Environmental Geosciences Article

5780
 
We use sediment ages and mercury (Hg) concentrations to estimate past and future concentrations in the South River, Virginia, where Hg was released between 1930 and 1950 from a manufacturing process related to nylon production. In a previous study, along a 40 km (25 mi) reach, samples were collected from 26 of 54 fine-grained deposits that formed in the lee of large wood obstructions in the channel and analyzed for grain size, Hg concentration, and organic content. We also obtained radiometric dates from six deposits. To create a history that reflects the full concentration distribution (which contains concentrations as high as 900 mg/kg [900 ppm]), here, we treat the deposits as a single reservoir exchanging contaminated sediments with the overlying water column, and assume that the total sediment mass in storage and the distribution of sediment ages are time invariant. We use reservoir theory to reconstruct the annual history of Hg concentration on suspended sediment using data from our previous study and new results presented here. Many different reconstructed histories fit our data. To constrain results, we use information from a well-preserved core (and our estimate of the total mass of Hg stored in 2007) to specify the years associated with the peak concentration of 900 mg/kg. Our results indicate that around 850 kg (1874 lb) of Hg was stored in the deposits between 1955 and 1961, compared to only 80 kg (176 lb) today. Simulations of future Hg remediation suggest that 100-yr timescales will be needed for the South River to remove Hg-contaminated sediments from the channel perimeter through natural processes.

Explorer Article

Explorer Foundation Update

12439
 
Explorer Foundation Update

It has a new name, a new energy and a new lineup of experts, all primed to spread geoscience knowledge around the world. “It” is AAPG’s newly named Global Distinguished Lecture Program – emphasis on the “global” – which dates back to 1941 but continues to be the Association’s flagship initiative for offering the latest in geologic science to AAPG affiliated geological societies and universities.

Explorer Making a Difference

1832
 

Explorer Policy Watch

2879
 
Explorer Policy Watch

The media had been buzzing all morning with news that the administration was planning to open additional areas of the outer continental shelf (OCS) to exploration and production as part of a new energy plan.

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