Nitrogen Isotope and N2/Ar Biogeochemistry of the Peru Suboxic Zone

世界海洋的亚氧中间水域虽然只占海洋总体积的一小部分(0.1%)，但在海洋的氮循环及其生物地球化学和同位素特征中发挥着至关重要的作用。激活将氮气转化为氮气的微生物过程需要亚氧条件。正因为如此，亚氧水域充当了主要的汇，将氮从生物圈中移除。马萨诸塞大学达特茅斯分校的一名海洋化学家正在与GEOMAR/基尔大学的科学家合作，完成对秘鲁海岸外东热带南太平洋的广泛实地研究，这是三个主要的开阔洋亚黑区之一。将对从秘鲁边缘附近的一系列横断面收集的水样进行同位素和气体比率分析，以评估以下方面：(1)对秘鲁亚氧区对海洋氮和氮同位素收支的净影响的洞察；(2)氮汇强度与边缘沉积物中保存的氮同位素信号之间的关系。这项研究的结果将使科学界更好地了解海洋氮循环和亚氧水域之间的关系。至于更广泛的影响，这项研究将完善对海洋氮循环和气候变异性之间过去相互作用的古记录的解释，并有助于全球海洋循环的数值模拟研究。这项研究代表了美国、德国和秘鲁科学家的合作努力。作为该项目的一部分，一名研究生将得到支持和培训。

The suboxic intermediate waters of the world's oceans, though constituting only a small fraction of total oceanic volume (0.1%), play a vital role in the ocean's nitrogen cycle and its biogeochemical and isotopic signatures. Suboxic conditions are required to activate the microbial processes that convert nitrogen to N2 gas. Because of this, suboxic waters act as a predominant sink, removing nitrogen from the biosphere. An ocean chemist from the University of Massachusetts at Dartmouth is working in collaboration with scientists from GEOMAR/Kiel University to complete an extensive field study of the Eastern Tropical South Pacific Ocean off the coast of Peru, one of the three major open ocean suboxic zones. Water samples, collected from a series of transects off the Peruvian margin, would undergo isotopic and gas ratio analyses to assess the following: (1) insights on the net impact of the Peru suboxic zone on oceanic nitrogen and nitrogen isotope budgets and (2) the relationship between the intensity of the nitrogen sink and the nitrogen isotope signal preserved in margin sediments. Results from this research would provide the science community with a greater understanding of the relationship between the oceanic nitrogen cycle and suboxic waters. As regards broader impacts, this research would refine the interpretation of paleo-records with respect to past interactions between the oceanic nitrogen cycle and climate variability and contribute to numerical modeling studies of the global oceanic cycle. This study represents a collaborative effort between U.S., German, and Peruvian scientists. One graduate student would be supported and trained as part of this project.