Prairie-pothole wetlands are an important freshwater resource in the Northern Great Plains of the United States and play a crucial role in providing vital ecosystem services. Changes in hydrology, water stable isotopes, and water chemistry of these wetlands are a function of processes including evaporation, precipitation, groundwater exchange, and surface-water flows. Understanding mechanisms influencing chemical changes under highly variable meteorological and complicated hydrological conditions is important for managing wetland responses to future climate change. We examined changes in water stable isotopes and water chemistry in the water of two adjacent, but hydrologically different (closed-basin vs open-basin), prairie-pothole wetlands over two years at the Cottonwood Lake Study Area, North Dakota. Our goals were to: (1) characterize the effects of meteorological variation (normal vs wet) and basin differences on wetland hydrological processes; and (2) identify patterns in water chemical changes and main drivers of identified changes between closed-basin and open-basin prairie-pothole wetlands. Our results indicated that meteorological variations and basin morphological had noticeable effects on hydrological processes and chemical conditions in our study wetlands. In both wetlands studied, higher phosphorus concentrations were mostly related to increased rainfall. Additionally, the water of closed-basin was enriched in heavy isotopes and multiple dissolved ions due to higher evaporation and lack of losses to surface flows compared to the open-basin wetland. This study highlights the importance of considering the heterogenous hydrological conditions of prairie-pothole wetlands when studying their responses to future changes in climate.
