The Effects Of The Perform Of Prtroleum Pipeline Operation To The Physicochemical Properties Of Soil Of Farmland

A large quantity of constructions have great economic and social benefits while also have inevitable effect on regional eco-environment. To study the effect of the first and the second West-to-East gas pipeline(Gansu-Zhangye) on soil properties of farmland, four soil samples of corn field along the pipeline are taken from the four representative parts of the pipeline: the entrance of compressor station in Zhangye(the temperature of pipeline is 28.49℃), 10 km away from exit of Jiuquan compressor station in the first West-to-East gas pipeline(the temperature of pipeline is 47.8℃), 65 km away from exit of Jiuquan compressor station in the first West-to-East gas pipeline(the temperature of pipeline is 45.2℃), and the exit of Zhangye compressor station in the second West-to-East gas pipeline(the temperature of pipeline is 42.6℃). Samples are randomly taken from work sites(0m, 3m, 5m, 8m and 10 m respectively above the pipeline) and non-working site(15m above the pipeline), and all the samples are taken for three times. to study the effect of different distance from the pipeline on the soil temperature, soil moisture, soil nutrient and granular structure of the physical and chemical materials of soil. The results are as follows:2. The pipeline running changes the distribution rule of the soil moister content in the area 0-100 cm. In the vertical depth, variation of the soil moisture content in four sample sites is the same, no remarkable difference in the range of 0-40 cm, increasing in the range of 40-60 cm, and decreasing dramatically in the range of 60-100 cm. In the four samples, the nearer the distance above the pipeline, the greater effect of the soil moister content it has.3. After running for several years, the pipeline changed the structural units in physical, decreased the total content of soil aggregate, which caused the degradation of aggregate stability. The more distance away from pipeline, the MWD(Mean Weight Diameter) and the GMD(Geometric Mean Diameter) of soil aggregate increase. The aggregate content in the soil of mechanical stability(R>0.25) in the site 10 m respectively away from the exit of compressor station, Shangqin county, and the Linze county is remarkably higher than that in 5m and the range of effect of pipeline is 5-10 m. The aggregate content in the soil of mechanical stability(R>0.25) in the site 5m away from the entrance of compressor station is remarkably higher than that in 0m and the range of effect of pipeline is 0-5m. In the four sample places, the aggregate content of water stability affected by pipeline in non-working area and the site 10 m away from pipeline is remarkably higher than that in the sites in other groups and the two of them has no disparity, and the range of effect reaches up to 5-10 m.4. As for soil organic matter, total nitrogen and available phosphorus affected by pipeline, the content of them in non-working area is lower than that in working area, which indicates that pipeline causes the degradation of them. As for the available potassium, the content of it has no different between in non-working area and in working area, which indicates that pipeline has little influence on it. As for disturbance strength of nutrient content of soil, pipeline has great disturbance on total nitrogen, alkali-hydrolyzale nitrogen, available phosphorus and soil organic matter, while little disturbance on available potassium. In the vertical direction of all four sample places, construction has great disturbance on soil organic matter, alkali-hydrolyzale nitrogen, total nitrogen and available phosphorus, while little disturbance on total phosphorus, total potassium and available potassium. With the increase of soil depth, the degree of being disturbed of the nutrient in soil increases.5. Pipeline running is equivalent to heat source underground, which directly affects the temperature of soil. This paper, after analyzing, finds that temperature of soil is significantly correlated to content of soil aggregate, content of soil organic matter, total nitrogen and available phosphorus, while has little correlation with available potassium.