Anthropogenic aerosols as a source of ancient dissolved organic matter in glaciers

Nature Geoscience
By: , and 

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Abstract

Glacier-derived dissolved organic matter represents a quantitatively significant source of ancient, yet highly bioavailable carbon to downstream ecosystems. This finding runs counter to logical perceptions of age–reactivity relationships, in which the least reactive material withstands degradation the longest and is therefore the oldest. The remnants of ancient peatlands and forests overrun by glaciers have been invoked as the source of this organic matter. Here, we examine the radiocarbon age and chemical composition of dissolved organic matter in snow, glacier surface water, ice and glacier outflow samples from Alaska to determine the origin of the organic matter. Low levels of compounds derived from vascular plants indicate that the organic matter does not originate from forests or peatlands. Instead, we show that the organic matter on the surface of the glaciers is radiocarbon depleted, consistent with an anthropogenic aerosol source. Fluorescence spectrophotometry measurements reveal the presence of protein-like compounds of microbial or aerosol origin. In addition, ultrahigh-resolution mass spectrometry measurements document the presence of combustion products found in anthropogenic aerosols. Based on the presence of these compounds, we suggest that aerosols derived from fossil fuel burning are a source of pre-aged organic matter to glacier surfaces. Furthermore, we show that the molecular signature of the organic matter is conserved in snow, glacier water and outflow, suggesting that the anthropogenic carbon is exported relatively unchanged in glacier outflows.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Anthropogenic aerosols as a source of ancient dissolved organic matter in glaciers
Series title Nature Geoscience
DOI 10.1038/ngeo1403
Volume 5
Year Published 2012
Language English
Publisher Nature Pub. Group
Publisher location New York, NY
Contributing office(s) National Research Program - Central Branch
Description 4 p.
First page 198
Last page 201