HR: 0830h
AN: V21C-0539    [PDF]
TI: Diffuse mercury degassing at Po\'{a}s Volcano, Costa Rica, Central America
AU: * Nolasco, D
EM:
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Spain, Granadilla, 38611 Spain
AU: Meli\'{a}n, G
EM: gladys@iter.rcanaria.es
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Spain, Granadilla, 38611 Spain
AU: Marrero, R
EM:
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Spain, Granadilla, 38611 Spain
AU: Galindo, I
EM:
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Spain, Granadilla, 38611 Spain
AU: Hern\'{a}ndez, P A
EM:
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Spain, Granadilla, 38611 Spain
AU: Salazar, J L
EM:
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Spain, Granadilla, 38611 Spain
AU: P\'{e}rez, N M
EM:
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Spain, Granadilla, 38611 Spain
AU: Fern\'{a}ndez, M
EM:
AF: Centro de Investigaciones $Geof\'{i}sicas$, Univ. Costa Rica, Costa Rica, San $Jos\'{e}$, 1000 Costa Rica
AU: Ram\'{i}rez, C
EM:
AF: Centro de Investigaciones $Geof\'{i}sicas$, Univ. Costa Rica, Costa Rica, San $Jos\'{e}$, 1000 Costa Rica
AU: Alvarado, G
EM:
AF: ICE, Costa Rica, San $Jos\'{e}$, 1000 Costa Rica
AB: Degassing magma is the primary source of Hg in volcano-geothermal systems; therefore, Hg is an important constituent in volcanic gases. Diffuse H$g^{0}$ degassing studies from Po\'{a}s volcano have been yearly performed during the 2000-2003 period. Po s volcano is a large basaltic-andesite stratovolcano, located in the Central Cordillera of Costa Rica. The purpose of this study is to evaluate the spatial and temporal variantions of H$g^{0}$ in the soil atmosphere with changes on the volcanic activity. Soil gas H$g^{0}$ content was measured using a Jerome 431-X portable analyzer, and hundreds of measurements were performed during each survey. Sampling site distributions were similar for all the surveys covering an area of 3.4 k$m^{2}$. For the four surveys, few percent of the total data showed soil H$g^{0}$ concentrations higher than the upper detection limit of the instrument, 380 ppbV. Most of the study area showed background values of soil H$g^{0}$ content, about 50 ppbV. Peak values of soil H$g^{0}$ ($>$ 300 ppbV) were mainly observed inside the main crater of Po\'{a}s volcano. For the 2000 survey, peak values ($>$ 300 ppbV) were detected at the dome within the crater. For the 2001-2003 surveys, peak values of soil H$g^{0}$ were also osberved at the eastern sector of the main crater. These observed spatial variations of soil H$g^{0}$ anomalies are temporarily correlated with an increase of fumarolic activity in the eastern part of the crater. In addition, spatial distribution of peak values of H$g^{0}$ in the eastern sector of the crater follows a N-S trending parallel to local faulting. Soil H$g^{0}$ distribution were spatially well correlated with $CO_{2}$ efflux data for the period 2000-2003 (Meli\'{a}n et al., 2001). These results suggest that a deep perturbation of the Po\'{a}s volcanic-hydrothermal system has been responsible for the observed spatial distribution pattern of soil volatiles.
UR: http://www.iter.es
DE: 8199 General or miscellaneous
DE: 8400 VOLCANOLOGY
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting