| Contents of cadmium, lead, copper and antimony in Chau embankment soil of South Dongting Lake were quantitatively analyzed, and the state of pollution was evaluated by the geo-accumulation index, the results show that cadmium pollution is generally serious, The average content of that reaches 3.047 mg·kg-1, lead is below the pollution level, copper should be controlled although with less pollution, and antimony shows an obviously uneven distribution.Based on the serious situation of Cd pollution in the wetland of Dongting Lake, a study was conducted to evaluate the Cd enrichment characteristics and repairing effects of eight dominant plants growing in Dongting Lake area. The results show that Artemisia selengensis is an outstanding species to repair Cd pollution for its remarkable capacity to accumulate Cd from lake soil. Artemisia verlotorum shows a good capacity to absorb Cd and could be selected as a potential candidate to treat Cd pollution. Because of their higher Cd accumulation in the root parts and their higher biomass of stem and leave which could be harvested every year, Phragmites australis and Miscanthus lutarioriparius could also play a role in controlling Cd pollution in the wetland of Dongting Lake.Artemisia selengensis grown in Dongting Lake wetland has been recently observed as a plant with a good capacity of enriching Cd. A pot experiment was conducted to study the biological traits and the Cd accumulation characteristics of Artemisia selengensis to Cd stress during its growth period. The final results showed that the leaves were injured apparently associated with significant decrease of above-ground biomass when Cd concentrations in soil were higher than 40 mg·kg-1. Artemisia selengensis could complete its life cycle at a high Cd concentration (100 mg·kg-1) and showed a stronger resistence to soil Cd. The bioavailable Cd accounted for about 15.3%-37.1% of total soil Cd, and this proportion was closely related to Cd accumulation in Artemisia selengensis. There were no significant differences of Cd concentrations in the plants during their different growth phases, but a lower Cd accumulation was observed in stems and leaves at the seedling stage than the other stages because of low biomass. During the adult stage of Artemisia selengensis, Cd accumulation was up to 492 mg·kg-1-588 mg·kg-1 under the Cd treatment of 40 mg·kg-1-60 mg·kg-1. These data suggested that Artemisia selengensis was an outstanding species that could be selected as a potential candidate to repair Cd pollution from lake soil. Under the Cd stress in different, series of parameters such as activities of Antioxidant enzyme, content of Soluble protein and Malondialdehyde in leaves and roots were determined during different growth period of Artemisia selengensis, which in purpose to clarify the mechanisms of Cd stress tolerance. The results show that all of the above-mentioned index are significantly affected by cadmium. The soluble protein content of organ increased by 16.5-19.1% under the treatment within 20 mg·kg-1 of Cd at seedling stage, and reduced nearly by 30% under treatment of 100 mg·kg-1. Activities of SOD,POD and CAT doesn't give obvious change under the Cd treatment less than 10 mg·kg-1, a significant increase of CAT and POD is observed at the Cd concentration of 10-80 mg·kg-1, in addition, the plant could adapt to the stress environment gradually under the effect of 40 mg·kg-1 Cd for a long time. The content of MDA increase continuously throughout the whole process. The three kinds of antioxidant enzymes play a good role in defensing Cd poisoning.A research of Cd subcellular distribution in vegetative organs of Artemisia selengensis was conducted using the method of fractionation, the results show that the concentration of Cd in leaves is 2-3 times more than stems and roots under treatment of 30 mg·kg-1, but the extraction of Cd in the former is much smaller than the latter because of the biomass, and the subcellular distribution ratio of Cd is 16:5: 1 (Between the three of Cell wall, Cytosolic and Organelles). The concentration of Cd in Cell wall and Cytosolic rise significantly with the increase of additional Cd2+, but is not the case in Organelles. Long period of Cd exposure or high concentrations of Cd stress will cause serious harm to the plant or even death. In the roots, the main detoxification mechanisms for Cd rely on the storage of vacuole.Using the Cd-contaminated soil as culture medium, a pot experiment was carried out to explore the affect by chelating agents on the biomass and Cd accumulation of Artemisia selengensis. The results show that the biomass of stems and leaves decreased by the impact of HEDTA, EDTA and DTPA, but the content of Cd in aerial parts of plants increased respectively by 35.5%,98.4% and 42.1%, as well as the effective content of Cd in soil, the opposite effect was observed in the add of lime. The growth of plants were promoted by the organic matter and fertilizer, however, the effect of Cd enrichment was not the case. Overall, the chelate applied at the seedling stage has a greater impact than the adult stage.
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