No Particle Mass Enhancement from Induced Atmospheric Ageing at a Rural Site in Northern Europe

Abstract

A large portion of atmospheric aerosol particles consists of secondary material produced by oxidation reactions. The relative importance of secondary organic aerosol (SOA) can increase with improved emission regulations. A relatively simple way to study potential particle formation in the atmosphere is by using oxidation flow reactors (OFRs) which simulate atmospheric ageing. Here we report on the first ambient OFR ageing experiment in Europe, coupled with scanning mobility particle sizer (SMPS), aerosol mass spectrometer (AMS) and proton transfer reaction (PTR)-MS measurements. We found that the simulated ageing did not produce any measurable increases in particle mass or number concentrations during the two months of the campaign due to low concentrations of precursors. Losses in the reactor increased with hydroxyl radical (OH) exposure and with increasing difference between ambient and reactor temperatures, indicating fragmentation and evaporation of semivolatile material.

Ship plumes in the Baltic Sea Sulfur Emission Control Area: chemical characterization and contribution to coastal aerosol concentrations

“…Further, the fact that the reactor was kept in an air-conditioned space increases the losses when it is colder outside (e.g. during nights), which was also seen by Ahlberg et al (2019). No trend in the enhancement of particle mass with OH exposure was seen, likely due to the comparably low exposures.…”

“…There are several other parameters which affect the absolute emission of PM as well as the particle composition, such as fuel type, operation conditions, engine load, engine properties, and maintenance. Ship exhaust also contains elevated levels of nitrogen oxides (NO x , including NO 2 and NO), sulfur dioxide (SO 2 ), carbon monoxide (CO), carbon dioxide (CO 2 ), and volatile organic compounds (VOCs) (Sinha et al, 2003;Chen et al, 2005;Alföldy et al, 2013;Moldanová et al, 2009;Huang et al, 2018;Cooper, 2001). Concentrations of CO 2 can be used to estimate emission factors of gases and particles.…”

“…To date, a number of atmospheric studies of individual ship plumes have been conducted in harbour areas (Alföldy et al, 2013;Healy et al, 2009;Jonsson et al, 2011;Lu et al, 2006;Westerlund et al, 2015) and also in the Arctic (Aliabadi et al, 2015). One study of aged plumes from a shipping lane has been performed by Kivekäs et al (2014), off the west coast of Denmark, measuring plumes with an atmospheric age of about 1 h. In the study by Kivekäs et al (2014) ship plumes were measured at a coastal station about 25-50 km from the shipping lane, where there was good potential to study the impact of ship emissions on land concentrations and how particles are aged during semi-long-range transport.…”

Ship plumes in the Baltic Sea Sulphur Emission Control Area: Chemical characterization and contribution to coastal aerosol concentrations

“…OFRs can be used for qualitatively observing ships that contribute a lot to secondary aerosol inland, but should preferably be placed closer to the shipping lanes. Care must also be taken to ensure that reported secondary particle formation is not influenced by the background condensation sink (Palm et al, 2016;Ahlberg et al, 2019). 360…”

Ambient Aerosol Measurements in Different Environments

“…Aerosol particles are both primarily emitted in the atmosphere and secondarily formed from atmospheric processing of organic and inorganic precursors, with the secondary organic aerosol (SOA) constituting a substantial fraction of the mass of submicron aerosol in populated areas around the world; this contributes to poor air quality and premature mortality [9]. In the first ambient oxidation flow reactor measurements in Europe, Ahlberg et al [4] demonstrated that there was no increase in particle mass or number concentrations during the two months of the campaign, which was primarily attributed to limited gaseous precursor concentrations and, to a lesser extent, to a net particle mass loss of ~10%, correlated to ambient temperature and OH exposure. It was shown that, with ambient PM 1 concentrations in the order of 3 µg m −3 , one order of magnitude higher precursor concentrations would have been needed to form significant amounts of SOA in the reactor.…”