Effect Of Different Organic Acids On Cadmium Remediation In Calcareous Soil

?Purpose?The use of organic acids to enhance the activity of heavy metals to enhance the absorption of heavy metals by plants is widely used.In this paper,the effect of organic acids on the cadmium recovery of calcareous soil was studied.Through the soil column test,the effects of different organic acids on the leaching and morphology of cadmium in soil were studied,and the organic acid with better activation effect was selected.Through the pot experiment,the effects of organic acids on the accumulation of cadmium and soil cadmium in crops were studied by the type,amount and application method of organic acids,which provided a reference for the repair of cadmium in calcareous soil.?Method?In this study,different organic acids were used to elute cadmium-contaminated soil,compare the content of Cd in soil before and after leaching and the form of Cd in soil.Potted simulation experiments were carried out to repair heavy metal cadmium in soil by combining different organic acids with plants,and compare the effects of different organic acids on Cd accumulation in soil and soil Cd.The effects of different types,dosages and application times on the accumulation of cadmium and soil cadmium in plants were studied,and the repairing effects of different methods were compared.?Main results?1.Effect of Different Organic Acids on Cd Leaching Effect in Calcareous SoilDifferent organic acids have different leaching effects on cadmium.Under the leaching of organic acids,the Cd content in the soil decreased,and the Cd content in the eluent decreased with the increase of the number of leaching.The largest leaching amount was fulvic acid,the smallest is oxalic acid,the amount of leaching is 1622.87ug and 810.4ug respectively.Organic acids mainly affect the exchangeable fraction and residual fraction in the soil.Organic acids mainly affect the exchangeable and residual states in the soil,and the three organic acids?alone?significantly increase the bioavailability of Cd in the soil.2.Effect of Different Organic Acids on Cd Repairing Effect in Calcareous SoilUnder the application conditions of different organic acids,the accumulation of heavy metal Cd and the morphology of Cd in soil have different effects on the two crops.The accumulation of cadmium in the aboveground part of Chinese cabbage is higher than that in the lower part of the ground,and the lower part of the corn is higher than the upper part of the ground.For the form of Cd in the soil,the cabbage is mainly exchangeable,and the corn is dominated by carbonate.Citric acid significantly promoted the accumulation of Cd in the Chinese cabbage,and more effectively repaired the heavy metal Cd in the soil.3.Effect of the amount of organic acid and the application method on the soil Cd remediation effectUnder the two application regimes,fulvic acid and low concentration of citric acid promoted the absorption of Cd by absorption.Low concentration of citric acid promoted the accumulation of Cd in absorption.The fractional application mode effectively increased the bioavailability of Cd,and the exchangeable fraction of Cd in the soil under each treatment increased.The split application mode is higher than the one direct application mode in terms of activating the Cd effect relative to the two regimes.Under the condition of low dosage of organic acid,the repairing effect is better under two conditions.4.Effect of the application times of organic acids on the remediation effect of Cd pollution in calcareous soilUnder the condition of D10 treatment,the dry matter quality,Cd content and absorption of the aboveground part were the highest,and the content of Cd in the soil was the lowest.For the exchangeable fraction of Cd in the soil,the ratio of D7 was the highest.In summary,the repair effect of D10 is better.?Conclusion?1.The superior leaching effect of fulvic acid on soil Cd is more effective in activating Cd in soil.2.Citric acid significantly increased the Cd content of plants and the exchangeable state of Cd,and decreased the content of Cd in soil;it had a significant effect on the activation of Cd and the accumulation of Cd.3.Direct one-time application,the highest absorption in the ground is 1g pot^-1 citric acid.For each treatment,the exchangeable fraction and the residual state are dominant.For FH1 treatment,the exchangeable Cd content is the highest.Under the treatment of ZH2,the residue content is the highest.The application of the two methods significantly promoted the activation of Cd in the soil.4.For fulvic acid,applied once every 10 days,a total of 3 times the repair effect is better.