三维镁铝层状双金属氢氧化物对微藻的毒性影响及致毒机制

Toxicity effects and mechanism of three-dimensional MgAl layered double hydroxides to microalgae

为探究三维镁铝层状双金属氢氧化物(3D-MgAl-LDH)对微藻的毒性影响及致毒机制,本研究选取小球藻(Chlorella vulgaris)和斜生栅藻(Scenedesmus obliquus)作为受试藻,借助X射线粉末衍射仪、傅里叶红外光谱仪、扫描电子显微镜和激光粒径分析仪等测试技术表征3D-MgAl-LDH的组成及形貌,通过改变3D-MgAl-LDH暴露浓度、暴露时间以及溶出物质SDS浓度,明晰各因素对两种微藻的毒性影响,并测定3D-MgAl-LDH暴露后微藻的细胞结构、光合色素含量和抗氧化酶(MDA、SOD)活性以揭示其致毒机制.结果表明:1)3D-MgAl-LDH是由LDH和SDS共组成的三维花状材料.2)随3DMgAl-LDH浓度增加,两种微藻的生长抑制率均呈增加趋势(P<0.05),其中小球藻对3D-MgAl-LDH毒性影响更为敏感,而斜生栅藻对3D-MgAl-LDH毒性影响表现出更强的耐受性.3)随3D-MgAl-LDH暴露时间延长,两种微藻的生长抑制率均逐渐减小,表明微藻对3D-MgAl-LDH的胁迫作用产生抗逆性.4)3D-MgAl-LDH对小球藻和斜生栅藻的致毒机制主要包括细胞割伤、遮光效应和氧化应激.本研究结果为LDHs应用于实际废水治理的潜在风险评估提供理论依据.

In order to explore the toxicity effect and toxicity mechanism of Three-dimensional MgAl layered double hydroxide(3D-MgAl-LDH)on microalgae,Chlorella vulgaris and Scenedesmus obliquus were selected as the tested algae.The composition and morphology of 3D-MgAl-LDH were characterized by x-ray diffraction(XRD),scanning electron microscope(SEM),fourier infrared spectroscopy(FT-IR)and laser particle size analyzer.To understand the toxicity effects,various experimental factors were systematically investigated,including exposure concentration,exposure time and SDS concentration of dissolved substances of 3D-MgAl-LDH.Moreover,the toxicity mechanisms were explored based on the analysis of cell structure,photosynthetic pigment content and antioxidant enzyme activity(MDA,SOD)of microalgae after 3D-MgAl-LDH exposure.Results showed that 1)3D-MgAl-LDH composed by LDH and SDS exhibited a well three-dimensional flower-like structure.2)With the increase of 3D-MgAl-LDH concentration,the inhibition rates of Chlorella vulgaris and Scenedesmus obliquus showed an increasing trend(P<0.05).In comparison,Chlorella vulgaris was more sensitive to 3D-MgAl-LDH toxicity,while Scenedesmus obliquus was more tolerant to 3D-MgAl-LDH toxicity.3)With the extension of 3D-MgAl-LDH exposure time,the growth inhibition rates of both microalgae presented a gradually decreased trend,indicating that the microalgae possessed stress tolerance under 3DMgAl-LDH stress.4)The toxic mechanisms of 3D-MgAl-LDH on Chlorella vulgaris and Scenedesmus obliquus were cell laceration,shading effect and oxidative stress.This study provided a theoretical basis for potential risk assessment of the application of LDHs in practical wastewater treatment.