强壮前沟藻生消过程中水体的散射特性

Scattering characteristics of alga Amphidinium carerae Hulburt in the cycle of growth and decay

基于2011年7月藻类培养实验期间的实测数据,研究了强壮前沟藻生消过程中水体的散射特性.结果表明,强壮前沟藻本次培养周期共21d,前15d为生长期,之后进入消亡期;生消过程中水体散射光谱变化明显,叶绿素浓度较低时,散射系数随波长增加近似呈幂函数衰减,而叶绿素浓度较高时,蓝绿光波段散射系数随波长增加呈现近似线性增大趋势,红光波段叶绿素强吸收造成的散射谷更明显;生长期和消亡期时,散射系数与叶绿素浓度幂函数回归的可决系数均随波长增加逐渐增大,750nm波段达到最大值,R2分别为0.95、0.97;生长期时,蓝光波段散射占总散射量的比例逐渐减小,而红光波段逐渐增大,绿光波段变化较小,但基本呈现增大趋势,水色由蓝绿色逐渐变为红褐色,消亡期时,恰恰相反;生长期和消亡期的绿蓝、红蓝、红绿波段散射比与叶绿素浓度均存在正相关关系,说明随叶绿素浓度增加水色逐渐趋近于长波颜色.

Based on the measured data in an algal culture experiment in July 2011, the present study analyzed scattering characteristics of alga Amphidinium carerae Hulburt in the cycle of growth and decay. The results showed that, in the whole culture period of alga （21 days） , the growth phase started from the 1st day till the 15th day, then the alga entered into its decay phase. Meanwhile, the scattering spectra varied significantly. Under low- chlorophyll conditions, the scattering coefficient declined as a power function with the wavelength increasing. But when the chlorophyll concentration was high, the scattering coefficient nearly became an increasing linear function of wavelength at blue-green band, and scattering trough at red band was deepened remarkably due to strong absorption of chlorophyll-a. However, either in the growth or decay phase, the regressed coefficient of determination of power function between chlorophyll concentration and spectral scattering coefficient was found to increase gradually with wavelength. The best eorrelativity appeared at 750 nm （R2 reached 0.95 and 0.97, respectively for the growth and decay phase）. Moreover, in the growth phase, the proportion of integrated scattering coefficient in the blue band for the whole visible light region decreased gradually, while the proportion of scattering coefficient increased obviously in the red band. As for the green band, the proportion increased only slightly. Correspondingly, the water color gradually varied from blue-green to red-brown. Contrarily, in the decay phase, the change of water color was totally reversed. Furthermore, the positive correlations were acquired between chlorophyll concentration and the ratios of scattering coefficients between different bands （ green-to-blue, red-to-blue and red-to - green）, which proved that the water color changed toward longer wavelength with increase of chlorophyll concentration.