Effects Of Bone Meal Materials On Immobilization Remediation Of Cd Contaminated Soils

National Soil Pollution Status Survey Bulletin showed that the situation of Cd pollution is the most serious in China,exceeding the standard point of 7.0%.It found that the area of cadmium-contaminated cultivated land in China has reached 2×10~4 hm~2,and there was 1.46×10~9 kg agricultural products contaminated by Cd every year.Nowadays,there are many methods for remediation of Cd polluted farmland,including physical remediation technologies,chemical remediation technologies,bioremediation technologies.Among these techniques,chemical immobilization remediation technologies is suitable for repairing largescale medium and low levels of heavy metal contamination due to its advantages of rapid,simplicity,and high-efficiency.Static culture and pot experiment were conducted to clarify the effects of bone meal on the remediation effect of Cd contaminated soil,soil fertility and plant biochemcial characterization.Therefore,it provides theoretical and technological support for remediation of large-scale Cd contaminated soils using bone meal.The main findings and conclusions are as follows:(1)Under static culture experiment,p H in acid soil was increased after the application of fish and bovine bone meal,and it was opposite for alkaline soil.The contents of available Cd was reduced under different treatments of bone meal,the amount of TCLP-Cd under fish bone meal treated soil decreased by 3.9%~49.7%(alkaline soil)and 2.9%~17.0%(acid soil),respectively,and for bovine bone meal treated soil it decreased by 38.9%~71.9%(alkaline soil),and 8.6%~18.2%(acid soil).The soil fertility under different addition of bone meal was enhanced excepted for alkaline soil under the application of bovine bone.The amount of organic carbon functional groups such as phenol,aromatic C or quinone C=O,and Fat C was increased,and while it was inhibited for C-O and silicate.After applying bone meal,the content of TCLP-Cd in alkaline soil was significantly negatively correlated with organic matter(p<0.01),and for acid soils it exhibited remarkable negative correlation among TCLP-Cd,p H,organic matter,available phosphorus and available potassium(p<0.01).(2)Under pot experiment,the biomass of Brassica campestris L.in Tianjin soil was reduced under the addition of fish and bovine bone meal and it was increased for Hunan and Henan soils.As a whole,the content of chlorophyll in Brassica campestris L.was enhaced,it increased by 11.18%,7.99% and 14.35% for Tianjin,Hunan and Henan soils,respectively.The activties of POD,APX,GSH-ST and Pro was increased under different treatments of bone meal.When compared with the control,the Cd content in aboveground of Brassica campestris L.after applying fish bone meal in Tianjin,Hunan and Henan soils decreased by 7.13%-39.76%,16.06%-32.54% and 5.96%-39.03%,respectively,and 47.67%-59.66%,28.18%-41.95% and 20.25%-47.96% respectively,for bovine bone meal.After bone meal treatments,there was a significant negative correlation between Cd content and APX activity of Brassica campestris L.stems and leaves in Tianjin soil(p<0.01),under Hunan soil there was a significant negative correlation between Cd content and POD activity(p<0.05).and under Henan soil there was a significant negative correlation between Cd content in stems and leaves and GSH-ST and Pro(p<0.05).(3)Under pot experiment,the addition of fish bone meal could decrease the p H in Tianjin and Henan soils,whiel the p H in Hunan soil was increased.The value of p H under bovine bone meal treated Tianjin soil was decreased,and it was opposite for Henan and Hunan soils.The trend of soil organic matter content was consistent with the soil p H.After applying the bone meal,the soil fertility was increased,and the contents of available N,P and K were enhanced.The application of bone meal converted the fraction of Cd from an unstable form to a stable form,the concentration of available Cd was inhibited,and while it was enhanced for residual form of Cd.The population of Proteobacteria in the soil treated with different levels of bone meal was increased,but it was prohibited for Actinobacteria and Acidobacteria.Under the treatment of bone meal,the exchangeable Cd content of soil in Tianjin was significantly positively correlated with soil organic matter(p<0.01),and there was a significantly negative correlation between available P and available potassium(p<0.01).After applying bone meal in Hunan soil,the exchangeable Cd content was significantly negatively correlated with soil p H,organic matter,available N,P and K(p<0.01).After applying bone meal in Henan soil,the exchangeable Cd content was significantly negative correlation with soil available N and P(p<0.01).