Research On Different Materials Adopted In Copper Contaminated Soil Remediation

Peat is so precious as a kind of natural resources for its multifunctions. In order to exploit some materials to take the role of peat in repairing the copper contaminated soil, we selected greenery waste, activated greenery waste, humic acids, peat and a calcareous Chao Soil to study their adsorption-desorption characteristics of Cu2+.On this basis, the incubation experiments were conducted to study the transformation the speciation of Cu by adding different volumes of the greenery waste, activated greenery waste and peat separately into the self-made copper contaminated soil A and soil B, which have different concentration of Cu between each other. At the same moment, comparing the extracting efficacy of the available Cu by CaCl2-DTPA, AB-DTPA and Tessier sequential chemical extraction procedures. The main conclusions obtained were summarized as follows:1) With the increase of Cu2+concentration in the solution, the adsorption of Cu2+by the greenery waste, activated greenery waste, humic acids, peat and a calcareous increased in the equilibrium solution at the same pH. And both Langmuir and Freundlich equations fitted the adsorption data well. The adsorption capacity of Cu2+by these materials followed the order:greenery waste>activated greenery waste> peat>humic acids> calcareous Chao Soil, which suggested that greenery waste, activated greenery waste, and peat had strongest ability to fix Cu2+among four organic materials and a soil.2) As the increasing of the addition of materials in the comtaminated soil, the amount of total Cu, the proportion of the Cu fraction bound to carbonate and its Fe-Mn oxide form all decreased, and the proportion of organic-Cu, the extraction by DTP A decreased in the comparative experiment of Cu extraction by different agents. The extracted amounts of copper by AB-DTPA were significantly more than what extracted by CaCl2-DTPA in the same soil, the extracting efficiency of copper by AB-DTPA and CaCl2-DTPA in the mixture of soil A and materials were higher than that in the mixture of soil B and materials. The copper extractions taked by DTP A have conspicuous correlations with the bioavailable fractions of Cu extracted by Tessier procedures. 3) After these materials added in the copper contaminated soil, fractionation and availability of copper are obviously affected in the first four months, and also the transformation of copper in the soil was more actived. The forms of Cu in the soil were more likely to translate into less actived forms with the time flies, and the biovailable fractions of Cu reduced with the scale of materials enlarged. Following the increase of copper concentration in the soil, the copper was more and more fixed as Fe-Mn oxide form, and the contents of exchangeable copper decreased.Above all, the figures showed the greenery waste, activated greenery waste and peat all have excellent effect in renovating the copper contaminated soil, but accompanied with peat gradually become scarce and its wantonly exploiting, so it is possible to replace peat with greenery waste in urban soil remediation, which can not only to relive the copper accumulation in the urban soil effectively, but also can improve the proportion of organic matter in the soil. All of these can also promote the waste recycling, improve the environmental quality, and have positive effect to protect peat and its ecological environment. In addition, DTPA can extract some copper from OC-Cu, lead to the evaluation results higher than normal, so adopted Tessier procedures to follow-up study as evaluating the bioavailable copper.