Study Indicates Methane Uptake Not Sensitive to Nitrogen Addition in Alpine Grassland
2016-10-25
Methane (CH4) is a colorless odorless gas that occurs abundantly in nature and as a product of certain human activities. Methane is among the most potent of the greenhouse gases.
The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases.
Statistics showed that the CH4 concentration in the atmosphere has increased dynamically from 720 ppb before 1750 to 1803 ppb in 2011 because of large anthropogenic CH4 emissions since the industrial revolution.
Atmospheric Nitrogen (N) is deposited via precipitation (wet deposition) and as gases and particles (dry deposition). As a k part of global climate change, extreme elevation of Nitrogen deposition has an obvious impact on CH4 uptake in terrestrial ecosystem.
But it remains unclear how nitrogen (N) deposition affects soil methane (CH4) uptake in semiarid and arid zones. This is what scientists at the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences have been doing. It took LIU Xuejun and his team five years to define the degree of the impact of N addition on CH4 uptake, taking alpine grassland in the Tianshan Mountains as a research sample.
The results indicate that interannual variability in CH4 uptake was impacted by precipitation and temperature and was not sensitive to elevated N deposition in alpine grassland.
In situ field experiment was conducted by the team from 2010 to 2014 to systematically study the effect of various N application rates on CH4 flux. Their study showed that no significant influence of N addition on CH4 uptake. However, large inter-annual variability in CH4 uptake was observed, which was depended mainly on seasonal variability in precipitation and temperature.
Further study reveals that CH4 uptake was positively correlated with soil temperature, air temperature and to a lesser extent with precipitation, and was negatively correlated with soil moisture and NO3 −-N content.
The study was published on Scientific Reports recently. It provides a better scientific evidence for accurate evaluation of CH4 uptake in alpine grassland. For more information about the study, please refer to http://www.nature.com/articles/srep32064.