Assessment of leaching protocols to determine the solubility of trace metals in aerosols

Morgane M G Perron; Michal Strzelec; Melanie Gault-Ringold; Bernadette C Proemse; Philip W Boyd; Andrew R Bowie

doi:10.1016/j.talanta.2019.120377

Assessment of leaching protocols to determine the solubility of trace metals in aerosols

Talanta. 2020 Feb 1:208:120377. doi: 10.1016/j.talanta.2019.120377. Epub 2019 Sep 19.

Authors

Morgane M G Perron¹, Michal Strzelec², Melanie Gault-Ringold³, Bernadette C Proemse², Philip W Boyd⁴, Andrew R Bowie⁴

Affiliations

¹ Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia. Electronic address: morgane.perron@utas.edu.au.
² Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia.
³ Antarctic Climate and Ecosystems CRC, University of Tasmania, Battery Point, Tasmania, Australia.
⁴ Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia; Antarctic Climate and Ecosystems CRC, University of Tasmania, Battery Point, Tasmania, Australia.

PMID: 31816697
DOI: 10.1016/j.talanta.2019.120377

Abstract

Atmospheric deposition of aerosols to the ocean provides an important pathway for the supply of vital micronutrients, including trace metals. These trace metals are essential for phytoplankton growth, and therefore their delivery to marine ecosystems can strongly influence the ocean carbon cycle. The solubility of trace metals in aerosols is a key parameter to better constrain their potential impact on phytoplankton growth. To date, a wide range of experimental approaches and nomenclature have been used to define aerosol trace metal solubility, making data comparison between studies difficult. Here we investigate and discuss several laboratory leaching protocols to determine the solubility of key trace metals in aerosol samples, namely iron, cobalt, manganese, copper, lead, vanadium, titanium and aluminium. Commonly used techniques and tools are also considered such as enrichment factor calculations and air mass back-trajectory projections and recommendations are given for aerosol field sampling, laboratory processing (including leaching and digestion) and analytical measurements. Finally, a simple 3-step leaching protocol combining commonly used protocols is proposed to operationally define trace metal solubility in aerosols. The need for standard guidelines and protocols to study the biogeochemical impact of atmospheric trace metal deposition to the ocean has been increasingly emphasised by both the atmospheric and oceanographic communities. This lack of standardisation currently limits our understanding and ability to predict ocean and climate interactions under changing environmental conditions.

Keywords: Aerosols; Iron; Leaching protocols; Micronutrients; Solubility; Trace metals.