论文部分内容阅读
研究目的:研究纳米银对黄瓜和小麦的毒性及在植物中的转运和分布,探讨其毒性机制,为纳米银的环境风险评估提供科学依据。创新要点:1.选取单子叶和双子叶植物为对象,比较研究纳米银对其萌发阶段和生长阶段的毒性效应及其影响因素;2.多数研究中的纳米银均有表面修饰,本研究选择无表面修饰的纳米银材料,排除表面活性剂的干扰因素;3.以络合剂半胱氨酸掩蔽解离出的银离子,探讨纳米银颗粒对植物毒性的贡献。研究方法:通过植物根长(图2)和生物量(图3)分别评价萌发和生长阶段纳米银的植物毒性。利用电感耦合等离子体质谱(ICP-MS)测定植物组织银元素的含量(图7)。通过组织切片,利用透射电镜(TEM)观察植物根中银的微观分布(图6)。通过在暴露介质中添加半胱氨酸掩蔽银离子来评价纳米银颗粒对植物毒性的贡献(图3和5)。重要结论:在较高暴露浓度情况下,纳米银和银离子对小麦和黄瓜都具有明显的毒性。但当纳米银浓度低于200 mg/L,银离子浓度低于5 mg/L时,两者均能促进黄瓜根系的生长。两种植物在营养生长阶段比萌发阶段对纳米银的毒性更敏感。纳米银暴露后,银首先积聚于植物的根,然后被转移到地上部。为评价纳米银释放的银离子的作用,我们测定了暴露后介质中银离子的浓度。在种子萌发阶段,黄瓜和小麦的暴露液中约0.03%和0.01%的纳米银溶解,而在营养生长阶段,溶解的纳米银达到0.17%和0.06%。半胱氨酸作为银离子的强络合剂,能够彻底消除纳米银对黄瓜和小麦的作用,说明纳米银的植物效应可能来自于其释放的银离子。
The purpose of this study is to study the toxicity of nano-silver to cucumber and wheat and its transport and distribution in plants, and to explore its toxicity mechanism to provide a scientific basis for the environmental risk assessment of nano-silver. Innovative points: 1. Select monocotyledonous and dicotyledonous plants as the object, compare the toxic effects of nano-silver on the germination stage and the growth stage of nano-silver and its influencing factors; 2. The nano-silver in most studies have surface modification, No surface modification of nano-silver material, excluding the interference of surfactants; 3 with the complexing agent cysteine masked silver ions dissociated to explore the contribution of nano-silver particles to plant toxicity. Methods: The phytotoxicity of nano-silver in germination and growth stage was evaluated by root length (Fig. 2) and biomass (Fig. 3) respectively. Plant elemental silver content was determined by inductively coupled plasma mass spectrometry (Fig. 7). The microscopic distribution of silver in plant roots was observed by transmission electron microscopy (TEM) through tissue sections (Fig. 6). The contribution of nano-silver particles to phytotoxicity was evaluated by adding cysteine-masked silver ions in the exposure medium (Figures 3 and 5). Important Conclusions: Silver and silver ions show significant toxicity to both wheat and cucumber at higher exposure levels. However, when the silver nanosilver concentration was less than 200 mg / L and the silver ion concentration was less than 5 mg / L, both could promote the root growth of cucumber. Both plants are more susceptible to the toxicity of nanosilver during the vegetative growth phase than during the germination phase. After the silver nanosilver is exposed, the silver accumulates first in the plant’s roots and is then transferred to the shoots. To evaluate the effect of silver ions released by nano-silver, we measured the concentration of silver ions in the medium after exposure. In the seed germination stage, about 0.03% and 0.01% of the nano-silver dissolved in the cucumber and wheat exposure solutions, whereas in the vegetative growth stage the dissolved nano-silver reached 0.17% and 0.06%. As a strong complexing agent of silver ions, cysteine can completely eliminate the effect of silver nanoparticles on cucumber and wheat, indicating that the plant effect of silver nanoparticles may come from the silver ions released by silver ions.