[Spectral absorption coefficients of optically active substances in Lake Dianchi]

A field investigation in Lake Dianchi was carried out in November, 2009, and a dataset including absorption coefficients and concentration of water components was collected. Absorption properties and its spatial distribution of Lake Dianchi have been systematically analyzed, the results show that: (1) Absorption spectral curve of total particles (a(p)) are similar with that of phytoplankton (a(ph)), which indicates that phytoplankton absorption dominates absorption of total suspended particles; (2) Significant relationships are found between a(ph) (440), a(ph) (624), a(ph) (675) and concentration of chla, and cyanophyta dominats the quantity of the algae in water columns; (3) There are more phytoplankton existed in northern lake than other areas because of higher level of eutrophication. Comparing with other water columns, discrepancies mainly appear as below: (1) The mean value of slope of absorption spectral curve of non-algal particles (S(d)) in Lake Dianchi is much bigger than that in other case-II waters; (2) The mean value of slope of absorption spectral curve of chromophoric dissolved organic matter (CDOM) S(g) in Lake Dianchi is much smaller than that in other case-II waters; (3) Specific absorption of phytoplankton (a(ph)*) at 440 nm and 675 nm is at intermediate level, and a(ph)* value is susceptible to different regions, seasons, population structure of phytoplankton and so on.