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Rapid degradation of bensulfuron-methyl upon repeated application in paddy soils

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Journal of Environmental Sciences 2004年第1期16卷 49-52页

作者： xiexiao-mei LIUWei-ping ABIDSubhani CollegeofEnvironmentalandResourceSciences DepartmentofResourcesScienceZhejiangUniversitvHangzhou310029China CollegeofEnvironmentalandResourceSciences DepartmentofEnvironmentalScienceZhejiangUniversityHangzhou310029China

Rapid degradation of bensulfuron-methyl upon repeated application in paddy soils was studied. The results showed that the DT _ 50 of bensulfuron-methyl was reduced from 16 d to 9 d in soil with one-year bensulfuron-methyl application. Rapid bensulfuron-methyl degradation was happened to previously untreated soil by addition 5% rapid bensulfuron-methyl adapted soil and was inhibited following pre-treatment with broad-spectrum antibiotic chloramphenicol. In bensulfuron-methyl adapted soil mineralisation of 14 C labeled bensulfuron-methyl to 14 CO_2 occurred at a faster rate than with previously untreated soil. It was concluded that rapid bensulfuron-methyl degradation upon repeated application is probably linked to the adaptation of soil bacteria which can utilize bensulfuron-methyl as a source of carbon and energy.

关键词： bensulfuron-methyl rapid degradation paddy soil

Effects of pesticides on soil biochemical characteristics of a paddy soil

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Journal of Environmental Sciences 2004年第2期16卷 252-255页

作者： xiexiao-mei LIAOMin HUANGChang-yong LIUWei-ping ABIDSubhani CollegeofEnvironmentalandResourceSciences DepartmentofResourcesScienceZhejiangUniversityHangzhou310029China. CollegeofEnvironmentalandResourceSciences DepartmentofEnvironmentalScienceZhejiangUniversityHangzhou310029China

The impact of triazophos, bensulfuron-methyl, chlobenthiazone on soil biochemical characteristics in a paddy soil under controlled moisture(flooded soil) and temperature(25℃) condition was studied. The electron transport system(ETS)/dehydrogenase activity displayed a negative correlation with triazophos, bensulfuron-methyl, chlobenthiazone concentrations, and the activity decreased as the concentration of the pesticides increased. The higher doses, 5 and 10 field rates, of triazophos, bensulfuron-methyl, chlobenthiazone significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect against the control. The relative toxicity of triazophos, bensulfuron-methyl, chlobenthiazone in decreasing the ETS activity was in the order: triazophos > chlobenthiazone > bensulfuron-methyl, irrespective of the rates of application. Triazophos, bensulfuron-methyl, chlobenthiazone caused an improvement in the soil phenol content and it increased with increasing concentration of triazophos, bensulfuron-methyl, chlobenthiazone. Triazophos, bensulfuron-methyl, chlobenthiazone incorporation did not produce any significant change in soil protein content. The response of biomass phospholipid content was nearly similar to ETS activity. The phospholipid content was decreased with the addition of triazophos, bensulfuron-methyl, chlobenthiazone in the order of triazophos > chlobenthiazone > bensulfuron-methyl; and the toxicity of applied amount was in the order: 10 FR(field rate) > 5 FR > 1 0 FR > 0 5 FR > control.

关键词： triazophos chlobenthiazone bensulfuron-methyl soil biochemical characteristic

Cadmium Release in Contaminated Soils due to Organic Acids

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Pedosphere 2004年第2期14卷 223-228页

作者： LIAOMin xiexiao-mei DepartmentofResourcesScience CollegeofEnvironmentalandResourceSciencesZhejiangUniversityHangzhou310029（China）.E-mail：liaomin@***

There is limited information on the release behavior of heavy metals fromnatural soils by organic acids. Thus, cadmium release, due to two organic acids (tartrate andcitrate) that are common in the rhizosphere, from soils polluted by metal smeltersor tailings andsoils artificially contaminated by adding Cd were analyzed. The presence of tartrate or citrate at alow concentration (= 2 mmol L^(-1) for citrateand >= 15 mmol L^(-1) for tartrate) apparently promoted Cd release. Under the same conditions, theCd release in naturally polluted soils was less than that of artificially ***, as the initial pH rose from 2 to 8 in the presence of citrate, a sequentialvalley and then peak appeared in the Cd release curve, while in the presence of tartrate the Cdrelease steadily decreased. In addition, Cd release was clearly enhanced as the electrolyteconcentration of KNO_3 or KC1 increased in the presence of 2 mmol L^(-1) tartrate. Moreover, ahigher desorption of Cd was shown with the KCl electrolyte compared to KNO_3 for the sameconcentration levels. This implied that the bioavailability of heavy metals could be promoted withthe addition of suitable types and concentrations of organic acids as well as reasonable fieldconditions.

关键词： artificially contaminated soil cadmium organic acid polluted soil release

Combined Effects of Nutrient and Pesticide Management on Soil Microbial Activity in Hybrid Rice Double Annual Cropping System

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Rice science 2004年第3期11卷 140-146页

作者： xiexiao-mei LIAOMin LIUWei-ping SusanneKLOSE NaturalResourcesScienceDepartment CollegeofEnvironmentalandResourcesSciencesZhejiangUniversityHangzhou310029China EnvironmentalScienceDepartment CollegeofEnvironmentalandResourcesSciencesZhejiangUniversityHangzhou310029China InstituteofSoilScience FacultyofForestGeoandHydroSciencesDresdenUniversityofTechnologyTharandtD-01735Germany

Combined effects on soil microbial activity of nutrient and pesticide management in hybrid rice double annual cropping system were studied. Results of field experiment demonstrated significant changes in soil microbial biomass phospholipid contents, abundance of heterotrophic bacteria and proteolytic bacteria, electron transport system (ETS)/dehydrogenase activity, soil protein contents under different management practices and at various growth stages. Marked depletions in the soil microbial biomass phospholipid contents were found with the advancement of crop growth stages, while the incorporation of fertilizers and/or pesticides also induced slight changes, and the lowest microbial biomass phospholipid content was found with pesticides application alone. A decline in the bacterial abundance of heterotrophic bacteria and proteolytic bacteria was observed during the continuance of crop growth, while the lowest abundance of heterotrophic bacteria and proteolytic bacteria was found with pesticides application alone, which coincided with the decline of soil microbial biomass. A consistent increase in the electron transport system activity was measured during the different crop growth stages of rice. The use of fertilizers (NPK) alone or combined with pesticides increased it, while a decline was noticed with pesticides application alone as compared with the control. The soil protein content was found to be relatively stable with fertilizers and/or pesticides application at various growth stages in both crops undertaken, but notable changes were detected at different growth stages.

关键词： nutrient management pesticide management soil microbial activity hybrid rice