Influence of tritium exposure route on vegetation types at the Savannah River Site.

Plant, soil, water, and other media from various locations at the Savannah River Site were measured for total tritium (T) content and T speciation to characterize T in these areas, as well as investigate its uptake behavior and the transport of T species in these media. This characterization included the isolation and measurement of T in tritiated water (HTO), and (when possible) exchangeable organic bound T (E-OBT) and non-exchangeable organic bound T (NE-OBT). Two areas of interest were investigated: (1) a holding pond with T-contaminated water and (2) open basins or streams with low to background levels of T.

Historical record of tritium from tree cores at the Savannah River Site.

Tree cores from various locations at the Savannah River Site (SRS) and local area were measured for total tritium (T) content and T speciation to include tritiated water (HTO), exchangeable organic bound T (E-OBT) and non-exchangeable organic bound T (NE-OBT) species. The tree cores dated back to the 1960's or prior which provided an opportunity to measure T over the last 60-70 years. The total T levels from pine and oak tree cores were consistent with the record of known T atmospheric releases from nuclear activities at the SRS between the mid-1950's and 1990's with a notable peak in T tree core levels during the late 1960's.

Stable carbon and nitrogen isotopes explain methylmercury concentrations in stream food webs of Lake George, New York (USA).

Mercury has been studied extensively in lakes due to health risks associated with the consumption of contaminated fish, while stream ecosystems have received less attention. To better understand mercury bioavailability in the lower food web of streams, we collected macroinvertebrates (predators and detritivore) along with autochthonous (epilithic algae) and allochthonous (leaf litter) basal resources in eight streams entering Lake George. Samples were analyzed for methylmercury (MeHg), total mercury, and carbon and nitrogen isotopes (δC & δN) to determine how mercury concentrations in basal resources, biomagnification rates, and environmental factors (watershed characteristics and water chemistry) effected MeHg concentrations in predatory macroinvertebrates.

Does Raising the Arms Modify Head Tremor Severity in Cervical Dystonia?

Background: A defining characteristic of dystonia is its position-dependence. In cervical dystonia (CD), sensory tricks ameliorate head tremor (HT). But it remains unknown whether raising the arms alone has the same impact.