Guer­rero Negro

Guer­rero Negro, Baja Cal­i­for­nia.

Guer­rero Negro, the largest town located in the munic­i­pal­ity of Mulegé in the state of Baja Cal­i­for­nia Sur, is known for its salt works. The first salt mine was estab­lished in 1957 around the Ojo de Liebre coastal lagoon The com­pany even­tu­ally became in Expor­ta­dora de Sal, S. A. (Salt Exporters, Inc.), the great­est salt mine in the world.
Com­mer­cial salt ponds in Guer­rero Negro pro­duce methane gas whose iso­topic sig­na­tures may help sci­en­tists to under­stand the ori­gin of methane in Mars atmos­phere. Iso­topes are a key to under­stand­ing the ori­gin of methane because organ­isms tend to use more of the lighter iso­topes. Bio­genic methane usu­ally, but not always, con­tains a higher per­cent­age of the lighter carbon-​12 than non-​biogenic methane, which con­tains rel­a­tively more of the heav­ier carbon-​13 (Pot­ter et al., 2009; Har­ris et al., 2012).
The salt flats of Guer­rero Negro are an excel­lent out­door lab­o­ra­tory because pools of increas­ing salin­ity are cre­ated as ocean water is evap­o­rated to con­cen­trate the salt. Car­bon and hydro­gen iso­topes of the methane found in the Area 9 com­prise “a pretty unique sig­na­ture,” which falls out­side the accepted range of bio­genic methane, and thus begs for a more com­plete expla­na­tion, says iso­tope expert Jeff Chan­ton, a pro­fes­sor of Oceanog­ra­phy at Florida State Uni­ver­sity. For that rea­son alone, the salt ponds in Baja are worth study­ing.
Dr. David Des Marais and his col­leagues, from the NASA Ames Research Cen­ter in Moun­tain View (CA), have stud­ied micro­bial mats of a series of salt evap­o­ra­tion ponds that run along the Pacific shore­line near Guer­rero Negro. They believe the mats may hold impor­tant clues to what life was like on early Earth. They also hope to gain insight into how to search for signs of life on plan­ets around dis­tant stars. Only in cer­tain extreme envi­ron­ments it is pos­si­ble to find nearly pure micro­bial ecosys­tems. Guer­rero Negro is a suit­able place for that because the water in the evap­o­ra­tion ponds there is so salty that micro­bial mats can com­pete suc­cess­fully. The mats under study live in water 2 to 3 times as salty as sea­wa­ter (Hoehler et al., 2001; Vogel et al., 2009).

Ref­er­ences:

Har­ris, J. H., Capo­raso, J. G., Walker, J. J., Spear, J. R., Gold, N. J., Robert­son, C. E., Hugen­holtz, P., Goodrich, J., McDon­ald, D., Knights, D., Mar­shall, P., Tufo, H., Knight, R., and Pace, N. R. 2012. Phy­lo­ge­netic stratig­ra­phy in the Guer­rero Negro hyper­saline micro­bial mat. The ISME Jour­nal, 111.

Hoehler, T. M., Bebout, B. M., and Des Marais, D. J. 2001. The role of micro­bial mats in the pro­duc­tion of reduced gases on the early Earth. Nature. 412: 324327.

Pot­ter, E. G., Bebout, B. M., and Kel­ley, C. A. 2009. Iso­topic Com­po­si­tion of Methane and Inferred Methanogenic Sub­strates Along a Salin­ity Gra­di­ent in a Hyper­saline Micro­bial Mat Sys­tem. Astro­bi­ol­ogy. 9: 383390.

Vogel, M. B., Des Marais, D. J., Turk, K. A., Par­enteau, M. N., Jahnke, L. L., and Kubo, M. D. Y. 2009. The Role of Biofilms in the Sed­i­men­tol­ogy of Actively Form­ing Gyp­sum Deposits at Guer­rero Negro, Mex­ico. Astro­bi­ol­ogy. 9: 875893





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