Developing An Approach To Extract And Detect Biomarker Molecules In Organic Matter Of Rice Paddy Soil

Since the end of 20th century,the global warming and extreme weather are increasingly concerned worldwide.An important reason for causing a global climate anomaly is that human disturbance led to some changes in carbon cycling of terrestrial ecosystem and the concentrations of carbon dioxide in the atmosphere is upgrading quickly.In the global carbon cycling,earth is the largest organic carbon pool of terrestrial ecosystem soil.The organic matter is an important part of soil and plays a key role in the carbon cycling of whole terrestrial ecosystem.Increasing the soil organic carbon pool and improving soil carbon sequestration potential can be effective to the speed-increasing emissions of carbon dioxide which is blamed on the industry in the short time.They are the effective way to abate the change of global climate and ensure global food security.In order to find out the behavior and composition of organic matter in the soil,the soil science introduces two concepts of fast carbon pool and stable carbon pool.Generally,the plant residues,roots and root exudates are the major contributions in the input channels of soil organic carbon.Some biological macromolecules(such as lipids,lignin and tannin)are difficult to be decomposed because they have unique molecular characteristics and those biological macromolecules are called biomarkers.Different soil in different ecosystem have different source of plant species and proportion,so each soil has the special natural biomarker.The biomarker is good tool used for studying the composition,source and behavior of soil organic matter.Studies have shown that,the paddy soil is unique human-cultivated soil under the long-term role of planting rice,itself has a high density of carbon and carbon sequestration potential than other soils.This study gets three different age(0a,50a,300a)paddy soils that from same sources as samples to searching the experimental conditions of extracting biomarkers sequentially(extracting free lipids by total solvent extraction;extracting bound lipids by base hydrolysis;extracting lignin's phenol by CuO oxidation)and makes qualitative analysis its results.The main results are as follows:(1)In the study,we optimized the extraction solvent/soil volume of total solvent extraction,the reaction temperature of alkali hydrolysis and the temperature and the no oxygen conditions of oxidation copper reaction,has respectively building the extraction and identification method for free lipids,bound lipids and lignins phonel,the results were march to GC-MS qualitative identification effect.The baseline is smooth and maps are clear.(2)The biomarkers of paddy soils in free lipids by TSE(total solvent extraction):In the carbohydrates,.alpha.-D(+)Glucose,.beta.-D(+)Glucose,Trehalose are unique to paddy soil;In the steroids,Stigmasterol,.beta.-Sitosterol are unique to paddy soil;In the n-alkanes,n-Hentriacontane is unique to paddy soil;In the n-alkanols,n-Hexadecanol,n-Docosanol,n-Tetracosanol,n-Hexacosanol,n-Octacosanol,n-Triacontanol are unique to paddy soil;In the n-alkanoic acids,n-Dodecanoic acid,n-Tetradecanoic acid,n-Hexadecenoic acid(C16:1),n-Octadecadienoic acid(C18:2),n-Octadecenoic acid(C 18:1),n-Docosanoic acid,n-Tetracosanoic acid,n-Hexacosanoic acid are unique to paddy soil.The biomarkers of paddy soils in bound lipids by BHY(base hydrolysis):In the n-alkanoic acids,n-Eicosanoic acid,n-Docosanoic acid,n-Tetracosanoic acid,n-Hexacosanoic acid and n-Octacosanoic acid are unique to paddy soil;In the n-alkanols,n-Tetradecanol,n-icosanol,n-Docosanol,n-Tetracosanol,n-Hexacosanol and n-Octacosanol are unique to paddy soil;In the steroids,.beta.-Sitosterol is unique to paddy soil.The biomarkers of paddy soils in lignins phenol by CUO(CuO oxidation):p-Hydroxybenzaldehyde,Vanillin(V),Acetovanillone(V),Ethanedioic acid,Fumaric acid(C),2-Methyl-2-hydroxypropanoic acid,Methylmaleic acid and 4-Methyl-2-hydroxypentanoic acid are unique to paddy soil.(3)The results of detection show that,the major source of biomarkers,molecular in the paddy soil organic matter include:the n-alkanols in biomarkers is from suberine of plant roots.The major source of n-alkanes in biomarkers is fungi.The major source of steroids in biomarkers is lignin.The major source of trehalose in carbohydrates is predominantly fungi in soil.The biological molecular's diversity of organic matter in paddy soil with 50 years is between the mother soil and long-term plant paddy soil.(4)Molecular biomarkers identified by the above methods in paddy soil under 20cm been cut or disappeared soon,suggests that long-term planting rice plough stunted root growth,and organic matter has been limited in deep distribution.The dominant plant species of virgin soil are coniferous gymnosperms in the early and later evolved into herbaceous angiosperms.The part of below 20cm of the soil which is Planting rice 50 years has some same characteristic with uncultivated soil.The study shows that the methods which we optimized can be used to search the sources of organic matter in paddy soils and the trace of land-use change dynamics of organic matter.The quantitative detection methods needs to be further developed in the future to evoluate the inlulence of human activities to soil organic matter quantitatively.