Formation rates for various products of hydrogen sulfide oxidation by δ-MnO₂ were studied as a function of pH, temperature, concentration of the reactants, and ionic strength at the environmentally-relevant conditions. The main goals of this work were studying the effects of these parameters on speciation of zero-valent sulfur, including individual polysulfides and revealing the mechanism of its formation. A reaction between hydrogen sulfide and manganese dioxide is the fastest environmentally-relevant abiotic process of polysulfides formation, reactive sulfur species, which participate in complexation of metals, pyrite formation, sulfurization of organic matter and may serve as a substrate for microorganisms. In the pH range of 7.0 to 10.5, zero-valent sulfur accounted for > 55% of the sulfur in the products of hydrogen sulfide oxidation, while at pH ≥ 7.5, the formation rates of polysulfide zero-valent sulfur were higher than those of particulate zero-valent sulfur formation. Speciation of polysulfides on the initial stage of the reaction shows significant shift toward the higher polysulfides compared to their speciation calculated under assumption of thermodynamic equilibrium in both H₂S - S_n²⁻ - S_8(aq) - α-S₈ and H₂S - S_n²⁻ - S_8(aq) - S_8(coll) systems. We suggest that the shift in the speciation of polysulfide system results from the presence of a short-living highly reactive sulfur atoms, which are formed on the first stage of the reaction: two-electron transfer from hydrogen sulfide to manganese dioxide. Results of this study provide constraints on the rates of polysulfide formation at the redox interfaces of the stratified aquatic systems, and allows quantitative assessment of their role in sulfur cycling.

δ-MnO ₂氧化硫化氢各种产物的生成速率在环境相关条件下，研究了 pH 值、温度、反应物浓度和离子强度的函数。这项工作的主要目标是研究这些参数对零价硫（包括单个多硫化物）形态形成的影响，并揭示其形成机制。硫化氢和二氧化锰之间的反应是多硫化物形成、反应性硫物种的最快的与环境相关的非生物过程，其参与金属络合、黄铁矿形成、有机物硫化并可作为微生物的底物。在 7.0 到 10.5 的 pH 范围内，零价硫占硫化氢氧化产物中硫的 55% 以上，而在 pH ≥ 7.5 时，多硫化物零价硫的生成速率高于颗粒零价硫的生成速率。多硫化物在反应初始阶段的形态与在假设两个 H₂ S - S _n ²⁻ - S _8(aq) - α-S ₈和 H ₂ S - S _n ²⁻ - S _8(aq) - S _8(coll)系统。我们认为多硫化物体系的形态转变是由于存在短寿命的高反应性硫原子，该硫原子在反应的第一阶段形成：从硫化氢到二氧化锰的双电子转移。这项研究的结果限制了分层水生系统氧化还原界面处多硫化物的形成速率，并允许对其在硫循环中的作用进行定量评估。