کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5758646 | 1623006 | 2017 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Carbon cycling in the mantled karst of the Ozark Plateaus, central United States
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The nature of carbon (C) cycling in the unsaturated zone where groundwater is in contact with abundant gas-filled voids is poorly understood. The objective of this study was to trace inorganic-C cycling in a karst landscape using stable-C isotopes, with emphasis on a shallow groundwater flow path through the soil, to an underlying cave, and to the spring outlet of a cave stream in the Ozark Plateaus of northwestern Arkansas. Carbon dioxide (CO2) concentration and isotopic composition (δ13C-CO2) in gas and dissolved inorganic carbon (DIC) concentration and isotopic composition (δ13C-DIC) in water were measured in samples collected from two suction-cup soil samplers above the cave, three sites in the cave, and at the spring outlet of the cave stream. Soil-gas CO2 concentration (median 2,578 ppm) and δ13C-CO2 (median â 21.5â°) were seasonally variable, reflecting the effects of surface temperature changes on soil-CO2 production via respiration and organic-matter decomposition. Cave-air CO2 (median 1,026 ppm) was sourced from the soil zone and the surface atmosphere, with seasonally changing proportions of each source controlled by surface temperature-driven air density gradients. Soil-DIC concentration (median 1.7 mg Lâ 1) was lower and soil-δ13C-DIC (median â 19.5â°) was lighter compared to the cave (median 23.3 mg Lâ 1 and â 14.3â°, respectively) because carbonate-bedrock dissolution provided an inorganic source of C to the cave. Carbon species in the soil had a unique, light stable-C isotopic signature compared to the cave. Discrimination of soil-C sources to karst groundwater was achieved, which is critical for developing hydrologic budgets using environmental tracers such as C.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geoderma Regional - Volume 10, September 2017, Pages 64-76
Journal: Geoderma Regional - Volume 10, September 2017, Pages 64-76
نویسندگان
Katherine J. Knierim, Erik D. Pollock, Matthew D. Covington, Phillip D. Hays, Kristofor R. Brye,