پاسخ برخي از فرآيندهاي چرخه نيتروژن خاك به علف كش آترازين

چكيده انگليسي :

The Response of Some Soil N Cycle Processes to Atrazine Leila soltani 9 April 2011 Department of Soil Science Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiDr F Nourbakhsh farshid@cc iut ac irAbstractSoil microorganisms and the processes they control are essential for long term support of agriculturalsystems therefore the effects of pesticides on microbial biomass of the soil and their activity haveattracted many attentions Although widespread use of chemical compounds in agriculture increase theamount of crop it leads to soil pollution and surface water as well as ground water pollution which area threat to human health For this reason investigation and control of the process of their degradationand their side effects in agricultural soils are of great importance One of the herbicides which islargely used in Iran and other parts of the world is Atrazine Atrazine is a major herbicide forcontrolling wide leaf weeds in corn and other graminaceous fields The objectives of the current studywere to investigate 1 the fate of Atrazine in soil following incubation under optimum conditions and2 the effects of Atrazine on soil net N mineralization arginine ammonification respiration rate metabolic quotient and soil amidohydrolases Soil samples were collected from 0 15 cm layer ofagricultural soils from Shervedan and Juzdan Isfahan Iran To achieve the two goals of study twoindependent experiments were run First Different concentrations of Atrazine 0 0 2 0 4 0 6 1 10 50 100 250 500 and 1000 mg atrazine kg 1dry wight soil were added to soils Triplications of soilswere incubated for 3 and 60 days Aerobic N mineralization arginin amonification urease L glutaminase and L asparaginase activities were measured Second the release of ammonia wasmonitored in a long incubation study in order to recognize the kinetic behavior of Atrazinedecomposition in calcareous soils Results indicated that in both soils of Shervedan and Juzdan aerobicN mineralization and the activity of urease and L glutaminase enzymes as time elapsed significantlyincreased The mentioned biological properties were positively responded to enhancement of Atrazineconcentration As time elapsed arginin amonification decreased The activity of L asparaginase wasirresponsive to Atrazine addition as well as incubation time Apparently L asparaginase did not followthe trends observed for the activity of soil urease and L glutaminase Among the soil biologicalproperties studied in the present research metabolic quotient was the most responsive one to additionof Atrazine It has already been extensively reported that the metabolic quotient is a sensitive index tostress conditions Actually the metabolic quotient indicate the cell maintenance costs and it is likelythat Atrazine has generally increased the stresses for soil microbial populations so that the rate ofrespiration per unit of soil microbial biomass has been considerably increased for soil Moreover inorder to investigate the kinetics of Atrazine induced nitrogen mineralization soil samples were treatedwith concentration of atrazine 0 and 1000 mg atrazine kg 1 soil and were incubated for 60 days Nmineralization in both soils of shervedan and juzdan were conformed well to exponential first orderkinetics The results showed that atrazine degradation in both soils started with a time delay phase andincreased with time incubation The time delay was 4 to 10 days which is a short period In this study microbial respiration microbial biomass carbon and metabolic quetient were measured The resultsshowed that metabolic quotient was heavily affected and increased which represents a kind of stress inmicrobial population of the soil Key words atrazine soil enzymes metabolic quetient kinetic of N mineralization

سلطاني، ليلا

پاسخ برخي از فرآيندهاي چرخه نيتروژن خاك به علف كش آترازين

آنزيم هاي خاك , كسر متابوليكي , روند زماني معدني شدن نيتروژن