Characteristics Change Of Dissolved Organic Matter In Lake Sediments

Lake Eutrophication is one of the most important environmental problems in the world, and also in China. Apart from the effects of external sources of nitrogen and phosphorus inputs to the lake, eutrophi cation of lakes is also closely related to its endogenous factors, especially for a large number of shallow lakes in China. With the external source pollution to be gradually controled, the impact of eutrophi cation from its sediment is growing importance.Dissolved organic matter in lake sediments (DOM) is a kind of organic compound contained with active biological activity physical and chemical reactivity, its content and structure changes directly affect the environmental behavior of nitrogen and phosphorus, and is impact to eutrophi cation of lakes. Based on this, to study the characteristics change of dissolved organic matter in lake sediments, this paper is mainly about:1. Typical sediment samples from The Erhai Lake, Taihu Lake, and Dianchi Lake were choused to comparison of extraction agent choice experiments. The results show that:Other things equal, use pure water, potassium chloride, calcium chloride solution as the extracting agent to extract DOM, respectively, pure water as the extraction agent who extracts its content is relatively high, and its three-dimensional fluorescence structure is more clearly, better reproducibility and stability; When antibacterial agent were added, more or less cause interference to the DOM content in lake sediments and affect the final results of the analysis, without the antibacterial agent was to be done; To consider more true and accurate reveal the characteristics of DOM in lake sediments, chose water as extraction fluid without antimicrobial agent to extract DOM, and as the basis for subsequent extraction of the means to study the DOM content and structure of lake sediments of the distribution.2. Use four lakes’DOM from sediment samples (Erhai Lake, Poyang Lake, Dongting Lake and Chaohu Lake) to show the differences between each other. Results indicated that:in the present study conditions, the DOM levels in four lake sediments was:Erhai Lake>Dongting Lake> Poyang Lake> Chaohu Lake, content of Erhai is particularly prominent, Dongting Lake and Poyang Lake is similar; DOM of Erhai sediment have more humic substances and protein-like substances than other lakes, which visible humic-like substances significantly; DOM in the Dongting Lake, Poyang Lake sediments contain more humic substances, in the sediment of Poyang Lake there are more represented in the class of tyrosine protein substances, Dongting Lake contains less protein-like substances, DOM in the lake sediments contain less protein-like substances and humic-like substances; DOM in the lake sediments come from different sources, biological is the main source to sediment DOM of Erhai Lake, DOM of The other three lake sediments is both the result of biological origin and terrestrial, also the terrestrial input sources for the main terminal.3. Choose sediments from Erhai Lake, Poyang Lake, and Dongting Lake for DOM bioavailability culture experiments. Results indicated that:In the training process its structure significantly changes and more consistent, Mainly reflected in changes in protein-like material, especially for tyrosine or tryptophan which with simple structure.DOM bioavailability accounted for20%-50%of total Content; Bioavailability of the lakes in descending order are:Poyang Lake> Dongting Lake> Erhai Lake.4. Select four seasons of surface sediments from Erhai for study on seasonal change. Found:Seasonal changes on DOM content in sediments of Erhai Lake is closely related to its corresponding water quality conditions, showing a negative correlation. Erhai Lake sediments’s DOM structure in seasonal change mainly in the southern winter, for the increase in the visible humic-like and the disappearance of protein-like substances; DOM in Erhai Lake sediments were mainly came from biological source of a large range, and showed some seasonal variations, winter and summer single, simple, spring and autumn diverse and complex.5. DOM were come from Erhai seven points’ sediment samples for study the different components change. Experiments showed:we got four compounds from DOM in Erhai lake sediment, HOA、HOB、HIM、HON, does not contain ATM; Concentration distribution of each component in descending order as:HON> HIM> HOA> HOB, Four kinds of components are quite different structure, according to the complexity were:HOA> HON> HIM> HOB; DOM in the Erhai Lake sediments up to neutral material component, there were components of the complex structure of the HOA and a small amount of HOB with simple structure, the DOM difference between each points of lake Earhai sediment samples because of the difference in HON and HIM’s content, proportion and structure.