秋季太湖水下光场结构及其对水生态系统的影响

Underwater light field structure and its impact on aquatic ecosystems of Lake Taihu in autumn

水生态系统中光能的分配很大程度上决定了水生态系统的结构和功能,利用2007年11-12月太湖水体光学特性和组分浓度数据,对秋季太湖水下光场结构特征和水体组分光竞争能力的表征光学量(漫衰减系数、平均余弦)和影响因素(吸收系数比重)进行了分析研究.结果表明,秋季太湖水下辐照度呈现单峰分布,最高值为583nm左右;根据Kd可将黄质和非色素物质主导程度的强弱分为弱、较强、强三个等级;Kd(PAR)平均值为4.61±1.54m-1,水体真光层厚度平均值为1.11±0.35m;太湖水下光场的光能主要分布在青光和黄绿光波长范围内,约占总能量的60%,蓝光和红光波长范围内的能量约占30%,这样的光谱结构有利于铜绿微囊藻和斜生栅藻的生长.

Allocation of light in the aquatic ecosystems determined the ecosystem function and type. Based on the measured data of optical properties and the concentrations of water substances in Lake Taihu during November to December, 2007, the optical parameters （diffuse attenuation coefficient, the average cosine） and impact factors （the proportion of absorption） were studied. The results showed that： the irradiation showed a single peak distribution and the max value was at 583nm wavelength; the dominant degree of CDOM and Non-pigment particles could be divided into weak, strong, stronger according to the Kd; the average value of Kd （PAR） and depth of the euphotic zone is 4.61±1.54m^-1 and 1.11±0.35m, respectively; solar energy was mainly distributed in the cyan, green and yellow wavelength range, which was about 60 percent of the total energy, it just about 30 percent in blue and red wavelength. This spectral structure favored the growth ofMicrocystis aeruginosa and Scenedesmus obliquus.