研究了赤潮对近岸水体生物光学特性的影响.从大连湾采集11个站位的水体生物光学数据,分析了赤潮发生时生物要素、反射光谱以及吸收光谱的变化特征.结果表明,大连湾本次赤潮由微微型藻类引起;赤潮对水体遥感反射率的光谱形状影响明显,与正常水体相比,由于高浓度叶绿素a的强吸收作用,导致440、632 nm波段附近出现反射谷,红光波段荧光峰高度远大于正常水体,且存在"红移现象",760 nm波段存在氧气响应刺峰,近红外波段悬浮物反射峰增强;赤潮对水体吸收系数光谱的影响主要体现在数值大小上,对比发现各水色组分的吸收系数远大于正常水体,特征波段处aph(440)、aph(675)、ad(440)、ag(440)分别增大了13.4、14.5、5.0、3.8倍.本研究确定了近岸海域发生赤潮时水体生物光学要素的变化特征,为卫星遥感监测赤潮提供了理论依据.
Effects of harmful algal bloom(HAB) on bio-optical properties of coastal waters were studied.Bio-optical data were collected from 11 stations in the Dalian Bay,for an analysis of variable characteristics of biological factors,reflectance and absorption spectra as responses to HAB.The results indicated that,(1) the HAB which occurred in the Dalian Bay was caused by picophytoplankton.(2) Remote sensing reflectance showed an obvious difference with the normal waters: the strong absorption of the high concentration chlorophyll-a leaded to two reflection dips near 440 and 632nm bands,a much larger fluorescence peak height around the red band accompanied by a "red shift",a sharp peak of oxygen response at 760 nm,and an enhanced reflection peak of suspended matter in the near-infrared band.(3) In addition,effects of HAB on absorption coefficient spectrum mainly reflected in the numerical size and much stronger absorption of ocean color constituents than the normal waters had been found,the aph(440),aph(675),ad(440) and ag(440) increased to 13.4,14.5,5.0 and 3.8 times of the values of normal waters,respectively.Variation features of bio-optical elements were examined and identified when HAB occurred in the Dalian Bay,which provides a way to monitor HAB by satellite remote sensing.