The Effect Of Weathered Coal Activated By Ultrasonic On The Forms Of Lead And Cadmium In Soil And Soil Enzyme Activity

The heavy metal pollutants in soil have many characteristics, such as strong cumulative, long hazard cycle and disater governance. So it receives people’s attention, and all countries in the world have different degree of soil heavy mental pollution.Humic acid is widely existing in water, peat, lignite and weatherd coal. Its application renge is very wide. Not only it can improve soil environment, but also can prevent soil heavy metal pollution. In recent years, there are more and more researches about humic acids in coal as additives for heavy metal polluted soil management. But the main focus on the effect of humic acids on heavy metal ions adsorption in soil surface, but the study of humic acids on plants absorbing heavy metal and soil property is less. This topic mainly research humic acids in weathered coal activated by ultrasonic on pakchoi cabbage’s absorbing lead and cadmium and soil enzyme activity, providing the theoretical basis of increasing humic acids fertilizer at the regional of lead and cadmium single poison. The main conclusions are as follows:(1)Conclusion about the effect of weathered coal activated by ultrasonic:Ultrasonic can obviously improve the production of free humic acids in weathered coal, but it is influenced by many factors. A certain range, the content of free humic acids in weathered coal increases with water-coal ratio, ultrasonic power and ultrasonic time increase. The results show that the best activation conditions are as follows:water-coal ratio8:1, the ultrasonic power200W, ultrasonic time25min. The content of free humic acids in weathered coal is7.79%on the condition, and it increased6.56times. The research provided theoretical basis of making efficient quality humic acids products with weathered coal.(2) Conclusion about the effect of weathered coal activated by ultrasonic on pakchoi cabbage’s absorbing lead and cadmium and soil enzyme activity:when add weathered coal of10、20、40、60g/kg, the weak acids extraction, reductive and oxydic form of lead and cadmium in soil was reduced in different degrees; it can effectively reduce the removability of lead and cadmium in soil and decrease significantly the content in pakchoi cabbage; it also can significantly decrease the biotoxicity of lead and cadmium in soil and improve the soil enzyme activity (such as catalase, urease and sucrase). So here is the conclusion, appropriate weathered coal activated by ultrasonic volume of20-40g/kg can significantly alleviate metallic lead and cadmium single pollution, providing the theoretical basis of increasing humic acids fertilizer at the regional of lead and cadmium single poison.