The Atmospheric Mercury Network: measurement and initial examination of an ongoing atmospheric mercury record across North America

摘要

The National Atmospheric Deposition Program (NADP) developed and operates acollaborative network of atmospheric-mercury-monitoring sites based in NorthAmerica – the Atmospheric Mercury Network (AMNet). The justification forthe network was growing interest and demand from many scientists and policymakers for a robust database of measurements to improve model development,assess policies and programs, and improve estimates of mercury drydeposition. Many different agencies and groups support the network,including federal, state, tribal, and international governments, academicinstitutions, and private companies. AMNet has added two high-elevationsites outside of continental North America in Hawaii and Taiwan because ofnew partnerships forged within NADP. Network sites measure concentrations ofatmospheric mercury fractions using automated, continuous mercury speciationsystems. The procedures that NADP developed for field operations, datamanagement, and quality assurance ensure that the network makesscientifically valid and consistent measurements.AMNet reports concentrations of hourly gaseous elemental mercury (GEM),two-hour gaseous oxidized mercury (GOM), and two-hour particulate-boundmercury less than 2.5 microns in size (PBM_2.5). As of January 2012,over 450 000 valid observations are available from 30 stations. AMNetalso collects ancillary meteorological data and information on land use andvegetation, when available. We present atmospheric mercury data comparisonsby time (3 yr) at 21 individual sites and instruments. Highlighted arecontrasting values for site locations across the network: urban versusrural, coastal versus high elevation and the range of maximum observations.The data presented should catalyze the formation of many scientificquestions that may be answered through further in-depth analysis andmodeling studies of the AMNet database. All data and methods are publicallyavailable through an online database on the NADP website (href=" http:/adp.sws.uiuc.edu/amn/"target="_blank">http:/adp.sws.uiuc.edu/amn/). Future network directions areto foster new network partnerships and continue to collect, quality assure,and post data, including dry deposition estimates, for each fraction.