Repair Effects Of Different Modifiers On Calcareous Soil Cadmium Pollution

Objective: Agricultural soil polluted by heavy metal is very serious in our country. Cd is one of the most important heavy metal elements for its high toxic. In recent years, the investigation on remediation of Cd contaminated soil is becoming an urgent issue to solve.The method of Amendments repaired contaminated soil by adsorption, ion exchange, surface precipitation, complexation mechanism of redox on heavy metals elements in the soil.Amendments ediation is an economic, and efficient with characteristics of cost-effective and high secure at present. Therefore, it could provide a reference for improvement of Cd contaminated soil to study the effect of Amendments on translation, uptake and accumulation of Cd in soil in Agricultural production.Method:In this pot experiment, Chinese cabbage and Canola were sown in the pots.The biomass and Cd content of cabbage and Canola were measured. The test is divided into two parts: The first part was the pre-test, absorption of Cd in Canola and Chinese cabbage were studied with organic fertilizer application. The second part was amendments of manure,humic acid, bio-carbon and sepiolite were added to the soil. A pot experiment was conducted to study the influence of different amendments on biomass of Chinese cabbage, Cd content and Cd forms content in three soils that Cd content was normal(soil A), 1.5(soil B)and 3mg·kg-1(soil C).Result: The pre-test results were:(1) The Cabbage and Canola biomasses increased with the organic fertilizer application.(2) Cd adsorption of Canola and Chinese cabbage was significantly increased in organic fertilizer treatment on contaminated soil. The effects on Chinese cabbage was lower than the Canola. The enrichment of Cd in Chinese cabbage was significant.The main results of the study were :(1) There was no significant difference for biomass of Canola and Chinese cabbage in the Amendments treatments on normal soil. Chicken manure significantly increased the aboveground biomass of Chinese cabbage and Canola on soil containing 1.5 mg Cd kg-1. The lower amount of chicken manure significantly increased the aboveground biomass of Chinese cabbage and Canola on soil containing 3.0 mg Cd kg-1. But the higher amount of chicken manure significantly increased the Chinese cabbage biomass only.(2) There was no significant difference in Cd content of Chinese cabbage and Canola on different Amendments on normal soil. Four Amendments significantly redused Cd content of Chinese cabbage and Canolaon soil containing 1.5 mg Cd kg-1. There were different effects on Cd content of Canola and Chinese cabbage with different amount of amendments.(3) Cd content of Chinese cabbage and Canola were significantly increased by Humic acid,bio-carbon and chicken manure in normal soil. There were observed that Cd content of soilwere significantly different among the Amendments treatments on soil containing 1.5 mg Cd kg-1. All Amendments significantly reduced Cd content of soil planting Chinese cabbage, and Cd content of soil planting Chinese cabbage was significantly higher in the humic acid treatment than others.(4) The humic acid, manure and bio-carbon treatments increased the proportion of bioavailable state. The sepiolite treatment reduced the proportion of bioavailable Cd. Bio-carbon treatment increased the proportion of carbonate-bound Cd. The main forms of Cd was exchangeable Cd, carbonate-bound Cd and Fe-Mn oxide-bound Cd in the chicken manure treatment. The effect of Amendment on Cd forms plays an important role in repair of soil.Conclusion: Organic fertilizer not only could improved crop growth, but also could promote the uptake of Cd in Chinese cabbage and Canola. The biomasses of Canola and Chinese cabbage were significantly increased in the chicken manure treatment. Different amendments had significantly effect on Cd content of Canola and Chinese cabbage. Manure, bio-carbon and humic acid had activated function on Cd of soil, but Sepiolite suppressed availability of Cd in soil.