Study On Phytoremediation Technology Of Cr Contaminated Soil Assisted By Chemical Substances

Phytoremediation is a type of remediation technique of containminated soil which is based on tolerance and hyperaccumulation to one or some kinds of pollutants. It used plants and their coexist micro-biosystems to clean up environmental pollutants. Phytoremediation techniques contain: phytoextraction, phytostablization, phytovolatilization, phytofiltration and rhizofiltration. Among these method, phytoextraction is the most hopeful one, so it may form the scale of industrialization in future. Traditional phytoremediation focus on the hyper-accumulator, however, most of them need special living conditions, have no ornamental values and lack of biomass, so these disadvantages restrict their appliance and development. Therefore, some scientists transfer their consideration to some normal plants which have genetic relationship with hyper-accumulator, in order to solve these bottlenecked problems. Most of these plants have some common characteristics as follows: their seeds are easy to get, their price is lower, they are easy to plant and control, no ecological risks and good ability to concentrate heavy metals from soil. Crucifer takes the majority of hyper-accumulators which have been discovered and recognized, so it may have the best potential to become remediation plants. I investigated and analyzed the situation of Cr contaminated soil in Chongqing. Cr(â…¢) is main chemical form in purple earth, it is absorbed by soil colloids tightly and lack of mobility. Meanwhile, I choose the Chinese mustard and Flowering Kale as remediation plants, in order to research the basic principle of phytoremediation. If the Flowering Kale may both used as repairing and ornamental vegetation, that's the best.The results show that: Cr(â…¢) is main form in soil, it is absorbed by soil colloids and lack of mobility, so it is difficult to use phytoremediation technique to remediate contaminated soil. After adding the chemical substances into simulating polluted soil, the available Cr increased. It is helpful to absorb by plants; Cr³⁺ and Cr⁶⁺ both have inhibitory effect to Flowering Kale's germination and Cr⁶⁺'s effect is more obvious than Cr³⁺'s. But the Cr's less-mobility and the reducing condition of soil, the inhibitory effect is weaker. Thus, Flowering Kale's seeds can survive in Cr contaminated soil; Seeding can growing well after transplant in polluted soil. Color of Flowering Kale's leaves has no change; Chinese mustard and Flowering Kale show damage, to different extent, after adding chemical substances including wilting phenomenon and yellow spot on leaves; The biomass of two plants has obvious decrease after adding chemical substances, contrary to Chinese mustard Flowering Kale can gain more phytomass; Contrary to CK concentration of Cr in all parts of two plants has obvious increase, the increasing range from 2 to 4 times. The Cr of root has increased the most; According to study of Cr configuration in shoot of Flowering Kale, it indicates the Cr(â…¢) and organic Cr are the main configuration in tissue of plants, the organic Cr may easy to absorb by plants; Research shows that the Flowering Kale can absorb more Cr assisted by chemical substances. The Color has less change after adding chemical substance in soil so it has good potential being used as both ornamental plant and remediation plant.