Monitoring of elemental mercury in ambient air around an Egyptian natural gas processing plant

Abstract Gaseous elemental mercury (Hg°) emitted into the ambient air around an Egyptian plant was determined during the different stages and processing of natural gas. Around 34 locations were selected beside the natural gas treatment process (inlet separation, dehydration, sweetening, NGL removal, condensate shipping, water removal and flaring processes). Mercury concentration measurements in the ambient air were performed for a period of one month. The elemental mercury was collected on a gold coated silica trap by amalgamation and then measured with cold vapor atomic absorption spectrometry via double amalgam technique. The measured mercury concentrations for all measuring locations were in the range 8.3–212.2 ng/Sm 3 . The highest average Hg° concentration (212.2 ng/Sm 3 ) was found at the open drain of the condensate storage tank (CSA‒OD); and this concentration is higher than the maximum acceptable level (200 ng/Sm 3 ) according to the U.S. agency for toxic substances and disease registry (ATSDR). However, this concentration still below the maximum limit (300 ng/Sm 3 ) of U.S. environmental protection agency (EPA). The mercury concentration in all other sites (33 locations) have an acceptable level located in the range 8.3–114.9 ng/Sm 3 . Therefore, all the sites around the Egyptian gas processing facilities were environmentally safe for humans except the CSA‒OD site referenced to ATSDR.