Hydroxyl radical formation and soluble trace metal content in particulate matter from renewable diesel and ultra low sulfur diesel in at-sea operations of a research vessel

Abstract

Reactive oxygen species, including hydroxyl radicals generated by particles, play a role in both aerosol aging and PM2.5 mediated health effects. We assess the impacts of switching marine vessels from conventional diesel to renewable fuel on the ability of particles to generate hydroxyl radical when extracted in a simulated lung lining fluid or in water at pH 3.5, for samples of engine emissions from a research vessel when operating on ultra-low sulfur diesel (ULSD) and hydrogenation-derived renewable diesel (HDRD). Samples were collected during dedicated cruises in 2014 and 2015, including aged samples collected by re-intercepting the ship plume. After normalizing to particle mass, particles generated from HDRD combustion had slightly to significantly (5-50%) higher OH generation activity than those from ULSD, a difference that was statistically significant for some permutations of year/fuel/engine speed. Water soluble trace metal concentrations and fuel metal concentrations were similar, and compared to urban Los Angeles samples lower in soluble iron and manganese, but similar for most other trace metals. Because PM mass emissions were higher for HDRD, normalizing to fuel increased this difference. Freshly emitted PM had lower activity than the "plume chase" samples, and samples collected on the ship had lower activity than the urban reference. The differences in OH production correlated reasonably well with redox-active transition metals, most strongly with soluble manganese, with roles for vanadium and likely copper and iron. The results also suggest that atmospheric processing of fresh combustion particles rapidly increases metal solubility, which in turn increases OH production.

Source apportionment of atmospheric PM<sub>10</sub> Oxidative Potential: synthesis of 15 year-round urban datasets in France

“…For the PdB site, the contributions are a bit lower. Although only 2 sites presented an HFO factor, and similarly to previous studies (Hu et al, 2008;Kuang et al, 2017;Moldanová et al, 2013;Wang et al, 2020), it suggests that the PM originated from this source may significantly contribute to the total OP around harbor cities.…”

A light-driven burst of hydroxyl radicals dominates oxidation chemistry in newly activated cloud droplets

“…The collection and analysis methods are described in more detail by Kuang et al . ( 32 ) and are described only briefly here. PM2.5 or PM4 was collected on 47-mm Teflon filters (Pall Inc.) in sets of five, plus matched field blanks at three urban locations in California: Claremont, an urban/receptor site in southern California, during summer when SOA peaks; Fresno, during winter when biomass burning aerosol makes a substantial contribution to particulate matter (PM), especially at night and in the morning; and West Los Angeles, a relatively clean urban site about 8 km from the Pacific Ocean.…”

Water-soluble iron emitted from vehicle exhaust is linked to primary speciated organic compounds

“…In the presence of H 2 O 2 , Fe(III) is known to undergo Reaction (1) (Neyens and Baeyens, 2003;Pignatello et al, 2006), resulting in the formation of Fe(II) and HO 2 (Pignatello et al, 2006;Rubio-Clemente et al, 2014), which degrades into superoxide, O − 2 , and H + (Reaction 2). Superoxide has the ability to oxidize organic compounds, particularly aromatic structures (Reaction 3) (Lair et al, 2008). The resulting structures of these oxidized compounds typically have two oxygen atoms, which could be arranged in various functional groups (Lair et al, 2008;Rubio-Clemente et al, 2014) as observed from the HPLC chromatograms.…”

“…Superoxide has the ability to oxidize organic compounds, particularly aromatic structures (Reaction 3) (Lair et al, 2008). The resulting structures of these oxidized compounds typically have two oxygen atoms, which could be arranged in various functional groups (Lair et al, 2008;Rubio-Clemente et al, 2014) as observed from the HPLC chromatograms. Oxidized single-ring aromatic structures have a strong affinity to iron and have the ability chelate iron into aqueous solution Hosseini and Madarshahian, 2009).…”