Study Of Combined Pollution Between Glyphosate And Cu And Its Influence On The Soil Enzyme And Microorganism Carbon/Nitrogen

This paper taking herbicide glyphosates and the copper as typical model organic matters and the heavy metal pollutants,Combined pollution between glyphosate and Cu and its influence on the soil enzyme and microorganism carbon and nitrogen were studied and the main results were summarized as follows:The effect of glyphosate on the leaching of Cu from a heavy metal contaminated soil was studied in the laboratory using sieved soil columns.The Cu content in the leaching fluid and the heavy metal biological valid density of earth pyramid lower level in soil had been increased because of the existence of glyphosate.Adsorption kinetics of glyphosate and Cu were studied using a continuous flow experimental setup on two soils with different characteristics.On WuShan soil,the adsorptive capacity of Cu²⁺ is bigger than the Red soil,because compares with the Red soil,WuShan soil has the high cation exchange quantity,the pH value and the organic content.But the adsorptive capacity of glyphosate is higher than on the Red soil.Lagergren-first-order kinetic model fit the experimental data of glyphosate and Cu²⁺ adsorption the best.Glyphosate significantly increased the adsorption quantity of Cu²⁺ on the Red soil,Due to glyphosate on Red soil has high affinity,glyphosate between Red soil and Cu²⁺ as a "bridge",thus increased the Red soil to the Cu²⁺ adsorption,However,glyphosate decreased the adsorption of Cu²⁺ on the Wushan soil,because adsorption of glyphosate on this soil was weak,and the complex of glyphosate and Cu²⁺ tended to be highly soluble in water,thus preventing Cu²⁺ from exchanging with Ca²⁺ and Mg²⁺ ions on the soil surface.On the other hand,the presence of Cu²⁺ decreased the adsorption of glyphosate on both soils,which may be attributed to the lower affinity of Cu²⁺-glyphosate complex to the soils than the affinity of glyphosate alone. The presence of copper reduced the biomass of rape obviously,because we chose the glyphosate-tolerant rape,the presence of glyphsoate did not affect the biomass of rape.The presence of copper increased the absorption of copper in the rape markedly,when glyphosate and copper coexisted in the soil,the presence of glyphosate significantly reduced the absorption of copper in the rape.The low concentration of copper obviously promote the soil urease activity,but the highly concentration of copper inhibited it.The presence of glyphosate inhibited the urease activity significantly.When glyphosate and copper coexisted,the presence of glyphosate increased the copper toxicity to the urease activity,both performances for positive synergism.The low concentration copper has obviously decreased the soil alkalinity phosphatase activity,but the high concentration of copper has inhibited the soil acid phosphatase activity.Low concentration of glyphosate reduced the activity of the soil acid phosphatase,but high concentration of glyphosate promote the activity of soil acid phosphatase slightly;When glyphosate and copper coexisted,the low concentration glyphosate reduced the copper toxicity,reduced the inhibitory action of copper to the phosphatase activity in soil,both performances for antagonism.but high concentration of glyphosate increased the copper toxicity,increased the activity of the soil acid phosphatase,both performances for synergism.The presence of copper suppressed the soil sucrase activity obviously,the presence of glyphosate also reduced the soil sucrase activeness;When low concentration copper,the presence of glyphosate reduced the copper toxicity,increased the soil sucrase activity,both performances for antagonism.But under the highly concentrated copper condition,the presence of glyphosate increased the copper toxicity,reduced the soil sucrase activity,both performances for antagonism.The presence of copper reduced the content of microorganism carbon obviously,but increased the microorganism nitrogen content;glyphosate reduced the content of microorganism carbon.Low concentration of glyphosate increased the content of microorganism nitrogen in the soil,but high concentration of glyphosate reduced the contentration of microorganism nitrogen in the soil.Under the same concentration of copper,the presence of glyphosate reduced the contentration of microorganism nitrogen.