Mt Erebus is an active alkaline volcano located on Ross Island, Antarctica. The constant activity and its location in the pristine Antarctic environment, far from interfering pollution sources, makes this volcano and exceptional site for volcanic gas measurements. During three austral summer seasons (1997-98, 1999-2000, and 2000-2001) the CO2 flux from the plume of Mt. Erebus was measured by the direct airborne technique. Results of 21.4, 23.3, and 22.2 kg/s show the flux of CO2 remained constant during the three measurements conducted over the four-year period and ranks Mt. Erebus in the top ten of known volcanic CO2 emission rates worldwide.

The amount of CO2 lost through flank degassing was also measured. Mt. Erebus offers a unique situation as flank degassing is visible from fumarolic ice towers or as steaming warm ground. Measurements from 42 of the ice towers as well as soil gas measurements from the warm ground areas indicate that CO2 lost by this form of degassing is not significant (<2% of plume flux). Isotope samples collected from inside ice caves and from warm ground verify the magmatic nature of the CO2 emissions.

Current global volcanic CO2 estimates significantly underestimate the contribution from subaerial volcanism despite its importance to the pre-industrial geochemical carbon cycle. This is becoming clearer as more measurements are being conducted on volcanoes and the contribution from both passive and diffuse degassing may actually be more significant than that from eruptive degassing. Current global estimates of subaerial volcanic CO2 is approximately 2.0-2.5 Tmol/yr (representing 300 to 600 active volcanoes worldwide), but the contribution from only 24 volcanoes yields a CO2 flux of 1.7 Tmol·yr-1 (2.7 Tmol/yr if the value for Pinatubo is included).

In addition, volcanoes emit large amounts of trace metal and other elemental species into the atmosphere. By using the simple chemical trap method, the flux of Pb (2x10e-3 kg/s) and Hg (6x10e-4 kg/s) were determined for Mt. Erebus. A simple box model indicates that Mt. Erebus emits sufficient Pb to account for elevated Pb concentrations found in snow and ice samples at South Pole and Dome C, which were previously blamed on anthropogenic sources. Using previously reported trace element emission results collected by the LiOH-impregnated filter technique, the accuracy of the chemical trap method proven effective as the average flux values for all chemical species studied relative to sulfur (Cl, F, Pb, Hg, As, Se and Sb) were found to be within the error range of the results from the filter method. The utility of the chemical trap method was further supported by measurements at a second volcano, White Island, New Zealand.