太湖水体散射光谱特性及其形成机理研究

Research of Scattering Spectrum Characteristic and Formative Mechanism of Taihu Lake Waters

基于2006年10月,2007年3月和2007年11月三次太湖野外实测颗粒物散射(bp)和后向散射(bbp)光谱数据,分别计算其光谱幂指数斜率、总悬浮物(TSPM)、有机物(OSPM)和无机物(ISPM)的比散射和比后向散射系数,进而探讨太湖水体bp和bbp光谱特征及其形成机理。结果表明,TSPM,ISPM和OSPM比散射系数平均值分别为:0.634(550 nm),1.057(532 nm)和0.396(532 nm)gm-2,ISPM和OSPM比后向散射系数平均值分别为0.0051(532 nm)和0.0022(532 nm)gm-2;2006年10月,2007年3月和2007年11月,后向散射率(B)平均值分别为:0.01078,0.01375和0.01251;bbp和bp及其B具有较强的光谱依赖性,但OSPM和有色溶解有机物(CDOM)在短波长以及叶绿素在675 nm的强吸收作用一定程度上减弱了该特征;bbp光谱斜率幂指数与ISPM/OSPM,532 nm处的bbp(532 nm)具有较强的相关性,而与粒径分布斜率相关性较小。

Scattering coefficient bp,backscattering coefficient bbp and concentration of particles are obtained from Taihu lake waters during three campaigns in Oct.2006,Mar.2007 and Nor.2007.Specific scattering and backscattering coefficient of total suspended particle（TSPM）,inorganic suspended partide（ISPM） and organic suspend particle matter（OSPM）,and spectral power exponents slope are calculated from sampling data.Then the spectral characteristic and formative mechanism of bp and bbp are explored further.The result indicates that the average value of specific scattering coefficients of TSPM,ISPM and OSPM are 0.634（550 nm）,1.057（532 nm） and 0.396（532 nm） gm-2,respectively.The average value of specific backscattering coefficients of ISPM and OSPM is 0.0051（532 nm） and 0.0022（532 nm） gm-2.The average backscattering ratio（B） in Oct.2006,Mar.2007 and Nov.2007 is 0.01078,0.01375 and 0.01251,respectively.bbp,bp and B have strong wavelength dependence.However,strong absorption effects of OSPM and CDOM at short wavelength and chlorophyll at 675 nm make the wavelength dependence weak.Spectral exponent has strong relation with ISPM/OSPM,bbp（532 nm）,but week relation with the particle size distribution slope.