Effects Of Cd Stabilization In Soil On The Growth And Accumulation Of Maize

The large-scale industrial development and the deep-degree urbanization in China has brought us the rich material life, but at the same time, caused irreversible damage and pollution for our survival environment. In recent years, the problem of environmental pollution has been the focus in the vision of general public because of various "health accidents" due to the pollution. The pollution of soil which is the fundamental of the agricultural has taken more and more attention, especially the problem of heavy metal pollution in soil which is easy to accumulate, difficult to control and full of strong toxicity is the research hot topic, and how to dispose the toxic heavy metals in the soil is a big difficulty.All of the physical, chemical and biological disposal methods in the research to solve the contaminated soil of heavy metals have their own advantages, but also have shortcomings.Therefore, to seek a kind of method which is economical, effective and no secondary pollution is the most important. And according to the study, adding stabilization agent to the contaminated soil is an effective method to reduce heavy metal activity and bioavailability.The study took loess and sand in Gansu Province mixture as experience material, and CdCl₂ as pollution source to make Cd contaminated soil with the concentration of 2.0, 4.0, 6.0,8.0, 12.0, 16.0mg/kg. Then attapulgite clay from Linze County, Gansu Province and organic matter from Gansu Shuangtai Aotu science and Technology Co., Ltd were added as the stabilization agent according to the addition of 0, 10, 20, 40, 60, 80g/kg to conduct the soil culture experiment. The maizes were planted after 48 days. The plant germination and growth changes were studied according to the potted planting experiment with two stabilization agent adding, and the accumulation of heavy metal Cd in the plant was researched. Then the paper analyzed the effects of the two kinds of stabilization agents on the plant growth and heavy metal accumulation. The results showed that:?1? Both the two kinds of stabilization agents Attapulgite and organic matter could promote plant germination effectively. The emergence rate reached a maximum value with attapulgite and organic matter addition of 40⁶0g/kg. Compared to CK treatment, the emergence rate increased 50%¹00% under the treatment of two stabilization agent adding,but excessive amounts adding had an inhibitory effect on the emergence rate.?2? Attapulgite and organic matter could promote plant growth to increase the biomass.The biomass of over ground part increased along with stabilization agent dosage increasing,reached maximum in the 40g/kg⁸0g/kg range. But root biomass increased at first and then decreased along with the adding amount, reached maximum in the 40g/kg⁶0g/kg range.Therefore the appropriate concentration of stabilization agent should be added according todifferent concentrations of Cd pollution, because both Attapulgite and organic matter had hormesis effect on plants.?3? The addition of Attapulgite slightly inhibited the plant height, but had no effect on the elongation of the root. The addition of the organic matter could inhibit the elongation of the root and had no effect on the plant height.?4? Attapulgite and organic matter can immobilize heavy metals in soil effectively, and had a significant impact on the enrichment content of heavy metals in plants and accumulation. But the experiment proved that, attapulgite and organic matter could immobilize heavy metals effectively, on the other hand can promote plant growth, so the heavy metal enrichment content in the plant was influenced from the multiple factors, but the accumulation of heavy metals increased absolutely. So the appropriate concentration of stabilization agent should be added according to different concentrations of Cd pollution.?5? The plant emergence rate, biomass, plant height and root length has certain correlation with the bioavailability of the heavy metals. The sensitivity of growth indexes on the bioavailability of heavy metals was that: root length > plant height > biomass >emergence rate. The heavy metal bioavailability had significant correlation with heavy metal accumulation in the plants.