Abundance and Fractional Solubility of Aerosol Iron During Winter at a Coastal City in Northern China: Similarities and Contrasts Between Fine and Coarse Particles

Abstract

Iron (Fe), an essential micronutrient for all the living organisms, plays important roles in photosynthesis, respiration and nitrogen fixation of marine phytoplankton (Moore et al., 2013). Although it is one of the most abundant elements in the crust, concentration of dissolved Fe in oceanic water is very low, limiting primary productivity and affecting phytoplankton ecosystem structures in many open oceans (Boyd & Ellwood, 2010;Jickells et al., 2005;Tagliabue et al., 2017). In high nutrient low chlorophyll (HNLC) regions (e.g., Southern Ocean, subarctic North Pacific and east tropical Pacific) which cover around 30% of global oceans, Fe supply directly limits or colimits photosynthesis and thus primary production (Jickells et al., 2014). Moreover, Fe supply limits or colimits microbial nitrogen fixation and thus also affects primary production over vast tropical nutrient-poor regions (e.g., tropical Pacific, South Atlantic, and Indian Ocean) (Jickells et al., 2014). There are evidence that increased supply of soluble Fe to some oceanic regions would increase primary productivity (Boyd et al., 2007;Tang et al., 2021), having important implications for CO 2 uptake and climate (Jickells et al., 2005). It has been proposed that increase in dust and thus Fe deposition during the last glacial maximum caused increase in carbon export to deep ocean and decrease in atmospheric CO 2 (Martin, 1990).Major external sources of Fe in surface oceans include aerosol deposition, riverine input, continental margins, hydrothermal activities and glacial sediments, and aerosol deposition is a major Fe source for open oceans (Conway & John, 2014;Jickells et al., 2005;Tagliabue et al., 2017). In addition, aerosol Fe (as well as other transition metals such as Cu and Mn) also plays important roles in chemical reactivity of aerosol particles (Alexander et al., 2009;Martin & Good, 1991) and their health effects (Daellenbach et al., 2020;Fang et al., 2017). However, a large fraction of aerosol Fe may not be bioavailable. Fe availability is in fact poorly defined and understood, and soluble Fe has been widely used as a proxy for bioavailable Fe (Baker & Croot, 2010;Meskhidze et al., 2019).

Persistent Uptake of H2O2 onto Ambient PM2.5 via Dark-Fenton Chemistry

“…Furthermore, the stability of these complexes may be significantly impacted by aerosol pH, resulting in a nonlinear trend between the fractions of different forms of complexes and pH. , Figure d displays the Fe solubility under different aerosol pHs. Summer PM 2.5 showed a higher Fe solubility (9%) than winter PM 2.5 (6%), which may be ascribed to the proton-promoted dissolution . These findings indicate complex interactions among the dissolved Fe, oxalate, and pH in aerosols.…”

“…Summer PM 2.5 showed a higher Fe solubility (9%) than winter PM 2.5 (6%), which may be ascribed to the proton-promoted dissolution. 14 findings indicate complex interactions among the dissolved Fe, oxalate, and pH in aerosols. For summer PM 2.5 , the acidic condition enhances the Fe solubility and stabilizes the oxalate in the form of Fe-oxalate.…”

“…The heterogeneous reactions between H 2 O 2 and particles significantly influence H 2 O 2 budget and the aerosol oxidation capacity. − For instance, Qin et al found that H 2 O 2 uptake accounted for more than 65% of the total removal for gas-phase H 2 O 2 . Additionally, the migration and conversion of gas-phase H 2 O 2 to the particle phase can deliver oxidants to aerosols and further enhance the production of various oxidized compounds, , thereby deteriorating air quality and causing adverse health effects.…”

The Effects of Aminium and Ammonium Cations on the Ice Nucleation Activity of K‐Feldspar

“…We investigated the effects of the ammonium and aminium cations on the dissolution of K‐feldspar particles, in attempt to better understand the observed changes in the ice nucleation activity of K‐feldspar in the presence of aminium cations. Dissolution of K and Al from K‐feldspar was measured using Inductively Coupled Plasma Mass Spectrometry (ICP‐MS, Agilent 7900) (Zhang et al., 2021). K and Al were chosen because they are main elements of K‐feldspar.…”

Elucidating the Mechanism on the Transition-Metal Ion-Synergetic-Catalyzed Oxidation of SO2 with Implications for Sulfate Formation in Beijing Haze

“…Dissolved Fe(III) ions are the reactive oxidants for the Fe(III)-catalyzed oxidation of SO 2 , but the speciation of irons and the formation of sulfite species are controlled by the aqueous phase acidity. 44,45 In the absence of NH 3 , the initial acidity of the seeded Fe(III)-containing particles could inhibit the hydrolysis of SO 2 , leading to low levels of S(IV) species and an ignorable amount of sulfate formed on the aerosol phase without NH 3 . Although the S(IV) concentration increased in the presence of NH 3 , the enhanced hydrolysis of Fe(III) resulted in the dissolved Fe(III) relative to the total dissolved iron species decreasing dramatically.…”