Hydrochemical Processes in Snow‐Covered Basins

Abstract

This article reviews several aspects of snow hydrochemistry: the chemistry of snowfall including chemical incorporation in snowfall and snowfall chemistry variability, the chemistry of cold, dry snowcovers including snow redistribution, snow–atmosphere chemical exchange and in‐pack chemical transformations, the chemistry of wet and melting snowcovers including solute leaching, particulate interactions and microbial activity, and snow‐covered basin hydrochemistry with an emphasis on nutrient chemistry. The emphasis is on the processes of chemical transformation in seasonal snowpacks and meltwaters with strong attention to the broad ecosystem view of snow chemistry rather than solely focusing on acidification effects from snowmelt. The seasonal snowcover is shown to be a dynamic hydrochemical system with strong ecological interactions. Besides wet deposition by snowfall and rain, the processes of wind redistribution, dry deposition, volatilization, crystal metamorphism, photolysis, microbial uptake and release, solute elution, and meltwater movement strongly affect the chemistry of both the snowpack and meltwaters. Snowmelt chemistry alone is rarely directly responsible for major chemical fluctuations in water bodies, but meltwater has an important role in transporting ions from soils and organic material to water bodies.

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

“…[36] The consistency of this observation with the water isotopes continues to suggest that energy inputs and sublimation are principal drivers influencing SWE. There are, however, several other processes which can influence chemistry in mountain snowpacks including wet and dry deposition, wind redistribution, volatilization, melt, vegetation/leaf litter, and biologically mediated oxidation [Pomeroy et al, 2005]. The chemistry in new snowfall has limited spatial variability (Table 5) and no distinct repetitive pattern across storms, which agrees with other studies [Williams and Melack, 1991].…”

“…Nitrate and TDN are not elevated in vegetation and show no association with SWE and/or SFI. Variability in nitrate is complex as this species has been shown to volatilize in positive net all‐wave radiation environments [ Pomeroy et al , 1999], is prone to photochemical/biological reactions [ Pomeroy et al , 2005], and may be influenced by canopy/leaf litter interaction and in snow reactions.…”

“…The annual snowpack of the western United States is also a significant factor in the structure and function of high‐elevation ecosystems. Snowmelt controls soil moisture [ Molotch et al , 2009] which impacts biogeochemical fluxes, the establishment and survival of vegetation, and water availability for the vegetation growing season [ Fagre et al , 2000], and atmospheric deposition stored in the seasonal snow cover often dominates the bulk chemical input to seasonally snow covered catchments [ Pomeroy et al , 2005; Williams and Melack , 1991]. Consequently, our ability to quantify the spatial distribution of snow water equivalent (SWE) and snowpack chemical loading in high‐elevation, seasonally snow‐covered basins is of utmost importance, both from the water resources perspective and for evaluation of the hydrologic and hydrochemical response of high‐elevation catchments [ Kattelmann and Elder , 1991].…”

“…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.…”

Snow and frost: implications for spatiotemporal infiltration patterns – a review

“…Many studies show that large fractions of snowfall (30–60%) might be lost by sublimation of the snow intercepted in the canopies and that losses can be related to canopy density (e.g. Kuzmin, ; Hedstrom and Pomeroy, ; Pomeroy et al ., ; Lundberg and Koivusalo, ; Lundberg et al ., ; Winkler et al ., ; ; López‐Moreno and Latron, ; López‐Moreno and Stähli, ). Analysis of processes and governing factors for canopy snow sublimation can be found in, e.g.…”