b'Carnegie Science|Fall 2020 5The group performed a downwelling field experiment at Searsville Reservoir in Woodside, California. Pipes pumped oxygenated surface water into the depths to prevent the formation of dangerous, low-oxygen dead zones. Images courtesy Nona Chiariello . . . downwelling technology could be used alongside longer-term plans to reduce nutrient pollution. fountain water across the surface. Their models indicate that downwelling would be three to 100 times more efficient than bubbling and 10,000 to 1 million times more efficient than fountains. They then did a field experiment at the Searsville Reservoir in Woodside, California, which demonstrated that downwelling could increase oxygen saturation in the immediate area surrounding the pumps by between 10%-30%, enough to alleviate hypoxic stress for many marine organisms. However, this did not extend for more thanCarnegie postdoctoral fellow David Koweek was lead a handful of meters beyond the vicinity ofauthor on the study. the pipes that did the pumping. ThisImage courtesy Carnegie Institution for Sciencemeans that an extensive network would be necessary for any major effort to fightBut these price tags are relatively dead zones in an economically importantsmall compared to the costs of upgrades to or ecologically sensitive area. wastewater treatment facilities and According to the researchers, theyfertilizer-reduction programs that limit believe that downwelling technology maynutrient inputs to the water. This suggests show potential to scale up to areas inthat downwelling technology could be which annual dead zones create greatused alongside longer-term plans toDavid Koweek is conducting field work. He is rowing ecological and economic distress, such asreduce nutrient pollution. the boat in back.the Chesapeake Bay or the Gulf of Mexico.Reducing nutrient pollution is theImage courtesy Carnegie Institution for ScienceThey estimate that the energy required toonly way to eliminate hypoxia power the pumps could cost tens ofpermanently, Caldeira said. However, our millions of dollars each year. Operatingwork shows that downwelling is aCOAUTHORS:downwelling pumps year-round in thetechnological solution that could mitigateOther coauthors on the paper are Carnegies Clara Garca-Snchez (now at Delft University of Technology) Chesapeake could cost between $4-$47the risk of low-oxygen dead zones whileand Philip Brodrick (now at the Jet Propulsion million; in the Gulf, the same could costnutrient management strategies are put inLaboratory), as well as Parker Gassett of the University between $26-$263 million.place.of Maine.'