The optical characteristics and sources of chromophoric dissolved organic matter (CDOM) in seasonal snow of northwestern China
<p>Chromophoric dissolved organic matter (CDOM) plays an important role in the global carbon cycle and energy budget but is rarely studied in seasonal snow. A field campaign was conducted across northwestern China from January to February 2012, and surface snow samples were collected at 39 sit...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-01-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/13/157/2019/tc-13-157-2019.pdf |
| Summary: | <p>Chromophoric dissolved organic matter (CDOM) plays an important
role in the global carbon cycle and energy budget but is rarely studied in
seasonal snow. A field campaign was conducted across northwestern China from
January to February 2012, and surface snow samples were collected at 39 sites
in Xinjiang and Qinghai provinces. Absorption and fluorescence
spectroscopies,
along with chemical analysis, were used to investigate the optical
characteristics and potential sources of CDOM in seasonal snow. The abundance of CDOM, shown as the absorption coefficient at 280 nm,
<span class="inline-formula"><i>a</i><sub>CDOM</sub>(280)</span>, and the spectral slope from 275 to 295 nm
(<span class="inline-formula"><i>S</i><sub>275−295</sub>)</span> ranged from 0.15 to 10.57 m<span class="inline-formula"><sup>−1</sup></span> and
0.0129 to 0.0389 nm<span class="inline-formula"><sup>−1</sup></span>. The highest average
<span class="inline-formula"><i>a</i><sub>CDOM</sub>(280)</span> (<span class="inline-formula">2.30±0.52</span> m<span class="inline-formula"><sup>−1</sup>)</span> was found in
Qinghai, and the lowest average <span class="inline-formula"><i>S</i><sub>275−295</sub></span> (<span class="inline-formula">0.0188±0.0015</span> nm<span class="inline-formula"><sup>−1</sup>)</span> indicated that the snow CDOM in this region had a strongly
terrestrial characteristic. The lower values of <span class="inline-formula"><i>a</i><sub>CDOM</sub>(280)</span> were found at sites located to the north of the Tianshan Mountains and
northwestern Xinjiang along the border of China (<span class="inline-formula">0.93±0.68</span> m<span class="inline-formula"><sup>−1</sup></span> and
<span class="inline-formula">0.80±0.62</span> m<span class="inline-formula"><sup>−1</sup></span>). Parallel factor (PARAFAC) analysis
identified three types of fluorophores that were attributed to two humic-like
substances (HULIS, C1 and C2) and one protein-like material (C3). C1 was
mainly from soil HULIS, C3 was a type of autochthonously labile organic
matter, while the potential sources of C2 were complex, including soil,
microbial activity, anthropogenic pollution, and biomass burning.
Furthermore, the regional variations of sources for snow CDOM were assessed
by analyses of chemical species (e.g., soluble ions), fluorescent components,
and air mass backward trajectories combined with satellite-derived active-fire
locations.</p> |
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| ISSN: | 1994-0416 1994-0424 |