氮是限制寡营养盐海域海洋浮游植物生长的元素之一。在开阔大洋，生物可利用活性氮主要由深层海水供应到表层海洋，生物固氮和大气氮沉降也是上层海洋活性氮的源。21世纪以来，由于化肥和化石燃料的大量使用，导致了大量人为活性氮通过大气输送并沉降到开阔海域。根据模型估算结果，在过去的100年，从大气到开阔大洋的氮输入增加了两倍多，占海洋外部氮输入的三分之一。据计算，通过大气输送并沉降到开阔海域的人为活性氮使得全球海洋生产力提高了3%，区域海洋生产力提高了25%。然而除了一些近岸环境外，迄今为止，少有证据表明人为氮输入引起开阔海域氮循环和生态系统的显著改变。

Nitrogen is one of the essential nutrients limiting phytoplankton growth throughout much of the low-latitude surface ocean. Biologically available nitrogen, or fixed N, is primarily supplied to the surface ocean from nutrient-rich subsurface water, but it is also added by in situ biological N fixation and atmospheric deposition. Atmospheric transport and deposition of reactive nitrogen (nitrogen oxides, ammonium and/or ammonia, and N-bearing organic compounds) is an increasingly important source of fixed N to open-ocean surface waters, owing to the rapid increase in emissions from fertilizer usage and combustion of fossil fuels. Model estimates suggest that N input from the atmosphere to the open ocean has more than doubled over the past 100 years, accounting for up to one-third of the ocean’s external N supply (1). This dramatic increase in anthropogenic atmospheric N (AAN) has been calculated to have increased ocean productivity by 3% globally (1) and up to 25% regionally (2). However, except in some near shore environments (3), there is little evidence so far that anthropogenic N inputs have led to significant changes in the open ocean’s N cycle and ecosystems.

研究人员Haojia Ren等在2017年在国际顶尖期刊《Science》上发表了一篇名为“21st-century rise in anthropogenic nitrogen deposition on a remote coral reef”的研究论文。由于东沙岛远离陆地，上层海洋的活性氮主要来源于深层水供给和大气沉降，因此东沙岛是研究大气氮的理想位置。

Haojia Ren and other research fellows published a paper entitled “21st-century rise in anthropogenic nitrogen deposition on a remote coral reef” in the international top journal Science in 2017. Since Dongsha Atoll was far from land and the reactive nitrogen in the upper ocean mainly came from deep water and atmospheric deposition, Dongsha Atoll became an ideal location for studying atmospheric nitrogen.

作者发现2003-2012年间，中国南海东沙岛珊瑚中的氮同位素值（6.3±0.5）明显不同于1968-1977的值（7.6±0.4）。通过进一步分析全球大气活性氮沉降通量发现，从2000年以后通过大气沉降到上层海洋的活性显著增加。同时，东沙岛珊瑚中的氮同位素值与中国1960-2010间化石燃料的使用和肥料的使用也呈现相同的变化趋势。作者认为东沙岛珊瑚中氮同位素值的改变主要是由于中国大陆活性氮排放增加所致。最后作者建议改进燃烧技术或改用可再生能源来降低东亚地区氮氧化物排放，这在一定程度上可缓解北太平洋受人为氮排放的影响。

The authors found that the nitrogen isotope values (6.3 ± 0.5) in corals from Dongsha Atoll in the South China Sea during 2003-2012 were significantly different from those during 1968-1977 (7.6 ± 0.4). Further analysis of global atmospheric reactive nitrogen deposition fluxes revealed a significant increase in activity through atmospheric deposition to the upper ocean after 2000. Meanwhile, the nitrogen isotope values in corals of Dongsha Atoll showed the same trend with the use of fossil fuels and fertilizers in China between 1960 and 2010. The authors concluded that the change in nitrogen isotope values in corals of Dongsha Atoll was mainly due to the increase of reactive nitrogen emissions from mainland China. Finally, the authors suggested improving combustion technologies or switching to renewable energy sources to reduce nitrogen-oxide emissions in East Asia, which may, to some extent, mitigate the Northern Pacific Ocean from anthropogenic nitrogen emissions.

参考文献：https://www.science.org/doi/full/10.1126/science.aal3869

简述翻译者：海南大学研究生王晨