Tuesday, May 30

1:50 p.m. Estimating Nitrogen Loss in Streams With an Empirical Model, Session H22A-02. Location: Renaissance Hotel Grand C. Richard Alexander, USGS Reston.

Disturbances to the ecosystems of many shallow estuarine and coastal marine waters, such as areas of the Gulf of Mexico and Chesapeake Bay, have been linked to increases in nitrogen flux in streams and rivers during the past several decades. Yet sources contributing to these increased changes are not well understood. The author will examine the effect of channel depth on the contribution of nitrogen by streams and rivers to coastal ecosystems. 3:30 p.m. Evidence for Conservative Transport of Nitrate in the Mississippi River, Session H22A-07. Location: Renaissance Hotel Grand C. Donald Goolsby, USGS Denver, CO.

River boats aren't the only thing the Mississippi River transports effectively. In this study covering a 2,250-km reach, relatively little nitrate was lost from the water column. More than 60% of the 2,140 metric tons per day of nitrate discharged from the Mississippi River originated upstream of St. Louis, more than 1,900 km from the river's mouth.

3:40 p.m. The Impact of Sustained Drought on Chesapeake Bay, Session H22C-06. Location: Renaissance Hotel Grand N. Thomas Cronin, USGS Reston.

Drought affects the salinity, clarity, and nutrient influx of estuaries. By analyzing major droughts in the 16th century, the author will describe the effect these changes might have on hydrologic conditions and biological communities in the Chesapeake Bay during a possible modern prolonged drought in the mid-Atlantic region.

4:05 p.m. Holocene Climate variability of Palmer Deep, Antarctica, Ocean Drilling Program Site 1098, Session OS22A-10. Location: CC 32. Lisa Osterman, USGS Reston.

The author will describe how sediments sampled from Palmer Deep, Antarctica, document cooling of ocean waters and expansion of persistent sea ice from early to late Holocene.

Wednesday, May 31

9:30 a.m. Role of Interactions Between Groundwater and Wetland Surface Water in Recharging and Storing Mercury Within the Surficial Aquifer System of the Northern Everglades, Session H31C-05. Location: CC 27. Judson Harvey, USGS Reston. This study describes how controls on surface-water flows in the Northern Florida Everglades by water managers seeking to reduce flooding and maintain adequate water supply have affected the movement of mercury between surface water and shallow ground water.

10:45 a.m. Seismicity and Seismic Hazards in Eastern North America I, Session S31C. Location: CC Room 10-12. Joan Gomberg, USGS Memphis, presiding.

1:30 p.m. Seismicity and Seismic Hazards in Eastern North America II, Session S32A. Location: CC Room 10-12. Thomas Hanks, USGS Reston, presiding.

The central and eastern U.S. have been sites for some of the strongest earthquakes on record in the lower 48 states, and damaging earthquakes are on record for nearly every state East of the Mississippi River. The East has lower earthquake return rates than the West, however, making earthquake hazards assessment more difficult. Earthquakes in the East have a higher potential impact than those in the West because damaging waves travel farther, the East has a greater population density living among an older inventory of structures, and the public is not prepared. In these sessions, scientists will discuss possible ways to overcome the difficulties of studying these low probability/high impact hazards. 1:30 p.m. Poster: Atmospheric Wet Deposition of Trace Elements to a Suburban Catchment in Northern Virginia, Session A32B-01. Location: CC Hall D. Kathryn Conko, USGS Reston.

Elevated levels of copper and zinc found in Lake Anne in Reston, VA, but not found at remote sites sampled in the region, suggest a local source of these elements – possibly wear on automobile brakes and tires from nearby traffic.

Thursday, June 1

1:30 p.m. Poster: Earthquake Hazards and Cities, Session U42A-06. Location: CC Hall D. John Filson, Earthquake Hazards Program Coordinator, USGS, Reston.

This poster presentation describes recent work of the USGS on earthquake hazards assessments and rapid earthquake notification in the San Francisco Bay area, Seattle, Memphis, and Los Angeles regions. Projects included are a pilot system for rapid location and notification of strong ground shaking in Los Angeles; a study of future earthquake probabilities that shows a 70% chance for at least one damaging earthquake within the next 30 years in the San Francisco Bay area; and the Advanced National Seismic System, a major initiative to increase the seismic instrumentation in all urban areas threatened by earthquakes.

3:30 p.m. Effects of Erosion and Sediment Deposition on the Historical and Modern U.S. Carbon Budget, Session U42B-07. Location: CC Room 29. Eric Sundquist, USGS Woods Hole, MA.

The loss of carbon from agricultural soils has long been recognized as a significant historical source of atmospheric carbon dioxide. Enhancement of soil erosion has been identified as one cause of carbon loss to the atmosphere. However, the redeposition of eroded sediments is a possible mechanism of carbon sequestration. This study shows that accelerated erosion and deposition can enhance both oxidation and burial of terrestrial organic carbon relative to pre-agricultural or relatively undisturbed conditions.

As the nation's largest water, earth and biological science, and civilian mapping agency, the USGS works in cooperation with more than 2000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, to contribute to the conservation and the sound economic and physical development of the nation's natural resources, and to enhance the quality of life by monitoring water, biological, energy, and mineral resources.