High export of nitrogen and dissolved organic carbon from an Alpine glacier (Indren Glacier, NW Italian Alps)

Abstract

Mountain glaciers can export large amounts of nitrogen (N) and carbon (C) to downstream aquatic ecosystems. To date, however, the number of studies that analysed concentrations and fluxes of N forms and dissolved organic carbon (DOC) from glaciers in the European Alps and worldwide is limited, given the high complexity of data gathering in harsh highelevation environments. In this work, we rely upon new, unexploited data from field campaigns pursued during 2012-2015 at high elevations (> 3000 m a.s.l.) of the Indren Glacier (NW Italian Alps) to i) develop glacio-hydrological modelling and stream flow estimates within a heavily glacier-fed catchment, ii) provide N forms and DOC concentrations and estimated fluxes in meltwater, and iii) provide possible explanations of cryospheric control upon water chemistry. Water and soil samples were also collected at two lower-elevation sites along the glacial stream to investigate the downstream variability of N forms and DOC. Nitrate-N, dissolved organic nitrogen (DON), and DOC concentrations (0.21 ± 0.12, 0.19 ± 0.14, 1.16 ± 0.63 mg L −1 , respectively) and yields (220, 210, 1,279 kg km −2 yr −1 , respectively) were among the highest considering other glaciated areas of the globe, probably due to high atmospheric N and C depositions. Limited effect of soil on water characteristics was found and attributed to the reduced soil development in recently deglaciated areas (after the Little Ice Age), thus underlining the role of glacier melting in determining N and C dynamics in high-elevation, Alpine surface waters.

Microbial Communities in Vermiculation Deposits from an Alpine Cave

“…(Filippa et al, 2010). Colombo et al (2019) studied the nitrogen forms in meltwater samples collected in the period 2012-2015 from the Indren Glacier (ca. 4,000 m a.s.l., Mt.…”

Key rules of life and the fading cryosphere: Impacts in alpine lakes and streams

“…Changes in nutrient regimes due to cryosphere loss are expected to affect ecological dynamics in alpine aquatic ecosystems. For example, increases in N:P ratios due to disproportionate runoff of inorganic N from melting glaciers (Colombo et al, 2019; Saros et al., 2010; Slemmons & Saros, 2012; Figure 3, left) will likely induce P limitation and negatively affect fast‐growing, P‐rich organisms (Figure 3, right). The effects of nutrient limitation may be particularly severe given the short growing season of alpine environments, which impose strong selection pressures for rapid growth and development.…”

Patterns and Drivers of Extracellular Enzyme Activity in New Zealand Glacier-Fed Streams

“…In addition to sediments and water, GFSs also deliver DOC (e.g., Hood et al, 2009Hood et al, , 2015Singer et al, 2012), nitrogen (N) (Hodson et al, 2005;Wadham et al, 2016;Colombo et al, 2019), and phosphorus (P) (Hodson et al, 2004;Föllmi et al, 2009;Hawkings et al, 2016) to downstream ecosystems-all of them typically at low concentrations. However, concentrations of P generally increase with greater glacier influence in comparison to N, probably due to elevated rates of rock comminution beneath the glacier and dust deposition on glacier surfaces (Elser et al, 2020).…”