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Research On The Characteristics Of Soil Pesticide Residues And Microbial Remediation In The Panax Notoginseng Planting Area

Posted on:2019-06-29Degree:MasterType:Thesis
Country:ChinaCandidate:Y LiFull Text:PDF
GTID:2430330566973454Subject:Environmental Science and Engineering
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Pesticides are indelible contribution to agricultural production and the development of society,but the pesticide residues become a potential threat to human's health and ecological environment due to the irrational and widespread application.In this study,the extraction and determination methods of fungicides were established for analyze the common pesticides(pentachloronitrobenzene,chlorothalonil,procymidone,iprodione,pyrimethanil and pyraclostrobin)of Panax Notoginseng planting region in Yunnan Province.The soil samples were collected to investigate the pesticide residues level of fungicides and iprodione was select as the representative pesticide because of its high occurence and residue level in reaserch area.The degrading bacteria of representative pesticide were isolated from contaminated soil and identified by analyzing 16 S rDNA sequence combined with morphology,physiological and biochemical characteristics.Following,the optimum degradation conditions for biodegradating pesticide were investigated to enhance the the biodegradation effect.The isolates were applied to contaminated soil remediation,and the microbial communities dynamic were sequced and analyzed during the process bioremediation.The main experimental results are as following:(1)The comparison determination of target pesticides by using gas chromatography(GC-ECD)and liquid chromatography(HPLC)showed that the HPLC-PDA assay was suitable for determination of iprodione,pyrimethanil and pyraclostrobin,the GC-ECD assay was used for determination of Pentachloronitrobenzene,chlorothalonil,procymidone.The QuEChERS method was used to extract the iprodione,pyrimethanil and pyraclostrobin in soil,and the ultrasonic extraction method was used for extraction of Pentachloronitrobenzene,chlorothalonil,procymidone.(2)The investigation of fungicide residues in soil samples from Yunnan province shows that iprodione and PCNB were both detected.The mean content of heterotrophic urea,five chloro-nitrobenzene,rot-fungi,bacteria-clear,adriamycin and pyrazole ether are 63.48,3.69,28.37,7.92,39.37 and 74.64?g/kg,respectively.Generally,the concentration of fungicides in soil which is planting Panax notoginseng is most high,and the concentration of fungicides in soil which has been planted Panax notoginseng is lower,and the concentration of fungicides in soil which never been planted Panax notoginseng is lowest.(3)A strain KMS-1 was isolated from heterotrophic urea contaminated soil,and identified as Bacillus sp.based on 16 S rDNA gene sequence and phylogenetic analysis.The degradation experiment showed that the concentration of heterotrophic urea was reduced to 2.56 mg/L from 25 mg/L after 7-day cultivation,and the degradation rate was 41.4%.Metabolites are identified by using HPLC and LC-MS/MS,and the main products is 3,5-Dichloropheylcarboximide.The enzyme-localized experiments showed that the hydrolytic-enzymes belong to extracellular enzymes of the strain KMS-1.(4)Soil culture experiment in lab showed that the strain KMS-1 could promote the degradation of heterotrophic urea.On 15 d,the degradation rates for control group(CK),the Organic Manure treatment Group(F),the bacteria treatment group(J)and the Organic Manure treatment Group(JF)were 82.97%,92.36%,95.4% and 96.2%,respectively.Strain KMS-1 could enhance the degradation of heterotrophic urea,and organic manure slightly effect the degradation ability of KMS-1.(5)The strain KMS-1 may affect the diversity of bacterial communities in soil environment.The content and toxicity of pollutants are gradually reduced with time increasing.Meanwhile,the microorganisms recover to normal metaboilic level and the diversity of community will return to the relative equilibrium level.The analysis of soil bacterial community at genus level showed that there are differences in the bacterial community structure between the treatments without KMS-1 strain(CK,F)and treatments with the KMS-1 strain(J,JF).While the bacterial composition of F treatment was similar to that of CK,and the community composition of J treatment was similar to that of JF.
Keywords/Search Tags:Panax Notoginseng, Soil, Fungicide, Residue, KMS-1 strain, Degradation
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