> Managing CO2 levels was a particular challenge, and a source of controversy regarding the Biosphere 2 project's alleged misrepresentation to the public. [...] The crew worked to manage the CO2 by occasionally turning on a CO2 scrubber [...] In November 1991, investigative reporting in The Village Voice alleged that the crew had secretly installed the CO2 scrubber device, and claimed that this violated Biosphere 2's advertised goal of recycling all materials naturally.
> A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate in a process called carbonatation, thereby sequestering both carbon and oxygen.
> Managing CO2 levels was a particular challenge, and a source of controversy regarding the Biosphere 2 project's alleged misrepresentation to the public. [...] The crew worked to manage the CO2 by occasionally turning on a CO2 scrubber [...] In November 1991, investigative reporting in The Village Voice alleged that the crew had secretly installed the CO2 scrubber device, and claimed that this violated Biosphere 2's advertised goal of recycling all materials naturally.
> A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate in a process called carbonatation, thereby sequestering both carbon and oxygen.