Greenhouse gas dynamics in lakes receiving atmospheric nitrogen deposition

Michelle L. McCrackin, James Elser

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Abstract

Anthropogenic nitrogen (N) inputs have been found to influence emissions of greenhouse gases from a variety of ecosystems; however, the effects of N loading on greenhouse gas dynamics in lakes are not well documented. We measured concentrations of carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2O) in 26 lakes in the Colorado Rocky Mountains (USA) receiving elevated (5-8 kg N ha -1 yr -1) or low (<2 kg N ha -1 y -1) levels of atmospheric N deposition. The mean CO 2 concentration in surface waters was 27 mol L -1 and did not differ between deposition regions. The CH 4 concentration was greater in low-deposition lakes (167 nmol L -1) compared to high-deposition lakes (48 nmol L -1), while the opposite was true for N 2O. The concentration of N 2O in surface water averaged 29 nmol L -1 in high-deposition lakes compared to 22 nmol L -1 in low-deposition lakes. Nitrous oxide is of particular interest because it is more potent than CO 2 as a greenhouse gas and because of its role in the destruction of stratospheric ozone. To understand the potential magnitude of lake N 2O production related to atmospheric N deposition, we applied two published methodologies for determining emissions from aquatic ecosystems to available data sets. We estimated contemporary global N 2O emissions from lakes to be 0.04-2 Tg N y -1, increasing to 0.1-3.4 Tg N y -1 in 2050. The contemporary estimates represent 13-95% of emissions from rivers and estuaries, suggesting that further research is required to better quantify emission rates from lentic ecosystems.

Original languageEnglish (US)
Article numberGB4005
JournalGlobal Biogeochemical Cycles
Volume25
Issue number4
DOIs
StatePublished - Nov 1 2011

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ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Environmental Science(all)
  • Atmospheric Science

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