Research On Plant Toxicity Of P-nitrophenol And It’s Microbial Degradation Characteristics

With the advance of the modernization process,as a new forming pollution contaminant,the amount of nitrophenols is arising.P-nitrophenols are classified as "Priority Pollutants" due to it’s hard-degradable and biotoxicity,with it’s long-term exposure in the environment,soil,surface water and groundwater is suffering contamination to different extent.Currently,there are many nitrophenol detection were only in river segments,but plants soil and groundwater are bound to be be influenced by the residual of nitrophenol under the intensification of agricultural activity.For the surface plants and groundwater,the effects of nitrophenols migrating between soil and groundwater will not be ignored.However,there is a lack of research on phytotoxicity of p-nitrophenols.And in-situ remediation of nitro-phenol contaminated is only at the soil level.Based on the above problems,by using arabidopsis as experimental object in this paper,I explored the morphological and physiological changes of arabidopsis seeds and arabidopsis seedlings,culturing through the solid medium and hydroponic under different concentrations of nitro phenol pollution.At the same time,selecting the effective degradation strain under low temperature and the optimal degradation condition of the strain was investigated,the degradation process in the groundwater was simulated also.The main conclusions are as follows:(1)Due to direct contact with p-nitrophenol,Arabidopsis root system was affected badly,and the root length and the number of plant leaves were decreased.With the increase of the concentration of p-nitrophenol,the activity of antioxidant enzymes in arabidopsis decreased after a short increase.When the stress concentration exceeded the threshold(3 mg/L),the arabidopsis lose self-repair ability,partly Death or even whole plant death.(2)Appropriate addition of Sucrose as carbon sourse can promote the growth of Arabidopsis roots,which enhances the tolerance of root system to p-nitrophenol to some extent.When the concentration of sucrose is 2g/100 mL,the growth promote effect is the best.(3)An aerobic bacterium capable of degrading p-nitrophenol were screened and named as DL,identify the strain is Pseudomonadaceae.sp according to the colony characteristics and 16 SrDNA sequence.The DL can degradate the p-nitrophenol within 200 mg/L,the higher the substrate concentration,the longer time will be required.Under low temperature(10℃),the maximum tolerance concentration of p-nitrophenol for DL is 75 mg/L,and under the low concentration(<10 mg/L),DL could rapidly degradete pnitrophenol within 8 h.The response-surface model showed that the degradation results were the best when the temperature = 28 ℃,pH = 7 and the initial inoculation amount was 0.11.And the confirmatory experiments showed that the simulation results were very close to the real value.(4)Through the mini-column simulation experiment,it was found that the quartz sand column had adsorption effect on the p-nitrophenol,but it will reach the adsorption saturation soon,and the removal rate of p-nitrophenol was only about 30 %.The removal rate of p-nitrophenol was increased 67 % after biological enhancement by DL,and it was more persistent.And the nitrate content meet the national drinking water standard after biodegradation of DL.