Study On The Migration And Transformation Of Oil-contaminants In The Soil

Recent fifty years, because of the exploitation of Daqing oilfield, soil and water werepolluted seriously, especially local pollution. As the material basis of life, if the pollution of soilis beyond its selfpurification capability, the ability of soil living will decrease, even die away,which is harmful for human's health, social economy and ecosystem. So it is important to studythe migration and transformation of contaminants in the soil for protecting soil environmentduring the development of oilfield.By experiment of adsorption and migration, the law of transformation and migration of oilcontaminants in the soil were studied. The main contents and results are following:1. The adsorption and desorption of petroleum contaminants on chernozem at static stateThe kinetics and main influencing factors of adsorption and desorption of petroleumcontaminants on chernozem at static state were studied. The results show that the speed ofadsorption is rapid, homeostasis can be got in almost 4h. At low concentration the adsorptionisotherm accords with Langmuir and Freundlich adsorption models. R2 is equal to 0.9964 and0.9858 respectively. But at high concentration it accords with Linear model, R2 0.9852. Manyfactors effect on the adsorption and desorption including SOM, sand, temperature, pH and salt.Desorption shows lag.2. Vertical transformation of petroleum contaminants in chernozemThe transformation characteristics of petroleum were studied in chernozem at differentpollution intensity, quantity of water and length of column by watering with pure water. Theresults show that contaminants peak appears before 30cm, but all kinds of contaminants can bemeasured at the bottom of all columns. The deepness of contaminants peak depend on pollutionintensity, quantity of water and column length. The transformation of C17 and biphenyl is strong,and C24 can transform far away. naphthaline concentration is very low because of sublimationin column. Contaminants can cumulate at 63cm, which show contaminants would threatengroundwater at suitable surroundings and quantity of contaminants.3. Theory of transformation and migrationBy analysing transformation and migration of contaminants in soil, the results show thatmigration and transformation were effected by many factors including adsorption/desorption,diffusion, distribution, biodegradation and environmental conditions such as temperature,humidity, pH and so on. Adsorption/desorption can effect on the diffusion, distribution andbiodegradation. The main means of transformation is biodegradation at the suitable temperatureand humidity. And distribution and confusion are the main means of contamination migration.