The Experiment Study Of Restoration Capability On Rye To The Hg, Pb Polluted Soil

The heavy metal pollution in soil has got extensive attentions and more regards home and abroad. The preventive methods including phytoremediation is also one of the environmental hotspots and difficulties home and abroad. According to the general situation of pollution soil in research areas combining with the phytoremediation preventive methods, This thesis is in order to confirm the restoration ability of rye as to Hg ,Pb pollution soils and judge the rye whether can be the hyperaccumulator about Hg, Pb. The research choose the farmland soil in southern suburbs of Xi'an as the experimental soil and simulate the polluted soil by adding the aqueous solution of HgCl₂ ,Pb(CH3COO)₂. It also sets the constitution density gradient followed by the standard of Environment Quality Standard for Soil (GB15618-1995) and designed three experiments: The soil adsorption experiment, Seed toxicity experiment and pot experiment which includes inflicting nutrition elements or not .All the experiments aim to provide the foundations for the phytoremediation of Hg,Pb polluted soil.The conclusions are as follows:(1)In the soil adsorption experiment, The absorption quantity of soil to Hg is increasing with the corresponding density increment .The adsorption rate of Hg declines gradually and Pb has an obvious decreasement when its treated concentration is 1500/kg.It is calculated that the maximum adsorbing quantities to Hg is 444.55mg/kg by Freundlich equation within the its concentration and the theoretical maximum adsorbing quantities to Pb is 64516.12 mg/kg by Langmuir equation whatever the concentration of Pb changes. In interaction treatments, The absorption quantity of soil to Hg has a downtrend and the absorbency reduces adding Pb as Hg is under high concentration . When the Pb concentration is the same, the soil's absorbency for Pb makes no difference as the Hg concentration is more than 2.0mg/L.(2) In the seed germination toxicity experiment, The germination power and the germination rate of the rye seed are all decrease and the inhibition index is gradually increase along with the increment of treated concentration when Hg, Pb is treated singly. In interaction treatments, When the Pb concentration is the same, the germination power and the germination rate of the rye seed have no clear discipline along with the corresponding concentration increment of Hg. When the Hg concentration is the same, the germination power and the germination rate of the rye seed are increased and then decreased with the corresponding concentration increment of Pb and get the maximum when its treated concentration is 200mg/L. The germination of rye seed has got best effects as Hg8.0 and Pb 200mg/kg have an interaction.(3) In pot experiments without nourishment, the rye grows well apparently. From data analysis results , when Hg, Pb is treated singly, The physiological quality indices of rye have been inhibited in various degree, such as plant height,chlorophyll and conductivity etc. The BC to Hg is more than one but TC is all less than one which shows that the rye be hyperaccumulators about the Hg polluted soil inadequately.The BC and TC to Pb are all less than one which shows that the rye falls short of the characteristics of hyperaccumulators about the polluted soil by Pb.In interaction treatment, By the two elements combined action, Chlorophyll amounts decline and conductivities ascend. When the Pb concentration is the same, the absorption quantity to Hg of rye increase with the concentration increment of Hg. When the Hg concentration is the same, the absorption quantity to Pb of rye is less than the Pb treated singly.(4) In fertilized pot experiments, the rye grows very well apparently. From data analysis results:â‘ After adding N element, The physiological quality indices of rye ,such as fresh weight and the plant height, are lower than the original level and are higher than original level after adding P element.â‘¡The absorption quantity to Hg of rye are much more than former after fertilized (the promoter action of N is stronger than P). The BC is much more than one and most of the amounts accumulate in the roots, which make the rye be hyperaccumulators about the Hg polluted soil inadequately.Owing to the plentiful biomass, developed roots system, lower in price and adaptable , the rye can be used for solidification of Hg in soil and have restoration ability to some extent.â‘¢N element inhibits absorption of rye to Pb. Although P element promotes absorption quantity of the roots to Pb, the BC is still much less than one, which makes the rye not be hyperaccumulators for the Pb polluted soil absolutely.