Colloid Mobilization in a Fractured Soil during Dry–Wet Cycles: Role of Drying Duration and Flow Path Permeability

2015 ◽  
Vol 49 (15) ◽  
pp. 9100-9106 ◽  
Author(s):  
Sanjay K. Mohanty ◽  
James E. Saiers ◽  
Joseph N. Ryan
Keyword(s):  
Flow Path ◽  
Colloid Mobilization

scholarly journals A thermodynamic formulation of root water uptake

2016 ◽  
Vol 20 (8) ◽  
pp. 3441-3454 ◽  
Author(s):  
Anke Hildebrandt ◽  
Axel Kleidon ◽  
Marcel Bechmann
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Water Distribution ◽  
Bound Water ◽  
Root Water Uptake ◽  
Flow Path ◽  
Thermodynamic Evaluation ◽  
Entire Flow ◽  
Soil Water Distribution

Abstract. By extracting bound water from the soil and lifting it to the canopy, root systems of vegetation perform work. Here we describe how root water uptake can be evaluated thermodynamically and demonstrate that this evaluation provides additional insights into the factors that impede root water uptake. We derive an expression that relates the energy export at the base of the root system to a sum of terms that reflect all fluxes and storage changes along the flow path in thermodynamic terms. We illustrate this thermodynamic formulation using an idealized setup of scenarios with a simple model. In these scenarios, we demonstrate why heterogeneity in soil water distribution and rooting properties affect the impediment of water flow even though the mean soil water content and rooting properties are the same across the scenarios. The effects of heterogeneity can clearly be identified in the thermodynamics of the system in terms of differences in dissipative losses and hydraulic energy, resulting in an earlier start of water limitation in the drying cycle. We conclude that this thermodynamic evaluation of root water uptake conveniently provides insights into the impediments of different processes along the entire flow path, which goes beyond resistances and also accounts for the role of heterogeneity in soil water distribution.

Colloid Mobilization and Transport in Undisturbed Soil Columns. II. The Role of Colloid Dispersibility and Preferential Flow

2004 ◽  
Vol 3 (2) ◽  
pp. 424-433 ◽  
Author(s):  
C. Kjaergaard ◽  
P. Moldrup ◽  
L. W. de Jonge ◽  
O. H. Jacobsen
Keyword(s):  
Preferential Flow ◽  
Soil Columns ◽  
Undisturbed Soil ◽  
Colloid Mobilization

Colloid Mobilization and Transport in Undisturbed Soil Columns. II. The Role of Colloid Dispersibility and Preferential Flow

2004 ◽  
Vol 3 (2) ◽  
pp. 424-433 ◽  
Author(s):  
Charlotte Kjaergaard ◽  
Per Moldrup ◽  
Lis W. de Jonge ◽  
Ole H. Jacobsen
Keyword(s):  
Preferential Flow ◽  
Soil Columns ◽  
Undisturbed Soil ◽  
Colloid Mobilization

scholarly journals Role of Manganese Oxyhydroxides in the Transport of Rare Earth Elements Along a Groundwater Flow Path

2019 ◽  
Vol 16 (13) ◽  
pp. 2263 ◽  
Author(s):  
Liu ◽  
Guo ◽  
Pourret ◽  
Chen ◽  
Yuan
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Emerging Contaminants ◽  
Shallow Groundwater ◽  
Flow Path ◽  
Solution Ph ◽  
Study Approach ◽  
The North ◽  
Mn Concentration

Rare earth elements (REE) are known to be emerging contaminants in hydrosphere, but roles of hydrous manganese oxyhydroxides (HMO) in REE transport in groundwater remains unknown. In this study, groundwater was sampled along a flow path in the North China Plain to determine the behavior of REE surface complexation to HMO by a modeling and field study approach. Results show that the proportion of neodymium (Nd) complexed by HMO ranges from 0.2% to 95.8%, and from 0.3% to 99.6% in shallow groundwater and deep groundwater, respectively. The amount of complexed REE increases along the flow path. REE bound to HMO exhibit decreasing trends with increasing atomic number. The process was determined to be independent of pH, HMO content, and metal loading. This finding further demonstrates HMO-REE complexation plays a key role in transport of REE in groundwater through preferential scavenging of light REE (LREE) over heavy REE (HREE). Nevertheless, carbonate ligands appear to be robust competitors in reducing the amount of REE sorbed to HMO when solution pH rises above 8.0. Assuming that 50% of Mn concentration occurs as HMO, the amount of complexed REE was predicted to show a more marked decrease in LREE compared to that of HREE.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

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