Studies On Key Technologies For Reclamation Of Deserted Farmland Contaminated By Cu And Cd Comprehensively

In this work, as an case study, about 0.5 mu(1 mu equals to 666 m2) deserted farmland contaminated by Cu and Cd comprehensively in Sumen Hetan Town Guixi City was taken to be remediated using 3 different kind of soil stabilizers. Basing on the current investigation results of the experimental plot, different addition ratios of soil stabilizer(treatments) were designed and the contents of bioavailable Cu/Cd, acid soluble Cu/Cd and bioavailable N/P in soils treated by different kind of stabilizer and added ratio were analyzed. By analysis of the influences of environment and fertility quality of the soil on the growing situations of pakchoi, the main factors of affected the yield and quality of pakchoi were found out, and basing on which, the key techniques for reclamation of soil contaminated by heavy metals.Results showed that:(1) The experimental plots were contaminated by Cu and Cd; content of Cd could reach up to 5.36 mg/kg, nearly 18 times higher than the standard value, which exceeded the standard value seriously, while content of Cu could reach up to 141.5 mg/kg, nearly 3 times higher than the standard value; soil p H was around 5.06, indicating acidic; content of organic matter(O.M.) was 1.25%, which indicated the soil was sterile mineral soil; contents of bioavailable of P2O5, NH4+, and NO3- were 91mg/kg, 19.19 mg/kg and 1.48mg/kg respectively.(2) The 3 chosen stabilizers had some stabilization effects on heavy metals in the experimental plots, which were different in optimum added ratios; the best stabilization effect of heavy metal in soil could be reached when added 0.5% activate carbon(44.43% and 18.45% discount for Cu and Cd respectively), 0.1% for self-made stabilizer(36.1% and 11.51% discount for Cu and Cd respectively) followed, finally, 0.1% commercial stabilizer M(Cu and Cd discount 40.65% and 8.13% respectively); addition of M and self-made stabilizer could increase the contents of bioavailable N and P, which were useful for the increase of soil fertility.(3) Pakchoi seeds didn’t sprout in the untreated experiment plot, there is no direct linear correlation between Cu and Cd content in pakchoi and Cu and Cd content in soil,indicating after heavy metal contaminated soil restored, the soil available Cu and Cd content decreased, for plants to absorb heavy metals It does not have a decisive role, may also be affected by other factors of soil fertility;when the soil fertility quality improved, could promote the growth of pakchoi,at the same time, it can inhibit the absorption of pakchoi soil Cu,Cd and other heavy metals,,indicating soil fertility indicators can increase the effect of heavy metal pollution in reclamation of abandoned farmland.(4) To re-cultivate deserted farmland contaminated by heavy metal, it is necessary to appropriately increase soil fertility simultaneously while to improve soil environment quality; both of soil environment quality and soil fertility are the key factors of affecting reclamation for deserted farmland contaminated by Cu/Cd.