Atmosphere
Carbon atoms are continuously exchanged between the atmosphere, the biosphere, the lithosphere (soil) and the hydrosphere (principally oceans). The dynamic of this exchange develops at different levels but usually includes an atmospheric phase. For this reason the quantities and forms of atmospheric carbon are changeable and over a certain time scale can be studied locally and regionally. Carbon in the atmosphere is therefore normally studied in relation to specific sources, drains and processes, both natural and anthropogenic. The most important carbon compounds in the atmosphere are radioactive carbons, in particular CO2 and CH4, given their importance as greenhouse gases and the fact that they are more susceptible, above all carbon dioxide, to human control.
In 2002 a regional study of electricity generation in North America demonstrated that 30% of Mexico’s carbon dioxide emissions were produced by the activities of the electricity industry. National emission inventories have placed the emphasis on CO and while the country is rich in coastal ecosystems which act as existing and potential methane producers, few quantitative studies exist. While the study of ocean-atmosphere and vegetation-atmosphere flows has only recently begun, existing photosynthesis and forestry production studies could serve as a useful basic source.
The constitution of the Mexican Carbon Program emphasized the fact that the atmosphere is a recipient of greenhouse gases produced through a variety of natural and anthropogenic processes in terrestrial and aquatic ecosystems and a greater interaction is required between research teams working in other thematic areas.
At the global level, a network has been created for the monitoring of carbon flows, “Fluxnet”. In Mexico there are only two monitoring sites with towers: one is in La Paz (with data since 2001) and the other is in the south of Sonora (with data since 2004). This latter tower is functional but not operational. The carbon flows measured by these towers vary according to the seasonal vegetation (dry season and rainy season); and a greater level of absorption has been recorded in the forested areas (Sonora) than in the desert (La Paz). Unfortunately, few large scale campaigns for the measurement of carbon flows exist in Mexico. An urgent task is the drawing up of measurement protocols that would serve to orient those who begin to take measurements in order to collect a series of data with intercalibrated methods and establish a national network using basic comparable information. The following methods for the measurement of CO2 concentrations can be used in Mexico: gradient measurements, turbulent correlation, LIDAR and Fourier Transformed Infrared (FTIR), as well as gas chromatography and simple infrared sensors.
