Optical absorption properties of water components in Xixi wetland of Hangzhou

Abstract

Water optical properties are important factors that affect phytoplankton biomass, carbon formation and carbon output of the upper body. Water spectral absorption properties are among the most important inherent optical properties. This paper was a preliminary analysis on spectral absorption properties of water suspended particle, de-pigmented particle, pigment particle and chromophoric dissolved organic matter (CDOM) in main channel of Hangzhou Xixi Wetland National Park phase I. The results indicate that the absorption spectrum of suspended particle is similar to the de-pigmented particle, while the absorption spectrum of pigment particle is almost submerged in the de-pigmented particle; The absorption spectrum of de-pigmented particle and CDOM follows the exponential decay law, the former slope Sd average value of the exponential function in the range of 400-700nm is 9.56±0.86μm-1, the latter slope Sgaverage value of the exponential function in the range of 400-500nm is 14.28±1.23μm-1. The absorption peak of chlorophyll a of pigment particle near 440nm is virtually not existent and also very weak at 675nm. According to the absorption contribution rate of each component to the total absorption, de-pigmented particle is the greater contributor than pigment particle and CDOM in this field campaign. In addition, according to water mass classification based on the contribution rate of absorption coefficient at 440nm, vast majority of the water body in study area could be classified into the most optical complex water mass type.