珊瑚礁岛屿淡水透镜体研究综述

淡水透镜体是珊瑚礁岛屿上重要的地下淡水资源，对于满足人们的日常生活需要和维护珊瑚礁岛屿的生态系统非常关键。文章回顾了国内外珊瑚礁岛屿淡水透镜体的研究历程，介绍了它的理论和特征，综述了其发育和演化与岛屿的水文地质、气候、潮汐、地形和植被等的关系。另外，自然压力，诸如干旱、海水入侵、海平面升高和岛的机械侵蚀等，以及人为压力，如过多抽取淡水、污染、地形改变和海岸工程等，都对珊瑚礁岛屿淡水透镜体的稳定造成了威胁，对这类干扰方面的研究也有很多。文章还介绍了常用的淡水透镜体研究模型，包括物理模型、解析模型和数学模型，并对其在淡水透镜体中的研究应用作了概述。对中国珊瑚礁岛屿淡水透镜体的研究现状也作了介绍，研究涉及西沙群岛永兴岛珊瑚礁淡水透镜体的厚度、抽取地下水导致的倒锥现象和生物修复等方面。最后，文章对南海珊瑚礁岛屿淡水透镜体的研究作出展望，提出开展对南海其他珊瑚礁岛屿淡水透镜体的研究工作，以及如何使抽取的地下水除污并可供饮用。

Review on the Study of Freshwater Lens in the Coral Reef Island

Freshwater lens is an important groundwater resource in coral reef islands, and is essential to meet people’s needs and maintain the ecosystem of the island. In this paper, researches on the freshwater lens in the coral reef island are reviewed, including its theory and characteristics. Some factors related to the development of the freshwater lens are summarized, such as, those of hydrogeology, climate, tide, topography and vegetation of the island. The threats from natural and human activities are more serious to freshwater lens than before and need more attention, for example, drought, seawater intrusion, sea-level rising, mechanic erosion of the island, over-drawing of fresh water, pollution, the changes of the landform and coastal construction, etc. may cause damages on freshwater lens. In this paper, some models used in the study of the freshwater lens are described, such as physical models, analytical models and numerical models. The study of the freshwater lens in China is also introduced. Most researches are focused on Yongxing Island of the Xisha Islands. The study contents involve the thickness of the freshwater lens, its changes with rain, the up-coning of the interface caused by withdrawing of the groundwater, and bioremediation of the freshwater lens. Finally, prospect for the study of the fresh-water lens in coral reef islands is given in the paper. It is suggested that more islands in the South China Sea should be studied, and techniques to clean the pollution of groundwater and make the water drinkable should be developed.