| Apparent adsorption experiment, pot experiment of pakchoi, exposure experiment of earthworm were conducted in order to evaluate the effect of corn straw derived biochar (pyrolyzed at 700℃) amendment at different concentrations (0.5%, 1%, 2%, 5%) on Cu immobilization, pakchoi biomass and Cu bioaccumulation as well as earthworm SOD activity. Appropriate application rate of biochar was expected to identify. The result of adsorption experiment showed that biochar was effective in enhancing apparent sorption of uncontaminated soil on Cu2+. Compared with CK, the pH and organic matter of Cu spiked soil increased by 0.21~1.05 units and 4.8~23.13 mg/kg respectively after biochar addition and incubation. Biochar had the ability to prompt the inactivation of Cu in soil. After biochar application, Cu concentration in shoot of pakchoi decreased from 89.2 mg/kg to 80.5 ~38.6 mg/kg, and Cu content (multiply shoot dry biomass by Cu concentration) in shoot decreased from 0.149 mg to 0.141~0.097 mg. The effect of decrease in the bioavailability of Cu in the soil enhanced as the application rate of biochar rose. However, compared with 2% of biochar treatment, shoot dry weight of pakchoi decreased as well as SOD activity of earthworm increased when 5% of biochar were applied. These results indicated possible pernicious effect on pakchoi and earthworm when biochar added at 5%. |
