Experimental Study On The Degradation Of Reed Organic Carbon In Mudflat Sediment

The estuary intertidal area is located in a transitional zone of the junction of land and sea, the environment undergo hydrodynamism mixing effect intensely, material and energy conversion rapidly under diverse physical and chemical factors, which affect the transformation and degradation of organic carbon directly or indirectly. Reed is the dominant species in temperate zone coastal wetlands, understanding the production and degradation behavior in the intertidal is the main content of this carbon cycle of coastal environment.In this paper, we process a laboratory study on the degradation of reed organic carbon in mudflat sediment, simulating intertidal zone of different biological and chemical conditions, to expound microbial degradation and chemical degradation of reed organic carbon and to reveal degradation rule of reed organic carbon in mudflat sediment.The optimal procedure is followed. Fresh sediment was extracted with sterilized and aged seawater at first, and added with Tween-80 solution, then uniformly dispersed by a thoroughly oscillating, kept steady for precipitation. After filtered through a sterilized membrane (1.2μm, sterilized in boiling water repeatedly), the supernatant was added an appropriate amount of FDA solution to react in dark for 3h at the temperature ranging at 25-30 ℃. Followed by the optimal termination by acetone, the fluorescence intensity of the reacted solution was measured within 25min using a molecular fluorescence photometer at the excitation wavelength of 488nm and emission wavelength of 530nm, and the detection range of this method was 3.0×103-1.1×105 (ind./g, dry weight). The microbial activity was reported in the fluorescence content in per unit sediment mass (μg/g dry weight).The method of culture experiment. Reed chips as a source of organic matter, and control the training system of oxidation-reduction, visible light and UV radiation, and the bacteria-aseptic conditions, sampling respectively at 0、1、3、5、8、15、26、40 and 63 days, then detection and analysis of organic carbon, lignin, microbial abundance and activity indexs. The experimental study results show that.Degradation of reed organic carbon in the oxidation and reduction conditions:In the training process the organic carbon content of oxidation/reduction antibacterial samples show a downward trend, then training with the organic carbon content was relatively stable, and reducing environment relative to the oxidizing environment was more obvious to the change of organic carbon content. Oxidative environment plays more intense change than reducing environment on lignin content ∑8.Degradation of reed organic carbon in visible and UV light conditions:At different culture time, organic carbon content was relatively stable after the first change to reduce. The content of ultraviolet radiation group was significantly decreased in early training before 8 days, and then the culture was carried out with gradually stabilized. The content of lucifuge group was no significant variation and relative to the light and UV radiation group was relatively stable of its trends. Therefore, visible light on the degradation of organic carbon have a certain role in promoting, and UV radiation effect on the degree of degradation of organic carbon was stronger than visible light. UV radiation group compared to light and dark groups was more significant on decreasing of lignin content.Microbial degradation of reed organic carbon:In the oxidation and reduction conditions organic carbon contents were generally presented the degradation rule that was rapidly reduce in the beginning then rising and decline steady finally. In the training system microbial activity, microbial count and unit bacterial activity of groups were generally presented the trend that was consistently the first growth then decrease and the final balance, and reducing environment was higher than oxidizing environment. With cultured the lignin content trends of bacterial samples show reduce overall, corresponding to the changes of organic carbon.In conclusion, in the oxidation and reduction environment have the different degradation effects of reed organic carbon, the ratio of reed organic carbon degradation rate constant in the oxidation and reduction environment is 0.109 using of multi-G two component dynamic model, so the degree of degradation of organic carbon in reduction was slightly stronger than oxidation environment. The methyl/methoxyl degradation degree of anoxic group was a bit stronger than oxic group. It shows that oxidation degradation and methyl/methoxy degradation occure quilibrium that white-rotfungi and brown rotfungi to degrade was balanced, and was given priority with oxidation degradation of white-rotfungus. During training the lignin of light sample was inmoderate degradation and UV radiation and lucifuge group was in the condition of without degradation, so visible light was more advantageous to the degradation of lignin compared with ultraviolet. Light of lignin to methyl/to methoxyl degradation degree have different effects. There was a negative correlation between organic carbon content and microbial activity andmicrobial count, bacterial action takes an important role in the degradation of reed organic carbon. Oxidative degradations acid aldehyde ratio (Ad/Al)v of the bacteria group show a gradual increase in trend, (Ad/Al)v>0.3 on the training 63 day that means the degradation of lignin was moderate and oxidation environment on the degree of the degradation of lignin is relatively high, While bacteriostatic group was lower in order to suggest that bacteria and fungi microorganisms were main degradation of lignin. Under controlled culture conditions, bacterial reduction is strongest to the degradation of organic carbon, followed by bacterial oxidation and ultraviolet once again the visible light and reduction chemical degradation, and finally oxidation chemical degradation.