Influences Of Bamboo-charcoal Amendment On The Adsorption Of Glyphosate, Lead And The Microbial Activity In Soils

It mainly has done the following research work in this paper. the adsorption-desorption of herbicide glyphosate, heavy metal lead in soils and their mutual influence; the influence of bamboo-charcoal on the adsorption of glyphosate, lead in soils; the influence of bamboo-charcoal on microorganism and enzyme activity in soil which was single and compound polluted by glyphosate, lead. the field tests of soil correctives improveing soils. The main results are as follows:1. The adsorption isotherm of glyphosate on the four different kinds of soils can correspond to the Freundlich adsorption isotherm equation; The adsorptive capacity of red soil is larger than the others, the next are Huanghe soil, huangchao soil and shajiang black soil; The adsorption behaviors are concerned with the physial and chemical properties of the soils; The Kf was increased with increasing clay content, ferric oxide content and decreased with soil pH's increase, but it had no connection with the CEC. the glyphosate is very difficult to be desorbed from the soils, especially on red soil, the desorption rates are all below 25%. The hysteresis coefficients are all over one which indicated that the desorption of glyphosate existed hysteresis. The adsorption of glyphosate in Huanghe soil, red soil are increased by the presence of Pb²⁺, and the adsorption intensity increased along with the Pb²⁺ concentration's increase.The adsorption of Pb²⁺ on the soils can correspond to the Freundlich adsorption empirical equation. The adsorptive content and intensity of Huanghe soil which has higher CEC content and pH is larger than the acidic red soil. The adsorptive content and intensity of Pb²⁺ on soils is decreased by the presence of glyphosate.2. The adsorption of glyphosate on bamboo-charcoal indicated that the adsorptive content is little, and the adsorptive intensity is related to the particle size of bamboo-charcoal. The smaller the particle size of bamboo-charcoal is, the stronger the adsorption of glyphosate is. The adsorption content and content of glyphosate in bamboo-charcoal is less than that in soils. Maybe the reason is that the alkalescent environment formed by bamboo-charcoal is not conductive to the adsorption. The amendment with bamboo-charcoal can decrease the adsorption of glyphosate in soils, and the falling degree in acidic red soil is bigger than Huanghe soil.bamboo-charcoal had a great adsorptive capacity for Pb²⁺, the particle size of bamboo-charcoal impact the adsorptive content greatly. The smaller the particle size of bamboo-charcoal is, the stronger the adsorption of Pb²⁺ is. The best condition of adsorbing Pb²⁺ in water is absorbing four hours, pH=6-7, 25℃and 10 mg/L dosage. The amendment with bamboo-charcoal could improve the adsorptive intensity, max adsorption content of pb2+ in soils.3. When the soils were treated with glyphosate singlly, glyphosate restrained bacteria from growing up firstly, and then stimulated it. The actinomyces was restrained all the time. But the restraining became weaken along with the time. Glyphosate inhibited the activities of amylase, urease and catalase, and the higher concentration of glyphosate, the stronger the inhibite. When the soils were treated with lead singlely, the bacteria, actinomyce were restrained from growing up; the activities of amylase, urease and catalase were restrained collectivity, but the activities of bacteria, actinomyce were stimulated at beginning. When the soils were treated with bamboo-charcoal singlely, at the first one and three weeks, the activities of bacteria, amylase, urease and catalase were inhibited, and then they were stimulated at the seventh to eleventh weeks; the actinomyces'growing up were stimulated all the time. When the soil were amended with bamboo-charcoal, the toxicity of lead and glyphosate was decreased, and the activities of microbe and enzyme were stimulated.4. The field test results indicate that the three soil correctives which contain charcoal, bamboo-charcoal and attapulgite improve the same type soil differently, As the charcoal and bamboo-charcoal having the similar physical and chemical properties, they have the similar improving effects. The same soil correctives improve the different type soil differently. It is possilby because that soils have the different physical, chemical properties and biological character. The 1 m2 area and field tests results of huanghe soil and red soil indicate that the microbial activity and rice'yield are different amended with the same soil corrective.the reason mainly are differentthe soil environment of rice'growing up and the different management. The reasons why correctives have different improvement effects require specifically further studying. Analyzed from the rice's yield, the charcoal can greatly improved the shangjianghe soil, huangchao soil and huanghe soil. the bamboo-charcoal can greatly improved huangchao soil and huanghe soil. The attapulgite can greatly improved shangjianghe soil and huanghe soil. Analyzed from microbial activity and rice'yield , charcoal and bamboo-charcoal improved soil better than attapulgite.