• Investing uncertainty and sensitivity in integrated, multimedia environmental models: tools for FRAMES-3MRA

  Elucidating uncertainty and sensitivity structures in environmental models can be a difficult task, even for low-order, single-medium constructs driven by a unique set of site-specific data. Quantitative assessment of integrated, multimedia models that simulate hundreds of sites, spanning multiple geographical and ecological regions, will ultimately require a comparative approach using several techniques, coupled with sufficient computational power. The Framework for Risk Analysis in Multimedia Environmental Systems-Multimedia, Multipathway, and Multireceptor Risk Assessment (FRAMES-3MRA) is an important software model being developed by the United States Environmental Protection Agency for use in risk assessment of hazardous waste management facilities. The #MRA modeling system includes a set of 17 science modules that collectively simulate release, fate and transport, exposure, and risk associated with hazardous contaminants disposed of in land-based waste management units (WMU). The 3MRA model encompasses 966 multi-dimensional input variables, over 185 of which are explicitly stochastic. Design of Super MUSE, a 215 GHz PC-based, Windows – based Supercomputer for Model Uncertainty and Sensitivity Evaluation is described. Developed for 3 MRA and extendable to other computer models, an accompanying platform-independent, Java based parallel processing software toolset is also discussed. For 3 MRA, comparison of stand-alone PC versus Super MUSE simulation executions showed a parallel computing overhead of only 0.57 seconds/simulation, a relative cost increase of 0.7% over average model runtime. Parallel computing software tools represent a critical aspect of exploiting the capabilities of such modeling systems. The Java toolset developed here readily handled machine and job management tasks over the Windows cluster, and is currently capable of completing over 3 million 3MRA model simulations per month on Super MUSE. Preliminary work is reported for an example uncertainty analysis of Benzene disposal that describes the relative importance of various exposure pathways in driving risk levels for ecological receptors and human health. Incorporating landfills, waste piles, aerated tanks, surface impoundments, and land application units, the site-based data used in the analysis included 201 facilities across the United States representing 419 site-WMU combinations.

  (www.sciencedirect.com)
• An international perspective on hazardous waste practices

  In developing countries, public health attention is focused on urgent health problems such as infectious diseases, malnutrition, and infant mortality. As a country develops and gains economic resources, more attention is directed to health concerns related to hazardous chemical wastes. Even if a country has little industry of its own that generates hazardous wastes, the importation of hazardous wastes for recycling or disposal can present health hazards. It is difficult to compare the quantities of hazardous wastes produced in different countries because of differences in how hazardous wastes are defined. In most countries, land filling is the most common means of hazardous waste disposal, although substantial quantities of hazardous wastes are incinerated in some countries. Hazardous wastes that escape into the environment most often impact the public through air and water contamination. An effective strategy for managing hazardous wastes should encourage waste minimization, recycling, and reuse over disposal. Developing countries are especially in need of low-cost technologies for managing hazardous wastes.

  (www.sciencedirect.com)