Aqueous Fluorescence Fingerprint Characteristics And Pollution Source Identification Of The Estuary Section Of The Yangtze River

The area along the Yangtze River estuary is densely populated,with a high degree of urbanization,developed industries and intensive industries.The quality of the water environment directly affects economic development and people’s health,and monitoring changes in water quality is of great significance.In this paper,taking the Yangtze River estuary as the research object,combined with conventional water quality parameters,aqueous fluorescent fingerprint,liquid chromatography and Fourier transform ion cyclotron resonance mass spectrometry methods,the characteristics of the water quality fluorescent fingerprints in the estuary of the Yangtze River were systematically explored,and pollution sources were traced.and analysis of characteristic pollutants.The main preliminary conclusions are as follows:（1）The water quality of the main stream in the estuary section of the Yangtze River is stable throughout the year within the range of Class II surface water environmental quality.The p H is 7.67-8.53,and the wet period>the normal period in October>the dry period>the normal period in April;the conductivity is 279-486μS/cm,and the average conductivity is the highest in the dry period;ammonia nitrogen is 0.10-0.71 mg/L,Wet period>Dry period>October normal period>April normal period;total nitrogen was 0.80～1.88 mg/L,April normal period>January dry period>October normal period>dry period;total phosphorus was 0.05～0.16 mg/L,Wet period>dry period>October normal period>April normal period;permanganate index is 1.58～2.83 mg/L,wet period>dry period>October normal period>April normal period;TOC ranged from 1.63 to 4.58 mg/L,showing the wet period>the normal period in April>the normal period in October>the dryr period.According to the"Surface Water Environmental Quality Standard"（GB3838-2002）,the water quality of the main stream of the Yangtze River estuary was excellent in four periods,and the overall water quality of the tributaries of the Yangtze River estuary section was in good condition,and there was still a Class IV water section,and the water quality was worse than that of the main stream.（2）Aqueous fluorescent fingerprint in the Yangtze River estuary mainly includes three fluorescence peaks,denoted as peak A,peak B,and peak C,and their[excitation wavelength,emission wavelength]are[280,340]nm,[235,345]nm and[250,450]nm,wherein peak A and peak B are protein-like peaks,and peak C is humic-like peak.The results of parallel factorization of water quality fluorescent fingerprints in different periods show that there are three main fluorescent components in the mouth of the Yangtze River,which are C1-type protein components,C2-type humus components,and C3-type humus components.The main fluorescent components in each period The similarity is above 0.8,and the intensity of C1 and C2 components increases suddenly near the estuary（samples CJ-11 and CJ-12）.The fluorescence peak positions of the three tributaries（HP,LH,and LQ rivers）of the water quality fluorescence fingerprints are roughly the same as those of the main stream of the Yangtze River,but the intensity of the fluorescence peaks is 10 to 20 times higher than that of the main stream.Correlation analysis shows that peak B and peak C may come from the same pollution source during the normal water season in October;peak A and peak B may come from the same pollution source during the dry season in January and the normal water season in April,which shows the pollutants and pollution sources of the Yangtze River in different periods.There are differences.During the dry season in January,the intensities of peak A and B were highly correlated with ammonia nitrogen.During the wet period in August,the intensity of peak A and peak B was poorly correlated with each water quality parameter.（3）The apparent molecular weight of the organic matter in the main stream of the Yangtze River Estuary is about 500-2000 Da,which is polluted by printing and dyeing.The tributary HP River contains wastewater from the printing and dyeing industry,carrying organic compounds with molecular formulas C₁₂H₁₂O₃S,C₁₃H₁₀O₆S₂,C₁₂H₈O₇S₂and C₂₃H₂₀O₆S₂,which may be the reason for the specific water quality fingerprints near the main stream of the Yangtze River（samples CJ-11and CJ-12）.The tributaries of the LH and LQ rivers also have the same fluorescent fingerprint signal as the HP river,and their confluence into the main stream of the Yangtze River will also have a certain negative impact on their water quality.At the same time,clothing,garment textile and printing and dyeing enterprises have been found near the sampling points upstream of its three tributaries,and its drainage into the tributaries may be the main reason for the presentation of fluorescent fingerprint signals for printing and dyeing.