June 2010, Vol. 22, No.6

Research Notes

NOAA Compiles Ocean and Great Lakes Data

The U.S. National Oceanic and Atmospheric Administration (NOAA) has created an online and standardized compendium of timely and tailored data on the oceans and Great Lakes. Types of data included in the compendium include water level, salinity, temperature, and wind and wave data.

The national effort to link federal and nonfederal sources of ocean and coastal observations and forecasts is now complete, a NOAA news release says. NOAA worked with other federal agencies and 11 independent regional associations of ocean observing partners during a yearlong project to compile data and make it available online through the U.S. Integrated Ocean Observing System (IOOS®) at www.ioos.gov. The system is designed to ensure protection of people and property near water, assist with maritime commerce, enhance water quality, and provide information for research, the news release says.

Study Reveals Transition of Microorganisms in Hydrothermal Vents Through Time

Marine microbes found in small numbers in young, more active hydrothermal vents become more abundant and dominate in older vents, according to a study conducted by researchers at the University of Washington (UW; Seattle). The study, reported in the Proceedings of the National Academy of Sciences, was conducted at the Lost City hydrothermal vent field in the mid-Atlantic Ocean. There, scientists have access to microorganisms living in vents that range in age from newly formed to tens of thousands of years old, according to a UW news release.

Chimneys in the field have been dated to 30,000 years old, but researchers only have looked at microbes in the vents’ chimney structures up to approximately 1200 years old, explained William Brazelton, a UW postdoctoral researcher.

Analyses by Brazelton and colleagues revealed that DNA sequences of microbes rare in young vents were abundant in older vents where the ecosystem has changed, the news release says. Young chimneys vent hotter and more-alkaline fluids, but as the chimneys age, the fluids become cooler and less alkaline. This ecosystem change enables different microorganisms to thrive in a cycle of near-disappearance and dominance that could occur repeatedly over time, the news release says.

“We showed a complete archaeal community turnover in 1000 years, and it probably occurred faster than that,” Braxelton said. Models show that the field may have started venting 1 million years ago, meaning there could have been 1000 community shifts if each one required 1000 years, he added.

“We are just beginning to understand which factors are most important in influencing which microbes,” Braxelton said. “That’s why we focused on age in this study — it provides a very nice proxy for all of those factors.” In the future, Braxelton plans to study older chimneys, which share similar ecosystems, since they stopped venting hot fluids many years ago, he said. The older chimneys will be difficult to study, since they are made of a harder substance similar to concrete and are less porous with fewer microbes inhabiting them, he said.

Water venting from Lost City generally is 93°C (200°F) or cooler, and the structures are pure carbonate, the news release says. The vents are highly alkaline and rich in methane and hydrogen gases, important energy sources for the microbes inhabiting them. “All other hydrothermal systems that have been discovered to date produce chimneys made of metal-sulfides,” Brazelton said, because the venting fluids are more acidic and hotter.

The Lost City’s microbial community represents a long history of genetic memory that enabled rare organisms to rapidly exploit new niches as they appeared, because they had been selected for similar conditions in the past, the news release says. “The Lost City system provided an excellent test case because the relatively low diversity made the data easy to interpret, and the long life span of the system (and the ability to date the carbonate chimneys) allowed us to estimate how long species can remain rare before blooming,” Brazelton said. “I am confident that the same processes occur in all vent systems and probably in all ecosystems in general.”

The U.S. National Science Foundation (Arlington, Va.), NASA, and the W.M. Keck Foundation (Los Angeles) funded the research. Other co-authors include John Baross, oceanography professor at UW; Chuan-Chou Shen, associate professor at National Taiwan University (Taipei); Lawrence Edwards, a professor at the University of Minnesota (Minneapolis); and Kristin Ludwig, a recent UW graduate now at the Consortium for Ocean Leadership (Washington, D.C.).

Movement of Contaminants in Groundwater Revealed

A recent series of studies published by the U.S. Geological Survey (USGS) tracked the movement of contaminants in groundwater and public-supply wells. Four studies conducted in aquifers in California, Connecticut, Nebraska, and Florida show that not all wells are equally vulnerable to contamination.

Differences in the general chemistry of the aquifer, groundwater age, and paths within aquifer systems that allow water and contaminants to reach a well all contribute to an aquifer’s vulnerability to contamination, according to a USGS news release. Each factor varies in its importance, depending on the area’s natural geology and human land-use activities, such as well construction and operation. Findings from the four different systems can be applied to similar aquifer settings throughout the nation, the news release says.

The results of the studies could help public water-supply managers reduce movement of contaminants to wells by prioritizing monitoring programs and deciding on land-use planning, well modifications, or changes in pumping scenarios, according to Sandra Eberts, the study team leader. The research began in 2001.

Drinking water from groundwater systems can be affected by naturally occurring contaminants, such as radon, uranium, and arsenic, as well as such man-made compounds as fertilizers and solvents, according to the news release.

In the Central Valley aquifer near Modesto, Calif., the USGS study found that agricultural and urban development enabled uranium to enter the upper part of the aquifer and drain into the lower part when it’s not pumping. As a result, well managers have changed their pumping schedule, which has reduced the amount of contaminated water pumped from the well, the news release says.

The glacial aquifer system in Woodbury, Conn., included “young” groundwater, which was vulnerable to contamination from man-made compounds. Dry wells in the area were used to capture stormwater runoff and reroute it directly into the aquifer, eliminating the filtration of some contaminants by the soil.

Irrigation wells in the High Plains Aquifer, near York, Neb., were found to enable water containing nitrate and volatile organic compounds to leak down from an overlaying shallow aquifer into the aquifer that serves as drinking water source for the area’s public-supply well.

A large percentage of young water and contaminants from a shallow sand aquifer in the system near Tampa, Fla., were found to travel along natural conduits until reaching a supply well that reaches down into a lower rock aquifer that serves as a source of drinking water. Because of the natural conduits, the supply well is vulnerable to man-made contaminants in the upper aquifer, and the mixing of water from the two aquifers caused arsenic concentrations to increase in water reaching the supply well, according to the news release.

For more information see http://oh.water.usgs.gov/tanc/NAWQATANC.htm.


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