| This experiment takes a sewage irrigated soil in Shanxi province as the tested soil, takes corns and rapes as the tested crops. The research is about the effect of fly ash, attapulgite, bentonite, zeolite, chicken manure, straw carbon, humic acid, corn straw and sludge and other nine kinds of passivation materials to the distribution of Cu and Cr in the sewage irrigated soil and crops according to the pot experiment. The purpose of this paper is that select the passivation materials of heavy metal which are economic efficiency and environment friendly and suitable for the region to use, and provide theoretical basis and technical support for the remediation and sustainable utilization of heavy metal polluted soil. The results were as follows:1?The trend of the change of five Tessier forms of Cu and Cr in soil with different passivation materials by planting crops were different. The carbonate combination Cu and the five forms of Cr showed a decreasing trend, while the other forms of Cu showed an increasing trend. Attapulgite, bentonite, and humic acid significantly promote soluble carbonate combination Cu conversion into insoluble Fe-Mn oxides, organic and residual Cu; bentonite and zeolite significantly promote soluble exchangeable and carbonate combination Cr conversion into insoluble Fe-Mn oxides, organic and residual Cr.The analysis results of the mobility factor of Cu and Cr showed that the MFCu and MFCr in soil of almost all the treatments were lower than the control in addition to the treatment of chicken manure after planting corns. The most obvious reducing effect of MFCu were attapulgite, sludge and bentonite, followed by zeolite and humic acid; the most obvious reducing effect of MFCr were bentonite, sludge and zeolite. It showed that the passivation materials could reduce the bioavailability of Cu and Cr in soil, and reduced the hazards to human and the environment.2? The content of five different leaching agent effective Cu?Cr all showed decreasing trend, the most obvious reducing effect of Cu were bentonite, humic acid,attapulgite and fly ash; and the most obvious reducing effect of Cr were bentonite, humic acid, fly ash and corn straw.The total uptake of Cu in the upper part of rapes was significantly positively correlated with CaCl2-Cu, the total uptake of Cu in the upper part of corns was significantly positively correlated with EDTA-Cu; the total uptake of Cr in the upper part of corns had extremely significant positive correlation with DTPA-Cr. This showed that CaCl2(0.01mol/L) and EDTA(0.05mol/L) is suitable for being evaluation indexes as Cu pollution of lime soil; DTPA(0.005mol/L) is suitable for being evaluation indexes as Cr pollution of lime soil.3?The lowest enrichment ability on Cu?Cr of leaves of rapes were zeolite, bentonite, humic acid, attapulgite. The enrichment ability of different parts of corns are different, the order is root> leaf> stem> cob, and the enrichment ability of each treatment were lower than control. The lowest enrichment ability of each parts on Cu were bentonite, fly ash, sludge, humic acid, attapulgite; and the lowest enrichment ability on Cr were attapulgite, bentonite fly ash. It showed that passivation materials could inhibition the absorption of Cu?Cr in corns.4?The growth situation of rapes and corns were different after the treatment of the passivation materials. The maximum dry weight of rapes were attapulgite and bentonite; and the most obvious effect was bentonite. It showed that adding passivation materials could improve the growing of crops.5?Excessive Cr and Cu could influence the physiological and biochemical activities of corns. During the growth of corns, the content of Chlorophyll, the activities of CAT and POD showed a trend of first increasing and then decreasing, and the content of each treatment were higher than control, and the most obvious were bentonite, attapulgite and fly ash; The content of MDA increased first and then decreased, and the content of proline first decreased and then increased, and the contents of each treatment were lower than control, and the most obvious were sludge and attapulgite. It showed that passivation materials could improve the content of chlorophyll content in leaves of corns, and prevent the cell from membrane lipid peroxidation,hydroxyl radicals and other toxic.6?The Cu?Cr content of leaves of rapes in each treatment did not exceed the national food hygiene standards, the Cu content of zeolite in leaves of rapes was the lowest, followed by bentonite, attapulgite and humic acid. In addition to the control, The contents of Cu and Cr in stem, leaf and cob of the other treatments did not exceed the limit of national feed standards. The lowest content of Cu and Cr were sludge, bentonite, fly ash and attapulgite, bentonite, respectively.In a word, the contents of Cu?Cr in leaves of rapes and various parts of corns did not exceed the national food hygiene standards and feed standards after adding passivation materials. Therefore, rapes can be used as edible crop planting and corns can be used as feeds or industrial raw materials planting in the sewage irrigated areas after adding passivation materials. Bentonite, zeolite, attapulgite, humic acid, sludge and fly ash can significantly reduce the content of Cu; zeolite, bentonite and attapulgite can significantly reduce the content of Cr. Additionally, attapulgite, bentonite and sludge can significantly reduce the mobility factor of Cu, followed by zeolite and humic acid; bentonite, sludge and zeolite can significantly reduce the mobility factor of Cr. It showed that the most obvious passivation effect to Cu in this area are attapulgite and bentonite, followed by zeolite and humic acid; the most obvious passivation effect to Cr in this area are zeolite and bentonite. These can be used as passivation materials in Cu?Cr contaminated soil based on the actual situation of the local, respectively. |
PDF Full Text Request