Location: Soil and Water Management ResearchTitle: CO2 and N2O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica Author
|La Scala, N|
Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2015
Publication Date: 4/28/2015
Publication URL: http://handle.nal.usda.gov/10113/60950
Citation: Thomazini, A., De Sa Mendonca, E., De Bortoli Teixeixa, D., Carreiro Almeida, C., La Scala, N., Spokas, K.A., Pasqualoto Canellas, L., Millori, D. 2015. CO2 and N2O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica. Science of the Total Environment. 521-522:336-345. Interpretive Summary: An improved understanding of the cycling of carbon is needed to accurately model and predict the loss of carbon in various soils-climate combinations. Some of the most informative systems to examine this process are in new soils, where we get an opportunity to isolate various factors that are not possible to do with more mature soils. In this study we examined the cycling of carbon and the production of greenhouse gases in soils from Antarctica that represents a sequence of time after a glacier retreat. From this work, we observed that the rate of carbon cycling is impacted greatly by vegetation. Vegetation quadrupled the rate of soil carbon mineralization even without the presence of growing plants. This indicates that there is an alteration in the soil microbial community as a result of the vegetation growth and has implications on the use of a bare soil control in above ground carbon respiration studies. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved models for net carbon exchange based on mechanistic processes, which can be used to improve soil carbon management.
Technical Abstract: Polar regions represents a large carbon (C) sequestration reservoir in the world. Studies of alterations in C cycle are extremely important to identify changes due to climate change, especially among polar environments. The objectives of this study were to examine (i) patterns of soil CO2-C emission and (ii) quantity and quality of soil organic matter across a glacier retreat chronosequence in the Antarctic Peninsula. Field measurements were carried out during January and February 2010, across vertical retreat zone of White Eagle Glacier, King George Island, Antarctic. Soil samples were collected along a 500-m-long transect to a 20 cm depth, totalizing 28 samples, for soil organic matter characterization and carbon mineralization dynamics. Field CO2-C emission measurements and soil temperature were carried out at regular intervals of 25 m, totalizing 21 sites sampled. At each site, soil CO2-C emission and soil temperature were taken with and without vegetation, when possible. CO2 and N2O production potentials were assessed through 100 days laboratory incubations at a 22oC. Soils exposed for longer time showed elevated values of salts and a sandy texture. Lower total organic C (3.59 g/kg), total N (2.31 g/kg) and labile C (1.83 g/kg) were recorded near the glacier than in sites away from the glacier. Lower values of humified organic matter were recorded away from the glacier. Soil CO2-C emission and soil temperature increased with distance from the glacier. The presence of vegetation on average increased CO2-C emission by 440%, or the equivalent of 0.633 g of CO2-C m-2 h-1. Newly exposed soils are more temperature sensitive than soils exposed for longer time. Distance from the glacier corresponds to advanced soil development, high soil organic C and N contents and vegetation establishment. Soils covered by vegetation are related to high amounts of organic C and N and less humified organic matter. Our results suggests that as soil sites become free of ice, soil development increases with labile C input from vegetation and a corresponding increase in soil CO2-C emission. Despite the importance of exposure time on CO2 production and emissions, there was no significant trend in soil N2O production potentials as a function of overall glacial recession, with the maximum production rates occurring in the locations immediately before vegetation appearance.