Dimethyl sulfur compounds including dimethylsulfoniopropionate (DMSP), dimethyl sulfide (DMS), and dimethyl sulfoxide (DMSO), play a crucial part in global sulfur cycling. The eastern Indian Ocean (EIO), characterized by its remarkable diversity of biomes and climate dynamics, is integral to global climate regulation. However, the regulation mechanism of DMS (P, O) in the EIO remains to be elucidated in detail. This paper presented a field survey aimed at investigating the spatial distribution of DMS (P, O) and their relationships with environmental and biological factors in the EIO. The surface concentrations of DMS, DMSPt, and DMSOt varied from 0.07 to 7.37 nmol/L, 0.14 to 9.17 nmol/L, and 0.15 to 3.32 nmol/L, respectively, and their distributions are attributed to high Chl-a concentration near Sri Lanka and the influence of ocean currents (Wyrtki jets, Bay of Bengal runoff). Higher concentrations of DMS (P) and DMSOt were predominantly observed in water columns shallower than 75m and deeper than 75m deep, respectively. The monthly DMS fluxes in the study area peaked in August. Temperature and Dissolved Silica Index (DSI) were the key environmental determinants for DMS distribution, while nitrate (NO3-) was the primary factor for both DMSPt and DMSOt. In terms of biological factors, Prochlorococcus and Synechococcus were significant contributors to DMS (P, O) dynamics. Synechococcus was the dominant influence on the DMS source and DMSPt sink, whereas Prochlorococcus primarily consumed DMSOt. Furthermore, the structural equation modeling (SEM) revealed the relationship between DMS, DMSPt, DMSOt, and the key environmental/biological factors, as well as among them, and together they formed a co-regulatory network in the EIO. This contributes significantly to the advancement of global ecosystem models for DMS (P, O).

中文翻译：

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东印度洋二甲硫化合物空间分布及环境/生物协同调控机制

二甲硫化合物，包括二甲磺基丙酸酯 (DMSP)、二甲硫醚 (DMS) 和二甲亚砜 (DMSO)，在全球硫循环中发挥着至关重要的作用。东印度洋（EIO）以其生物群落和气候动态的显着多样性为特征，是全球气候调节不可或缺的一部分。然而，EIO中DMS（P，O）的调节机制仍有待详细阐明。本文提出了一项实地调查，旨在调查 EIO 中 DMS（P、O）的空间分布及其与环境和生物因素的关系。 DMS、DMSPt 和 DMSOt 的表面浓度分别为 0.07 至 7.37 nmol/L、0.14 至 9.17 nmol/L 和 0.15 至 3.32 nmol/L，其分布归因于斯里兰卡附近的高 Chl-a 浓度以及洋流的影响（Wyrtki 急流、孟加拉湾径流）。较高浓度的 DMS (P) 和 DMSOt 主要分别在浅于 75 m 和深于 75 m 的水柱中观察到。研究区月DMS通量在8月份达到峰值。温度和溶解二氧化硅指数 (DSI) 是 DMS 分布的关键环境决定因素，而硝酸盐 (NO3-) 是 DMSPt 和 DMSOt 的主要因素。从生物因素来看，原绿球藻和聚球藻属是 DMS (P, O) 动态的重要贡献者。聚球藻属是对 DMS 源和 DMSPt 汇的主要影响，而原绿球藻主要消耗DMSOt。此外，结构方程模型（SEM）揭示了DMS、DMSPt、DMSOt与关键环境/生物因素之间以及它们之间的关系，并共同形成了EIO中的共同监管网络。这对 DMS (P, O) 全球生态系统模型的进步做出了重大贡献。