| Dongping Lake holds a crucial position as the final water-transferring lake of the east line of the South-to-North Water Transfer project and the water source of West-to-East Water Deliver project in Shandong province.Its water quality is directly related to the beneficiaries of the water diversion project.The nutrient sources and water environment of Dongping Lake were systematically understood and the characteristics of dissolved organic matter in Dongping Lake were analyzed to determine the coupling relationship between them.The paper analyzed the characteristics of dissolved organic matter in Dongping Lake through field surveys and read literature and UV absorption technology and EEMS-PARAFAC.Based on the research above,the main conclusion as following:(1)The changes of the water environment in Dongping Lake were mainly influenced by the Yellow River from the 1850 s to the 1960 s,although humans live around Dongping Lake in the historical period,the impact on Dongping Lake is relatively small,and the change of the water environment of Dongping lake was mainly influenced by the human activities after the 1960 s.And Especially after the 1990 s,Dongping Lake water quality and eutrophication rapidly deteriorated.(2)Because the Dawen River Basin is dominated by agricultural land and three days raining before sampling,a large number of nitrogen into the river,resulting in the decreasing trend from Wenkou dam to the out of lake;phosphorus contribution is small,Dawen River and Dongping Lake are phosphorus nutrition restrictions,which Dawen River is more serious;The formation of "lake effect" in Wenkou dam resulted in significantly higher nutrient levels than other points.Samples are analyzed into two-classes and four-types fluorescent components,which are two humic-like fluorescent components(C1,C3)and two protein-like fluorescent components(C2,C4).The total CDOM fluorescence intensity showed exogenous characteristics,but the main fluorescent components are humic-like fluorescent components.(3)Different hydrodynamic disturbances cause sediment resuspension and have a significant effect on SS and other water particles,DTN and DTP and other dissolved substances have not been significantly affected due to particulate matter adsorption and biological rapid utilization.Characterization of humification index,endogenous biological activity,DOM source and its degradation degree of fluorescence index and the M values that characterize the mass of CDOM are also not changed by hydrodynamic disturbances of different intensities.Dissolved and granular organic matter showed different trends,POM is significantly affected by hydrodynamic disturbances,but the proportion in the particles increases with the disturbance,DOM did not change significantly with different intensity hydrodynamic disturbances,and a(355)also has no significant difference between the control group and the experimental group,witch indicated that different intensity hydrodynamic disturbances did not affect CDOM concentration.(4)Samples are analyzed into two-classes and four-types fluorescent components,which are two humic-like fluorescent components(C1,C3)and two protein-like fluorescent components(C2,C4).The humic-like fluorescent component C3 exhibits a spatial distribution characteristic decreasing from the estuary to the lake heart,the protein-like fluorescent component C2 has a decreasing change from the lake to the periphery.All the water quality parameters indicate that the Lake was moderately or highly eutrophied and its water on the whole was close to Grade IV in quality set in the ―Standard for Quality of Surface Water Environment‖ of the country and failed to meet the requirement of the water diversion project.All the water quality parameters show strong extraneousness.Terrigenous humic-like fluorescent C1 was significantly related to DOC and COD,which may indirectly reflect degree of the organic pollution of the water,while protein-like fluorescent component C2 was significantly and positively related to TN.Therefore,the two components,C1 and C2 can be used as indicators for rapid determination and long-term monitoring of water eutrophication in the Dongping Lake. |
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