Concentrations of major ions in stream water from the Soft Plume River on Subantarctic Marion Island were measured. During the annual relief voyage, samples were collected daily over a 16-day period (21 April–6 May 2015) from three sites along the stream to better understand temporal and spatial variability of stream water chemistry on the island. The chemical composition of the stream is dominated by the sea salts Na+ and Cl−. Mean solute concentrations for Na+ and Cl− are 7 ± 0.58 and 12.5 ± 0.84 mg/L, respectively. The mean molar Na:Cl ratio for all samples is 0.86 ± 0.05, with a range from 0.71 to 0.99 (n = 47), and there is a strong, significant positive correlation between Na+ and Cl− concentrations (r = 0.80; p < 0.001). These values are consistent with previous studies from Marion Island and other Subantarctic islands. Temporal variation in ion concentrations was small. The largest detected change was a decrease in most solute concentrations that coincided with two precipitation events. This decrease was largest at the highest altitude and the shallowest site, suggesting that there was more rainfall at this location. These findings confirm the dominance of the surrounding ocean as the main source of the island’s stream water chemistry and illustrate spatiotemporal patterns that provide an insight into mechanisms affecting their composition on Subantarctic Marion Island.

中文翻译：

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亚南极马里恩岛河流水化学的时空变异性

测量了来自亚南极马里恩岛软羽河的溪流水中主要离子的浓度。在一年一度的救援航行中，在 16 天的时间里（2015 年 4 月 21 日至 5 月 6 日）每天从河流沿岸的三个地点收集样本，以更好地了解岛上河流水化学的时空变化。流的化学成分主要是海盐 Na+ 和 Cl-。Na+ 和 Cl- 的平均溶质浓度分别为 7 ± 0.58 和 12.5 ± 0.84 mg/L。所有样品的平均 Na:Cl 摩尔比为 0.86 ± 0.05，范围从 0.71 到 0.99 (n = 47)，并且 Na+ 和 Cl− 浓度之间存在很强的显着正相关（r = 0.80；p < 0.001）。这些值与先前对马里恩岛和其他亚南极岛屿的研究一致。离子浓度的时间变化很小。检测到的最大变化是与两次降水事件同时发生的大多数溶质浓度的下降。这种下降在海拔最高和最浅的位置最大，表明该位置的降雨量更多。这些发现证实了周围海洋作为该岛溪流水化学的主要来源的主导地位，并说明了时空模式，这些模式提供了对影响亚南极马里恩岛上其组成的机制的深入了解。