| 江苏滨海平原弱透水层封存的古咸水及其运移过程 |
| |
| 引用本文： | 李静,张亚年,梁杏,刘彦. 江苏滨海平原弱透水层封存的古咸水及其运移过程[J]. 地质科技通报, 2022, 41(1): 90-98. DOI: 10.19509/j.cnki.dzkq.2021.0158 |
| |
| 作者姓名： | 李静 张亚年 梁杏 刘彦 |
| |
| 作者单位： | 中国地质大学（武汉）环境学院;水利部长江勘测技术研究所;江苏省地质调查研究院自然资源部地裂缝地质灾害重点实验室 |
| |
| 基金项目： | 国家自然科学基金项目41977167国家自然科学基金项目41502231江苏省地质勘查基金项目苏国土资函[2014]842号 |
| |
| 摘 要： | 滨海平原弱透水层广布且多赋存古咸水,其盐度分布及运移过程深刻影响着含水层地下水的演变,却得到甚少关注。采集了江苏滨海区7个浅层钻孔弱透水层原状样品,压榨法收集孔隙水。利用孔隙水天然示踪剂ρ(Cl-),ρ(Br-)剖面和数值模拟分析了弱透水层孔隙水盐度特征和运移机制。得出浅层孔隙水ρ(Cl-)垂向剖面存在2个趋势:①峰值在表层,沿深度逐渐下降;②峰值在深度25m左右,向两端浓度降低。孔隙水ρ(Cl-)为486.2~38036.7 mg/L,Cl/Br比值为72~360(均值241)。ρ(Cl-)与Cl/Br比值关系及剖面分布说明孔隙咸水为海相成因,来自于全新世海侵时期的古海水,并受到后期淡水的稀释。弱透水层孔隙水一维垂向运移数值模型表明海侵-海退事件控制了海岸带弱透水层孔隙水的盐度演变,全新世古海水仍封存在沉积物中,更新世时期的海水已被驱替。孔隙水运移以扩散为主,垂向运移速率为0.43~15.8 mm/Ma。在相对高渗透性的粉砂地层中,可能还受到侧向对流的影响。弱透水层中古海咸水的重新分布,尤其在地下水超采条件下,可能成为地下水的重要咸化来源。
|
| 关 键 词： | 弱透水层 孔隙水 滨海平原 咸化 运移 |
| 收稿时间： | 2021-07-08 |
Paleo-salt porewater trapped in the clayey aquitard and its transport processes in Jiangsu coastal plain |
| |
| Li Jing,Zhang Yanian,Liang Xing,Liu Yan. Paleo-salt porewater trapped in the clayey aquitard and its transport processes in Jiangsu coastal plain[J]. Bulletin of Geological Science and Technology, 2022, 41(1): 90-98. DOI: 10.19509/j.cnki.dzkq.2021.0158 |
| |
| Authors: | Li Jing Zhang Yanian Liang Xing Liu Yan |
| |
| Affiliation: | (School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China;Changjiang Institute of Survey Technical Research,Ministry of Water Resources,Wuhan 430011,China;Key Laboratory of Earth Fissures Geological Disaster of Ministry of Natural Resources,Geological Survey Institute of Jiangsu Province,Nanjing 210018,China) |
| |
| Abstract: | Clayey aquitards are widespread in the coastal plain and they are capable to preserve paleo-saltwater. Its salinity distribution and transport process play an important role on the evolution of aquifer groundwater, yet they have attracted little attention. In this paper, undisturbed clayey samples in seven boreholes along the Jiangsu coastal plain were collected and porewater was extracted by squeezing. Based on the natural tracers Cl- and Br- profiles and numerical simulation, porewater salinity characterization and transport mechanism were analyzed. The results showed that two trends of porewater Cl- variations are observed: one is that Cl- peak value is near surface and decreases with depth; the other one is that the Cl- peak value is at depth of 25 m and decreases towards both ends. Porewater has a Cl- range of 486.2-38 036.7 mg/L and Cl/Br of 72-360(average: 241). The relations between Cl- and Cl/Br ratios and the profile signature indicate that saline porewater is of marine origin, and from the Holocene transgression seawater. Subsequently, they were diluted by freshwater. Aquitard porewater 1-D transport model suggests that the transgression and regression events are dominant for the salinity evolution. Holocene seawater is still trapped in the sediment whereas Pleistocene seawater has been flushed out. In aquitard, diffusion is dominant for solute transport with the vertical velocity of 0.43-15.8 mm/yr and influenced by advection in higher permeability sand layers. The redistribution of paleo-saltwater, in particular, in the condition of groundwater over-extraction, would be the important saline source for aquifer groundwater. |
| |
| Keywords: | aquitard porewater coastal plain salinization transport |
| 本文献已被 维普 等数据库收录！ |
| 点击此处可从《地质科技通报》浏览原始摘要信息 |
|
点击此处可从《地质科技通报》下载免费的PDF全文 |
|
