Carbon and nitrogen trends in soil chronosequences of the Transantarctic Mountains

Determination of carbon and nitrogen levels in soils of ice-free areas of the Transantarctic Mountains, along with their origin, may determine whether these soils serve as a source or sink of carbon with an increasingly warmer climate. Organic and inorganic forms of carbon and nitrogen were measured in five soil chronosequences in the Transantarctic Mountains using flash combustion and spectrometry. Accumulation of coal carbon was significant in the Beardmore Glacier area and was quantified using chemi-thermal oxidation followed by flash combustion. Carbon levels decreased with drift age for two of the sequences. Decreases in carbon in the Hatherton Glacier sequence were due primarily to high levels of carbon in young ice-cored drifts. Carbon content increased with drift age for the Beardmore Glacier sequence due to the presence of coal in older drifts. Nitrogen content increased with age for a majority of the soil chronosequences. Inorganic carbon and all forms of nitrogen were significantly and positively correlated with mean annual precipitation. Our results suggest that carbon levels in similar settings do not significantly change over time; changes in temperature or moisture associated with microclimate likely play a much larger role in carbon and nitrogen levels.

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► Carbon levels were similar in soils across a wide age range.
► Coal comprised a large portion of the carbon in Beardmore Glacier soils.
► Nitrogen levels increased with soil age.
► Climate is more important than time for carbon contents of Antarctic soils.