Biogeochemical Controls on Diel Cycling of Stable Isotopes of Dissolved O2 and Dissolved Inorganic Carbon in the Big Hole River, Montana
详细信息 查看全文
- 作者：Stephen R. Parker ; Simon R. Poulson ; Christopher H. Gammons ; and Michael D. DeGrandpre
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：September 15, 2005
- 年：2005
- 卷：39
- 期：18
- 页码：7134 - 7140
- 全文大小：930K
- 年卷期：v.39,no.18(September 15, 2005)
- ISSN：1520-5851
文摘
Rivers with high biological productivity typically showsubstantial increases in pH and dissolved oxygen (DO)concentration during the day and decreases at night, inresponse to changes in the relative rates of aquaticphotosynthesis and respiration. These changes, coupledwith temperature variations, may impart diel (24-h) fluctuationsin the concentration of trace metals, nutrients, and otherchemical species. A better understanding of diel processesin rivers is needed and will lead to improved methods ofdata collection for both monitoring and research purposes.Previous studies have used stable isotopes of dissolvedoxygen (DO) and dissolved inorganic carbon (DIC) as tracersof geochemical and biological processes in streams,lakes, and marine systems. Although seasonal variation in
18O of DO in rivers and lakes has been documented, nostudy has investigated diel changes in this parameter. Here,we demonstrate large (up to 13”) cycles in 18O-DO fortwo late summer sampling periods in the Big Hole River ofsouthwest Montana and illustrate that these changesare correlated to variations in the DO concentration, theC-isotopic composition of DIC, and the primary productivityof the system. The magnitude of the diel cycle in 18O-DO was greater in August versus September because ofthe longer photoperiod and warmer water temperatures. Thisstudy provides another biogeochemical tool for investigatingthe O2 and C budgets in rivers and may also be applicableto lake and groundwater systems.
18O of DO in rivers and lakes has been documented, nostudy has investigated diel changes in this parameter. Here,we demonstrate large (up to 13”) cycles in 18O-DO fortwo late summer sampling periods in the Big Hole River ofsouthwest Montana and illustrate that these changesare correlated to variations in the DO concentration, theC-isotopic composition of DIC, and the primary productivityof the system. The magnitude of the diel cycle in 18O-DO was greater in August versus September because ofthe longer photoperiod and warmer water temperatures. Thisstudy provides another biogeochemical tool for investigatingthe O2 and C budgets in rivers and may also be applicableto lake and groundwater systems.