Variability of Meltwater and Solute Fluxes From Homogeneous Melting Snow at the Laboratory Scale

Harrington, Robert F.; Bales, R. C.; Wagnon, Patrick

doi:10.1002/(sici)1099-1085(199607)10:7<945::aid-hyp349>3.0.co;2-s

Cited by 25 publications

(16 citation statements)

References 14 publications

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“…Seasonal snow cover also plays a unique role in high‐elevation catchment hydrochemistry, as snowpacks accrue chemicals through wet and dry deposition over the snow accumulation season and then rapidly release them during melt [ Pomeroy et al , 2005] via the snowmelt ion pulse [ Bales et al , 1989; Cragin et al , 1996; Harrington et al , 1996]. Studies on the chemical content of snow cover have sought to locate pollution sources [ Pichlmayer et al , 1998; Mast et al , 2001], explored spatial and vertical variability of snow chemistry [e.g., Tranter et al , 1987; Kuhn et al , 1998; Rohrbough et al , 2003], and examined the relative influences of vegetation on snow chemistry [ Hudson and Golding , 1998; Pomeroy et al , 1999; Stottlemyer and Troendle , 2001] with solute concentrations often higher under canopies than in open areas.…”

Section: Introductionmentioning

confidence: 99%

Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

Gustafson

Brooks

Molotch

et al. 2010

Water Resources Research

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[1] Changes in both climate and vegetation may dramatically impact the amount of water stored in seasonal snow cover and the timing of spring snowmelt. This study quantifies how spatial variability in solar radiation affects the spatial and temporal patterns in snow water equivalent (SWE), snow chemistry, and snow water isotopes in the Jemez Mountains, New Mexico. Depth, density, stratigraphy, temperature, and snow samples were collected approximately monthly from five locations between January and April 2007 to quantify the effects of solar forcing on snowpack water and chemical balance. Locations varied in solar forcing due to topography and vegetation, while minimizing variability in precipitation, elevation, aspect, interception, and wind redistribution. Snowfall (340 ± 5 mm) was similar across all sites, but peak SWE at maximum accumulation ranged from 187 to 340 mm. Solute concentrations were highest directly under canopies, intermediate in nonshaded forest openings, and lowest in shaded forest openings. Conservative solute concentrations (SO 4 2− , R 2 = 0.80), Cl − (R 2 = 0.60), and isotope values (d 18 O R 2 = 0.96) were inversely related to SWE at maximum accumulation. Mass balance estimates of snowpack water balance using solute concentrations and isotopes indicated that sublimation ranged from <2% to ∼20% of winter precipitation, consistent with previous studies at the site. The strong relationships between solar forcing, SWE, and chemistry suggest that snow chemistry at maximum accumulation can be used to estimate overwinter sublimation. Furthermore, variability in solar forcing also can be used to refine spatial estimates of catchment solute and isotope input at melt.

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Section: Introductionmentioning

confidence: 99%

Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

Gustafson

Brooks

Molotch

et al. 2010

Water Resources Research

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“…Paper number 98WR00557. 0043-1397/98/98WR-00557509.00 ions in the snowpack profile [Colbeck, 1981;Bales et al, 1989], heterogeneous flow paths [Jones, 1985;Bales, 1990;Marsh and Pomeroy, 1993;Harrington et al, 1996], metamorphic history [Davis, 1991;Hewitt et al, 1991], snowpack energy fluxes [Suzuki, 1991;Williams et al, 1996], and scale effects on sampling [Marsh and Pomeroy, 1993].…”

Section: Introductionmentioning

confidence: 99%

Modeling ionic solute transport in melting snow

Harrington¹,

Bales²

1998

Water Resources Research

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Abstract.A numerical model that includes the effects of mass transfer between mobile and immobile liquid phases, advection, hydrodynamic dispersion, and melt-freeze episodes was developed to simulate ionic solute transport in melting snow. Model calibration using a tracer-infused laboratory snowpack experiment yielded a dispersivity of 0.05 cm and a mobile-immobile phase mass-transfer coefficient of 4 x 10 -6 S -1, but these parameter values are tentative because of the artificial nature of the experiment. The modeled concentration of meltwater flowing out the bottom of the snowpack was sensitive to residual water saturation, flow rate, dispersivity, mass-transfer rate, and the initial distribution of solute within the pack, similar to experimental observations. The model was applied to a small watershed, and it was found that the ability of the model to accurately simulate solute movement depends on the validity of the assumption of one-dimensional flow and on the accuracy of modeling the snowpack energy balance. IntroductionThe release of the chemical impurities from melting snow introduces chemicals stored in the snowpack into streams, lakes, and subsurface water. The release of a disproportionately large fraction of the ionic solute into the earliest fraction of meltwater, termed the "ionic pulse," occurs because ionic solute is segregated to the exterior of the snow grains during snow formation in the atmosphere and during snowpack metamorphism, and the solute later mixes with earliest meltwater to percolate through the snowpack.

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“…Ice grain growth and grain boundary migration caused segregation of the radionuclides during the recrystallisation process. High concentrations were present at the grain surfaces and in the spaces between them and were therefore easily leachable with the next meltwater wave (Bales et al, ; Berg, ; Cragin et al, ; Harrington, Bales, & Wagnon, ; Hewitt et al, ). Residual percolating meltwater during the freeze cycles contained high portions of Cs‐134 and Sr‐85 because the low transport velocities provided enough time for a strong concentration of the nuclides in the remaining water.…”

Section: Resultsmentioning

confidence: 99%

Influence of melt-freeze-cycles on the radionuclide transport in homogeneous laboratory snowpack

2017

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Radionuclides released to the environment and deposited with or onto snow can be stored over long time periods if ambient temperature stays low, particularly in glaciated areas or high alpine sites. The radionuclides will be accumulated in the snowpack during the winter unless meltwater runoff at the snow base occurs. They will be released to surface waters within short time during snowmelt in spring. In two experiments under controlled melting conditions of snow in the laboratory, radionuclide migration and runoff during melt‐freeze‐cycles were examined. The distribution of Cs‐134 and Sr‐85 tracers in homogeneous snow columns and their fractionation and potential preferential elution in the first meltwater portions were determined. Transport was associated with the percolation of meltwater at ambient temperatures above 0 °C after the snowpack became ripe. Mean migration velocities in the pack were examined for both nuclides to about 0.5 cm hr−1 after one diurnal melt‐freeze‐cycle at ambient temperatures of −2 to 4 °C. Meltwater fluxes were calculated with a median of 1.68 cm hr−1. Highly contaminated portions of meltwater with concentration factors between 5 and 10 against initial bulk concentrations in the snowpack were released as ionic pulse with the first meltwater. Neither for caesium nor strontium preferential elution was observed. After recurrent simulated day‐night‐cycles (−2 to 4 °C), 80% of both radionuclides was released with the first 20% of snowmelt within 4 days. 50% of Cs‐134 and Sr‐85 were already set free after 24 hr. Snowmelt contained highest specific activities when the melt rate was lowest during the freeze‐cycles due to concentration processes in remaining liquids, enhanced by the melt‐freeze‐cycling. This implies for natural snowpack after significant radionuclide releases, that long‐time accumulation of radionuclides in the snow during frost periods, followed by an onset of steady meltwater runoff at low melt rates, will cause the most pronounced removal of the contaminants from the snow cover. This scenario represents the worst case of impact on water quality and radiation exposure in aquatic environments.

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Variability of Meltwater and Solute Fluxes From Homogeneous Melting Snow at the Laboratory Scale

Cited by 25 publications

References 14 publications

Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

Estimating snow sublimation using natural chemical and isotopic tracers across a gradient of solar radiation

Modeling ionic solute transport in melting snow

Influence of melt-freeze-cycles on the radionuclide transport in homogeneous laboratory snowpack

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