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

Abstract

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.

ANaganishiain high places: functioning populations or dormant cells from the atmosphere?

“…Many of the substrates used for growth by this organism are plant-derived compounds (e.g. cellobiose, arbutin, salicin) indicating that it can take advantage of Aeolian transported plant material that is likely the main source of organic matter to extreme high-elevation ecosystems (Ley et al 2004; Mladenov et al 2012; Vimercati et al 2016). Our working hypothesis is that N. friedmannii on Llullaillaco and other volcanoes are dormant during long periods of dryness and only come out of dormancy and opportunistically metabolise Aeolian organic debris following the melting of rare snow events.…”

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

“…Atmospheric deposition of N on the river wetted surface (2637 km 2 between Wolfe Island and Québec) was estimated from a mean ± SD value of 5.8 ± 1.8 kg N ha -1 year -1 for southern Québec (Ouimet and Duchesne 2009). In the absence of recent regional estimates, atmospheric deposits of C (7 kg C ha -1 year -1 ) and P (0.15 kg P ha -1 year -1 ) from the Colorado Rocky Mountains were used (Mladenov et al 2012). …”

“…Shoreline and riverbed erosion and atmospheric deposition (Ouimet and Duchesne 2009;Mladenov et al 2012) were obtained from literature data. Erosion of the bed and banks of the St. Lawrence River was previously estimated in the order of 65% of the suspended sediments measured at Québec .…”

Characteristics of wet carbon deposition in a semi-arid catchment at Loess Plateau, China

“…Furthermore, it has been demonstrated that emissions of incomplete fossil fuel combustion were a key source of DOC in precipitation, such as in 55 northern and Tibetan of China (Li et al, 2016;Pan et al, 2010) , USA (Mladenov et al, 2012;Raymond, 2005), Europe (Siudek et al, 2015) and New Zealand (Willey et al, 2000). For instance, contribution of fossil fuel combustion in DOC was around 22-28% in North America, European, and Tibetan of China.…”

“…Consequently, it is worth noting that atmospheric dust scavenged by precipitation may be another source of organic carbon, which might differ from other regions. Moreover, Mladenov et al (2012) In this study, data were collected from monitoring stations of rainfall quality in atmospheric wet deposition at a catchment of LPR. The primary goal of this study is to evaluate the magnitude of DOC and DIC flux from atmosphere so as to understand atmospheric wet deposition process during concentrated rainfall season in LPR.…”