| Heavy metal contamination of soil is a longstanding problem,and has been paid more and more attention due to its threaten to human production life and health in recent years.Besides,how to reduce the risk of polluted soil caused by heavy metal has been taken seriously gradually.Chemical passivation repair is a rapid and effective method for heavy metal polluted soil repair,and it is also one of the commonly used methods for heavy metal polluted agricultural land both in domestic and foreign.The effects of organic and inorganic amendments on remediation of Cu,Zn and Cd polluted soils and the leaching amount of heavy metals on crop were investigated in this paper,the effects of peat(A),bamboo charcoal(B),vermiculite(C)and bonemeal(D)to the toxic leaching of heavy metals and soil pH were studied by soil toxicity test.Peat was selected as organic amendment for its better repair effect on acid polluted soil remediation and for soil acidity improvement,vermiculite and bonemeal were selected as inorganic amendments because the two materials were better to passivate Cd in heavy metals compound polluted soils.The soil culture experiments were conducted to study the effects of peat,vermiculite and bonemeal and their combinations on availablity and forms of Cu、Zn、Cd in soils,the pot experiments were conducted to study the effects of the three amnedments were used separately and mixedly on biomass and content of Cu、Zn、Cd in spinach,respectively,compound amendments(peat + vermiculite + bonemeal)and application proportion(2: 1: 1)was selected because heavy metals compound polluted soil remediation effect was best under those condition.The experiment draws the following conclusions:(1)In the soil toxicity leaching test,the amendments could significantly reduce the toxic leaching of Cu,Zn and Cd.When the amount of amendments is constant,the order of reduction of soil Cu toxicity leaching was peat + vermiculite> peat + bone meal> bamboo charcoal> peat> bamboo charcoal> bamboo charcoal + vermiculite> vermiculite> bonemeal,The order of reduction of soil Zn toxicity was peat + vermiculite>peat + bonemeal> peat> bamboo charcoal> bamboo charcoal + vermiculite> bamboo charcoal + bonemeal> vermiculite> bonemeal,The order of reduction of soil Cd toxicity was peat + Bonemeal> peat + vermiculite> bamboo charcoal + bonemeal> bamboo charcoal + vermiculite> bonemeal> vermiculite> peat> bamboo charcoal.The combination of peat and vermiculite showed a better passivation effect on Cu and Zn,while the combination of peat and bone meal showed abetter passivation effect on Cd.(2)The contents of availability of Cu,Zn and Cd in soil were significantly decreased while adding peat,vermiculite and bonemeal respectively,and this significance increased with the increasing amount of the amendments.The results showed that peat had better passivated effect on Cu and Zn,and bonemeal showed better passivated effect on Cd,while peat had lower passivated effect on Cd than that of inorganic amendments of bonemeal and vermiculite.In addition,compared with the condition when admendment dosage was 1% and 2%,when the dosage of admendment was 0.5%,repair effect showed great difference,and the difference of repair effect was very small between 1% and 2% modified agent dosage.(3)The organic-inorganic compound amendments showed a better effect on the decreasing of availability of Cu,Zn and Cd in heavy metal polluted soil.The mixed agents of 0.5% peat + 0.25% vermiculite + 0.25% bonemeal(peat: vermiculite: bonemeal is 2: 1: 1)was the best,with 60.61%,68.30% and 58.71% decreased,respectively,which was compared to the blank control group at the 42 nd day.(4)The amendments could significantly reduce the content of Cu,Zn and Cd in spinach,and the mixture with 0.5% of peat + 0.25% of vermiculite + 0.25% of bonemeal(Peat: vermiculite: bonemeal is 2: 1: 1)is the best.In this experiment group,the content of Cu,Zn and Cd in the spinach was reduced by 77.04%,78.16% and 82.92%,respectively,which was compared to the blank control group,(5)The amendments could significantly improve the yield of spinach,and the mixture with 0.5% of peat + 0.25% of vermiculite + 0.25% of bonemeal(Peat: vermiculite: bonemeal is 2: 1: 1)is the best.In this experiment group,the yield of spinach increased 145.69%,which was compared to the blank control group. |
