Diurnal dynamics of CH₄, CO₂ and N₂O fluxes in the saline-alkaline soils of the Yellow River Delta, China

Abstract

Salt-affected soils are extensively present and constitute about 7% of total land surface. However, our knowledge about greenhouse gas (GHG) turnover between the atmosphere and the saline soils is very limited. In order to evaluate the potential of GHG consumption in saline soils, we measured gas fluxes of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) from the soil surface to the atmosphere under saline-alkaline mudflat and various community types in the Yellow River Delta in China. In general, the emissions of GHG of different ecosystems showed a unique peak diurnal pattern, with the peak at 13:00 h and the lowest value at 07:00 h. The CH₄ and N₂O emission of different ecosystems followed the order: saline-alkaline mudflat>T. chinensis>S. salsa>P. australis, while the CO₂ emission followed the order: T. chinensis>P. australis>S. salsa > saline-alkaline mudflat. On the whole, saline-alkaline mudflat and different vegetations acted as CO₂ and N₂O source in spring, while saline-alkaline mudflat and P. australis communities acted as CH₄ source and CH₄ sink, respectively. However, T. chinensis and S. salsa communities acted as CH₄ sink before 12:00 h and CH₄ source after 12:00 h. Although measurements of the CO₂, CH₄ and N₂O fluxes were taken simultaneously, CH₄ and N₂O fluxes were strongly correlated with soil moisture, temperature and electrical conductivity, while no significant correlation was found between CO₂ flux with above environmental factors. These results probably suggest that factors other than soil temperature, moisture and salinity exerted a larger impact on fluxes than on CH₄ and N₂O release and/or that there were not enough samples for CO₂ flux measurements because of its higher spatial and temporal variability.

Keywords::

• Greenhouse gas
• Yellow River Delta
• saline-alkaline soils
• carbon dioxide
• vegetation
• nitrous oxide

Notes

^* These authors contributed to the work in the paper equally.

Additional information

Funding

This work was jointly supported by the National Basic Research Program of China [grant number 2013CB430403]; the Strategic Priority Research Program of the Chinese Academy of Sciences (CAS) [grant number XDA05030404], the National Natural Science Foundation of China [grant number 41201293], [grant number 41171216]; One Hundred-Talent Plan of the Chinese Academy of Sciences (CAS), the CAS/SAFEA International Partnership Program for Creative Research Teams, the Chinese Academy of Sciences (CAS) Visiting Professorship for Senior International Scientists [grant number 2012T1Z0010]; the Science & Technology Development Plan of Shandong Province [grant number 2010GSF10208]; the Science & Technology Development Plan of Yantai City [grant number 2011016]; Yantai Double-hundred High-end Talent Plan [grant number XY-003-02] and 135 Development Plan of YIC-CAS.