Nitrogen (N) is one of the essential nutrients for living organisms. Since entering the Anthropocene, N pollution in surface earth has been increasing and influencing ecosystem structure and function. It is commonly concerned by environmental earth science and ecology that how much N in natural environments is available for plants, which forms and to what proportions are actually used by plants, and how plants utilize N against environmental changes.

Supported by the Key Project (Grant No. 41730855) and Outstanding Youth Foundation (Grant No. 41522301) of Natural Science Foundation of China, Prof. Xue-Yan Liu in the Institute of Surface-Earth System Science of Tianjin University investigated sources and utilizing mechanisms of nitrate in plants of arctic tundra, temperate and tropical/subtropical forests with researchers in Kyoto University of Japan and Marine Biology Laboratory of USA. By applying novel methods of N and oxygen isotopes geochemistry in combination with parameters of soil N, plant N uptake and enzymatic reduction, they revealed that nitrate is an important N source for arctic tundra plants. This finding updated the knowledge of plant N availability in arctic tundra, which is critical for better understanding N and carbon cycling dynamics in arctic ecosystems and their responses to environmental changes. Moreover, this study quantified the direct acquisition of nitrate by plants in low-latitude regions and highlighted the importance and challenge to further investigate influences of atmospheric N pollution on soil N loading and plant N use.

These results have been published online in Proceedings of the National Academy of Sciences of the United States of America (PNAS) on March 15, 2018 (http://www.pnas.org/content/early/2018/03/13/1715382115), with the title of “Nitrate is an important nitrogen source for arctic tundra plants”.

Distributions of Δ17O and δ18O in nitrate of atmosphere-plant-soil systems