Just as the ozone hole above Antarctica is reaching its largest recorded size ever, scientists from the Smithsonian Environmental Research Center are heading south to capture data about the harmful solar rays streaming through it.
Photobiologist Patrick Neale and his colleagues are heading for the Ross Sea in the research vessel R.V. Nathaniel B. Palmer, an ice breaker ship, to examine the effects of the sun's rays on the micro-organisms living there. Neale wants to determine just how these organisms respond to the most harmful portion of radiation coming from the sun--ultraviolet radiation (UVR)--and how ozone depletion alters the amount and type of UV reaching the Earth.
"The ozone hole continues to be a regular feature around here, so the planning was made with the usual timing of its occurrence in mind. However, we did not know in advance that it would be so big this year," Neale said. The project is supported by the National Science Foundation's Office of Polar Programs, which also operates the ice breaker.
Previous studies have shown that UV inhibits photosynthesis in phytoplankton (free floating marine algae) and affects metabolism in bacterioplankton (bacteria suspended in water). But the effects vary with different wavelengths in the UV spectrum.
Short-wavelength UVB ranging from 290 to 320 nanometers is more dangerous than long-wavelength UVA ranging from 320 to 400 nanometers. Stratospheric ozone depletion increases the levels of biologically harmful, short-wavelength UVB in solar radiation.
Also, different species vary in their sensitivity to UVR, which may eventually affect biodiversity and has important implications because these tiny organisms form the base of the marine food web. While phytoplankton fix carbon, bacterioplankton play a vital role in mineralizing nutrients and provide a link through the food web to higher organisms. Neale's studies are aimed at assessing the impact of UV on these processes during variations in ozone and water transparency.
During the course of the six-week cruise, which ends Dec. 13, the ice breaker will make its way to a polynya, an ice-free area in an otherwise ice-covered sea, where scientists have recorded phytoplankton blooms before. But "our study is the first to investigate the UV responses of the bloom region," Neale said.
At the polynya, Neale will set up his instruments to record penetration of solar radiation into the water column and observe its effects on photosynthesis in phytoplankton. Collaborating research groups will measure metabolism in bacterioplankton. They will also measure water circulation to determine how long organisms are exposed to surface UV.
The Smithsonian Environmental Research Center in Edgewater, Md., is one of the nation's premiere centers for environmental research and education at the land-water margin. A diverse staff of senior scientists engages in interdisciplinary studies that address issues such as global change, watershed studies, maintenance of productive fisheries, changes in the environment from biological invaders, and understanding fragile wetlands and woodlands. In addition, SERC is a major environmental education center for the public and a professional training facility for the next generation of environmental scientists.