Water, Air, & Soil Pollution

, 228:80

Rinsing of Saline Water from Road Salt in a Sandy Soil by Infiltrating Rainfall: Experiments, Simulations, and Implications

  • Makoto Higashino
  • Andrew J. Erickson
  • Francesca L. Toledo-Cossu
  • Scott W. Beauvais
  • Heinz G. Stefan
Article

DOI: 10.1007/s11270-017-3256-1

Cite this article as:
Higashino, M., Erickson, A.J., Toledo-Cossu, F.L. et al. Water Air Soil Pollut (2017) 228: 80. doi:10.1007/s11270-017-3256-1
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Abstract

Saline melt water from road salt applications that has percolated into a fine sandy soil in winter is rinsed out of the soil by infiltrating rainwater in the following warmer seasons. This sequence of saturated and unsaturated flow processes associated with saline water transport in a fine sandy soil was studied by simulation and exploratory laboratory experiments. Experiments in soil columns of 300-μm sand revealed that two rinses of pure water, each of one pore volume, were sufficient to reduce the salt concentration by 99% of its original value in the soil column. Simulated time variations of salt concentration in the effluent from the column agreed with experimental results. Based on simulated and experimental results, a sandy soil must become saturated to experience pore water flow in order to efficiently rinse saline snowmelt water. Depending on the saturated hydraulic conductivity and the soil depth, days, weeks, or months of freshwater infiltration in summer are needed to rinse saline melt water from an unsaturated sandy soil after road salt applications in winter. This explains findings of significant salt concentrations in surface and shallow groundwater during summer months, long after road salt application and infiltration has ceased.

Keywords

Infiltration Percolation Pore water Porous media Rainfall Rinsing Road salt Solute transport Unsaturated soil Rainwater Hydraulic conductivity 

Notation (Units)

C

Concentration of salt (g cm−3)

Cc

Specific moisture capacity (cm−1)

Dm

Molecular diffusion coefficient of salt (cm2 s−1)

ds

Grain diameter (cm)

Dzz

Dispersion coefficient (cm2 s−1)

g

Gravitational acceleration (9.8 m s−2)

Ke

Effective hydraulic conductivity (cm s−1)

Ks

Hydraulic conductivity at saturation (cm s−1)

l

The constant (=0.5)

L

Soil depth (cm)

m

The constant

n

The constant (=2.68)

p

Pressure (N m−2)

Se

Effective water saturation

Ss

Specific storage coefficient (cm−1)

t

Time (hour)

t+

Normalized time

tdry

Time required for effective hydraulic conductivity to reduce to less than 10% of the value at saturation (hours)

ts

Time required to become saturated (hours)

tr

Time required to reduce the total amount of salt in the soil to less than 1% of its initial value from a soil initially at saturation (hours)

ttotal

Time required to remove salt from a soil initially at field capacity (hours)

u

Velocity of pore water flow (cm s−1)

z

Vertical coordinate (cm)

α

The constant (=0.145)

β

The constant (β = 0 for saturated soil and β = 1 for unsaturated soil)

θ

Water content

θr

Residual water content

θs

Water content at saturation

ρ

Fluid (water) density (g cm−3)

Ψ

Pressure head (suction) (cm)

Copyright information

© Springer International Publishing Switzerland 2017

Authors and Affiliations

  • Makoto Higashino
    • 1
  • Andrew J. Erickson
    • 2
  • Francesca L. Toledo-Cossu
    • 3
  • Scott W. Beauvais
    • 4
  • Heinz G. Stefan
    • 2
    • 5
  1. 1.Department of Civil EngineeringOita National College of TechnologyOitaJapan
  2. 2.St. Anthony Falls LaboratoryUniversity of MinnesotaMinneapolisUSA
  3. 3.Department of GeologyUniversity of Puerto RicoMayaguezPuerto Rico
  4. 4.Department of HydrologySalish Kootenai CollegePolsonUSA
  5. 5.Department of Civil, Environmental and Geo- EngineeringUniversity of MinnesotaMinneapolisUSA

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