Development of matrix-specific standards for LA-ICP-MS zinc analysis in sand flathead (Platycephalus bassensis).

The use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to analyse soft tissues is limited because of the lack of suitable certified reference materials resulting in difficulties with calibration. In this study, several laboratory-prepared thin agarose sections were tested as matrix-specific standards. Our results showed 1 mm thin agarose sections were suitable as calibration standards for LA-ICP-MS Zn analyses in fish muscle, especially when the signal intensity of 66Zn was normalised to 13C. The thin agarose standard sections were used for LA-ICP-MS Zn analyses in the muscle of melanised and non-melanised sand flathead collected from a polluted estuary and assigned with different melanisation scores. Zn levels in melanised regions of fish muscle were determined to be significantly higher than non-melanised regions across all melanisation scores, though Zn levels in the melanised regions of muscle were not significantly different between sand flathead with different melanisation scores. In non-melanised regions of muscle from fish with melanisation and fish unaffected by melanisation, Zn levels were around baseline levels. Overall, this study has successfully developed matrix-specific standards for LA-ICP-MS analysis of soft tissues, thus allowing broader application of this analytical technique in future environmental pollution studies.

Correction to: Development of methodology to generate, measure and characterize the chemical composition of oxidized mercury nanoparticles.

The authors would like to call the reader's attention to the fact that, unfortunately, there was an unintentional oversight regarding the funding information in this manuscript; please find the correct information below.

Development of methodology to generate, measure, and characterize the chemical composition of oxidized mercury nanoparticles.

The phase of oxidized mercury is critical in the fate, transformation, and bioavailability of mercury species in Earth's ecosystem. There is now evidence that what is measured as gaseous oxidized mercury (GOM) is not only gaseous but also consists of airborne nanoparticles with distinct physicochemical properties. Herein, we present the development of the first method for the consistent and reproducible generation of oxidized mercury nano- and sub-micron particles (~ 5 to 400 nm). Oxidized mercury nanoparticles are generated using two methods, vapor-phase condensation and aqueous nebulization, for three proxies: mercury(II) bromide (HgBr2), mercury(II) chloride (HgCl2), and mercury(II) oxide (HgO). These aerosols are characterized using scanning mobility and optical sizing, high-resolution scanning transmission electron microscopy (STEM), and nano/microparticle interface coupled to soft ionization mercury mass spectrometric techniques. Synthetic nanoparticle stability was studied in aqueous media, and using a microcosm at ambient tropospheric conditions of ~ 740 Torr pressure, room temperature, and at relative humidity of approximately 20%. Analysis of microcosm airborne nanoparticles confirmed that generated synthetic mercury nanoparticles retain their physical properties once in air. KCl-coated denuders, which are currently used globally to measure gaseous mercury compounds, were exposed to generated oxidized mercury nanoparticles. The degree of synthetic mercury nanoparticle capture by KCl-coated denuders and particulate filters was assessed. A significant portion of nanoparticulate and sub-micron particulate mercury was trapped on the KCl-coated denuder and measured as GOM. Finally, we demonstrate the applicability of soft ionization mercury mass spectrometry to the measurement of mercury species present in the gaseous and solid phase. We recommend coupling of this technique with existing methodology for a more accurate representation of mercury biogeochemistry cycling. Graphical Abstract.