Harnessing the potential of biomonitors to assess atmospheric mercury pollution: recent insights and perspectives
(1) University of Siena - Dept. of Life Sciences, (2) University of Siena - Dept. of Physical Sciences, Earth and Environment
Atmospheric mercury (Hg) pollution is a global concern since this metal is ubiquitous and highly toxic. Addressing this issue requires reliable monitoring, as clearly stated in the Minamata Convention. However, the quantification of atmospheric Hg is a challenging task, impaired by large uncertainties, mainly due to instrumental constraints to determine the concentration of gaseous elemental Hg, the dominant atmospheric form of this metal. A common approach for overcoming limitations of instrumental techniques and reliably assessing the impact of airborne Hg in terrestrial ecosystems consists in using plant biomonitors and/or passive samplers. The latter has recently seen major breakthroughs, disclosing unprecedented possibilities for gaseous Hg quantification to be combined with, and in support of biomonitoring studies. An effective passive sampler (PAS) was successfully used for the detailed characterization of spatial and temporal variability of atmospheric gaseous Hg concentrations in different environments, including the former Abbadia San Salvatore Hg Mine (ASSM) in Central Italy. Notwithstanding the cessation of mining activities and the ongoing remediation and rehabilitation works, the ASSM remains a globally significant source of gaseous Hg and represents an invaluable open-air lab to establish quantitative relationships between Hg in biomonitors and in the atmosphere. At ASSM, we are currently deploying side-by-side transplanted lichen and moss samples along with the new PAS within a wide array of environmental conditions, from background up to very high concentrations. We are also conducting a tree-ring analysis to reconstruct the centennial history of the atmospheric Hg contamination at the mine site. Here we present comprehensive data from our ongoing research at ASSM, and the perspective offered by the integrated PAS-biomonitor approach to improve the current knowledge of the processes controlling Hg cycling in terrestrial ecosystems, as well as to support the management of contaminated areas.
Keywords: Terrestrial ecosystems, passive sampling, mercury, biomonitoring, mining
