| Soil is an important part of ecological system and the basis of agricultural production.Soil is also the source of healthy food. Hower, soil pollution is more serious with theindustrial development. And the world is facing several soil heavy metal pollution problems.Farmlands near the industrial and mining enterprises are suffering increasingly serious heavymetal pollution.Therefore, strengthening the monitoring, evaluation and reseach about thepollution of farmland are meaful for comprehensive treatment of heavy metal polluted tofarmland.Wastewater irrigation soil was chosen as research object. Firstly the irrigation soilsample near xi ’an was analyzed.The results showed that the concertration of Lead, Cadmium,Chromium, Mercury, Arsenic and so on in ZaoHe irrigation soil did not surpass the approvedfigure in national secondary standard soil(GB15618-1995), while the concentration ofCadmium and Lead are relatively high. The monitoring results of XianYang irrigation soilshowed that the Cd of irrigation soil concentration ranged form1.4to1.8mg/kg and theaverage concentration was1.6mg/kg; The Cr concentration ranged form152to189mg/kgand the average concentration was170mg/kg,surpassed the approved finger in nationalsecondary standard soil;Although Pb concentration was high, it did not surpass the approvedfinger in national secondary standard.Secondly, the pot experiment was conducted to the Cd, Cr single and compound pollutionof XianYang irrigation area. Oilseed rapes and oil sunflowersn were planted in the pollutedsoil,and added chemical enhancers ethylenediamine tetraacetic acid (EDTA) and citric acid(CA) to research whether they could effectively remediate the heavy metal contaminatedsoil. At the same time, added chemical passivation agent lime to study whether line couldrestrain the absorption for oil crops. The results showed that:(1) In the tested soil, compared with blank control, added1.6mg/kg of Cd and170mg/kg of Cr single and compound pollution are all promoted the growth of oil rapes.Thebiomass of oilseed rapes increase significantly, while no significant effect on even the cropplanting oil sunflowers growth;(2)In the contaminated soil, EDTA and CA can effectively promote the absorption ofoilseed rapes for Cd, Cr.Compared with CK, both single and compound heavy metal pollution,its amounts of absorption have increased significantly.But EDTA and CA inhibited thegrowth of oilseed rapes, its foliages appeared varying degrees of symptoms such as loss of green,yellow,dehydration and so on；(3) In the contaminated soil, added1.5g/kg of passivator lime has no impact on normalgrowth of oilseed rapes, it also can effectively restrain absorption of oilseed rapes for Cd,Cr.Relative to the oilseed rapes without modifier processing for the uptake of Cd, Cr, addedlime for oilseed rapes has declined significantly on the uptake of Cd, Cr;(4) Even the crop planting, as the result of EDTA and CA residual in the oilsee rapeexperiment phase to the oil sunflowers seedling growth show a certain inhibition. Comparedwith CK, after oil sunflowers seedling growth for20days, plant obviously small, yellow;(5) After harvest oilseed rapes then plant oil sunflowers, added2.5g/kg of EDTA andCA can effectively promote the oil sunflower absorption of Cd, Cr. Compared with CK, bothsingle and compound pollution, the absorption of oil sunflowers have increased significantly;(6) After harvested oilseed rapes then plant oil sunflowers,added1.5g/kg of passivatorlime has no impact on the normal growth of oil sunflowers, but it can effectively restrain theabsorption of oil sunflowers for Cd, Cr. Relative to the oil sunflowers without processing forthe uptake of Cd, Cr, oil sunflowers of added lime have declined significantly on the uptakeof Cd, Cr;(7) In contaminated soil,the enrichment coefficients of oilseed rapes and oil sunflowersof Cd, Cr are also less than1, so oilseed rape and oil sunflower can’t as hyperaccumulationplants for Cd, Cr,but they all show patience for Cd, Cr. |
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