Effect of Land Cover and Pattern on the Quality of Groundwater Discharged from Springs and Seeps at Pigeon Point, Southeastern North Dakota

摘要

Pigeon Point hosts a large group of springs and seeps along Sheyenne River, where the river cuts deeply though underflow sediments deposited in glacial Lake Agassiz. The north-facing slope and abundant cold, mineralized groundwater discharging at the face creates a wetland that hosts unusual boreal species. The pattern of water quality in the springs appears reversed from that expected: discharge at the lowest elevation, indicating longest and deepest flow path, has the least mineralized water, while springs discharging at higher elevation reveal increasing mineralization and reducing conditions. We suggest that differences in land cover and infiltration processes across the groundwater capture zone lead to this apparent reversal. To test this hypothesis, we installed drive-point piezometers and soil-water samplers up-gradient from the springs within dunes, wet meadow, and pasture. Water samples from these instruments and the springs were collected seasonally and analyzed for major cations, anions, and dissolved carbon content.