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Ocean Science An interactive open-access journal of the European Geosciences Union
Ocean Sci., 13, 623-632, 2017
https://doi.org/10.5194/os-13-623-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
29 Aug 2017
Determination of dissolved nitric oxide in coastal waters of the Yellow Sea off Qingdao
Chun-Ying Liu1,2,3, Wei-Hua Feng1,4, Ye Tian1, Gui-Peng Yang1,2,3, Pei-Feng Li1, and Hermann W. Bange5 1College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
2Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China
3Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Qingdao, 266100, China
4Key Laboratory of Engineering Oceanography, Second Institute of Oceanography, SOA, Hangzhou, 310012, China
5GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, 24105 Kiel, Germany
Abstract. We developed a new method for the determination of dissolved nitric oxide (NO) in discrete seawater samples based on the combination of a purge-and-trap setup and a fluorometric detection of NO. 2,3-diaminonaphthalene (DAN) reacts with NO in seawater to form the highly fluorescent 2,3-naphthotriazole (NAT). The fluorescence intensity was linear for NO concentrations in the range from 0.14 to 19 nmol L−1. We determined a detection limit of 0.068 nmol L−1, an average recovery coefficient of 83.8 % (80.2–90.0 %), and a relative standard deviation of ±7.2 %. With our method we determined for the first time the temporal and spatial distributions of NO surface concentrations in coastal waters of the Yellow Sea off Qingdao and in Jiaozhou Bay during a cruise in November 2009. The concentrations of NO varied from below the detection limit to 0.50 nmol L−1 with an average of 0.26 ± 0.14 nmol L−1. NO surface concentrations were generally enhanced significantly during daytime, implying that NO formation processes such as NO2 photolysis are much higher during daytime than chemical NO consumption, which, in turn, lead to a significant decrease in NO concentrations during nighttime. In general, NO surface concentrations and measured NO production rates were higher compared to previously reported measurements. This might be caused by the high NO2 surface concentrations encountered during the cruise. Moreover, additional measurements of NO production rates implied that the occurrence of particles and a temperature increase can enhance NO production rates. With the method introduced here, we have a reliable and comparably easy to use method at hand to measure oceanic NO surface concentrations, which can be used to decipher both its temporal and spatial distributions as well as its biogeochemical pathways in the oceans.

Citation: Liu, C.-Y., Feng, W.-H., Tian, Y., Yang, G.-P., Li, P.-F., and Bange, H. W.: Determination of dissolved nitric oxide in coastal waters of the Yellow Sea off Qingdao, Ocean Sci., 13, 623-632, https://doi.org/10.5194/os-13-623-2017, 2017.
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We developed a new method for the determination of dissolved nitric oxide (NO) in discrete seawater samples based on the combination of a purge-and-trap setup and a fluorometric detection of NO. With this method we have a reliable and comparably easy to use method to measure oceanic NO surface concentrations, which can be used to decipher both its temporal and spatial distributions as well as its biogeochemical pathways in the oceans.
We developed a new method for the determination of dissolved nitric oxide (NO) in discrete...
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