Nitrogen uptake regime regulated by ice melting during austral summer in the Prydz Bay, Antarctica
- PDF / 1,049,868 Bytes
- 7 Pages / 595 x 842 pts (A4) Page_size
- 39 Downloads / 158 Views
Nitrogen uptake regime regulated by ice melting during austral summer in the Prydz Bay, Antarctica Run Zhang1, Qiang Ma1, 2, Min Chen1*, Minfang Zheng1, Jianping Cao1, Yusheng Qiu1 1 College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China 2 Key Laboratory of Estuarine Ecological Security and Enviromental Health, Xiamen University Tan Kah Kee College,
Zhangzhou 363105, China Received 18 August 2018; accepted 22 October 2018 © Chinese Society for Oceanography and Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract
Using a combination of stable isotope (15N) and radionuclide (226Ra) analyses, we examine possible controls on the interactions between melting ice and the uptake of nitrogen in the Prydz Bay during the 2006 austral summer. We find that specific rates of uptake for nitrate and ammonium correlate positively to their concentrations, thus suggesting a substrate effect. In the study area, we observe that regions along open, oceanic water have high fratios (nitrate uptake/nitrate+ammonium uptake), while areas near the Amery Ice Shelf have significantly low fratios. Further analysis reveals a negative correlation between the f-ratio and the melt water fraction, thus implying that the melting of ice plays an essential role in regulating pelagic N dynamics in the Southern Ocean (SO). Stratification, produced by melting ice, should profoundly affect the efficiency of the SO’s biological pump and consequently affect the concentration of CO 2 in the atmosphere. Results presented in this study add information to an already significant base of understanding of the controls on pelagic C and N dynamics in the SO. This provides unique insights for either interpreting past changes in geologic records or for predicting future climate change trends. Key words: nitrogen uptake regime, ice melting, Prydz Bay, Antarctica Citation: Zhang Run, Ma Qiang, Chen Min, Zheng Minfang, Cao Jianping, Qiu Yusheng. 2019. Nitrogen uptake regime regulated by ice melting during austral summer in the Prydz Bay, Antarctica. Acta Oceanologica Sinica, 38(8): 1–7, doi: 10.1007/s13131-019-1434-2
1 Introduction The Southern Ocean (SO) plays an important role in the sequestration of carbon dioxide (CO2) in the global carbon cycle (Arrigo et al., 1999; DiTullio et al., 2000); therefore, it is vulnerable to change in carbon import and export caused by anthropogenic climate change. Biogeochemistry in the SO is highly diverse and dynamic. In the SO, nitrogen uptake processes play an essential role in biogeochemical cycles and the sequestration of atmospheric CO2 (Cochlan, 2008). Concepts of new and regenerated production have been widely used to link surface nitrogen dynamics with biogenic particle flux (Eppley and Peterson, 1979). Although nitrogen is not a limiting factor for primary production in the SO (Cochlan, 2008), the nitrogen uptake regime, represented by the well-known parameter f-ratio, regulates the majority of the net oceanic sequestration of atmospheric CO 2 . In other words, the f-ratio can be used as
Data Loading...
