Singlet Oxygen Analysis Of Photoinduced Formation Of Dissolved Organic Matter In Water And Ice Phases

Dissolved organic matter（DOM）is widely found in water bodies.A large number of functional groups in DOM can absorb sunlight and produce reactive photoinduced species（RPS）.These RPS are involved in the hydrolysis and polymerization of some organic pollutants,impact trace metals and photo inactivation of bacterial microorganisms in the aquatic environment.DOM has different properties due to its different sources,hydrochemical environment and formation mechanism.The changes of DOM concentration,as well as the structure and chemical properties of DOM itself,will greatly affect the ability of DOM photosensitization to generate RPS.The extremely low temperature directly affects the chemical and microbial degradation processes of pollutants.However,the photochemical reactions are not affected by temperature.DOM is a common component in environmental snow and ice,which means that the photochemical reactions observed in aquatic systems may also occur in snow and ice.Therefore,photochemical reaction plays an important role in the transformation of pollutants in ice.However,freezing causes ice to behave differently from liquid water,and the photochemical processes observed in aquatic systems cannot simply be applied to frozen systems.The steady-state concentration of~1O₂in ice under light condition is significantly higher than that in the same liquid phase sample,and the degradation of pollutants in ice caused by it may be very important.This study collected rivers,lakes,oceans and sewage treatment plant effluent water of water samples with different properties,the detection of various water samples before and after physical and chemical properties,frozen ultraviolet-visible absorption spectrum and the three dimensional fluorescence spectrum,and calculate the spectral feature parameters,comparison of different water samples the nature of the differences,the analysis of the effect of freezing and thawing process and the nature of the role of the sample.Furfuryl alcohol was used as ~1O₂molecular probe to detect the degradation amount of furfuryl alcohol.The ~1O₂produced by samples under illumination was quantified.The differences of photochemical activity of different water bodies were compared,and the correlation between the production amount and DOC,characteristic parameters and fluorescence intensity of samples was analyzed.The results showed that there was no significant correlation between the maximum absorbance and DOC（P>0.05）,and the peak-to-peak values of all samples were positively correlated with DOC.The type of organic matter contained in DOM is related to the nature of water.The freeze-thaw effect can reduce the organic matter content of samples,reduce the aromatic degree of most samples,and enhance the fluorescence intensity of samples.The amount of photogenic ~1O₂in the water phase was determined by DOC,aromatance,fluorescence intensity and other factors.The amount of photogenic ~1O₂in the ice phase was significantly higher than that in the water phase,which was positively correlated with DOC and negatively correlated with total dissolved solids.