BEIJING, Aug. 1 (Xinhua) -- Chinese scientists have reported that the riverine export of organic carbon and mercury from terrestrial ecosystems increased with the permafrost degradation in Arctic regions.
Arctic permafrost stores a large amount of organic carbon and mercury. Climate warming has resulted in wide permafrost degradation during past decades. As a result, some of the long-term accumulated organic carbon and mercury in the previously frozen soil can be easily mobilized and enter rivers.
The research team from the College of Earth and Environmental Sciences of Lanzhou University, in cooperation with U.S. scientists, calculated the exports of dissolved organic carbon, particulate organic carbon, mercury and methyl mercury in six large Arctic rivers flowing to the Arctic Ocean.
The results showed that about 22,000 Gg of dissolved organic carbon and 2,700 Gg of particulate organic carbon were exported to the Arctic Ocean each year from 2003 to 2017, with an annual export of 20 tonnes of mercury and 110 kg of methyl mercury. The highest exports of organic carbon and mercury were recorded in spring, while the lowest values occurred in winter.
The scientists also estimated that the organic carbon pools in 2,300,000 square kilometers of subsea permafrost varies from 270 to 1,450 Pg, which may contribute to greenhouse gas emissions in the future.