Seasonal Variation of in Water Constituents'''' Absorption Properties in Meiliang Bay of Taihu Lake
太湖梅梁湾水体组分吸收特性季节差异分析

Seasonal variance in absorption properties of water constituents was analyzed and predominant factor of spectrum absorption in different seasons was discussed using the data sets collected in August and November 2006 and March 2007 from Meiliang Bay in Taihu Lake. The results indicate that, the absorption of water constitutions has seasonal variation characteristic. Total suspended sediment has the greatest absorption coefficient in summer, the average absorption at band 440 nm is (7.49±3.0) m-1, while the least absorption presents in spring, with average absorption value of (2.86±0.73) m-1 at band 440 nm. The total absorption type varies with seasons. Non-algal particle absorption has less seasonal variation than total absorption. The difference of non-algal particle absorption coefficient and slope S were caused by different concentration and composition of non-algal particles. Because of high chlorophyll a concentration, phytoplankton absorption coefficient was great in summer, with average absorption value of (5.49±3.5) m-1 at band 675 nm. The average of phytoplankton absorption at band 675 nm in autumn is (2.03±1.14) m-1, less than that in summer. The least absorption presents in spring, with average absorption value of (0.62±0.25) m-1 at band 675 nm. Difference of chromophoric dissolved organic matter (CDOM) concentration and constitution, mainly resulted by different source of CDOM, causes the seasonal variation of its absorption coefficient and slope S value. The predominant absorption factor varies with seasons. In spring and autumn, non-algal particles were the predominant spectrum absorption factor in water, because the concentration of inorganic matter is higher than organic matters in the two seasons. While in summer, phytoplankton becomes the main effect factor of spectrum absorption in water.