PNNL

Abstract

Sea spray aerosol (SSA) and lake spray aerosol (LSA) from wave breaking contribute to 17 particulate matter (PM) in coastal regions near oceans and freshwater lakes, respectively. 18 However, SSA and LSA contributions to atmospheric aerosol populations in inland regions are 19 poorly understood due to difficulties differentiating them from other inland sources when using 20 bulk particle measurements. Herein, we show that SSA and LSA episodically contribute to 21 atmospheric aerosol populations at a rural site in northern Michigan >700 km and >30 km from 22 the nearest ocean and Great Lakes sources, respectively. During July 2014, individual SSA and 23 LSA particles were identified by single particle mass spectrometry and electron microscopy, 24 then combined with air mass trajectory analysis for source apportionment. During two multiday 25 transport events from Hudson Bay, SSA comprised 34% and 20% of PM mass (0.5-2.0 µm). 26 LSA transported from Lake Michigan reached a maximum of 11% of PM mass (0.5 – 2 µm) 27 during a daylong high wind event, but also contributed a 5% average background during 92% of 28 the study. Therefore, transported SSA and LSA particles can contribute to particle mass, altering 29 atmospheric composition, cloud formation, and human exposures at inland locations far from 30 marine and freshwater sources.