The Influence Of Sediment Subsiding On Dissolved Organic Matter In Water

In order to study the influence on sedimentation process of dissolved organic matter in this experiment,taking the city of Shenyang Xinkaihe river as the research object.During the process of sedimentation,different sedimentation times,sediment concentrations,pH,salinities and other factors have different effects on the water dissolved organic carbon(DOC)concentrations and the spectroscopic characteristics of dissolved organic matter in water.The experimental results show that in the process of sedimentation,different factors affect the DOC in water.In the initial stage of sediment deposition,soluble humic acid combined with hydrophobic organic matter increased the content of soluble organic matter in water.With the increase of sediment settling time,the amount of organic matter adsorbed by sediment was increased,and the content of DOC increased first and then decreased.With the sediment content increasing,the DOC content of water sample at the sampling site showed first decreased and then increased.With the increase of pH value,the dissociation of carboxyl groups and phenolic hydroxyl groups of dissolved organic carbon will increase the negative charge,at the same time,the content of OH-in the water is increasing,which makes the repulsive force of DOC increase in the water,that is not conducive to the adsorption of DOC with negatively charged particles.With the increase of salinity,the content of DOC in water decreased gradually,and the content of DOC in the lower water is affected by salinity higher than that of the upper water.With the increase of deposition time,UV-254 showed initially increased and then decreased,SUVA increased at first and then gradually balance.The content of aromatic substances in the water reaches the equilibrium state.With the increase of sediment concentration,the water samples of UV-254 showed initially decreased and then increased,the changing trend is the same with DOC.SUVA increased first and then decreased,it's show that the aromatic organics increased first and then decreased.pH value increased,UV-254 and SUVA gradually increased,and the UV-254 in lowerwater affected by pH greater than the upper water.With the increase of salinity,UV-254 and SUVA gradually decreases,it shows that the water in the aromatic substance gradually decreased and the DOM molecules in water constantly decreased.Three dimensional fluorescence spectroscopy showed that humic fluorescence peak and fulvic fluorescence peak are the main fluorescence peak after the sediment deposition.There are two fluorescence peaks in the form of "peak shoulder",they're soluble microbial fluorescence peak and aromatic fluorescence peak.Synchronous fluorescence spectroscopy showed that after sediment deposition,there are two distinct peaks can be seen,the fluorescent materials with excitation wavelength at 280~300nm and 330~350nm,two fluorescence peaks located in the soluble microbial fluorescent area and humic fluorescence area.