Teaching practice on the formation and treatment of combined pollution of potentially toxic elements and antibiotics
[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 Cu2+and Zn2+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 Cu2+was greater than 2.0 mg·L-1,wheat root growth was significantly inhibited,and the inhibitory effect increased with the increase of Cu2+concentration.5-10 mg·L-1 Zn2+promoted the growth of wheat roots and buds,and 30-120 mg·L-1 Zn2+inhibited the growth of wheat roots and buds.The inhibitory intensity was proportional to the concentration of Zn2+.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-1Cu2++OTC,(2.0+0.5)-(50.0+10.0)mg·L-1Cu2++Sul.The combined treatment of(30.0+1.0)-(120.0+50.0)mg·L-1Zn2++OTC and(30.0+1.0)-(120.0+10.0)mg·L-1Zn2++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 Zn2+>OTC>Cu2+>Sul.The sensitivity of wheat seed roots and buds to PTEs and antibiotics was Sul>Cu2+>OTC>Zn2+.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.
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