洞穴溶解有机质组分和循环过程的季节变化特征  

Seasonal variation characteristics of dissolved organic mattercomposition and cycle process in caves

作　　者：刘渝港 贺秋芳 沈立成 范佳鑫 LIU Yugang;HE Qiufang;SHEN Licheng;FAN Jiaxin(Chongqing Key Laboratory of Karst Environment,School of Geographical Sciences,Southwest University,Chongqing 400715,China)

机构地区：[1]西南大学地理科学学院,岩溶环境重庆市重点实验室,重庆400715

出　　处：《中国岩溶》2023年第3期456-471,共16页Carsologica Sinica

基　　金：国家重点研发计划项目(2016YFC0502306);国家自然科学基金项目(41472321)。

摘　　要：溶解有机质(DOM)是岩溶碳汇的关键部分和重要的碳源,但是对于DOM在岩溶含水层中的性质和代谢过程的研究仍然有限。本研究以重庆雪玉洞地下河为例,对洞穴有机碳的来源、组成以及微生物作用对季节补给源变化的响应进行探讨,为进一步了解微生物介导的有机碳转化过程提供研究基础。运用三维荧光EEM研究水体有色溶解有机质(CDOM)的性质和组分并反演地下河水中有机质的来源和组成,结合地下河水水化学特征和16S rDNA细菌群落及功能多样性的季节变化特征,以了解季节性补给源的变化对洞穴地下水DOM输入和性质的影响。结果发现,雪玉洞地下河水以微生物内源有机质为主(61%~77%),降雨是引起岩溶给地下河水中CDOM光谱特征变化的最重要因素,雨季外源有机质输入增加,地下河水中外源有机碳组分含量和芳香性、腐殖酸类物质增加,细菌群落多样性和代谢功能基因随之变化,洞穴中向外输出的外源有机碳增加;旱季地下河水滞留时间和蒸发作用增强,因而微生物对有机质的代谢降解过程更加充分,向洞外输出的有机碳以内源为主。本研究有助于增加对岩溶洞穴地下水系统中微生物对有机碳转化过程的理解。Dissolved organic matter(DOM)is the key part and important carbon source of karst carbon sink.The migration and degradation of DOM in karst aquifers is an important carrier of material and energy transfer.However,due to the lack of long-term and in-depth research on the content,composition and migration process of DOM in karst groundwater,the transfer and metabolism process of organic carbon in cave water system and its impact on karst carbon sink process are still unclear.Colored dissolved organic matter(CDOM),a colored soluble component in DOM,is often used to characterize DOM in marine and freshwater systems.It is also used to characterize the composition and change process of organic matter in the study of karst groundwater.16S rDNA high-throughput sequencing,a commonly used method for the detection of non-cultured microorganisms,can comprehensively detect and analyze the bacterial community composition and species abundance in environmental samples.This study collected samples from the underground river in Fengdu Xueyu Cave,Chongqing on a quarterly basis,analyzed their hydrochemical indexes and organic carbon content,and characterized the changes in the composition and structure of organic carbon using CDOM fluorescence and UV-visible spectrum information.Combined with 16S rDNA highthroughput sequencing,this study also analyzed the structural characteristics of bacterial communities in groundwater and the metabolic function genes of microorganisms based on Pecrust2 prediction.According to the metabolism and transformation process of organic carbon in cave water and its response to the external input of organic matter,we can understand the migration and transformation process of organic carbon in karst groundwater,and provide scientific information for the carbon cycle and carbon sink process of karst groundwater system.Xueyu Cave is located in the Longjiang Gorge in Fengdu county,Chongqing,the southwest karst region.The cave opening is exposed at the mid-mountain elevation of 340 meters.Affected by the subtr

关 键 词：有色溶解有机质 三维荧光光谱 微生物 岩溶洞穴 地下水 

分 类 号：X143[环境科学与工程—环境科学] Q938.8[生物学—微生物学]