浮游植物粒级结构的原位测量

浮游植物粒级通常采用采集水样的分级叶绿素法来测定,比较费时且难以实现剖面连续测量。本文提出了一种基于测定海水光吸收来反演浮游植物粒级结构的原位测量系统。该测量系统硬件主要由高稳定光源、光学窗口、样品管、光纤高精度微型光谱仪、数据采集系统等组成。测量数据基于遗传算法来分析浮游植物粒级结构。海上初步试验结果表明,该仪器能够测定水下300 m之内的浮游植物粒级结构,实现1 m剖面分辨率的连续测量,尤其适用于分析50~80m深度叶绿素最大值层的浮游植物粒级结构变化,在未来海洋浮游植物粒级结构测定中有良好的应用前景。

In situ measurement of phytoplankton size class

Size-fractionated filtration is a common approach for measuring phytoplankton size classes in marine observation. However,this approach is time-consuming and unsuitable for analysis of a large number of samples in profiling measurement. In this paper, an in situ measurement system was developed for retrieving the phytoplankton size classes using light absorption coefficient of seawater. The hardware system of this instrument consists of a light system, optical windows, sample cell, fiber optic cable, mini-spectrometers, and a data collection and control system. Based on the genetic algorithm, the measured absorption coefficients were transformed to phytoplankton size class. Experiments have been carried out in situ in the northern South China Sea. The results prove that the instrument can be used to measure and analyze phytoplankton size class in up to 300 m seawater depth with an vertical interval of 1 m. This system is especially suitable for analyzing the variability of phytoplankton size class in 50 to 80 m seawater depth, which is commonly called the maximum chlorophyll depth in open ocean. The instrument could be used for ocean profiling measurement of phytoplankton size classes, which exhibits favorable future application prospects in marine observation.