Determination of gaseous particulate selenium over a rural grassland in the UK

The atmosphere is identified as playing an important role in the mass balance of selenium (Se) in grassland ecosystems, potentially governing the critical levels for grazing livestock. This paper presents the first known measurements of gas phase Se in the U.K. atmosphere along with simultaneous particulate measurements. Sampling and analytical determination are difficult and detailed consideration was therefore given to method development. Particulate Se was trapped on 0.45 μm Millipore HA filters using a low velocity sampling method and determination by acid digestion and hydride atomic absorption. Gaseous Se is particularly difficult to trap and charcoal and nitric acid methods were compared.