Passive samplers are often employed to collect ozone concentration data in remote areas such as mountain forests (e.g. Sanz et al., 2007); such data can be subsequently used to assess the potential ozone risk for vegetation by estimating the AOT40 exposure index (e.g. Gerosa et al 2007). Lab sheets typically report ozone concentrations in mass unit per cubic meter (e.g. μg•m-3) and these values are then converted to ppb since this unit let to appreciate the relative abundance of the pollutant molecules with respect to the other molecules in ambient air. Moreover the AOT40 index to assess the vegetation exposure to ozone is based on this unit. Conversion from mass unit to ppb is usually carried out applying a standard coefficient of 1.96, referred to SATP conditions (Standard Ambient Temperature and Pressure = 25°C and 100 kPa). However, such conditions can greatly vary with the elevation and the average temperatures of the measuring periods at each site. Moreover the temperature at a certain elevation site depends on the temperature gradient which is not always known. As a consequence, the blanket application of a standard coefficient may lead to substantial errors in reporting and mapping ozone concentration and in the assessment of potential risk in terms of AOT40, particularly in mountain regions. In this paper, examples from two mapping exercises are presented, with regards to the ozone concentrations and the AOT40 estimation errors in the Italian Alps. Adiabatic lapse rates for temperature and pressure were applied to derive P and T at each given elevated station, starting from the T and P values recorded at some station located in the valley bottom. The error magnitude of concentration estimations ranged from 0 to 12% within the forest vertical distribution gradient, but much greater errors were recorded for AOT40 estimation during daylight hours.
|Citation:||Gerosa, G.; Finco, A.; Ferretti, M.; Gottardini, E. (2011). Errors in ozone risk assessment using standard conditions for the conversion of ozone concentrations from passive samplers in mountain regions. In: International Conference Ozone, climate change and forests: 14-16 June 2011, Prague, Czech Republic. url: http://cost-fp0903.ipp.cnr.it/events/conferenceprague.html handle: http://hdl.handle.net/10449/20810|
|Organization unit:||Sustainable Agro-Ecosystems and Bioresources Department # CRI_2011-JAN2016|
|Authors:||Gerosa, G.; Finco, A.; Ferretti, M.; Gottardini, E.|
|Title:||Errors in ozone risk assessment using standard conditions for the conversion of ozone concentrations from passive samplers in mountain regions|
|Scientific Disciplinary Area:||Settore BIO/07 - Ecologia|
|Appears in Collections:||03 - Conference object|