US-EPA Monitors Quality of Ambient Air with MARGA

摘要

The US-EPA has signed a long-term contract for the supply of up to 40 MARGA systems for their CASTNET measurement network across the USA. There are an additional 9 MARGA systems located in Scotland (2), South Korea(5), The Netherlands(1) and China(1).rnMARGA (Monitor for AeRosols and Gases in ambient Air) is an ambient air monitoring system that is capable of measuring the gas phase concentrations of NH_3, HNO_3, HCI, HNO_2, and SO_2, as well as the particulate matter (aerosol) concentrations of NO_3 , Cl~- SO_4~(2-) , NH_4~+, Na~+, K~+, Ca~(2+) and Mg~(2+). This unique instrument, developed by Applikon Analytical in cooperation with the Dutch Energy Research Institute (ECN), draws in a lm3 volume of air each hour. The gases are then quantitatively (more than 99.7%) absorbed in a wetted rotating denuder (WRD) and the aerosols, which pass through the WRD, are trapped in the steam-jet aerosol collector (SJAC).