English:
LEFT TO RIGHT, TOP TO BOTTOM: Russ Herwig holds a zooplankton sample bottle, with student Kim MacDonald in the background. Samples are fixed with preservative so they can be examined by scientists in other labs. Scientist handles one of the smaller tubes of treated ballast water. An open hatch leads to ballast tanks. Banks of ozone generator tubes. Connected to a microscope, this monitor offers enlarged views of the critters

Title: Coast watch
Identifier: coastwatch00uncs_16 (find matches)
Year: 1979 (1970s)
Authors: UNC Sea Grant College Program
Subjects: Marine resources; Oceanography; Coastal zone management; Coastal ecology
Publisher: (Raleigh, N. C. : UNC Sea Grant College Program)
Contributing Library: State Library of North Carolina
Digitizing Sponsor: North Carolina Digital Heritage Center

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simple, and there is no need to bring potentially harmful chemicals on board ship. "All you need is electricity and air," Cooper notes. A stream of oxygen-rich air is sent through an electrode, exposing the gas to 10,000 volts of electricity. The ozone gas that emerges is then sent to the 15 ballast tanks on board through a system of 1,200 diffusers, which Cooper While ozone kills microorganisms like bacteria and viruses almost immediately, larger organisms often escape treatment. However, when ozone reacts with bromide naturally present in seawater, bromine is formed. Bromine extends the effects of ozone treatment because it also can disinfect — and bromine does not degrade as rapidly as ozone. TESTING THE WATERS As one group of scientists monitors the effectiveness of the Tonsina's ozone treatment technology, another gathers samples of ballast water organisms. This means gaining access to each ballast tank through a service hatch, or manway — an access secured with many bolts, some rusted in place since last time the ship was
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LEFT TO RIGHT, TOP TO BOTTOM: Russ Herwig holds a zooplankton sample bottle, with student Kim MacDonald in the background. Samples are "fixed" with preservative so they can be examined by scientists in other labs. Scientist handles one of the smaller tubes of treated ballast water. An open hatch leads to ballast tanks. Banks of ozone generator tubes. Connected to a microscope, this monitor offers enlarged views of the critters. compares to aerators in fish tanks. The gas bubbles through the ballast water continuously while the ship is in transit. Ozone oxidizes the tissues of any ballast water organisms inside, destroying them. According to Cooper, the ideal ballast water treatment system would kill organisms of all sizes, a requirement that many potential technologies have failed to meet. "We're looking at every trophic level in the water system, from viruses and bacteria all the way up to fish," the UNC-W chemist says. This combination of ozone and bromine has the potential to eliminate entire populations of microbes and planktonic organisms within the ballast water tanks. Initial tests, conducted in Long Beach, Calif, and Port Angeles, Wash., have shown that the ozone treatments can kill up to 99.99 percent of the bacteria and phyto- plankton in ballast water. The system was somewhat less effective at destroying zooplankton, but the success rate was still above 90 percent. serviced. "The ship's crew has been extremely cooperative and very interested in watching our sampling efforts," Herwig says. Once the crusty hatches are cracked open, the team collects plankton samples, pulling a small plankton net, or "tow," through the tank. One tow will amass about 5,000 planktonic organisms in its stocking-shaped sieve. Microbe- laden water samples also were collected in five- liter Niskin bottles for subsequent lab analysis. "Collecting samples is the fun part," Continued COASTWATCH 9

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