Diel aqueous chemistry and biogeochemical processes in streams of karst area
Study on diel cycling can help to reveal relatively rapid biogeochemical processes in natural water(in-stream interaction)and discriminate drainage basin processes in recharge areas.Results from earlier studies showed that biological processes(photosynthesis and respiration),geochemical processes(bicarbonate equilibrium,calcite precipitation)are the main controlling factors on diel variations of pH value,specific conductivity(SpC)and concentrations of Ca2+and HCO3-in streams.Furthermore,the stream orders and forms even microenvironment of riverbed all have remarkable influence on diel aqueous chemistry,pH value and dissolved oxygen(DO)are mainly controlled by photosynthesis which is closely related to the air temperature.In high alkalinity and calcium content streams,representing carbonate-rich basin,calcification,acid secretion of or ganisms may play important roles in aquatic plant photosynthesis,thus result in diel hydrochemical cycling with daytime decrease(up to a 20%-30%decline)and nighttime increase of concentrations of Ca2+and HC03-Diel DIC cycling downstream caused by photosynthesis and their changes along the stream flow indicate that the stream is losing inorganic carbon along its flow path,and converting to organic carbon,such that inorganic C storage in streambeds will be an important net DIC sink in small productive streams.The effect of diel cycling of biogeochemistry on interpretation of carbon cycling,sink and source,especially on clarification of karst carbon sink stability and net carbon sink estimation trends becomes increasingly important in karst aquifer systems.Diel variability has implications for the design of long-term surface water monitoring programs and interpretation of water quality trends.
stream hydrochemistry diel variation biogeochemical processes karst carbon sink effect
ZHANG Cheng
Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamics,MLR & GZAR,Guilin,Guangxi 541004,China;International Research Center on Karst under the Auspices of UNESCO,Guilin,Guangxi 541004,China
国内会议
国土资源部广西岩溶动力学重点实验室和国土资源部岩溶生态系统与石漠化治理重点实验室2016年度学术委员会会议
广西桂林
英文
9-19
2016-12-02（万方平台首次上网日期，不代表论文的发表时间）