School of Earth and Environmental Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea.
Sci Rep. 2017 Aug 11;7(1):7921. doi: 10.1038/s41598-017-08518-5.
The abundance of fluorescent dissolved organic matter (FDOM) in the surface ocean plays a critical role in the growth of marine microorganisms and corals by affecting the optical properties (i.e., the penetration of UV radiation) of seawater. In general, it is known that rivers are the main source of FDOM to surface ocean waters. Here, however, we show that the concentrations of FDOM in coastal seawater off a volcanic island, Jeju, Korea, are dependent primarily on submarine groundwater discharge (SGD). Based on a significant correlation between Rn and salinity in seawater, fresh groundwater was found to be the main source of groundwater as well as fresh water in the bay. The addition of dissolved organic carbon (DOC) and protein-like FDOM to the bay via SGD was generally negligible or negative. However, SGD enhanced the inventory of humic-like FDOM (FDOM) in seawater by 2-3 times over all seasons, with conservative behavior of FDOM in bay seawater. These results suggest that SGD-driven fluxes of FDOM regulate its inventory in seawater and consequently play a significant role in determining the optical properties of coastal waters off islands and associated coastal ecosystems (i.e., corals).
海洋表面荧光溶解有机质（FDOM）的丰度通过影响海水的光学性质（即紫外线辐射的穿透性），对海洋微生物和珊瑚的生长起着至关重要的作用。一般来说，人们认为河流是海洋表面水中 FDOM 的主要来源。然而，在这里我们表明，韩国济州岛沿海海水中 FDOM 的浓度主要取决于海底地下水排泄（SGD）。基于海水中 Rn 和盐度之间的显著相关性，发现淡水是海湾地下水以及淡水的主要来源。通过 SGD 向海湾添加溶解有机碳（DOC）和类蛋白 FDOM 通常可以忽略不计或为负值。然而，SGD 增强了海水中腐殖质类 FDOM（FDOM）的库存，在所有季节中增加了 2-3 倍，并且海湾海水 FDOM 的行为保守。这些结果表明，SGD 驱动的 FDOM 通量调节了其在海水中的含量，从而在确定岛屿和相关沿海生态系统（即珊瑚）的沿海水域的光学性质方面发挥了重要作用。
