Salinity evolution of aquitard porewater associated with transgression and regression in the coastal plain of Eastern China
Salinity evolution of aquitard porewater associated with transgression and regression in the coastal plain of Eastern China
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DOI：
10.1016/j.jhydrol.2021.127050
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发表时间：
2021-10
影响因子：
6.4
通讯作者：
Jing Li;Gong Xulong;Xing Liang;Y. Liu;Jilong Yang;Xianmeng Meng;A. Alhassan
中科院分区：
文献类型：
--
作者：
Jing Li;Gong Xulong;Xing Liang;Y. Liu;Jilong Yang;Xianmeng Meng;A. Alhassan
含水层可以保存古咸水，并对含水层地下水产生长期而深远的影响，但却没有得到足够的重视。本文测量了中国东部中国滨海平原、渤海湾、莱州湾和江苏滨海平原含水层中天然示踪剂Cl-−、Br-−，δ-2H和δ-18O的5个一维垂直剖面，并结合已有的8个剖面，揭示了中全新世以来含水层孔隙水的盐分来源和跨含水层迁移的时间尺度。古海水受全新世海侵影响的证据是，在全新世底部约25米处的孔隙水中，出现了最大的Cl-−浓度、富含水的同位素和较低的Cl/Br值，Cl-−剖面的形状和相关的一维输运模式证实了全新世海水在沉积物中的存在，以及海侵和海退交替作用控制了滨海含水层孔隙水的盐度演化。扩散是含水层的主要输运方式，其上升速度在0.03~0.6 mm/年之间。反向平流流动影响了大范围抽水区域的溶质运移。人为活动增加了咸水在沿海地区渗入含水层的情况，因此有必要对海洋含水层咸水进行研究。
Aquitards can preserve paleo-saltwater and have a long and profound influence on the aquifer groundwater, yet they have received less attention. Here, five one-dimensional vertical profiles of the natural tracers, Cl−, Br−, δ2H, and δ18O of aquitard porewater were measured and combined with eight existing profiles collected from previous studies in three Eastern China coastal plains, Bohai bay, Laizhou bay, and Jiangsu coastal plain, to show the salinity origin and the timescale of the transport of porewater across aquitards since the mid-Holocene. Evidence of paleo-seawater impacted by Holocene transgression is noticed as peak Cl−concentration, enriched water isotopes, and lower Cl/Br ratios are observed in the porewater at about the bottom depth of Holocene of 25 m. The shape of Cl−profiles and associated 1-D transport models confirms Holocene seawater's presence in the sediment and the alternating transgression and regression control the salinity evolution of coastal aquitard porewater. Diffusion is the dominant transport across aquitard with an upward velocity between 0.03 and 0.6 mm/yr. Reverse advective flow has affected the solute transport in areas of extensive pumping. Anthropogenic activities enhance the leaching of salty porewater into aquifers in coastal areas, necessitating the need for research focused on marine aquitard salty water.