Apparent nitrous acid dissociation across environmentally relevant temperatures in freshwater and seawater

IF 3.8 1区地球科学 Q1 LIMNOLOGY

Limnology and Oceanography Pub Date : 2024-10-23 DOI:10.1002/lno.12714

Benedict Borer, Eric Bi, Ryan J. Woosley, Andrew R. Babbin

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Abstract

Nitrite is a ubiquitous compound found across aquatic systems and an intermediate in both the oxidative and reductive metabolisms transforming fixed nitrogen in the environment. Yet, the abiotic cycling of nitrite is often overlooked in favor of biologically mediated reactions. Here we quantify the apparent acid dissociation constant (pKa) between nitrous acid and its conjugate base nitrite in both freshwater and seawater systems across a range of environmentally relevant temperatures (5–35°C) using potentiometric‐based titration. In freshwater, we measured a pKa,NBS of 3.14 at 25°C and a pKa,T of 2.87 for seawater at the same temperature. We quantify substantial effects of both salinity and temperature on the pKa, with colder and fresher water manifesting higher values and thus a greater proportion of protonated nitrite at any given pH. Because nitrous acid is unstable and decomposes to nitric oxide, the implications for the nitrous acid dissociation constant on ecosystem function are broad.

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淡水和海水在环境相关温度下的表观亚硝酸解离度

亚硝酸盐是水生系统中普遍存在的一种化合物，也是环境中固定氮转化的氧化和还原代谢的中间产物。然而，亚硝酸盐的非生物循环往往被忽视，而生物介导的反应则被忽视。在此，我们利用电位滴定法，在淡水和海水系统中，在环境相关温度范围（5-35°C）内，量化了亚硝酸与其共轭碱亚硝酸盐之间的表观酸解离常数（pKa）。在淡水中，我们测得 25°C 时的 pKa,NBS 为 3.14，而在相同温度的海水中，pKa,T 为 2.87。我们量化了盐度和温度对 pKa 的重大影响，在任何给定的 pH 值下，较冷和较新鲜的水的 pKa 值较高，因此质子化亚硝酸盐的比例也较大。由于亚硝酸不稳定并会分解成一氧化氮，因此亚硝酸解离常数对生态系统功能的影响是广泛的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Limnology and Oceanography 地学-海洋学

CiteScore

8.80

自引率

6.70%

发文量

254

审稿时长

3 months

期刊介绍： Limnology and Oceanography (L&O; print ISSN 0024-3590, online ISSN 1939-5590) publishes original articles, including scholarly reviews, about all aspects of limnology and oceanography. The journal''s unifying theme is the understanding of aquatic systems. Submissions are judged on the originality of their data, interpretations, and ideas, and on the degree to which they can be generalized beyond the particular aquatic system examined. Laboratory and modeling studies must demonstrate relevance to field environments; typically this means that they are bolstered by substantial "real-world" data. Few purely theoretical or purely empirical papers are accepted for review.