scholarly journals Temperature effects on nitrogen cycling and nitrate removal-production efficiency in bed form-induced hyporheic zones

2016 ◽  
Vol 121 (4) ◽  
pp. 1086-1103 ◽  
Author(s):  
Lizhi Zheng ◽  
M. Bayani Cardenas ◽  
Lichun Wang
Keyword(s):  
Nitrogen Cycling ◽  
Temperature Effects ◽  
Production Efficiency ◽  
Nitrate Removal ◽  
Hyporheic Zones ◽  
Bed Form

scholarly journals Impact of Bed Form Celerity on Oxygen Dynamics in the Hyporheic Zone

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 62 ◽  
Author(s):  
Philipp Wolke ◽  
Yoni Teitelbaum ◽  
Chao Deng ◽  
Jörg Lewandowski ◽  
Shai Arnon
Keyword(s):  
Hyporheic Zone ◽  
Time Lapse ◽  
Oxygen Distribution ◽  
Anoxic Zone ◽  
Fine Grain ◽  
Uptake Rates ◽  
Hyporheic Zones ◽  
Bed Form ◽  
Gradual Disappearance ◽  
Oxygen Dynamics

Oxygen distribution and uptake in the hyporheic zone regulate various redox-sensitive reactions and influence habitat conditions. Despite the fact that fine-grain sediments in streams and rivers are commonly in motion, most studies on biogeochemistry have focused on stagnant sediments. In order to evaluate the effect of bed form celerity on oxygen dynamics and uptake in sandy beds, we conducted experiments in a recirculating indoor flume. Oxygen distribution in the bed was measured under various celerities using 2D planar optodes. Bed morphodynamics were measured by a surface elevation sensor and time-lapse photography. Oxygenated zones in stationary beds had a conchoidal shape due to influx through the stoss side of the bed form, and upwelling anoxic water at the lee side. Increasing bed celerity resulted in the gradual disappearance of the upwelling anoxic zone and flattening of the interface between the oxic (moving fraction of the bed) and the anoxic zone (stationary fraction of the bed), as well as in a reduction of the volumetric oxygen uptake rates due shortened residence times in the hyporheic zone. These results suggest that including processes related to bed form migration are important for understanding the biogeochemistry of hyporheic zones.

TEMPERATURE EFFECTS ON WASTEWATER NITRATE REMOVAL IN LABORATORY-SCALE CONSTRUCTED WETLANDS

1999 ◽  
Vol 42 (1) ◽  
pp. 185-190 ◽  
Author(s):  
S. L. Wood ◽  
E. F. Wheeler ◽  
R. D. Berghage ◽  
R. E. Graves
Keyword(s):  
Constructed Wetlands ◽  
Temperature Effects ◽  
Nitrate Removal ◽  
Laboratory Scale

Nitrogen Cycling in Piedmont Vegetated Filter Zones: II. Subsurface Nitrate Removal

1997 ◽  
Vol 26 (2) ◽  
pp. 337-347 ◽  
Author(s):  
Louis V. Verchot ◽  
E. Carlyle Franklin ◽  
J. Wendell Gilliam
Keyword(s):  
Nitrogen Cycling ◽  
Nitrate Removal

Characterization of carbides in M50NiL

1991 ◽  
Vol 49 ◽  
pp. 606-607
Author(s):  
L. S. Lin ◽  
K. P. Gumz ◽  
A. V. Karg ◽  
C. C. Law
Keyword(s):  
Temperature Effects ◽  
Base Composition ◽  
Lattice Parameter ◽  
Control Surface ◽  
Carbide Formation ◽  
Particle Sizes ◽  
Low Carbon ◽  
Fee Structure ◽  
Heat Treated

Carbon and temperature effects on carbide formation in the carburized zone of M50NiL are of great importance because they can be used to control surface properties of bearings. A series of homogeneous alloys (with M50NiL as base composition) containing various levels of carbon in the range of 0.15% to 1.5% (in wt.%) and heat treated at temperatures between 650°C to 1100°C were selected for characterizations. Eleven samples were chosen for carbide characterization and chemical analysis and their identifications are listed in Table 1.Five different carbides consisting of M6C, M2C, M7C3 and M23C6 were found in all eleven samples examined as shown in Table 1. M6C carbides (with least carbon) were found to be the major carbide in low carbon alloys (<0.3% C) and their amounts decreased as the carbon content increased. In sample C (0.3% C), most particles (95%) encountered were M6C carbide with a particle sizes range between 0.05 to 0.25 um. The M6C carbide are enriched in both Mo and Fe and have a fee structure with lattice parameter a=1.105 nm (Figure 1).

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