|  |
Program |
 |
| |
 |
General Session 2: Marine & estuarine biogeochemistry |
| |
|
|
The nitrification rate and nitrate dynamics in the Changjiang River estuary and its adjacent waters
Wednesday 11th @ 1540-1600
Conference Hall
Wentao Wang* , Key laboratory of marine ecology and environmental sciences, Chinese Academy of Sciences;Laboratory of Marine Ecology and Environmental Science, Qingdao National laboratory for Marine Science and Technology
Zaixing Wu, Key laboratory of marine ecology and environmental sciences, Chinese Academy of Sciences;Laboratory of Marine Ecology and Environmental Science, Qingdao National laboratory for Marine Science and Technology
Yongquan Yuan, Key laboratory of marine ecology and environmental sciences, Chinese Academy of Sciences;Laboratory of Marine Ecology and Environmental Science, Qingdao National laboratory for Marine Science and Technology
Xiuxian Song, Key laboratory of marine ecology and environmental sciences, Chinese Academy of Sciences;Laboratory of Marine Ecology and Environmental Science, Qingdao National laboratory for Marine Science and Technology
Zhiming Yu, Key laboratory of marine ecology and environmental sciences, Chinese Academy of Sciences;Laboratory of Marine Ecology and Environmental Science, Qingdao National laboratory for Marine Science and Technology
Presenter Email: wentao1221@sina.com
|
| As one of the most significant inorganic nitrogen compounds, nitrate is supplied to participate in the marine primary product activities from the terrestrial input and internal regeneration. Based on the investigations and in situ experiments in the Changjiang River estuary (CRE) and its adjacent waters in spring and autumn of 2014, the rates of nitrification and nitrate assimilation were calculated. Consequently, the input and output of nitrate in the investigated area was further analyzed according to the temporal and spatial comparisons. The results showed that the nitrification rates were 0.5~9.5 μmol•L-1•d-1, and the nitrate assimilation rates were 0~11.1 μmol•L-1•d-1 in spring. Under the influence of the Changjiang diluted water (CDW), the highest rates happened in the surface water of CRE, leading to the vast abundance of phytoplankton, especially Skeletonema costatum distributed near the CRE. In autumn, the rates of nitrification and nitrate assimilation were 0.2~4.0 μmol•L-1•d-1 and 0~3.6 μmol•L-1•d-1, respectively. It is similar to spring that the nitrate assimilation displayed high rate in CRE. However, nitrification rate reached its peak in the offshore area where nitrate was supposed to be highly limited. As a result, regenerated nitrate became a new resource of nitrate in such area. By extra support of nutrients, abundance of phytoplankton in autumn became five folds over in spring. As a whole, the result revealed that besides discharge of CDW, the role of nitrate internal regenerations would be also highlighted as a source of nitrate. Meanwhile, the regenerated nitrate would be also effective for the primary production in the CRE and its adjacent waters, especially in the offshore area. |
|
|
|
|