石油污染对土壤持水能力及供水强度的影响

目的]研究石油污染对土壤持水能力及供水强度的影响,为有机污染物在土壤中迁移与转化规律研究提供理论基础。方法]以陕北采油区的主要土壤类型—轻壤质黄绵土为研究对象,人为模拟获得5个不同梯度的石油污染土壤(0%,0.5%,1%,2%和4%),室内测定土壤水分特征曲线,采用Van Genuchten模型拟合获得模型参数,并以此为基础对比分析不同处理土壤持水能力、水分有效性、比水容量之间的差异。结果]石油污染引起土壤持水性显著降低,污染浓度越大,持水性越低;对土壤水分特征曲线影响的显著区间主要在水吸力(pF)为1.5的低吸力段和水吸力(pF)为3.5以上的高吸力段,石油污染对土壤结构性的影响更加显著;高浓度的石油污染引起土壤有效水含量下降,加剧了土壤的干燥化程度,不利于协调干旱气候与植物需水性之间的矛盾;随着石油污染浓度的增加,土壤比水容量也呈现出显著递减趋势,土壤可利用水分对应的吸力范围相应变窄。结论]石油污染显著降低了土壤的持水能力及供水强度,加剧了地区土壤旱情,给植物生产和生态环境带来严重危害。

Effects of Oil Pollution on Soil Water-holding Capacity and Water Supply Intensity

Objective] The effects of oil pollution on soil water holding capacity and water supply intensity were studied in order to provide a theoretical basis for the study of organic pollutants migration and transformation in soil.Methods] The main soil type (loessial soil) in the oil-producing area of northern Shaanxi was used as the test material, and five different levels of polluted soil (0, 0.5%, 1%, 2%, and 4%) were obtained by artificial simulation. The soil water retention curve obtained for each treated sample was analyzed using the van Genuchten model, to investigate the difference of soil water-holding capacity, water availability and specific water capacity among different treatments.Results] The water-holding capacity of soil was significantly reduced by oil pollution, and the greater the pollution concentration was, the lower the water-holding capacity was. Oil pollution had a significant influence on the soil water characteristic curve in the low suction section of pF1.5 and the high suction section above pF3.5, and its influence on soil structure was more significant. The high concentration of oil pollution caused the decrease of soil water availability, exacerbated soil desiccation, which was not conducive to the coordination of the contradiction between the arid climate and the water demand of plants. With the increase of oil pollution concentration, the soil specific water capacity also showed a significant decreasing trend, and the suction range corresponding to soil available water was narrowed.Conclusion] Oil pollution has significantly reduced the soil water-holding capacity and water supply intensity, exacerbated soil drought and brought serious harm to plant production and ecological environment.