The importance of fluid and gaseous mercury (Hg) emissions from hydrothermal systems in the shallow, coastal ocean is poorly constrained. However, there are indicators that they could be a significant natural Hg source. We evaluated the hydrothermal Hg emissions around Vulcano Island, Aeolian Arc, Italy, which is host to a marine shallow-water hydrothermal system (MSWHS) in Baia di Levante. Fluids were collected with porewater probes, and gases were collected into Tedlar© bags. Total Hg (THg) concentrations in the hydrothermal fluids ranged from 2.9 to 2888 pM. The concentrations of volatile Hg were below 8 pM and trended positively with increasing temperature. Monomethyl Hg (MMHg) was not detected. Total Hg in the gases ranged from 0.03 to 1.82 μmol/m³.

High concentrations of THg were associated with low Cl-concentrations, low pH-values, and high K/Cl and Mg/Cl ratios. Concentrations of THg in the hydrothermal fluids resulted from mixing between meteoric water, seawater, condensed fumarolic vapor, and a deep hydrothermal fluid. However, not all low-Cl fluids were high THg samples. Samples taken along the coast of the La Fossa crater contained substantially less THg (2.9 to 29.4 pM), despite similar hydrothermal indicators as those in the Baia di Levante samples. These data support subsurface circulation models, which discuss the downslope flow of condensed La Fossa crater gases to the coast. In the hydrothermally active area of Baia di Levante, concentrations of THg were elevated relative to background surface seawater, ranging from 40 to 5110 pM. In comparison, the remainder of the bay ranged from 0.8 to 2.4 pM.

The flux of Hg to the atmosphere from surface waters was calculated through dissolved Hg concentrations. The flux at each sampled site ranged from 0 to 19.6 pmol/m^2/hr. The highest flux rates were determined for those areas with visible hydrothermal activity, particularly those with high gaseous emission rates. Surface water concentrations declined rapidly away from point sources, indicating atmospheric emission, dilution through mixing, or scavenging and sedimentation. In hydrothermally active areas, Baia di Levante sediments contained THg concentrations of 2.42 nmol/g and 49.52 nmol/g, which were significantly above background (0.03 nmol/g).

The largest gaseous point source, Bambino, released >2 L of gas per second. Although, Hg concentrations in the gas were low (113 to 122 nmol/m³) relative to other measured point sources near the beach (1768 to 1817 nmol/m³), due to the volume of discharge, surface water concentrations were elevated (131 pM).

The Hg present in the hydrothermal system of Vulcano contributes Hg to the atmosphere and local seawater as a natural source.

浅海、沿海海洋热液系统排放的液态和气态汞 (Hg) 排放的重要性很少受到限制。然而，有迹象表明它们可能是重要的天然汞来源。我们评估了意大利 Aeolian Arc 的 Vulcano 岛周围的热液汞排放，该岛是 Baia di Levante 的海洋浅水热液系统 (MSWHS) 的所在地。用孔隙水探针收集流体，并将气体收集到 Tedlar© 袋中。热液中的总汞 (THg) 浓度范围为 2.9 至 2888 pM。挥发性汞的浓度低于 8 pM，并随着温度的升高呈正趋势。未检测到单甲基汞 (MMHg)。气体中的总汞含量范围为 0.03 至 1.82 μmol/m ³。

高浓度的 THg 与低 Cl 浓度、低 pH 值以及高 K/Cl 和 Mg/Cl 比率有关。热液中 THg 的浓度是由大气水、海水、冷凝的富马酸蒸气和深部热液混合引起的。然而，并非所有低 Cl 流体都是高 THg 样品。沿拉佛萨海岸采集的样本尽管热液指标与 Baia di Levante 样品中的热液指标相似，但陨石坑的 THg（2.9 至 29.4 pM）明显减少。这些数据支持地下环流模型，该模型讨论了冷凝的拉佛萨火山口气体向海岸的下坡流动。在 Baia di Levante 的热液活跃区，THg 的浓度相对于背景地表海水升高，范围从 40 到 5110 pM。相比之下，海湾的其余部分从下午 0.8 点到 2.4 点不等。

通过溶解的汞浓度计算从地表水到大气的汞通量。每个采样点的通量范围为 0 到 19.6 pmol/m ^2/ hr。那些具有可见热液活动的区域，特别是那些具有高气体排放率的区域，确定了最高通量率。远离点源地表水浓度迅速下降，表明大气排放、混合稀释或清除和沉淀。在热液活跃区，Baia di Levante 沉积物中的 THg 浓度为 2.42 nmol/g 和 49.52 nmol/g，明显高于背景（0.03 nmol/g）。

最大的气态点源 Bambino 每秒释放 >2 L 的气体。虽然相对于海滩附近的其他测量点源（1768 至 1817 nmol/m ³ ），气体中的汞浓度较低（113 至 122 nmol/m ³），但由于排放量大，地表水浓度升高（下午 131 点）。

Vulcano 的热液系统中存在的汞将汞作为天然来源贡献给大气和当地海水。