Cave aerosols: distribution and contribution to speleothem geochemistry

There is developing interest in cave aerosols due to the increasing awareness of their impacts on the cave environment and speleothem; this paper provides the first attempt to synthesize the issues. Processes of cave aerosol introduction, transport, deposition, distribution and incorporation are explored, and reviewed from existing literature. Key issues of specific aerosol processes of distribution and production as well as cave location and morphology effects are highlighted through the presentation of preliminary monitoring data. This study identifies the strong relationship between cave ventilation, cave aerosols and their consequent spatial distribution.The contribution of cave aerosol deposition to speleothem geochemistry is modelled and evaluated using a mass balance framework. As an example, speleothem trace element data from Obir Cave (Austria) are compared with aerosol inputs to evaluate their significance. The mass balance study demonstrates that generally, under normal continuous growth and environmental conditions aerosol deposition will be of only minor importance. However, it highlights specific scenarios in which aerosol contributions will be significant: speleothem hiatuses (or slow growth), high aerosol deposition, and secondary microbiological feedback.

► The type of speleothem formation and cave morphology will control cave aerosol deposition. ► Speleothem location will often govern whether deposition flux rates are significant. ► Cave aerosols are sensitive to environmental conditions and show temporal and spatial variations. ► Aerosol contribution to speleothem is dependent on growth rates, deposition flux, incorporation. ► Important aerosol/speleothem scenarios: hiatus, high deposition, microbial feedbacks.