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Images: Underneath and Overlooked: Groundwater

Groundwater comes from precipitation that falls on land. Some of this water evaporates into the atmosphere, gets taken up by plants, or flows into streams, but some infiltrates into the ground and recharges aquifers. Groundwater can flow from inland aquifers to lakes, streams, or coastal waters. On the seaward side, denser saltwater flows into sediments and establishes equilibrium with fresh groundwater. Tides and mixing along the freshwater-saltwater interface results in seawater circulation through the sediments. Scientists have estimated that groundwater provides only 5 percent of the water flowing into the ocean, but groundwater can easily contain more than 20 times the amount of chemicals in it as other freshwater sources, so groundwater can have significant impacts on coastal ocean chemistry and ecology. (Illustration by Jack Cook, Woods Hole Oceanographic Institution)

Matt Charette heads the Coastal Groundwater Geochemistry Laboratory at the Woods Hole Oceanographic Institution. The lab's research focuses on understanding the impacts of submarine groundwater discharge on the chemistry and ecosystems in the coastal ocean. (Image courtesy of Matt Charette, Woods Hole Oceanographic Institution)

WHOI marine chemist Matt Charette collects samples of groundwater flowing into Pamet Harbor in Truro on Cape Cod. He spent his childhood summers in Truro, which fostered his interests in the outdoors and coastal ocean. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)

Matt Charette and colleagues travel around the world studying groundwater flow to the ocean in various types of aquifers. Here he collects samples in Akumel Bay, Mexico. (Meaghan Gonneea, Woods Hole Oceanographic Institution)

Scientists in the Coastal Groundwater Geochemistry Laboratory also travel to cold places, such as Greenland, where groundwater once frozen at the bottom of glaciers drains into the ocean, carrying chemicals leached into the water from rocks and sediments on land. Those chemicals have impacts on the coastal ocean. (Image courtesy of Matt Charette, Woods Hole Oceanographic Institution)