versão impressa ISSN 0016-7169
Carbon dioxide flux was measured in March 2007 at the surface of the volcanic lake of El Chichón volcano, Mexico using the floating accumulation chamber method. The results of 162 measurements and the application of a standard statistical approach developed for these studies showed that the total CO2 flux from the crater lake is relatively high. The total emission rate calculated by sequential Gaussian simulation was 164 ± 9.5 t.d-1from the 138,000 m2 area of the lake. Two different mechanisms of degassing (diffusion through the water-air interface and bubbling) are well resolved by a graphical statistical approach (GSA). The highest fluxes were observed along inferred fault traces. Elevated degassing was also observed along main basement faults in the area. The average flux of CO2 over the entire crater floor of El Chichón (~ 308,000 m2) is inferred to exceed 370 t.d-1. Thus the total emission rate of CO2 from El Chichón crater is five times higher than at Kelud volcanic lake, Indonesia, but is similar to emission rates from other passively degassing active volcanoes worldwide.
Palavras-chave : CO2 flux; accumulation chamber; crater lakes; El Chichón.