Spatiotemporal Variation Of Organic Matter In Water Source Ecological Purification System And The Effect Of Aquatic Plants Release

To explore the salt lake water ecological purification system of water soluble organic matter removal characteristics and the influence of aquatic plants on organic matter removal,spectral characterization in combination with multivariate statistical method is used to drinking water supply in salt lake ecological purification system(based on the artificial wetland purification unit)of each processing unit in and out of the water monitoring analysis of organic matter concentration and spectral index changes.On the basis of mastering the seasonal variation characteristics of organic matter concentration and composition in each treatment unit of the water source ecological purification system,aiming at the influence of organic matter released by the growth of aquatic plants on the removal efficiency of organic matter in the water source ecological purification system,simulated experiments of organic matter and nutrients released by different types of aquatic plants in the laboratory were carried out.To master the characteristics of organic matter release during the growth and decay of different types of aquatic plants in the water source ecological purification system,and to provide scientific theoretical guidance for the optimal operation and management of the water source ecological purification system,the main research contents and results are as follows:1.Seasonal variation characteristics of organic matter in the inlet water of the ecological purification systemThe a(254)range of the whole year was 14.53-35.9 m-1,with the highest value in summer(30.79 m-1 on average)of Mangshe river.The annual SR value of raw water was 1.44,DOM was mainly derived from autologous sources,and the annual average value of E250/E365 was 5.1.The content of fulcrum acid in raw water was higher than that of humic acid.The annual mean value of A2/A1 was 0.1152,and the mean value of A2/A1 was the highest in winter and spring(0.1735 and 0.1328,respectively).The humification degree of organic matter was high.a(254)and a(355),β:α and BIX showed a high correlation.2.Seasonal variation characteristics of effluent organic matter in each treatment unit of the ecological purification systemDOM removal efficiency of constructed wetland purification unit is not high,index a(254)decreased by 10.71%in spring,BOD5 decreased by 1.57mg/L and 1.70mg/L after treatment in summer and autumn.In spring and summer,the Sr decreased,and the E240/E420 increased by 0.78 and 0.20,respectively,after the aquatic plants and submerged plants treated.The aquatic plants absorbed the macromolecular organic matter and released the small molecular matter,which effectively reduced the relative molecular weight of organic matter.In autumn and winter,the relative molecular weight of organic matter was opposite.The values of A2/A1 and A3/A1 in spring water decreased by 36.84%and 37.78%after treatment.Aquatic plants can effectively improve the freshness of organic matter.3.Decomposition process of aquatic plants3.Characteristics of organic matter and nutrients released by different types of aquatic plants in the ecological purification systemFour kinds of aquatic plants commonly used in the water source ecological purification system of Yanlong Lake were used as experimental materials,collected and decomposed into leaves,roots and stems for characterization.The results showed that in the unit carbon content,the nitrogen content of stem(33.05)was higher than that of root(22.98)and leaf(19.15),and the trend of phosphorus was the same.Compared with DOC/TC(5.59%～19.55%)and TDN/TN(1.58%～7.52%),the range of TDP/TP(4.17%～41.02%)is higher.Phosphor is more soluble in aquatic plants than carbon and nitrogen.DOP/DTP ratio ranged from 8.55%to 52.47%,with an average value of 26.21%.Inorganic nitrogen and phosphorus were the main sources of nitrogen and phosphorus released by aquatic plants.The leaves and the reed released the least organic matter,SUVA 254(average 0.78 L/mg C·m,0.77 L/mg C·m).4.Decomposition process of aquatic plantsDecomposition experiments on aquatic plant samples were carried out for 32 days.The results showed that the decomposition rate of reed was the lowest,which was 0.018 d-1.In the early stage of decomposition,the organic matter was rapidly released,among which the water plants and floating plants had strong ability to release organic matter.Each gram of dried sample increased CODMn by 17.53 mg/L and 18.53 mg/L,and consumed a large amount of oxygen in the water at the same time,and the DO decreased from 3.43 mg/L to less than 0.1 mg/L in the second day.Make the water body show anaerobic state.Submarine plants and floating plants have a stronger ability to release nutrients during decomposition,and the DOM released by aquatic plants is mainly autobiogenic,with relatively small molecular weight.The aromatic degree of DOM released from plant leaves is higher than that from stem and root,and the humification degree is higher.The research provides a scientific theoretical basis for the management of aquatic plants in water source ecological purification system.