The distribution of metals within the environment strongly depends on the formation of complexes with inorganic and organic ligands. These species can increase metal solubility, stabilize some of their oxidation states, activate some reactivity, and influence their bioavailability. In this work, the main ionic components (Fe2+/3+, Cu2+, Mn2+, Zn2+, Na+, K+, Ca2+, Mg2+, NH4+, Cl-, NO3-, PO43-, SO42-, CHOO-, CH3COO- ) in the water-soluble fraction of Antarctic (Victoria Land) and Arctic (Svalbard Islands) PM have been quantified. A chemical model, based on the interaction between the components has been defined and applied to the samples to identify the species occurring in a water solution after the dissolution of the PM. The speciation studies showed that most cations were as aquoions over the whole pH range, except for Fe which occurred predominantly in hydrolytic form. To better simulate the conditions that can occur when the PM acts as cloud condensation nuclei, the concentration of the components has been increased up to 1000 times, keeping the ratio between them constant. The role of the inorganic anion as complexing agents became important only for an increment of the concentration of 100 times, and the SO42- was the most involved in the formation of complexes. The organic complexing agents had minor importance, and a significant contribution has been observed only for those samples having a concentration of these components higher than 10-5 mol L-1 . Future studies will be necessary to improve the model using the formation constants and protonation constants of the ligands defined at lower temperatures (much similar to those of polar regions) and different ionic strengths. However, these first results allowed us to identify the chemical equilibria that most affect the soluble fraction of the metals bounded to the polar PM. This information contributes to a better knowledge of the atmospheric photochemistry processes and the biogeochemical cycles of these metals in the polar regions.
CHEMICAL SPECIATION OF ATMOSPHERIC PM FROM POLAR REGIONS
S. Bertinetti
First
;S. Berto;M. Malandrino;D. Vione;D. Fabbri;E. Conca;M. Marafante;O. Abollino;A. Annibaldi;
2022-01-01
Abstract
The distribution of metals within the environment strongly depends on the formation of complexes with inorganic and organic ligands. These species can increase metal solubility, stabilize some of their oxidation states, activate some reactivity, and influence their bioavailability. In this work, the main ionic components (Fe2+/3+, Cu2+, Mn2+, Zn2+, Na+, K+, Ca2+, Mg2+, NH4+, Cl-, NO3-, PO43-, SO42-, CHOO-, CH3COO- ) in the water-soluble fraction of Antarctic (Victoria Land) and Arctic (Svalbard Islands) PM have been quantified. A chemical model, based on the interaction between the components has been defined and applied to the samples to identify the species occurring in a water solution after the dissolution of the PM. The speciation studies showed that most cations were as aquoions over the whole pH range, except for Fe which occurred predominantly in hydrolytic form. To better simulate the conditions that can occur when the PM acts as cloud condensation nuclei, the concentration of the components has been increased up to 1000 times, keeping the ratio between them constant. The role of the inorganic anion as complexing agents became important only for an increment of the concentration of 100 times, and the SO42- was the most involved in the formation of complexes. The organic complexing agents had minor importance, and a significant contribution has been observed only for those samples having a concentration of these components higher than 10-5 mol L-1 . Future studies will be necessary to improve the model using the formation constants and protonation constants of the ligands defined at lower temperatures (much similar to those of polar regions) and different ionic strengths. However, these first results allowed us to identify the chemical equilibria that most affect the soluble fraction of the metals bounded to the polar PM. This information contributes to a better knowledge of the atmospheric photochemistry processes and the biogeochemical cycles of these metals in the polar regions.
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