Mike Tate

Mercury (Hg) emission and deposition can occur to and from soils, and are an important component of the global atmospheric Hg budget. This paper focuses on synthesizing existing surface-air Hg flux data collected throughout the Western North American region and is part of a series of geographically focused Hg synthesis projects. A database of existing Hg flux data collected using the dynamic flux chamber (DFC) approach from almost a thousand locations was created for the Western North America region. Statistical analysis was performed on the data to identify the important variables controlling Hg fluxes and to allow spatiotemporal scaling. The results indicated that most of the variability in soil-air Hg fluxes could be explained by variations in soil-Hg concentrations, solar radiation, and soil moisture. This analysis also identified that variations in DFC methodological approaches were detectable among the field studies, with the chamber material and sampling flushing flow rate influencing the magnitude of calculated emissions. The spatiotemporal scaling of soil-air Hg fluxes identified that the largest emissions occurred from irrigated agricultural landscapes in California. Vegetation was shown to have a large impact on surface-air Hg fluxes due to both a reduction in solar radiation reaching the soil as well as from direct uptake of Hg in foliage. Despite high soil Hg emissions from some forested and other heavily vegetated regions, the net ecosystem flux (soil flux+vegetation uptake) was low. Conversely, sparsely vegetated regions showed larger net ecosystem emissions, which were similar in magnitude to atmospheric Hg deposition (except for the Mediterranean California region where soil emissions were higher). The net ecosystem flux results highlight the important role of landscape characteristics in effecting the balance between Hg sequestration and (re-)emission to the atmosphere.

Preparing for the wide variety of disasters that can occur is challenging for any animal research facility, but the level of concern for human and animal health rises significantly when infectious agents and toxins are part of the scenario. Federal regulations provide detailed requirements for the development of an incident response plan (IRP) when select agents and toxins (SATs) are used. In addition to the usual issues associated with disaster planning, the IRP must address concerns associated with the potential theft, loss, or release of SATs that may affect both institutional personnel and the surrounding community. The level of detail in the IRP and the intensity of training should be appropriate for the level of risk involved. Regulations describe certain basic requirements but do not address the risks of SAT-exposed animals, which have been the subject of additional guidance to help implement regulatory requirements. A 2008 joint publication of the Centers for Disease Control and Prevention and the Animal and Plant Health Inspection Service describes scenarios in which SAT-exposed animals are handled in the same manner as the agent or toxin itself for the purpose of reporting a SAT theft, loss, or release. Events that resulted from the impact of Hurricane Ike at the University of Texas Medical Branch in Galveston provide a valuable opportunity to evaluate the effectiveness of the federal regulations and to build on lessons learned from this disaster. These lessons can help to supplement the regulatory requirements and improve the safety and security of handling both SATs and animals exposed to them during and after an emergency situation.