We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO₂. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe³⁺-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe²⁺-oxidation, dependent on microbially produced nitrate.

People spend increasing amounts of time at home, yet the indoor home environment remains understudied in terms of potential exposure to toxic trace metals. We evaluated trace metal (and metalloid) concentrations (As, Cu, Cr, Mn, Ni, Pb, and Zn) and health risks in indoor dust from homes from 35 countries, along with a suite of potentially contributory residential characteristics. The objective was to determine trace metal source inputs and home environment conditions associated with increasing exposure risk across a range of international communities. For all countries, enrichments compared to global crustal values were Zn > Pb > Cu > As > Cr > Ni; with the greatest health risk from Cr, followed by As > Pb > Mn > Cu > Ni > Zn. Three main indoor dust sources were identified, with a Pb–Zn–As factor related to legacy Pb sources, a Zn–Cu factor reflecting building materials, and a Mn factor indicative of natural soil sources. Increasing home age was associated with greater Pb and As concentrations (5.0 and 0.48 mg/kg per year of home age, respectively), as were peeling paint and garden access. Therefore, these factors form important considerations for the development of evidence-based management strategies to reduce potential risks posed by indoor house dust. Recent findings indicate neurocognitive effects from low concentrations of metal exposures; hence, an understanding of the home exposome is vital.

The performance of the Spectrace TN 9000 portable X-ray fluorescence (P-XRF) instrument for in situ sampling and analysis of contaminated soil was evaluated. The method was compared with laboratory analysis of the samples using ICP-AES and XRF as established methods for the assessment of contaminated land. The trueness of the field-based P-XRF results was affected by the soil moisture and the surface roughness of the in situ samples, after the correction of which, no bias was observed between the analytical results of the comparative methods. Relatively large measurement uncertainty (±55% for Pb) was caused by the small sample mass analysed and the small scale heterogeneity of the sample. This uncertainty was quantified using duplicate measurements and does not impair the delineation of ‘hot spots’ of contamination as it contributes less than 20% to the total variance. General advantages and limitations of the P-XRF methodology for the investigation of contaminated land were assessed and suggestions are made for the optimisation of the methodology.