Particle-bound mercury characterization in the central italian herbarium of the natural history museum of the University of Florence (Italy)

Museums air quality can be negatively affected by treatments with heavy metals compounds employed to prevent pest infestations. Among these, the past use of mercury dichloride(HgCl2) on herbaria artifacts currently produces high levels of indoor atmospheric gaseous mercury(Hg0) and possibly of particulate bound Hg (PBM), i.e., the particulate matter containing Hg. Thisstudy evaluates the PBM pollution in the Central Italian Herbarium (Natural History Museum of theUniversity of Florence, Italy), characterizing the size range and chemical speciation with SEM-EDSmicroanalysis. The analysis of the total Hg concentration in the samples allowed to calculate theworkers exposure risk to this pollutant. PBM is almost totally classifiable as fine particulate witha significant dimensional increase in a period of scarce attendance of the Herbarium rooms. Themicroanalysis indicates that Hg is essentially bound to S, highlighting the change of Hg speciationfrom the original association with Cl. The average Hg concentration reveals a potential health riskfor workers as result of multiple Hg exposure pathways, mainly by ingestion. The study providesinformation for characterizing PBM pollution that could affect a workplace atmosphere and a usefulbasis to evaluate and correctly design solution strategies to reduce the contamination levels andprotect workers' health.