کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6438249 | 1638016 | 2014 | 14 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Enhancement of denitrification in permeable carbonate sediment due to intra-granular porosity: A multi-scale modelling analysis
ترجمه فارسی عنوان
افزایش ضریتریفاسیون در رسوب کربنات نفوذ پذیر به دلیل تخلخل داخل دانه ای: یک تجزیه و تحلیل مدل چند بعدی
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
It has recently been hypothesized that bulk denitrification rates in carbonate sands may be enhanced by reactions occurring in the intra-granular pores, cracks and crevices. We tested this hypothesis using a series of flow and reactive transport models spanning from the pore-scale (â¼mm) to the continuum scales (â¼10Â cm bedforms). Pore-scale simulations solved the coupled Navier-Stokes and Brinkman equations and represented flow-through reactor experiments previously performed on coral reef sands. The results revealed that intra-granular transport and reactions can explain over-all denitrification enhancement. A sensitivity study with a single grain diffusive transport model showed that in the majority of cases, the resultant increase in denitrification was not coupled to nitrification within a single grain. Only for large grain diameters of 2 and 4Â mm was coupled nitrification-denitrification important. In most cases, coupled nitrification-denitrification instead arose as conditions became more reducing along a flow path, as is the case in quartz sands without intragranular pores. An intra-granular reaction rate based on a single grain model was incorporated into a continuum-scale Darcy flow and reactive transport model for a rippled sand bed, where porewater flow is driven by the turbulent current over the ripple. The results of the Darcy-scale model suggest that intra-granular pores increase the amount of slow-flowing areas within which coupled nitrification-denitrification can occur. We conclude that the complex advective flow field does not strongly inhibit denitrification enhancement by carbonate sand grains, as it does in silica sands. Thus, intra-granular reactions may enhance bulk denitrification in carbonate sediment with porous grains under natural advective conditions.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 141, 15 September 2014, Pages 440-453
Journal: Geochimica et Cosmochimica Acta - Volume 141, 15 September 2014, Pages 440-453
نویسندگان
Adam J. Kessler, M. Bayani Cardenas, Isaac R. Santos, Perran L.M. Cook,