Depth profiling investigation plays an important role in studying the dynamic processes of the ocean. In this paper, a newly developed hyphenated underwater system based on multi-optical spectrometry is introduced and used to measure seawater spectra at different depths with the aid of a remotely operated vehicle (ROV). The hyphenated system consists of two independent compact deep-sea spectral instruments, a deep ocean compact autonomous Raman spectrometer and a compact underwater laser-induced breakdown spectroscopy system for sea applications (LIBSea). The former was used to take both Raman scattering and fluorescence of seawater, and the LIBS signal could be recorded with the LIBSea. The first sea trial of the developed system was taken place in the Bismarck Sea, Papua New Guinea, in June 2015. Over 4000 multi-optical spectra had been captured up to the diving depth about 1800 m at maximum. The depth profiles of some ocean parameters were extracted from the captured joint Raman–fluorescence and LIBS spectra with a depth resolution of 1 m. The concentrations of SO 4 2 - and the water temperatures were measured using Raman spectra. The fluorescence intensities from both colored dissolved organic matter (CDOM) and chlorophyll were found to be varied in the euphotic zone. With LIBS spectra, the depth profiles of metallic elements were also obtained. The normalized intensity of atomic line Ca(I) extracted from LIBS spectra raised around the depth of 1600 m, similar to the depth profile of CDOM. This phenomenon might be caused by the nonbuoyant hydrothermal plumes. It is worth mentioning that this is the first time Raman and LIBS spectroscopy have been applied simultaneously to the deep-sea in situ investigations.

中文翻译：

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EXPRESS：使用组合多光谱法对海水进行深度剖面研究

深度剖面调查在研究海洋动态过程中起着重要作用。在本文中，介绍了一种新开发的基于多光学光谱的联用水下系统，并用于在遥控车辆（ROV）的帮助下测量不同深度的海水光谱。联用系统由两个独立的紧凑型深海光谱仪器、一个深海紧凑型自主拉曼光谱仪和一个用于海洋应用的紧凑型水下激光诱导击穿光谱系统 (LIBSea) 组成。前者用于获取海水的拉曼散射和荧光，LIBS信号可以用LIBSea记录。已开发系统的首次海试于 2015 年 6 月在巴布亚新几内亚的俾斯麦海进行。在最大潜水深度约 1800 m 处，已捕获了 4000 多个多光谱光谱。一些海洋参数的深度剖面是从捕获的联合拉曼荧光和 LIBS 光谱中提取的，深度分辨率为 1 m。SO 4 2 - 的浓度和水温使用拉曼光谱测量。发现有色溶解有机物 (CDOM) 和叶绿素的荧光强度在透光区有所不同。使用 LIBS 光谱，还获得了金属元素的深度剖面。从 LIBS 光谱中提取的原子线 Ca(I) 的归一化强度在 1600 m 附近升高，类似于 CDOM 的深度剖面。这种现象可能是由无浮力的热液羽流引起的。