合准二级动力学和Freundlich模型,说明其过程均为受化学吸附控制的多层吸附。土壤对Cd^(2+)的吸附机制主要为表面络合和沉淀作用,PE-MPs能覆盖土壤表面的活性位点,干扰Cd^(2+)与土壤中含氧官能团相互作用,进而减弱土壤对Cd^(2+)的化学吸附。PE-MPs能增强土壤中Cd的流动性,增加Cd对土壤生态系统污染的风险。
Microplastics affect the sorption of heavy metals by soils and alter their migration and transformation in soils.In this paper,the changes in the soil adsorption performance of cadmium(Cd)in the presence of polyethylene microplastics(PE-MPs)with different particle sizes(13,48,150μm)were investigated,to explore the related mechanisms with the help of scanning electron microscopy-X-ray spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,and Fourier trans⁃form infrared spectroscopy.The results showed that the effect of PE-MPs on soil adsorption of Cd^(2+)was manifested as in⁃hibiting the adsorption of Cd^(2+)and promoting the desorption of Cd^(2+);this effect was more obvious when the dose of PE-MPs was higher or the particle size was larger.Regardless of the presence or absence of PE-MPs,the sorption process of Cd^(2+)by soil was more consistent with quasi-secondary kinetics and the Freundlich model,indicating that the processes were multilayer sorption controlled mainly by chemisorption.The adsorption mechanism of Cd^(2+)by soil is mainly surface complex⁃ation and precipitation.PE-MPs can cover the active sites on the soil surface and interfere with the interaction of Cd^(2+)with oxygen-containing functional groups in the soil,thus weakening the chemisorption of Cd^(2+)by soil.It can be seen that PE-MPs can enhance the mobility of Cd in soil and increase the risk of Cd pollution to the soil ecosystem.
作者
周悦
马贵
廖彩云
周炎炎
丁家富
ZHOU Yue;MA Gui;LIAO Caiyun;ZHOU Yanyan;DING Jiafu(College of Chemistry and Chemical Engineering,Ningxia Normal University,Guyuan 756000,China)
出处
《环境科学与技术》
CAS
CSCD
北大核心
2023年第11期123-129,共7页
Environmental Science & Technology
基金
宁夏高等学校一流学科建设(教育学学科)资助项目(NXYLXK2021B10)。
关键词
聚乙烯微塑料
土壤
镉
吸附
解吸
polyethylene microplastics
soil
cadmium
adsorption
desorption
作者简介
周悦(1997-),女,硕士研究生,研究方向为土壤污染物环境行为,(电子信箱)947378129@qq.com;通讯作者:马贵,(电子信箱)82007056@nxnu.edu.cn。
