Department of Earth Sciences, The University of Hong Kong, Hong Kong, China.
The University of Hong Kong, Shenzhen Institution of Research and Innovation (SIRI), Shenzhen, China.
Nat Commun. 2023 Jun 24;14(1):3781. doi: 10.1038/s41467-023-39507-0.
Large-river deltaic estuaries and adjacent continental shelves have experienced multiple phases of transgressions and regressions to form interlayered aquifer-aquitard systems and are expected to host vast paleo-terrestrial groundwater hundreds of kilometres offshore. Here, we used offshore hydrogeology, marine geophysical reflections, porewater geochemistry, and paleo-hydrogeological models, and identified a previously unknown offshore freshened groundwater body with a static volume up to 575.6 ± 44.9 km in the Pearl River Estuary and adjacent continental shelf, with the freshwater extending as far as 55 km offshore. An integrated analysis of stable isotopic compositions and water quality indices reveals the meteoric origins of such freshened groundwater and its significance as potential potable water or raw water source for desalination. Hotspots of offshore freshened groundwater in large-river deltaic estuaries and adjacent continental shelves, likely a global phenomenon, have a great potential for exploitable water resources in highly urbanized coastal areas suffering from freshwater shortage.
大河三角洲河口和毗邻大陆架经历了多次海侵和海退，形成了互层含水层-隔水层系统，预计在数百公里外的近海地区拥有广阔的古地下水。在这里，我们利用近海水文地质学、海洋地球物理反射、孔隙水地球化学和古水文地质模型，在珠江河口和毗邻大陆架上确定了一个以前未知的近海淡水地下水体，其静态体积高达 575.6±44.9 立方千米，淡水延伸至离岸 55 公里处。稳定同位素组成和水质指数的综合分析表明，这种淡水地下水的成因是大气降水，其作为潜在饮用水或海水淡化原水的意义重大。大河三角洲河口和毗邻大陆架的近海淡水地下水热点可能是一种全球现象，对于遭受淡水短缺的高度城市化沿海地区来说，具有巨大的可利用水资源潜力。
