石油污染物在滨海盐渍土中的迁移规律

摘要

土中石油污染物具有不稳定性,随环境改变易向周边发生二次迁移,危及周围土体和水体.本文以滨海地区石油污染盐渍土为研究背景,考虑污染强度、石油污染物在土中的存留时间、土体密度为变量参数,探索即时淋滤和过时淋滤条件下土中石油污染物的二维向迁移规律.研究结果表明:即时淋滤条件下,石油污染物强度越大,其在盐渍土中迁移的越深,最大迁移深度为6 cm.干密度(1.2～1.4 g·cm-3)对盐渍土中石油污染物迁移深度的影响较小,但干密度越大,土体对石油污染物的截留能力越强,相同深度处石油污染物的浓度越低.在水平方向,污染强度越大,密度越大,石油污染物在土体中沿半径方向浓度递减幅度越大;过时淋滤条件下,石油污染物在竖直方向的迁移规律与即时条件下相似,但表层盐渍土对石油的截留能力更强,其在盐渍土中迁移的最大深度为4 cm,土体对石油类污染物的最大截留率为99.98％.在水平方向,污染强度越大,密度越小,石油污染物在土体中沿半径方向浓度递减幅度越大;盐渍土对石油污染物具有一定的吸附性,增大密度有利于提高吸附的稳定性.%Oil contamination in soil is instability and easy to migrate again under the action of environment. It then contaminates surrounding soil and even water. Experiments are undertaken on saline soil in inshore area. Variable parameters of pollution intensity, residual time of oil contamination in soil, and soil density are considered.Migration law of two-dimensional space under immediate filter and outdated filter condition are studied. Results indicate the following feature. (ⅰ) In the case of immediate filter condition, the migration depth of oil in saline soil is deeper with the increasing of oil contaminated lever, and the maximum migration depth is 6 cm. Dry density (1.2 g·cm-3-1.4 g·cm-3) has little effect on migration depth, but oil entrapment increases as dry density intensifies.The concentration of oil contamination on same depth is lower with the increasing dry density. As to horizontal direction, the concentration distribution of oil contamination decreases steeply with the increasing of oil contaminated lever and soil density. (ⅱ) In the case of outdated filter condition, the migration law of oilcontamination in vertical direction is similar to that of immediate condition, but oil entrapment of soil surface enhances, and the maximum migration depth in saline soil is 4 cm. The maximum oil entrapment rate (0 ～ 2 cm) is 99.98％. In the horizontal direction, the concentration distribution of oil contamination decreases largely with the increasing of oil contaminated lever and the decreasing of soil density. Saline soil has good ability to adsorb oil contamination and can be improved by increasing soil density.