基于遥感反演的浒苔绿潮暴发对有色溶解有机物与叶绿素时空分布特征的影响

浒苔的暴发会对水体生态环境产生巨大的影响, 对此进行遥感监测具有十分重要的意义。本文基于现场同步实测的有色溶解有机物(colored dissolved organic matter, CDOM)吸收系数、叶绿素浓度以及光谱数据建立遥感反演模型,再结合MODIS卫星影像提取山东半岛南侧近岸海域在各年份浒苔暴发前后CDOM与叶绿素浓度的时空分布特征。结果表明, 浒苔的消亡分解会在水体中产生大量的CDOM, 但浒苔的生长繁殖同样会消耗CDOM, 此外CDOM还受到浒苔暴发时期强烈的光降解作用。在各种因素的综合作用下, 研究区海域CDOM浓度在浒苔暴发时期微弱升高, 浒苔消亡后CDOM浓度则开始回落。浒苔在暴发期会抑制其他浮游微藻的生长, 使研究区海域叶绿素浓度有所降低, 而浒苔消亡后叶绿素浓度有所上升。水体中的叶绿素受多种生物地球化学因素的影响, 因此叶绿素浓度的降低与浒苔的暴发强度之间没有明确的相关性。遥感反演可以大范围快速地提取水体中各种要素的分布情况, 但就浒苔的暴发对海水中各要素的影响机制而言, 还需要结合各种生态环境因子进行综合分析。

Effects of Enteromorpha prolifera blooms on the spatial and temporal distributions of CDOM and chlorophyll by remote sensing

Enteromorpha prolifera outbreaks substantially influence the ecological environment of water, and remote sensing monitoring is of great importance. In this paper, a remote sensing inversion model was established based on the colored dissolved organic matter (CDOM) absorption coefficient, chlorophyll concentration, and spectral data measured synchronously in the field. Combined with the moderate resolution imaging spectroradiometer satellite images, the spatial and temporal distribution characteristics of CDOM and chlorophyll concentrations before and after Enteromorpha prolifera outbreaks in different years were extracted from the coastal waters south of the Shandong Peninsula. The results showed that the dissolution and decomposition of Enteromorpha prolifera produced a large amount of CDOM in the water, but Enteromorpha prolifera growth and reproduction also consumed CDOM. In addition, CDOM was subjected to strong photodegradation during Enteromorpha prolifera outbreaks. Under the comprehensive action of various factors, the CDOM concentration in the study area increased slightly during Enteromorpha prolifera outbreaks and began to fall after the death of Enteromorpha. Enteromorpha inhibited the growth of other planktonic microalgae during the bloom period, decreasing the chlorophyll concentration. However, after Enteromorpha prolifera extinction, the chlorophyll concentration increased to some extent. Chlorophyll is affected by many biogeochemical factors; therefore, the decrease in chlorophyll concentration and the intensity of Enteromorpha prolifera are not clearly correlated. Remote sensing inversion can quickly and widely extract the distribution of various elements in water; however, the effect mechanism of Enteromorpha prolifera outbreaks on various elements in seawater also needs to be comprehensively analyzed in combination with various ecological and environmental factors.