Müller Emanuel, von Gunten Urs, Tolu Julie, Bouchet Sylvain, Winkel Lenny H E
Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water (W+T), Eawag Ueberlandstrasse 133 CH-8600 Duebendorf Switzerland
Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environment Systems (D-USYS), ETH Zurich Universitätsstrasse 16 8092 Zürich Switzerland.
Environ Sci (Camb). 2024 Jan 8;10(3):620-630. doi: 10.1039/d3ew00787a. eCollection 2024 Mar 1.
Selenium (Se) is an essential micronutrient for many living organisms particularly due to its unique redox properties. We recently found that the sulfur (S) analog for dimethyl selenide (DMSe), dimethyl sulfide (DMS), reacts fast with the marine oxidant hypobromous acid (HOBr) which likely serves as a sink of marine DMS. Here we investigated the reactivity of HOBr with dimethyl selenide and dimethyl diselenide (DMDSe), which are the main volatile Se compounds biogenically produced in marine waters. In addition, the reactivity of HOBr with further organic Se compounds was tested, , SeMet (as -acetylated-SeMet), and selenocystine (SeCys as -acetylated-SeCys), as well as the phenyl-analogs of DMSe and DMDSe, respectively, diphenyl selenide (DPSe) and diphenyl diselenide (DPDSe). Apparent second-order rate constants at pH 8 for the reactions of HOBr with the studied Se compounds were (7.1 ± 0.7) × 10 M s for DMSe, (4.3 ± 0.4) × 10 M s for DMDSe, (2.8 ± 0.3) × 10 M s for SeMet, (3.8 ± 0.2) × 10 M s for SeCys, (3.5 ± 0.1) × 10 M s for DPSe, and (8.0 ± 0.4) × 10 M s for DPDSe, indicating a very high reactivity of all selected Se compounds with HOBr. The reactivity between HOBr and DMSe is lower than for DMS and therefore this reaction is likely not relevant for marine DMSe abatement. However, the high reactivity of SeMet with HOBr suggests that SeMet may act as a relevant quencher of HOBr.
硒（Se）是许多生物必需的微量营养素，特别是由于其独特的氧化还原特性。我们最近发现，二甲基硒（DMSe）的硫（S）类似物二甲基硫醚（DMS）与海洋氧化剂次溴酸（HOBr）反应迅速，而次溴酸可能是海洋中DMS的一个汇。在这里，我们研究了HOBr与二甲基硒和二甲基二硒化物（DMDSe）的反应活性，它们是海水中生物源产生的主要挥发性硒化合物。此外，还测试了HOBr与其他有机硒化合物的反应活性，即硒代蛋氨酸（SeMet，以乙酰化-SeMet形式）和硒代胱氨酸（SeCys，以乙酰化-SeCys形式），以及DMSe和DMDSe的苯基类似物，分别为二苯基硒（DPSe）和二苯基二硒化物（DPDSe）。在pH值为8时，HOBr与所研究的硒化合物反应的表观二级速率常数分别为：DMSe为(7.1 ± 0.7) × 10⁹ M⁻¹ s⁻¹，DMDSe为(4.3 ± 0.4) × 10⁹ M⁻¹ s⁻¹，SeMet为(2.8 ± 0.3) × 10⁹ M⁻¹ s⁻¹，SeCys为(3.8 ± 0.2) × 10⁹ M⁻¹ s⁻¹，DPSe为(3.5 ± 0.1) × 10⁹ M⁻¹ s⁻¹，DPDSe为(8.0 ± 0.4) × 10⁹ M⁻¹ s⁻¹，这表明所有选定的硒化合物与HOBr的反应活性都非常高。HOBr与DMSe之间的反应活性低于与DMS的反应活性，因此该反应可能与海洋中DMSe的减排无关。然而，SeMet与HOBr的高反应活性表明SeMet可能是HOBr的一种相关淬灭剂。
