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FATE AND TRANSPORT OF EMISSIONS FOR SEVERAL TRACE METALS OVER THE UNITED STATES
Citation:
HUTZELL, W. T. AND D. J. LUECKEN. FATE AND TRANSPORT OF EMISSIONS FOR SEVERAL TRACE METALS OVER THE UNITED STATES. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier Science Ltd, New York, NY, 396(2-3):164-179, (2008).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling Division (AMD) conducts research in support of EPA′s mission to protect human health and the environment. AMD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
A regional model for atmospheric photochemistry and particulate matter is used to predict the fate and transport of five trace metals: lead, manganese, total chromium, nickel, and cadmium over the continental United States during January and July 2001. Predicted concentrations of the metals are compared to observations. Lead predictions have the lowest mean differences with observations and the highest correlation coefficients. They best agree with observations made in January over residential and commercial areas in the eastern United States and worst with observations over remote forests and deserts located in the western United States during July. Manganese predictions show similar abilities to reproduce observations but had larger changes between months. Chromium and nickel predictions show diminishing ability to reproduce observations over both urban and rural areas. Cadmium predictions show the least ability to reproduce observations. Potential causes are examined for the errors in predictions. For errors in lead, manganese and perhaps chromium predictions, aerial suspension and biomass burning are suspected because simulations did not include emissions from these sources. Nickel, cadmium and, to a lower extent, chromium predictions suffer from errors in the emissions that represent current anthropogenic activities. Predicted concentrations of all metals show errors from not including sub-grid processes in meteorological and emission rates. Examples include sea breeze circulation along coastal areas and individual sources in urban areas. These errors reduce the ability to reproduce the time dependence of observations.