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δ(13)C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic.

Yu J, Xie Z, Sun L, Kang H, He P, Xing G - Sci Rep (2015)

Bottom Line: There were complex mixing sources outside and inside the Arctic Ocean.A keeling plot showed the dominant influence by hydrate gas in the Nordic Sea region, while the long range transport of wetland emissions were one of potentially important sources in the central Arctic Ocean.Experiments comparing sunlight and darkness indicate that microbes may also play an important role in regional variations.

View Article: PubMed Central - PubMed

Affiliation: Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, 230026.

ABSTRACT
The biogeochemical cycles of CH4 over oceans are poorly understood, especially over the Arctic Ocean. Here we report atmospheric CH4 levels together with δ(13)C-CH4 from offshore China (31°N) to the central Arctic Ocean (up to 87°N) from July to September 2012. CH4 concentrations and δ(13)C-CH4 displayed temporal and spatial variation ranging from 1.65 to 2.63 ppm, and from -50.34% to -44.94% (mean value: -48.55 ± 0.84%), respectively. Changes in CH4 with latitude were linked to the decreasing input of enriched δ(13)C and chemical oxidation by both OH and Cl radicals as indicated by variation of δ(13)C. There were complex mixing sources outside and inside the Arctic Ocean. A keeling plot showed the dominant influence by hydrate gas in the Nordic Sea region, while the long range transport of wetland emissions were one of potentially important sources in the central Arctic Ocean. Experiments comparing sunlight and darkness indicate that microbes may also play an important role in regional variations.

No MeSH data available.


(a) Box plots of atmospheric CH4 and (b) δ13C-CH4 between July (marked by red colour) and September (marked by black colour) over the OC, JS, NPO, BS, and CS regions (i.e., OC7 and OC9, JS7 and JS9, NPO7 and NPO9, BS7 and BS9, and CS7 and CS9, respectively). The lower and upper boundaries of the boxes represent the 25th and 75th percentiles, respectively. The lines and squares within or outside of the boxes mark the median and mean values, respectively. The upper and lower asterisks signify the maximum and minimum values.
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f3: (a) Box plots of atmospheric CH4 and (b) δ13C-CH4 between July (marked by red colour) and September (marked by black colour) over the OC, JS, NPO, BS, and CS regions (i.e., OC7 and OC9, JS7 and JS9, NPO7 and NPO9, BS7 and BS9, and CS7 and CS9, respectively). The lower and upper boundaries of the boxes represent the 25th and 75th percentiles, respectively. The lines and squares within or outside of the boxes mark the median and mean values, respectively. The upper and lower asterisks signify the maximum and minimum values.

Mentions: The CH4 concentrations in July and September for the same sampling regions are shown in Fig. 3a. Non-parametric tests indicated that the values in July and September were not significantly different. Figure 3b also shows no significant differences between the measurements of δ13C-CH4 in July and September in the OC, JS, and BS areas. However, the δ13C-CH4 values in NPO and CS regions were greater in July than in September.


δ(13)C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic.

Yu J, Xie Z, Sun L, Kang H, He P, Xing G - Sci Rep (2015)

(a) Box plots of atmospheric CH4 and (b) δ13C-CH4 between July (marked by red colour) and September (marked by black colour) over the OC, JS, NPO, BS, and CS regions (i.e., OC7 and OC9, JS7 and JS9, NPO7 and NPO9, BS7 and BS9, and CS7 and CS9, respectively). The lower and upper boundaries of the boxes represent the 25th and 75th percentiles, respectively. The lines and squares within or outside of the boxes mark the median and mean values, respectively. The upper and lower asterisks signify the maximum and minimum values.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555175&req=5

f3: (a) Box plots of atmospheric CH4 and (b) δ13C-CH4 between July (marked by red colour) and September (marked by black colour) over the OC, JS, NPO, BS, and CS regions (i.e., OC7 and OC9, JS7 and JS9, NPO7 and NPO9, BS7 and BS9, and CS7 and CS9, respectively). The lower and upper boundaries of the boxes represent the 25th and 75th percentiles, respectively. The lines and squares within or outside of the boxes mark the median and mean values, respectively. The upper and lower asterisks signify the maximum and minimum values.
Mentions: The CH4 concentrations in July and September for the same sampling regions are shown in Fig. 3a. Non-parametric tests indicated that the values in July and September were not significantly different. Figure 3b also shows no significant differences between the measurements of δ13C-CH4 in July and September in the OC, JS, and BS areas. However, the δ13C-CH4 values in NPO and CS regions were greater in July than in September.

Bottom Line: There were complex mixing sources outside and inside the Arctic Ocean.A keeling plot showed the dominant influence by hydrate gas in the Nordic Sea region, while the long range transport of wetland emissions were one of potentially important sources in the central Arctic Ocean.Experiments comparing sunlight and darkness indicate that microbes may also play an important role in regional variations.

View Article: PubMed Central - PubMed

Affiliation: Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, 230026.

ABSTRACT
The biogeochemical cycles of CH4 over oceans are poorly understood, especially over the Arctic Ocean. Here we report atmospheric CH4 levels together with δ(13)C-CH4 from offshore China (31°N) to the central Arctic Ocean (up to 87°N) from July to September 2012. CH4 concentrations and δ(13)C-CH4 displayed temporal and spatial variation ranging from 1.65 to 2.63 ppm, and from -50.34% to -44.94% (mean value: -48.55 ± 0.84%), respectively. Changes in CH4 with latitude were linked to the decreasing input of enriched δ(13)C and chemical oxidation by both OH and Cl radicals as indicated by variation of δ(13)C. There were complex mixing sources outside and inside the Arctic Ocean. A keeling plot showed the dominant influence by hydrate gas in the Nordic Sea region, while the long range transport of wetland emissions were one of potentially important sources in the central Arctic Ocean. Experiments comparing sunlight and darkness indicate that microbes may also play an important role in regional variations.

No MeSH data available.