Toxicological Effects Of Landfill Leachate On Mung Bean And Zebrafish

In the mid nineteenth century,upon China's entry into industrialized societies,science and technology as well as production levels increased rapidly,domestic waste production in cities increased rapidly,and the consequent disposal of domestic waste became an important environmental problem facing urban life.Sanitary landfilling,incineration and composting are the three main ways of disposal of domestic waste,among which sanitary landfilling is widely used because of simple engineering and low cost.But landfill will produce a polluted wastewater with complex organic matter composition and difficult degradation-landfill leachate.Inadvertent leakage of leachate can be a great threat to plants,aquatic animals and even humans.This study develops a garbage leachate toxic effect study using important agricultural crop mung bean and model animal zebrafish as experimental materials on the basis of clarifying the characteristics of leachate water quality.The findings of this paper are as follows:1.This research first analyzes the physical and chemical indicators,heavy metal content and organic species of the leachate.The COD_cr,BOD₅ and NH₃-N detection results of the leachate were 1759 mg/L,344 mg/L and 1815 mg/L,respectively.The content of six heavy metals of Cr,Pb,Cd,Mn,Cu and Zn is lower than the conventional discharge standard of leachate.The leachate contains 64 kinds of organic substances such as alkanes,substituted alkanes,esters,benzenes and phenols.That is to say,the water quality characteristics of leachate are:there are many kinds of organic matter,high content but low biodegradability,high total nitrogen and salt content,and low heavy metal content.It is a kind of organic wastewater that is difficult to biologically treat.2.Secondly,with the leachate as the target pollutant and mung bean as the plant model,the growth toxicity and genetic toxicity of the leachate on mung bean were explored through experiments.The results showed that the germination of mung beans in the leachate treatment group with a concentration of?5%was blocked,the germination rate was reduced,and the germination time was prolonged.1%leachate significantly increases the number of lateral roots,shoot length,fresh weight and chlorophyll content of seedlings;that is,it promotes plant growth at low concentrations.Concentration(?5%)treatment group significantly inhibited the growth of mung bean plants,and significantly reduced the chlorophyll content and MI index;the 10%leachate treatment group significantly hindered plant growth,significantly decreased root tip MI index,significantly increased MCN,and significantly increased leaf photosynthesis capacity Weakened,and slight lipid peroxidation occurs.In summary,the toxicological effect of leachate on mung beans is"low concentration promotion,high concentration inhibition";high concentration leachate has plant growth and development toxicity and genetic toxicity.In addition,compared with previous analysis of other phytotoxicity studies,it is found that different plants have different tolerance to leachate,and the overall performance is that the tolerance of monocots is greater than that of dicots.3.Finally,with the leachate as the target pollutant and zebrafish embryos as experimental animals,experiments were conducted to explore the toxicity of leachate on the growth and development of small fish embryos and the influence of leachate on various behaviors in the life activities of zebrafish larvae.The results of the study show that exposure to leachate can increase zebrafish mortality,significantly reduce hatching rate and heart rate,and slow trunk growth.In addition,zebrafish juveniles also have deformities such as spinal deformity,pericardial edema,hypopigmentation,and hypoplasia of head and eyes.The results of the study on the effect of leachate on larval movement behavior showed that the 1.0%treatment group significantly inhibited the spontaneous movement speed and light stimulation response of zebrafish juveniles.The effect of leachate on the social behavior of larvae showed that the 1.0%treatment group significantly inhibited the larvae's black and white area exploration frequency and swimming speed,and significantly reduced the larvae's time in the mirror area and the frequency of mirror attacks.In summary,the toxicological effects of leachate on zebrafish embryos/larvae are:inhibit embryo growth and development,induce embryo/larval malformations,and affect their normal motor behavior and social behavior.