| Research of heat, solute transport rule during freezing and thawing processes of soil is the important basic content for fields such as alkli-saline land reclamation, water-soil environment protection,water circulation,freeze-thaw injury prevention of hydraulic structures and so on.This paper studies on the variation law of frozen depth,freezing rate, and the transport disciplinarian of water, heat and mass (SO42-, NO3-,Ca2+and K+) after autumn irrigation for fluvo-aquic brown soil of Shenyang by tests of freeze-thaw processes.The main conclusions are as following:(1) Befor the frozen depth reach to the maximum, the frozen depth of different treatments of groundwater, 0.6% of calcium nitrate, 0.6% of potasium sulphate and no irrigation are 132 cm, 130 cm, 129 cm and 108cm in sequence respectively. And the frozen rate of these treatments are 1.16 cm·d-1,1.13 cm·d-1,1.10 cm·d-1 and 0.94 cm·d-1 respectively. The depth of these irrigation treatments compare with no irrigation treatment increase by 24cm, 22cm and 21cm respectively.These results embody that the original water content and species of soluble salt all have an effect on freezing process of soil.(2) The research use power function to fit freeze-thaw characteristic curves, which are measured in field at diffrent layers.Determining coefficient of these fitting equations are during 0.52-0.99.And these equations'significance are all significant by F-tests.(3) At the same temperature (-1 to -3 centigrade) during freezing process of soil, unfrozen water content of groundwater treatment are between 22.0% and 20.8%,25.5% and 20.8%, 22.2% and 18.5%, 18.0% and 15.7%,15% and 13.6% from 100cm upto surface layer by 20cm in sequence; content of addition 0.6% of calcium nitrate treatment are between 26.5% and 19.7%,20.1% and 19.0%,22.6% and 19.0%,20.0% and 17.2%,17.5% and 13% from 100cm upto surface layer by 20cm in sequence; content of addition 0.6% of potasium sulphate treatment are between 21.4% and 18.5%, 24.9% and 20%,24.9% and 19.7%,20.0% and 18.4%,17.2% and 15.6% from 100cm upto surface layer by 20cm in sequence. Results all above conclude that unfrozen water content increase with depth at the same temperature. At 0-40cm layer,unfrozen water content of all different treatments are below 20%.and the maximum content appear in addition 0.6% of potasium sulphate treatment,the second one is in addition 0.6% of calcium nitrate treatment, the minimum is in groundwater treatment at the same temperature.(4) After thawing period, the average ions concentration of sulfate,nitrate,calcium and potassium, are 657.2mg·kg-1, 507.2mg·kg-1, 425.7mg·kg-1 and 161.4mg·kg-1 in sequence in addition 0.6% of calcium nitrate treatment;1510.9mg·kg-1,351.6mg·kg-1, 352.1 mg·kg-1 and 239.4 mg·kg-1 in sequence in addition 0.6% of potasium sulphate treatment; 1036.2 mg·kg-1 , 320.6 mg·kg-1, 255.1 mg·kg-1 and 120.8 mg·kg-1 in sequence in groundwater treatment.Ions concentration above compare with that at freezing original period, in addition 0.6% of calcium nitrate treatment, decrease by 302.0 mg·kg-1, 216.8 mg·kg-1, 531 mg·kg-1 and 33.1 mg·kg-1 in sequence; in addition 0.6% of potasium sulphate treatment, decrease by 310.7 mg·kg-1, 29.8 mg·kg-1, 160.3 mg·kg-1 and 33.1 mg·kg-1 in sequence; in groundwater treatment,cationic decrease by 18.9 mg·kg-1 and 24.8 mg·kg-1 in sequence, anion increase by 158.1 mg·kg-1 and 16.4 mg·kg-1 in sequence. The average conductivity of soil after thawing period are 64.1μS·cm-1,76.7μS·cm-1 and 58.2μS·cm-1 in treatments of addition 0.6% of calcium nitrate, addition 0.6% of potasium sulphate and groundwater, which compare with conductivity at freezing original period, decreased by 6.5μS·cm-1 in addition 0.6% of calcium nitrate treatment and 1.5μS·cm-1 in addition 0.6% of potasium sulphate treatment, but that increase by 7.9μS·cm-1 in groundwater treatment. These results summarize that ions of sulfate, nitrate, calcium, potassium and conductivity of soil are leached after thawing.
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