Metal Ion Release from Fine Particulate Matter Sampled in the Po Valley to an Aqueous Solution Mimicking Fog Water: Kinetics and Solubility

Abstract

Metals are among the key aerosol components exerting adverse health effects. Their toxic properties may vary depending on their chemical form and solubility, which can be affected by aqueous processing during aerosol atmospheric lifetime. In this work, fine particulate matter (PM 2.5) was collected in the city centre of Padua in the Po Valley (Italy), during a winter campaign. Part of the sampling filters were used to measure the kinetics by which metal ions and other elements can leach from PM 2.5 to an aqueous solution mimicking fog water in the winter in temperate climate regions (pH 4.7, 5°C). The leaching process was interpreted by a first order kinetics, and the fitting of the experimental data allowed to obtain the leaching kinetic constants and the equilibrium concentrations (i.e., at infinite time) for all elements. The remaining filter parts were mineralised, through two subsequent extraction steps, and the extracts were analysed by ICP-MS to gain the total elemental content of PM for a large number of elements. We found that elements can leach from PM with half times generally between 10-40 minutes, which is a timescale compatible with atmospheric aqueous processing during fog events. For instance, aluminium(III) in PM 2.5 dissolved with an average k = 0.0185 min-1 , and t 1/2 = 37.5 min. Nevertheless, a fraction of each element was immediately solubilised after contact with the extraction solution suggesting that metal ion solubilisation may already had started during particle lifetime in the atmosphere.

Dissolved and Suspended Forms of Metals and Metalloids in Snow Cover of Megacity: Partitioning and Deposition Rates in Western Moscow

“…Another source is washing out from the atmosphere with an ultrafine (<0.45 µm) fraction of aerosols, which passes through filters in the process of snow meltwater filtration in the laboratory. The predominance of dissolved forms of MMs could also be attributed to a slightly acidic reaction (pH 5.6) of snow meltwater in background areas, as the cationogenic Ca, Zn, Na, Cd, Ni, Cu, Sr, Co, Mg, and Ba could be easily transferred from insoluble to soluble form in acidic waters [104,108,109].…”

Emerging investigator series: aqueous-phase processing of atmospheric aerosol influences dissolution kinetics of metal ions in an urban background site in the Po Valley

“…Weighing of the lters was carried out before and aer sampling, aer conditioning at a temperature of 20 AE 1 C and relative humidity of 50 AE 5% for at least 48 h, as in previous studies. 21,37,38 Each lter was cut into three parts (a portion of 3/4 and two of 1/8), where the rst part was used for measurements of element dissolution kinetics, and the other two parts were used for determining the total content of the elements and the soluble ions. The lter samples were then stored in a refrigerator (À18 C) until analysis.…”

“…Mixing time in the cell was evaluated in a previous study and found to be <2 min. 38 A 3/4 piece of lter was loaded in a glass holder and inserted in the cell. Samples (0.75 mL aliquots) were taken from the solution at the following times: 0, 2, 4, 6,8,10,12,14,16,20,24,28,32,60,120,180, and 240 min.…”

Daily Variations In Wet Deposition And Washout Rates Of Potentially Toxic Elements In Moscow During Spring Season

“…Thus, the Zn-Sb-Ni-Ca-Co-Bi-Sn-Al-W-Cr-Fe-Na-P association is mainly formed by the blown out particles of urban soils, road dust and deicing agents, which could be partially dissolved in rainwater. For instance, at the very beginning of the contact of an acidic (pH 4.7) mimicking fog water with atmospheric PM 2.5 , a significant part of K, Cd, Mn, Mo, V, Ba, Al, Fe, Sb, Cu, and Cr are transferred to the soluble form (Di Marco et al 2020).…”

“…Thus, the Zn-Sb-Ni-Ca-Co-Bi-Sn-Al-W-Cr-Fe-Na-P association is mainly formed by the blown out particles of urban soils, road dust and deicing agents, which could be partially dissolved in rainwater. For instance, at the very beginning of the contact of an acidic (pH 4.7) mimicking fog water with atmospheric PM 2.5 , a significant part of K, Cd, Mn, Mo, V, Ba, Al, Fe, Sb, Cu, and Cr are transferred to the soluble form (DiMarco et al 2020).The second association Cu-Ba-Pb-Cd-S-B includes elements with high EFs, that are coming from anthropogenic sources (Cu, Pb, Cd, S, B), as well as anthropogenic-terrigenous Ba. Copper, as well as Pb and Cd, are used in large quantities in vehicle brake pads and linings(Fabretti et al 2009;Grigoratos and Martini 2015).…”