Nitrate content and potential microbial signature of rock glacier outflow, Colorado Front Range

Williams, Mark W.; Knauf, M.; Cory, Rose M.; Caine, Nel; Liu, F.

doi:10.1002/esp.1455

Cited by 76 publications

(94 citation statements)

References 55 publications

(88 reference statements)

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“…and NO 3 -values are more similar to snowpack concentrations prior to contact with the ground than snow melt Williams et al 2007). While these observations are in line with the hypotheses of Saros et al (2010), the rapid transformation of NH 4…”

Section: Influence Of Periglacial Features On Surface Water Chemistrysupporting

confidence: 81%

Thawing glacial and permafrost features contribute to nitrogen export from Green Lakes Valley, Colorado Front Range, USA

et al. 2013

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Alpine ecosystems are particularly susceptible to disturbance due to their short growing seasons, sparse vegetation and thin soils. Increased nitrogen deposition in wetfall and changes in climate currently affect Green Lakes Valley within the Colorado Front Range. Research conducted within the alpine links chronic nitrogen inputs to a suite of ecological impacts, resulting in increased nitrate export. The atmospheric nitrogen flux decreased by 0.56 kg ha -1 year -1 between 2000 and 2009, due to decreased precipitation; however alpine nitrate yields increased by 40 % relative to the previous decade (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999). Long term trends indicate that weathering products such as sulfate, calcium, and silica have also increased over the same period. The geochemical composition of thawing permafrost, as indicated by rock glacial and blockfield meltwater, suggests it is the source of these weathering products. Furthermore, mass balance models indicate the high ammonium loads within glacial meltwater are rapidly nitrified, contributing *0.5-1.4 kg N ha -1 to the growing season nitrate flux from the alpine watershed. The sustained export of these solutes during dry, summer months is likely facilitated by thawing cryosphere providing hydraulic connectivity late into the growing season. This mechanism is further supported by the lack of upward weathering or nitrogen solute trends in a neighboring catchment which lacks permafrost and glacial features. These findings suggest that reductions of atmospheric nitrogen deposition alone may not improve water quality, as cryospheric thaw exposes soils to biological and geochemical processes that may affect alpine nitrate concentrations as much as atmospheric deposition trends.

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Section: Influence Of Periglacial Features On Surface Water Chemistrysupporting

confidence: 81%

Thawing glacial and permafrost features contribute to nitrogen export from Green Lakes Valley, Colorado Front Range, USA

et al. 2013

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“…Despite the high microbial activity observed in barren alpine soils, these environments and the microbial communities in them are also severely carbon-limited (Williams et al, , 2007Brooks and Williams, 1999;King et al, 2008). It is currently unclear how microbial communities in oligotrophic soils obtain the carbon (C) and energy necessary to sustain life.…”

Section: N Mladenov Et Al: Atmospheric Deposition As a Source Of Camentioning

confidence: 99%

Atmospheric deposition as a source of carbon and nutrients to an alpine catchment of the Colorado Rocky Mountains

et al. 2012

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Abstract. Many alpine areas are experiencing deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, atmospheric deposition sources may be an important source of C and nutrients for these environments. We evaluated the magnitude of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long-term dataset (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were 1.12 ± 0.19 mg l −1 , and weekly concentrations reached peaks as high at 6-10 mg l −1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. To investigate potential sources of C in atmospheric deposition, we evaluated the chemical quality of dissolved organic matter (DOM) and relationships between DOM and other solutes in wet deposition. Relationships between DOC concentration, fluorescence, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring, which may reflect an association of DOM with dust. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples. Our C budget estimates for the Green Lake 4 catchment illustrated that wet deposition (9.9 kg C ha −1 yr −1 ) and dry deposition (6.9 kg C ha −1 yr −1 ) were a combined input of approximately 17 kg C ha −1 yr −1 , which could be as high as 24 kg C ha −1 yr −1 in high dust years. This atmospheric C input approached the C input from microbial autotrophic production in barren soils. Atmospheric wet and dry deposition also contributed 4.3 kg N ha −1 yr −1 , 0.15 kg P ha −1 yr −1 , and 2.7 kg Ca 2+ ha −1 yr −1 to this alpine catchment.

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“…In the Canadian Rockies, melting alpine glaciers release concentrated organic pesticides into lake ecosystems and contribute 50-97% of the organochlorine inputs to these systems, resulting in higher concentrations relative to nonglacial lakes (12). In the southern Rocky Mountains of North America, an area with relatively high atmospheric reactive N (Nr) deposition (4-8 kg N ha -1 yr -1 ), meltwaters from ice and rock glaciers have elevated nitrate concentrations (13). Lake-water NO 3 -concentrations are also high in this area, but because of relatively high Nr deposition (7,14), the extent to which meltwater from ice and rock glaciers contribute Nr remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Melting Alpine Glaciers Enrich High-Elevation Lakes with Reactive Nitrogen

Saros

Rose

Clow

et al. 2010

Environ. Sci. Technol.

113

107

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See next page for additional authorsFollow this and additional works at: https://digitalcommons.unl.edu/geosciencefacpub Part of the Earth Sciences CommonsThis Article is brought to you for free and open access by the Earth and Atmospheric Sciences, Department of at DigitalCommons@University of Nebraska -Lincoln. It has been accepted for inclusion in Papers in the Earth and Atmospheric Sciences by an authorized administrator of DigitalCommons@University of Nebraska -Lincoln. Alpine glaciers have receded substantially over the last century in many regions of the world. Resulting changes in glacial runoff not only affect the hydrological cycle, but can also alter the physical (i.e., turbidity from glacial flour) and biogeochemical properties of downstream ecosystems. Here we compare nutrient concentrations, transparency gradients, algal biomass, and fossil diatom species richness in two sets of high-elevation lakes: those fed by snowpack melt alone (SF lakes) and those fed by both glacial and snowpack meltwaters (GSF lakes). We found that nitrate (NO 3 -) concentrations in the GSF lakes were 1-2 orders of magnitude higher than in SF lakes. Although nitrogen (N) limitation is common in alpine lakes, algal biomass was lower in highly N-enriched GSF lakes than in the N-poor SF lakes. Contrary to expectations, GSF lakes were more transparent than SF lakes to ultraviolet and equally transparent to photosynthetically active radiation. Sediment diatom assemblages had lower taxonomic richness in the GSF lakes, a feature that has persisted over the last century. Our results demonstrate that the presence of glaciers on alpine watersheds more strongly influences NO 3 -concentrations in high-elevation lake ecosystems than any other geomorphic or biogeographic characteristic. Melting Alpine Glaciers Enrich High-Elevation Lakes with Reactive Nitrogen

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Nitrate content and potential microbial signature of rock glacier outflow, Colorado Front Range

Cited by 76 publications

References 55 publications

Thawing glacial and permafrost features contribute to nitrogen export from Green Lakes Valley, Colorado Front Range, USA

Thawing glacial and permafrost features contribute to nitrogen export from Green Lakes Valley, Colorado Front Range, USA

Atmospheric deposition as a source of carbon and nutrients to an alpine catchment of the Colorado Rocky Mountains

Melting Alpine Glaciers Enrich High-Elevation Lakes with Reactive Nitrogen

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