Toxicity Response And Mechanism Of Phosphatase To Arsenic Pollution Under Soil PH

Arsenic pollution is one of the more serious heavy metal pollution problems in China.Its migration,transformation and biological toxicity in soil are restricted by the soil environment.Phosphatase is essential in the cycle of soil phosphorus,which can catalyze the hydrolysis and mineralization of organic phosphorus to release inorganic phosphorus.The activity can reflect the degree of soil phosphorus availability to a certain extent.Phosphatase is more sensitive to heavy metal pollution and is an important biological indicator for monitoring heavy soil pollution in soil.In this paper,the effect of arsenic pollution on soil phosphatase activity in the actual environment was studied under soil p H buffer conditions,and the mechanism of action of arsenic on soil phosphatase was analyzed in depth with the help of kinetic and thermodynamic methods to explore the soil p H The difference in response and mechanism of soil phosphatase to arsenic pollution under the optimal p H buffer solution will ultimately provide a basis for monitoring and remediation of environmental pollution.The main conclusions are as follows:（1）In the soil p H buffer system,soil phosphatase activity was significantly inhibited after pentavalent arsenic pollution.The degree of inhibition was related to arsenic concentration and soil fertility characteristics.The phosphatase activity and inhibition rate of alkaline soil were lower than acid soil;field arsenic pollution In soil,the phosphatase activity of soil with higher arsenic content is lower,and the total arsenic and arsenic form content have a significant negative exponential function relationship with the phosphatase activity of contaminated soil.（2）Kinetic studies have shown that in the soil p H buffer system,the K_m of alkaline soil phosphatase showed an upward trend after pentavalent arsenic pollution,the change trend of Vmax was small,and the change trend of K_m of acid soil phosphatase was up and down.Or unchanged,V_max decreased,and all soils showed a downward trend.Alkaline soil is a type of competitive inhibition or linear mixed inhibition,acidic soil is more complex.Soil fertility traits can significantly affect the binding capacity of arsenic with enzymes and enzyme-substrate complexes.Compared with the results of the pentavalent arsenic pollution test,the arsenic-contaminated soil phosphatase has a higher V_max,a smaller K_m range,and a lower V_max/K_m.Pentavalent arsenic pollution and field arsenic pollution tests show that V_max/K_m is a more sensitive arsenic pollution evaluation index.Thermodynamic studies on pentavalent arsenic pollution and field arsenic pollution show that the enzymatic reaction of soil phosphatase is a non-spontaneous reaction that requires heat absorption from the outside.（3）Compared with the optimal p H buffer system,under the pollution of pentavalent arsenic,the soil phosphatase activity and its inhibition rate in the soil p H buffer system are lower in alkaline soils and higher in acidic soils,and the kinetic parameters vary greatly.The constant is large.Under both buffer systems,alkaline soils are dominated by competitive inhibition;under arsenic contamination in the field,the relationship between soil p H buffer system arsenic and soil phosphatase activity is more obvious compared to the optimal p H buffer system;soil phosphatase The V_max and V_max/K_m values are higher,and the K_m range is larger.Using a soil p H buffer system can more accurately use phosphatase to evaluate the toxicity of arsenic.