Distribution And Source Of Organic Matters In Karst Underground River As Measured By Biomarkers

The distribution,source and transport process of organic matters in karst steam environment is very important for global carbon cycle.As a kind of vital water resources,karst water quality has close relation with the health and development of human beings.DOM is a kind of significant constituent for aquatic ecosystem production,mainly comes from biological residue and its metabolites.The content of DOM equal to 97% of the total organic maters in aquatic ecosystem.The DOM can led the variation of aquatic ecosystem production and the transportation of global carbon.And the transportation process between DOM and POM has bridge a way on global carbon cycle.The total water resource is huge in china while numerous underground water were polluted by people due to their lack of environmental protection concept during the process of economic construction.The big population is another reason that the water resource is poor in china.The civil underground water especially need more attention on water protect.Compared with the rude underground water,the theory of where the organic matters resources from and how they migration and transportation are obviously very important for the civil one.Also those are quite important for the research on the global carbon cycling and the water quality safety evaluation and management in underground water systems.Lao longdong underground water system was located in jinzhu village,nan'an district,Chongqing city which has a significant achievement in urbanization.As a classic civil karst underground water system,it has a complex way of land-use and land-cover.The river was developed as a tourist attractions and people can arrived in it for almost 1 kilometers.We collected this river system as my research area,aim to trace the source of organic matters and the contaminations and find out how the maters migration and transportation in the system.And provide more theoretical foundation for construction of sustainable development in karst underground waterregions.There are 3 main aspects in my research,firstly,we analyzed the organic matters and contaminations in laolong dong underground water system.Secondly,we compared the source of organic matters in laolong dong with that in qingmuguan underground water system to reveal the impact of urbanization for organic ingredients in this water system.Finally,we find out the way how organic matters is migration in this river by analyzed the river sediments.The result shows that,We can know from the complex index of alkanes,fatty acids and steriods that the main organic matters in laolongodng came from bacteria and the artificial input.And the fecal input has dramatically polluted the underground river and it is harmful effect the human healthy.The ingredients,content and migration and transportation of organic matters has a strong relativity with the environment such as rain and sun lite.For one aspect,with the rainfall infiltration,the organic matters in the soil were transferred into the karst river.So the ingredient of the river is getting more and more complex.For another aspect,due to the function of the sunshine,the diatoms changed the organic matters in the river.So the ingredients,content and migration and transportation of organic matters has changed.The content and composition of dissolved alkanes in Nanshan underground river system showed significant seasonal differences,and rain was the main reason for this difference.Due to the uneven feature of karst medium,there is a remarkable contrast between content,main constituents and constitute of alkanes in surface karst springs and underground river.The alkanes' import of underground river mainly concentrated in the rainy season.Surface karst spring has the same situation while the input quantity is much more than that in underground river during the dry season.And the content is relatively more stable.Microbial source input was dominated in the whole system.Control degree of microbial alkanes input is different in laolong debouchure.Xiannv cave and zhaokarst spring.Laolong debouchure has the weakest control while zhao karst spring has the strongest.The influence of microbe on organic matters was weak in May,July to October.Unlike alkanes,the input of fatty acid during the dry season is greater than that during the rainy season.The variation of components is different in each sampling sites.During the whole year,Laolong is much more stable than others.Zhaojia and xiannv had huge variations in January,February,July and August.Overall,fatty acids and alkanes represented the same source of organic matter.In dry season and frontal rainy season,the organic matters mainly came from microbes.While,in mainly rainy season,the organic matters mainly came from vegetation.By the analysis of n-alkanes and steroids in the study area,nanshan underground river system was effected by human activities,and the river was heavily contaminated.Pollutant mainly camefrom the direct input of human excrement and gas leaks.