潜在有毒元素和抗生素复合污染形成与治理研究的教学实践

Teaching practice on the formation and treatment of combined pollution of potentially toxic elements and antibiotics

该实验以小麦(Triticum aestivum L.)为研究对象,采用水培方法,形象直观地展现了潜在有毒元素Cu^(2+)、Zn^(2+)和抗生素土霉素(oxytetracycline,OTC)、磺胺嘧啶(sulfadiazine,Sul)单一及复合污染对小麦种子根和芽的毒性差异,以期为土壤潜在有毒元素和抗生素复合污染防治和土壤生态系统安全提供理论依据。实验表明,小麦种子的根和芽对单一污染的敏感程度依次为:Sul>Cu^(2+)>OTC>Zn^(2+);复合处理对小麦种子根伸长和芽长呈现“低促高抑”规律,且根长和芽长抑制率都随处理浓度的增大而增大。该实验从小麦种子的根和芽对环境污染物胁迫的直观感受,到环境污染物如何影响作物生长科学问题的提出与解决,加深了学生对复合污染影响植物生长的理解,激发了学生对环境学课程的热情和兴趣。

[Objective]The combined pollution of potentially toxic elements(PTEs)and antibiotics is of broad and current interest in environmental science.The traditional experimental teaching of environmental science usually only considers the toxicological effect of a single pollution of PTEs,and the assessment of the ecotoxicological effect of a combined pollution of two pollutants is rarely performed.[Methods]This article used wheat(Triticum aestivum L.)as the research object,adopted the hydroponics method,and then compared the PTEs Cu^(2+)and Zn^(2+)with the antibiotics oxytetracycline(OTC)and sulfadiazine(Sul)single and combined contamination.By observing the differences in the root and bud toxicity of wheat seeds by single and combined contamination,the study was designed to enable students to master the knowledge of the effects of single and combined contamination of PTEs and antibiotics on the growth characteristics of crop seeds.This method aims to provide a theoretical basis for the prevention and control of soil PTEs combined with antibiotics and is useful for the safety of the soil ecosystem.[Results]Compared with the control group,when the concentration of Cu^(2+)was greater than 2.0 mg·L−1,wheat root growth was significantly inhibited,and the inhibitory effect increased with the increase of Cu^(2+)concentration.5-10 mg·L−1 Zn^(2+)promoted the growth of wheat roots and buds,and 30-120 mg·L−1 Zn^(2+)inhibited the growth of wheat roots and buds.The inhibitory intensity was proportional to the concentration of Zn^(2+).Both 0.1 mg·L−1 OTC and Sul promoted the growth of wheat root and bud,0.5 mg·L−1 Sul inhibited the growth of wheat root and bud,1 mg·L−1 OTC significantly inhibited the growth of wheat root,and 5-50 mg·L−1 OTC significantly inhibited the growth of wheat bud.(2.0+0.5)-(50.0+50.0)mg·L−1Cu^(2+)+OTC,(2.0+0.5)-(50.0+10.0)mg·L−1Cu^(2+)+Sul.The combined treatment of(30.0+1.0)-(120.0+50.0)mg·L−1Zn^(2+)+OTC and(30.0+1.0)-(120.0+10.0)mg·L−1Zn^(2+)+Sul significantly inhibited the growth of wheat roots and buds.The bud length of the value of IC50(inhibition concentration 50%)of wheat seeds was higher than the root length under the same treatment.The inhibitory effect of single PTEs and antibiotics on wheat seed root elongation was greater than that on wheat seed bud length,and wheat root was more sensitive to pollutants than the bud.The combined pollution of high concentrations of PTEs and antibiotics had noticeable inhibitory effects on wheat roots and buds.The results showed that the IC50 values of wheat roots and buds were Zn^(2+)>OTC>Cu^(2+)>Sul.The sensitivity of wheat seed roots and buds to PTEs and antibiotics was Sul>Cu^(2+)>OTC>Zn^(2+).The effects of combined treatment of PTEs and antibiotics on the root and bud of wheat seeds were complex and weakly correlated,showing a pattern of“low promotion and high inhibition,”and the inhibition rates of root and bud length increased with the increase of treatment concentration.[Conclusions]This experiment integrates the scientific research focus point into teaching,which presents and solves the scientific problem of how environmental pollutants affect crop growth by intuitively perceiving the roots and buds of wheat seeds under environmental pollution stress.This experiment arouses students'enthusiasm and interest in environmental science courses and improves students'ability to think critically,scientifically practice,and innovate subtly.