The Research On Soil Enzyme Activity And Its Mechanism Affected By Nano Carbon Powder

Carbon nanopowder has a relatively unique, stable chemical structure, and theapplication is very extensive. Carbon nanopowder into the environment will eventually returnto the soil through various ways. And these fixed nanomaterials can occur biologicaltransshipment through swallowed, contact and so on, and accumulate through the food chainin the ecosystem, and the related reports at home and abroad have demonstrated that carbonnano-materials have irreversible effects on soil organisms. Therefore, the study of carbonnanopowder has a very important significance impact on the soil environment. Soil enzyme istreated as the most active biological active substances in the process of nutrient cycling andenergy flow of terrestrial ecosystems, and soil enzyme activity can be quickly reflected thestrength and direction of various biochemical processes in soil. Therefore, we can say that soilenzymes and microbial jointly promote the metabolic processes of soil, almost becomeindispensable indicator of soil quality monitoring and research.Based on the analysis of domestic and international research which are summarized, usethe indoor simulation experiment to study the effect of carbon nanopowder on the soilenzymes and microbial biomass, and analysis the behavior and enzyme activity of the jackbean urease that adsorbed by carbon nanopowder, soil clay, montmorillonite, kaolinite andstudied pure enzyme adsorption characteristics and influencing factors. The main conclusionsand progress are:1. The influence of carbon nanopowder acting on the different soil enzymes is different,and influences by the soil conditions. The soil urease activity can be activated at a certain lowconcentration of carbon nanopowder, and inhibited at a high concentration. Carbonnanopowder impact on soil alkaline phosphatase activity and urease is roughly same, but theregularity than soil urease is good.2. With the change of the concentration of carbon nanopowder, soil microbial biomasscarbon increased at low concentrations, and decreased at high concentrations. And underdifferent concentration of carbon nanopowder the three different test soils appeared inflectionpoint respectively. Among them, the higher fertility, soil microbial biomass carbon began toinhibition by carbon nanopowder concentration is higher. In this experiment, after addingcarbon nanopowder, the three kinds of soil microbial biomass and soil urease have similar butalso have different variation.. Therefore, those carbon nanopowders, to a certain extent, though affect the microbial soil to affect the enzyme activity. But other factors are bound toexist3. Under the condition of two different kinds of pH buffer, carbon nanopowder gel arebetter fit with the Langmuir adsorption isotherm equation, it is the monolayer adsorption.With the increase of pH, adsorption of enzyme on colloid gradually reduces. The activity ofenzyme that fixed on colloid is gradually reduced, but in the test range, the activity of fixedstate enzyme is still greater than zero. Carbon nanopowder is given priority to withhydrophobic forces, and combine with electrostatic force, hydrogen bond, van der Waalsforce and so on. the adsorption quantity of enzyme on the surface of colloid in Citrate bufferis greater than the Tris-HCl buffer, but considering the protective effect of the test on theactivity of Tris, make pure enzyme solution can be maintain stabile activity in the scopeexperiment research at a long time, therefore, it is recommended that use of Tris-HCl buffersolution in the a suitable range.4. As the same with clay, kaolin clay, montmorillonite, the process of Carbonnanopowder adsorb urease is an exothermic reaction. The higher the temperature, the moredifficult to the adsorption. The process of carbon nanopowder adsorb urease belongs tophysical adsorption, and the adsorption mainly rely on hydrophobic force. And carbonnanopowder having a great surface area, binding site of the enzyme is increased, theadsorption quantity increases sharply. In the experimental temperature range, the activity ofimmobilized enzyme absorbed by four kinds of colloid appeared increase, and then appeareddecrease. at35℃reaches the highest activity, and with the change of temperature, theactivity of urease immobilized at the surface of montmorillonite and Carbon nanopowder issmaller than clay and kaolin.that is to say the thermal stability of former immobilized enzymeare better than the latter.