Little is known about the element composition of groundwater along flow paths between wetlands. What is known is based on a few major elements, such as Na and Ca. We examined the spatial and temporal variation of elements in a depressional-wetland, groundwater-flow system in the Prairie Pothole Region of North Dakota, USA. Wetlands of the region are characterized by their occurrence in hydrologically connected complexes, where those at higher elevations in the groundwater flow system often recharge groundwater (recharge wetlands), while those at lower elevations receive groundwater (discharge wetlands). The aim of our study was to get a better understanding of factors affecting the distribution of more than 30 elements in groundwater along a flow path between recharge and discharge wetlands. We found that oxidation-reduction potential (ORP) decreased as electrical conductivity (EC) increased along the flow path. As EC increased, so did the concentrations of major ions, such as Na, Ca, and Mg. That was already well known. Less known, however, was that concentrations of Cs, Sn, U and Zr increased along the flow path as well. Not reported before was that concentrations of Sn increased strongly as ORP decreased. The concentrations of most elements in groundwater increased with lower relative elevation in the groundwater flow system, but notable exceptions were Ba and Zn, which both showed opposite patterns. Our results contribute to a better understanding of element cycling in groundwater between wetlands, which in turn is important for our understanding of resultant influences on associated biogeochemistry and ecosystem services.

关于沿湿地之间流动路径的地下水的元素组成知之甚少。已知的是基于一些主要元素，例如 Na 和 Ca。我们研究了美国北达科他州草原坑洼地区的洼地湿地地下水流系统中元素的时空变化。该地区湿地的特点是它们出现在水文相连的复合体中，地下水流系统中海拔较高的湿地经常补给地下水（补给湿地），而低海拔的湿地则接受地下水（排泄湿地）。我们研究的目的是更好地了解影响地下水中 30 多种元素在补给和排放湿地之间的流动路径中分布的因素。我们发现氧化还原电位 (ORP) 随着电导率 (EC) 沿流动路径的增加而降低。随着 EC 的增加，主要离子（如 Na、Ca 和 Mg）的浓度也随之增加。这已经是众所周知的了。然而，鲜为人知的是，Cs、Sn、U 和 Zr 的浓度也沿流动路径增加。之前没有报道过，随着 ORP 的降低，Sn 的浓度急剧增加。地下水流系统中大多数元素的浓度随着地下水流系统相对海拔的降低而增加，但值得注意的例外是 Ba 和 Zn，它们都表现出相反的模式。我们的结果有助于更好地了解湿地之间地下水中的元素循环，这反过来对于我们了解对相关生物地球化学和生态系统服务的影响很重要。