کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5765061 | 1626605 | 2017 | 42 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Assessing dissolved carbon transport and transformation along an estuarine river with stable isotope analyses
ترجمه فارسی عنوان
ارزیابی انتقال و تحول کربن حل شده در امتداد یک رودخانه استوایی با تجزیه و تحلیل ایزوتوپ پایدار
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
زمین شناسی
چکیده انگلیسی
Estuaries play an important role in the dynamics of dissolved carbon from rivers to coastal oceans. However, our knowledge of dissolved carbon transport and transformation in mixing zones of the world's coastal rivers is still limited. This study aims to determine how dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) concentrations and stable isotopes (δ13CDIC and δ13CDOC) change along an 88-km long estuarine river, the Calcasieu River in Louisiana, southern USA, with salinity ranging from 0.02 to 21.92. The study is expected to elucidate which processes most likely control carbon dynamics in a freshwater-saltwater mixing system, and to evaluate the net metabolism of this estuary. Between May 2015 and February 2016, water samples were collected and in-situ measurements on ambient water conditions were performed during five field trips at six sites from upstream to downstream of the Calcasieu River, which enters the Northern Gulf of Mexico (NGOM). The DIC concentration and δ13CDIC increased rapidly with increasing salinity in the mixing zone. The average DIC concentration and δ13CDIC at the site closest to the NGOM (site 6) were 1.31 mM and â6.34â°, respectively, much higher than those at the site furthest upstream (site 1, 0.42 mM and â20.83â°). The DIC concentrations appeared to be largely influenced by conservative mixing, while high water temperature may have played a role in deviating DIC concentration from the conservative line due likely to increased respiration and decomposition. The δ13CDIC values were close to those suggested by the conservative mixing model for May, June and November, but lower than those for July and February, suggesting that an estuarine river can fluctuate from a balanced to a heterotrophic system (i.e., production/respiration (P/R) < 1) seasonally. Unlike the DIC longitudinal trend, the DOC concentrations in the river estuary decreased from upstream to downstream, but to a much smaller degree. The DOC concentrations consistently showed a deviation from those suggested by the conservative mixing model, which may have been a consequence of in-stream photosynthesis. This river estuary consistently showed depleted δ13CDOC values (i.e., from â30.56â° to â25.92â°), suggesting that the DOC source in the mixing zone was highly terrestrially derived. However, in this relatively small isotopic range, δ13CDOC alone has limitations in differentiating carbon produced by aquatic photosynthesis from carbon produced by terrestrial photosynthesis in a river-ocean continuum.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Estuarine, Coastal and Shelf Science - Volume 197, 15 October 2017, Pages 93-106
Journal: Estuarine, Coastal and Shelf Science - Volume 197, 15 October 2017, Pages 93-106
نویسندگان
Songjie He, Y. Jun Xu,