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Variations in optical properties and water color during the formation of black bloom waters: a laboratory experiment |
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Abstract In the summer of 2007, a bloom of black water in Lake Taihu entered into the potable water supply of Wuxi city and left more than 1million people lack of drinking water. Recent evidence shows that these blooms involve massive production of dissolved organic carbon, most likely from inorganic carbon fixed in cyanobacterial blooms. Because blooms have limited spatial and temporal distributions, it is difficult to monitor them in situ. Remote sensing provides a new opportunity to monitor this complex carbon transformation. However, little is known about the temporal dynamics of optical properties of black bloom formation. In this study, we analyzed the daily transformation of particulate organic material to dissolved organic material, closely monitoring optical changes and water color during the simulation of a black water bloom in the laboratory. Results showed that during black water bloom formation: 1) CDOM absorption increased significantly, while absorption from suspended particulate inorganic matter decreased. 2) Phytoplankton pigments absorption (aph) varied over time. 3) Simulated water-leaving radiance and remote sensing reflectance decreased, allowingto examine spectral variations and water color in relation to bloom formation. These changes in optical properties of black bloom provided new opportunities to monitor these processes in lake conditions using remote sensing.
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Received: 12 June 2014
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