Toxicity Study Of Landfill Leachate On Maize Life Cycle

Landfill leachate as a kind of compound wastewater has great harm on environment.The present researches about leachate are mainly concentrated on two aspects: the treatment and the pollution effect.Therefore,this topic used the air stripping method to dispose the ammonia-nitrogen landfill leachate by the combination of single factor test and orthogonal test,and investigated the the effect of various factors on the ammonia nitrogen removal performance to get the best conditions.In addition,we analyzed the ecotoxicological effect of leachate by comparing the response of maize to leachate infecting the soaking and germination stages.Moreover,the present research also investigated the generational genetic effect of seed soaking with landfill leachate on the maize by the early cultivation experiment.The results showed that:1.The air stripping method to dispose the ammonia-nitrogen landfill leachate showed that the appropriate conditions were p H 11,reaction time 180 min,throughput 8.25 L·min-1,respectively.In that condition,the subsequent biochemical treatment system can be processed with the decrease of ammonia nitrogen concentration of landfill leachate.2.The change of physiological indexes including Chlorophyll(Chl)content,Malondialdehyde(MDA)and Reactive oxygen species(ROS)levels combined with yield all showed that soaking with leachate,but not germination generated a greater ecological risk on maize.After soaking treatment of maize with 50% leachate,the Chl,MDA and ROS levels during vigorous growth period were 47.3%,149.8% and 309.7% respectively of control,while the yield decreased to 68.6% of control.In addition,our results demonstrated that the leachate at lower levels(10%)could promote the growth.This is mainly embodied in that the yield of maize treated with 10% leachate at soaking stage increased to 116.0% of control.3.The mitotic index of maize treated with leachate at soaking and germination stages showed that low concentration promoted mitosis and high suppressed,while the micronucleus damage presented a dose-effect relationship.The results indicated the ecological risks of leachate on maize are cannot be ignored.4.The grey relational analysis(GRA)showed that ear row number and tassel branch number were the major factors affecting plot yield of maize treated with 50% leachate at stages of soaking and germination,respectively.5.The results of genetic effect of seed soaking showed that leachate affect the early growth and development of generational maize.Low concentrations(10%)of leachate promoted seed germination and seedling growth,while high concentrations(50%)showed restrained effects.Moreover,the toxicity effect on F2 generation of maize was relatively weakened compared with the F1 after seed soaking with leachate,and the significant differences on F2 were only appeared between high concentration group and control group.The germination rate,root length,shoot length and chlorophyll content of 50% treatment group were 81%,83%,79% and 89% of the control group,respectively.6.The generational genetic influence of seed soaking with leachate on root tip mitotic index showed that low concentration promoted mitosis and high suppressed,while the micronucleus damage presented a dose-effect relationship.The results indicated the ecological risks of leachate on F1 and F2 generations of mazie are still existing even at the low concentration.In general,our findings provided a certain practical significance by using Zea mays L.as model plant,and these results are helpful in understanding phytotoxicity of leachate,which provide additional reference data for ecological risk assessment and management of leachate.