The Physical And Chemical Properties Of DOM Solution Produced By Tubificids And Its Effects On Adsorption Of Cu And Cd By Sediments

There are a large number of benthic organisms in natural water body.These benthic organisms not only affect the physicochemical properties of water-sediment system through their biological disturbance,but also their metabolism produces dissolved organic matter,which can change the content and structure of dissolved organic matter in the water environment,it has an important impact on the migration and transformation of pollutants in water body.So,the study of dissolved organic matter is of great significance to the environment.As a common benthic organisms in natural water body,tubificid exist widely exist in the world's freshwater environment,with a huge amount of biomass and high biological density.DOM is a complex mixture of structural elements,which is an active chemical component of water ecology.It has an important effect on the physical and chemical properties of water environment and the transfer and transformation of pollutants.However,Few soluble organic matter produced by the earthworms is less studied,and many mechanisms of action are not clear.Therefore,this dissertation takes the dissolved organic matter of viburnum as the research object and carries on the following research.To study the physicochemical properties of turbid solubilized organic matter,twigs were cultured under laboratory conditions to obtain dissolved organic matter,and the pH and content of dissolved organic matter produced during the metabolic process were monitored,and the thawed dissolved organic matter obtained was used.Filtration method for molecular weight grading,and then through three-dimensional fluorescence spectroscopy,UV-Vis,Fourier infrared spectroscopy and elemental analysis and other analytical techniques to study the composition and properties of different molecular weight DOM,combined with acid-base functional group titration of DOM produced by twitch to understanding.The results showed that DOM had a wide range of molecular weight distribution,dominated by small molecules below 0.5 Dka,accounting for 40.54%-45.64%.The number and degree of substitution of the aromatic structure of the twitchy DOM are related to the molecular weight distribution.The content of the less than 0.5 KDa component is more complex,the aromaticity of the organic matter is lower,the non-humic acid organic material occupies a large proportion,and the hydrophilicity is strong.The degree of substitution of the benzene ring structure is higher.The DOM contains the class of fulvic acid,humic acid and protein-like components,and the earthworm DOM contains weakly acidic functional groups.To study the effect of DOM produced by twitches on the adsorption of heavy metals Cu and Cd by sediments.Adsorption kinetics and adsorption thermodynamic model were used to explore the effect of DOM on sediment adsorption of heavy metals Cu and Cd,and to study its influence mechanism.By adjusting the pH,the pH of the DOM for the optimal effect of adsorption of heavy metals Cu and Cd on sediments was obtained.The results showed that DOM produced by viburnum promoted the adsorption of Cu on sediments and inhibited the adsorption of Cd on sediments.Under the experimental conditions,the optimum experimental pH for Cu adsorption is 7.0,and the optimum experimental pH for Cd adsorption is 9.0.To study the binding properties of DOM and heavy metals Cu and Cd,the optimal concentration of DOM and heavy metals for DOM was explored using metal ion densitometer,and the optimum pH was investigated.The effects of DOM,Mechanism of action of Cu,Cd with heavy metals.The results showed that the basic rules of the effect of DOM on Cu and Cd were similar,but the effect of Cu was stronger.The maximum concentration of DOM at 30 mg/L was 107 ?mol/L,the maximum concentration of Cd at 96 ?mol/L In the UV region of DOM,fulvic acid was found,showing that fulvic acid and its protein-like fractions had more binding sites to Cu than to Cu.However,the DOM-Cd binding site mainly consisted of UV-like fulvic acid.The effect of pH value on the combination of DOM and heavy metals Cu and Cd is mainly due to the effect of DOM and its proteins on the surface of DOM,changing their surface group structure and affecting the coordination between DOM and Cu and Cd.DOM and heavy metals Cu,Cd reaction is hydroxyl,carboxyl and other functions of a variety of functional groups.