Release Way And Effect Factors On Dissolved Organic Matter From Sediments

The main ways of releasing dissolved organic matter(DOM) from sediment to the overlying water of the Xinkai River in Shenyang were determined.The effects of the change of time、temperature、pH、particle size、salinity and the concentration of DOC in the overlying water on the releasing DOM from the river sediment samples were studied,and the effect of spectroscopy characteristics of DOM from sediment to the overlying water were also studied.The results showed that the mixing of pore water influences the concentration of DOM from sediment to overlying water significantly.The next factor is the static release of the sediment.And suspension had the least influence to concentration of DOC.With the increasing of mud proportion, suspending time and static release time,the intensity of all kinds of fluorscent substance also increased.The release of DOM from sediment to the overlying water is affected by many factors.With the increasing of the releasing time,the concentration of DOC increased first and then decreased,it reached a maximum at 120h.The amount of concentration of DOC from sediment samples increased gradually with the increasing temperature,and the pH value could interfere the release of the DOC,it was promoted in the alkaline conditions.In certain salinity rage, the amount of DOC in the overlying water increased with the increment of the salinity,and the concentration of DOC incresed to the maximum salinity 30‰.The sediment disturbance could promote the migration of DOM from sediments to the overlying water under different release time、different temperature and different salinity.In static state,the amont of release of DOC is more than suspended under the different pH value. The releasing amount of DOC increased gradually with the increment of the size of sediments in static state. Under the conditions of sediments suspension,the releasing decreased gradually with the increment of the size of sediments.The migration of DOM from the overlying water to sediment when the contents of DOC in water is sufficiently high,and sediment disturbance could promote the DOM migrate from the overlying water to sediments.Because UV-254 and DOC had the same variation trend,UV-254 can be used as a surrogate parameter. The large SUVA value in the overlying water, indicated that there are a lot of macromolecular and hydrophobic organic contaminants.The results of three-dimensional fluorescence spectra indicated that there are one or several of aromatic fluorescence peak、fulvicfluorescence peak、 humic fluorescence peak and soluble microbial fluorescence peak in the overlying water.And the aromatic fluorescence peak is always exist,it is the main fluorescence substances of DOM.The results of synchronous fluorescence spectra suggested that the fluorescent materials with excitation wavelength of 280～300 nm and 320～380 nm in DOM fractions in river sediments were released into waters,the two fluorescence peak are tyrosine that was located at the left of aromatic fluorescence peak and soluble microbial fluorescence peak. And sediment disturbance could promote the migration of DOM from sediments to the overlying water.