Effects of meteorological variability on chemical changes in two hydrologically distinct prairie-pothole wetlands

Prairie-pothole wetlands are an important freshwater resource in the Northern Great Plains of North America and play a crucial role in providing vital ecosystem services. Changes in water levels, 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 predicting changes in wetland ecosystem services in response to future climate change. We examined changes in stable isotopes and 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 morphology had noticeable effects on hydrological processes and chemical conditions in our study wetlands. The water of the closed-basin wetland 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. In both wetlands studied, higher phosphorus concentrations were mostly related to the catchment runoff as rainfall increased. This study highlights the importance of considering the heterogenous hydrological conditions of prairie-pothole wetlands when studying their responses to future changes in climate.