Environmental impacts of tropospheric volcanic gas plumes
Recent studies suggest that the environmental effects of volcanic gas emissions in the lower troposphere have been underestimated. This chapter first briefly summarizes the techniques available for characterizing tropospheric volcanic gas plumes, including the composition and fluxes of emitted gases and aerosols, as well as their atmospheric dispersion. The second part documents the contribution of gas emissions from degassing craters to the composition of the atmosphere, including effects from dry and wet deposition chemistry. The third section deals with the detrimental impacts on vegetation, soils, and groundwater in relation to passive degassing activity. Improved understanding of the impacts of volcanic degassing on the atmospheric and terrestrial environment will require: (1) systematic two-dimensional and three-dimensional measurements of tropospheric volcanic plumes, (2) development of general physical and chemical models to describe the fate of volcanic gases and aerosols during transport in the troposphere, and (3) investigation of the response of diverse ecosystems to volcanogenic air pollution.