MIXING IT UP IN GOTHAM—WHOI Senior Research Assistant Jay Sisson (left) and Engineer Craig Marquette maneuver a box corer after plucking a 30-centimeter-deep sample of sediment from the bottom of the Hudson River in June 2001. Within sight of Manhattan, the researchers measured the rate at which sediment accumulates along this intersection between salty ocean water and fresh river water. (Photo by Rocky Geyer, Woods Hole Oceanographic Institution)
FLOOD OF ACTIVITY—A satellite image shows plumes of sediment suspended in the waters of the Fraser River as they pour into the Strait of Georgia in June 2003. The mixing of Rocky Mountain and Pacific waters creates one of the world’s most productive estuaries. (SeaWiFS Project, NASA/Goddard, and ORBIMAGE.)
A COASTAL MIXING BOWL— Nutrient- and sediment-laden fresh water from the Fraser River in British Columbia rides up and over salty ocean waters, which are beginning to march upriver during flood tide. The interaction of the two water masses of different salinities and densities in the estuary creates underwater turbulence and mixing that naturally flushes and energizes the coastal system.
SEEING THROUGH MUD—Photograph (left) and x-ray image (right) of sediments from a region of rapid deposition in the Hudson estuary. The sharp change in color (left) indicates a change from fresh, oxidized sediment to older, anoxic mud. X-rays reveals laminations of silt (light colors) and mud (dark) formed by repeated deposition and erosion over tidal cycles. (Chris Sommerfield, University of Delaware.)
GETTING DIRTY AT WORK—WHOI Assistant Scientist Peter Traykovski (left), Senior Research Assistant Jay Sisson, and a professional diver examine an instrument tripod covered with hydroids and mud after six months on the bottom of the Hudson River. Researchers chronicled currents, the flow of sediments, and changes in river bed elevation due to erosion and deposition. (Rocky Geyer, WHOI. )