研究人员表明，在150-200米水深，检测到氨和亚硝酸盐氧化的相对低的半饱和常数(即高底物亲和力)。涡流引起的高亲和力硝化细菌的位移和底物供应的增加，增强了氨和亚硝酸盐的氧化，消耗了透光层中的环境底物浓度。气旋涡流比氨氧化更强烈地促进了亚硝酸盐的氧化，降低了PNM亚硝酸盐的浓度并加速了其周转。
这些发现证明了在中尺度过程中硝化作用的两个步骤在空间上是分离的，并为PNM的物理—生态控制提供了见解。
研究人员表示，亚硝酸盐是氨氧化成硝酸盐(硝化作用)的中间产物，在海洋上层积累，形成一级亚硝酸盐最大值(PNM)。在西北太平洋副热带环流(wNPSG)中，PNM 的亚硝酸盐浓度相对较低，那里的涡旋频繁而强烈。为了解释这种低浓度的亚硝酸盐，团队研究了西太平洋次表层沉积物气旋性涡旋中的硝化作用。
附：英文原文
Title: Reduced nitrite accumulation at the primary nitrite maximum in the cyclonic eddies in the western North Pacific subtropical gyre
Author: Li Liu, Mingming Chen, Xianhui S. Wan, Chuanjun Du, Zhiyu Liu, Zhendong Hu, Zong-Pei Jiang, Kuanbo Zhou, Hongyang Lin, Hui Shen, Duo Zhao, Lanying Yuan, Lei Hou, Jin-Yu T. Yang, Xiaolin Li, Shuh-Ji Kao, Emily J. Zakem, Wei Qin, Minhan Dai, Yao Zhang
Issue&Volume: 2023-08-16
Abstract: Nitrite, an intermediate product of the oxidation of ammonia to nitrate (nitrification), accumulates in upper oceans, forming the primary nitrite maximum (PNM). Nitrite concentrations in the PNM are relatively low in the western North Pacific subtropical gyre (wNPSG), where eddies are frequent and intense. To explain these low nitrite concentrations, we investigated nitrification in cyclonic eddies in the wNPSG. We detected relatively low half-saturation constants (i.e., high substrate affinities) for ammonia and nitrite oxidation at 150 to 200 meter water depth. Eddy-induced displacement of high-affinity nitrifiers and increased substrate supply enhanced ammonia and nitrite oxidation, depleting ambient substrate concentrations in the euphotic zone. Nitrite oxidation is more strongly enhanced by the cyclonic eddies than ammonia oxidation, reducing concentrations and accelerating the turnover of nitrite in the PNM. These findings demonstrate a spatial decoupling of the two steps of nitrification in response to mesoscale processes and provide insights into physical-ecological controls on the PNM.
DOI: ade2078
Source: https://www.science.org/doi/full/10.1126/sciadv.ade2078