Studies On The Protection Of Secondary Salt Damage Soil Caused By The Deicing Salt At Tian’anmen Square

Beijing Tian’anmen Pinus tabulaeformis planting soil is analyzed in2010-2011, by laying of the compound adsorbed layer consisting of sepiolite, zeolite and the maturity of the landscaping waste, to prevent foreign chlorine secondary salt damage caused by the salt deicing salt on soil. Through the determination of the pH value, the EC values and Na-, C1-content and other physical and chemical nature of the index of soil in the prevention process, soil salinity, and other indicators are compared, and the compound adsorption layer of soil and hedgerow planting Pinus tabulaeformis soil protective effect is explored; follow-up monitoring of the indicators of soil properties, variation of pH value, EC values in soil background value are also analyzed; according to the physicochemical properties of the test soil, simulation test of soil column is established. Through the simulation of different concentrations of deicing salt solution infiltration process, the adsorption ability on the inorganic ions of different composition in the chlorine salts deicing salt of the adsorbed layer is summed up, in order to find the best material ratio of compound adsorbed layer, and the results are as follows:(1) According to the indoor soil column test, the new adsorbent of sepiolite, zeolite, the maturity of the landscaping waste are stronger than traditional adsorbents such as activated carbon adsorption of inorganic ions in deicing, many times the ratio of raw materials comequality than the strongest sepiolite: zeolite:the maturity of the landscaping waste=5:3:2ratio of adsorption of chlorine salts, deicing salt, inorganic ions adsorption rate of up to60%.(2) The adsorption layer consisting of sepiolite velvet, zeolite, humus material, deicing salt adsorption. The laying of the adsorbed layer, planting soil in Pinus tabulaeformis have a certain buffering effect on soil pH, EC values. After protection of pine planting soil, pH, EC values can be maintained within the range suitable for PINE GROWTH. The composite adsorbed layer of Na+, C1-strong adsorption of C1-there may be adsorption of the ceiling, that is, when Clis more than a certain amount of some of the C1-can not be adsorbed layer absorption.(3) Tian’anmen P. tabulaeformis soil EC in this background value increased gradually during the spring to autumn2011. This may be subject to the Tian’anmen Square around the vehicle and pedestrian impact. But overall, the soil EC values can be maintained at a low level, and it has little effect on the normal growth of P. tabidaeformis. Soil closing to the roadway of pine EC value was significantly higher than the sidewalk, presumably due to passing vehicles traveling a lot of snow containing deicing splash into the tree An, leading to the deicing salt content in the soil increased significantly.(4) The soil column leaching experiments show that, soil salinity changes widely in the topsoil to10cm, while little significant difference is found between20cm to80cm. This phenomenon may be related to the material structure of the adsorbed layer, The pore structure of sepiolite, zeolite make a certain limit to their adsorption capacity.