摘要
惰性有机碳(RDOC,Recalcitrant Dissolved Organic Carbon)作为难以被生物降解的有机碳,可以在水体中保存数千年,构成长期碳储。岩溶区浮游植物利用岩溶水中丰富的HCO–3进行光合作用,为异养细菌生长提供充足的有机质底物,促进异养细菌代谢,形成RDOC。本文以广西柳江为例,通过δ^(14)C示踪法、荧光实时定量PCR法、原位微生物法对流域内细菌基因丰度、RDOC浓度等进行培养和测试,结合环境因子对流域内RDOC的变化趋势进行分析讨论。研究区RDOC浓度介于1.46~2.66 mg·L^(-1)之间,平均1.85 mg·L^(-1),占DOC的48.16%~92.61%,平均占65.83%,表现出明显的时空变化特征:平水期水温升高、水体浊度降低,浮游生物初级生产力增加,产生较多内源有机碳,为异养细菌提供充足的有机质底物,细菌丰度和初级生产力增加,RDOC浓度明显高于丰水期,主要受流域内异养细菌生物效应影响;RDOC浓度在水库坝后明显减小,该采样点较缓的流速使有机质和生物聚合物更易沉降,进而留存在水体中的DOC及RDOC减少,主要受水动力条件控制。研究结果表明流域内RDOC受生物效应和水体理化性质共同影响,异养细菌是流域内RDOC的主要贡献者,同时浮游生物产生的内源有机碳对RDOC形成有促进作用。
Recalcitrant dissolved organic carbon is difficult to be biodegraded and constitute long-term carbon sequestration.The fertilization effect of karst water on phytoplankton increased the biomass,which theoretically provides sufficient organic substrates for heterotrophic bacteria promoting its metabolism,which could generate more RDOC.Samples were taken along the Liujiang River at Guangxi in July and September 2016.Theδ^(14)C method was used to measure the primary productivity of bacteria;the fluorescent real-time quantitative PCR method was used to measure the bacteria and AAPB abundance,and the in-situ microbial cultivation method was used to determine the RDOC concentration in the basin.Based on the results,the RDOC measured from 1.46~2.66 mg·L^(-1),with an average of 1.85 mg·L^(-1),accounting for 48.16%~92.61%of DOC which showed a significant seasonal and spatial variation.With the rise in water temperature and decreased turbidity,the plankton primary productivity increased during the normal season providing sufficient organic carbon for heterotrophic bacteria.The increased bacterial abundance and its primary productivity generated more RDOC than that in the wet season.However,the spatial variation of RDOC presented different responding mechanisms,which were mainly controlled by hydrodynamics.The slow flow rate of the site behind the reservoir dam was conducive to the growth and metabolism of aquatic organisms.The concentration of chlorophyll a,bacterial abundance,and both primary productivity of plankton and bacteria had all increased significantly at the site behind the reservoir dam,but the RDOC concentration decreased because the slow flow rate also made it easier for organic matter and biopolymers to settle,reducing the DOC concentration in water.The results indicated that biological effect,carbon sources,and specific hydrophysical/hydrochemical properties were the main impacting factors of RDOC.The heterotrophic bacteria were the main contributor to RDOC in the basin,and the endogenous organic carbon
作者
何若雪
李强
于奭
孙平安
HE Ruo-xue;LI Qiang;YU Shi;SUN Ping-an(Chengdu Technological University,Chengdu,Sichuan 611730;Key Laboratory of Karst Dynamics,Ministry of Natural Resources&Guangxi Zhuang Autonomous Region,Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin,Guangxi 541004)
出处
《地球学报》
CAS
CSCD
北大核心
2022年第4期438-448,共11页
Acta Geoscientica Sinica
基金
广西自然科学基金杰出青年基金项目“岩溶地球化学”(编号:2015GXNSFGA139010)
成都工业学院校级项目(编号:2021ZR023)联合资助。
关键词
惰性有机碳
异养细菌
生物效应
水动力条件
岩溶水
RDOC
heterotrophic bacteria
biological effect
hydrodynamic condition
karst water
