Studies On Movement Characteristics Of Contamination From City Runoff In Soil

Aimed at the issue of rain water utilization of Xi'an district, based on the relative research results home and aboard, according to the characteristics of the pollutants in the road runoff of Xi'an city, several kinds of representative contamination are chosen, the effects of the contamination on water movement and the transfer of the accumulation itself in soil are studied in laboratory. The research results are significant to rain water utilization of city, relief of city water shortage and conservation of ecological environment. Major findings are as follows:1. The exchange column's preparation and replacing was limited by experimental conditions in petroleum ether purification, transparency was instable after purifying by active carbon, the effect of extraction and purification was not marked after washed by sulfuric acid. Normal hexane's purification (washed by sulfuric acid) was simple and convenient and demands for transmittance of light were met.2. Experiment was conducted on the transfer of water and oil in soil after the upper 10cm soil layer was polluted by oil contamination to different extent. The research results indicated that the velocity of wetting front, cumulative infiltration amount, infiltration rate and stable infiltration ratehowever, it seemed to have no influence on infiltration. The results also showed that oil had very low ability to transfer. Although the oil on the soil surface moved down with water, only little can reach the lower soil layer, most of them was absorbed on the upper soil.3. Just as water movement, cumulative infiltration amount and the velocity of wetting front came down as the soil bulk density enhanced in the course of interruption infiltration of oil water. Nevertheless, when water polluted by oil infiltrated, cumulative infiltration amount and the velocity of wet front enhanced with the rise of initial soil water content which was contrary to the pure water movement.4. The results of one-dimension infiltration experiments indicated that convection dominated on the movement of ammonia nitrogen in soil. During infiltration, ammonia nitrogen cumulated on the topsoil. The concentration profile tended to distribute evenly during afterward water redistribution. In the course of leaching after interval, ammonia nitrogen moved down gradually with the increase of infiltration water amount.