据介绍，广泛的实地研究表明，内陆咸化地下水和海上淡水共存于珠江三角洲及其邻近陆架的同一含水层系统中。这种违反直觉的现象挑战了人们普遍持有的假设，即陆上地下水通常是新鲜的，而近海地下水是含盐的。
为了填补这一知识缺口，该研究团队开展了一系列复杂的古水文地质模型模拟，以探索内陆陆架系统中地下水系统的形成机制和演化过程。结果表明，陆架淡水地下水形成于晚更新世以来的低水位期，而陆架咸水地下水则是由全新世海侵期间的古海水入侵导致。
这表明陆地和近海地下水系统在地质时间尺度上经历了交替变化。研究结果强调，地下水系统对古气候变化的响应具有滞后性，滞后时间为7000-8000年，古气候作用力对现今地下水系统具有显著的残余影响。
附：英文原文
Title: Evolution of groundwater system in the Pearl River Delta and its adjacent shelf since the late Pleistocene
Author: Chong Sheng, Jiu Jimmy Jiao, Jinpeng Zhang, Yantao Yao, Xin Luo, Shengchao Yu, Yugen Ni, Shidong Wang, Rong Mao, Tao Yang, Linsen Zhan
Issue&Volume: 2024-04-12
Abstract: Our extensive field studies demonstrate that saline groundwater inland and freshened groundwater offshore coexist in the same aquifer system in the Pearl River delta and its adjacent shelf. This counterintuitive phenomenon challenges the commonly held assumption that onshore groundwater is typically fresh, while offshore groundwater is saline. To address this knowledge gap, we conduct a series of sophisticated paleo-hydrogeological models to explore the formation mechanism and evolution process of the groundwater system in the inland-shelf systems. Our findings indicate that shelf freshened groundwater has formed during the lowstands since late Pleistocene, while onshore saline groundwater is generated by paleo-seawater intrusion during the Holocene transgression. This reveals that terrestrial and offshore groundwater systems have undergone alternating changes on a geological timescale. The groundwater system exhibits hysteresis responding to paleoclimate changes, with a lag of 7 to 8 thousand years, suggesting that paleoclimatic forcings exert a significantly residual influence on the present-day groundwater system.
DOI: adn3924
Source: https://www.science.org/doi/10.1126/sciadv.adn3924