October 2010, Vol. 22, No.10
Phosphorus continues to plague Lake Erie
Even though the level of phosphorus entering Lake Erie has decreased, the health of the waterbody has not improved as expected. The Clean Water Act, passed in 1972, set the goal of limiting phosphorus entering Lake Erie to 10,000 Mg/yr (11,000 ton/yr). But the lake remains unhealthy in spite of this goal being reached more than a decade ago.
Symptoms of the lake’s poor health include algae mats covering much of the lake floor, blue-green algae blooms, algae on rocks, and a toxin in the water causing avian botulism type E in local wildlife, according to a Buffalo (N.Y.) State College news release.
The yearlong Nearshore and Offshore Lake Erie Nutrient Study, conducted by the Buffalo State College Great Lakes Center, found that the original phosphorus reduction goals assumed that nutrients would be mixed evenly throughout the entire lake, but this does not happen, the news release says. In addition, phosphorus in the water does not disappear; it remains in the lake’s sediment. The sediment and the phosphorus it contains continuously recirculate throughout the lake, and biological and chemical processes distribute the nutrients from the sediment back into the water, the news release says.
Pulling up filter socks' treatment ability
Scientists have an improved tool for removing contaminants from stormwater runoff. “Filter socks” — compost tucked into mesh tubes — can capture some silt, heavy metals, fertilizers, and petroleum products before they reach local waterways. Now, new research shows that adding flocculants to the mix enhances the socks’ treatment capacity.
Scientists at the U.S. Department of Agriculture’s Agricultural Research Service (ARS) and researchers at Filtrexx International LLC (Grafton, Ohio), manufacturer of the filter socks, studied the potential for flocculation agents to improve the socks’ performance, according to an ARS news release.
The study found that without the aid of flocculation agents, the socks removed the majority of clay and silt particles, 17% of ammonium nitrogen, 75% of Escherichia coli, 37% to 72% of heavy metals, 99% of diesel fuel, 84% of motor oil, and 43% of gasoline from runoff. When the flocculants are added, the socks remove even more pollutants: 27% of ammonium nitrogen, 99% of E. coli, 47% to 74% of heavy metals, 99% of motor oil, and 54% of gasoline, the news release says.
USGS examines mercury concentrations in fish
Even though mercury concentrations in fish decreased between 1969 and 1987, a U.S. Geological Survey (USGS) study has found the trend to be more variable between 1996 and 2005. USGS identified these different trends by examining state and federal fish-monitoring data from U.S. lakes, rivers, and reservoirs between 1969 and 2005.
From 1969 to 1987, 22 sites showed significant decreases, and only four of the 50 sites sampled showed increases in fish mercury concentrations. The 1970s showed a rapid decrease in mercury concentrations and gradual or no declines during the 1980s, a USGS news release says. Downward mercury trends in both sediment cores and fish were consistent with implementation of stricter regulatory controls of direct releases of mercury to the atmosphere and surface waters, the study found.
From 1996 to 2005, concentrations remained constant, but more increases were found in the Southeast than in the Midwest. These upward trends were associated with increases in wet deposition, which could be attributed, in part, to the influence of long-range global mercury emissions, the news release says.
The study report calls for a coordinated network of fish mercury monitoring sites for an improved view of these trends across the nation. The report, “Mercury trends in fish from rivers and lakes in the United States, 1969–2005,” published in the journal Environmental Monitoring and Assessment, is accessible at http://water.usgs.gov/nawqa/mercury.
Expedition explores deep-sea areas in Indonesia
The United States and the Republic of Indonesia partnered and launched an expedition to explore deep-sea areas in Indonesian waters, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).
Scientists expected to find discoveries advancing understanding of the undersea ecosystem, hydrothermal vent activity, marine biodiversity, acidification processes, and deep-ocean volcanically derived gases, the news release says.
During the first week of the exploration in the deep ocean north of Sulawesi, Indonesia, the NOAA ship Okeanos Explorer mapped a large undersea volcano using its multibeam sonar. The volcano rises more than 3000 m (10,000 ft) from the sea floor, according to NOAA. Scientists use sonar and a remotely operated vehicle on the ship that takes high-definition images to map the sea floor.
Throughout the expedition, the researchers sent live video, images, and other data to scientists at exploration command centers in both countries. Scientist logs, images, and teaching resources updated during the expedition (in both English and Bahasa Indonesian) can be found at http://oceanexplorer.noaa.gov.
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