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地下水开采、弱透水层释水,以及污染物迁移转化、高危废物深埋选址等水文地质和工程地质活动中,弱透水层的作用越来越受到重视.了解弱透水层孔隙水的演化特征是认识弱透水层作用的首要问题.采用机械压榨法提取了曹妃甸地区某钻孔0～100m粘性土孔隙水,对孔隙水化学特征进行了分析.结果显示钻孔粘性土孔隙水呈碱性,总溶解固体为7.26～26.89g/L,从浅到深逐渐减小;陆相沉积层Cl/Br比趋向无穷大,而海相沉积层仅为279～289.分析得出弱透水层孔隙水基本为岩层沉积水,陆相和海相沉积层孔隙水分别显示出淡水和海水起源特征,没有后期海水入侵影响迹象;Cl-、Na+变化趋势主要受蒸发浓缩作用影响,SO42-受硫酸盐的还原作用和石膏的溶解作用共同控制,Ca2+、Na+、K+还受到沉积过程中阳离子交换与吸附作用影响;由δ18O重建晚更新世古气温为5.21～5.81℃,浅部40m以内计算的气温偏高是由于全新世气候变暖、孔隙水向下扩散迁移混合的影响.
The role of aquitard is getting more and more attention in the exploitation of groundwater, the release of water in aquitard, the migration and transformation of pollutants, the site selection of buried sites of high-risk waste, etc. The understanding of the evolution characteristics of pore water in aquitard Is the primary problem to recognize the effect of aquitard.The pore water of 0 ~ 100m clay in a borehole of Caofeidian was extracted by mechanical compression method, and the chemical characteristics of pore water were analyzed.The results showed that pore water of borehole clay was alkaline, The total dissolved solids ranged from 7.26 to 26.89 g / L and gradually decreased from shallow to deep. The Cl / Br ratio of continental sediments tended to be infinite while the marine sediments were only 279 to 289. The results showed that the pore water in the aquitard For the sedimentary water in the rock strata, the pore water in the marine facies and marine sediments shows the origin of freshwater and seawater, respectively, and there is no sign of the influence of later seawater intrusion. The change trend of Cl- and Na + is mainly affected by the evaporation and concentration, and SO42- is reduced by sulfate And Ca2 +, Na + and K + were also affected by cation exchange and adsorption during the deposition. The δ18O reconstructed late Paleocene Paleoene temperature ranged from 5.21 ℃ to 5.81 ℃, and the depths within 40m The high temperature is due to the Holocene climate warming, pore water diffusion downward migration mixed effect.