Laura Meredith (PI) and William Smith (Co-I) were recently awarded $141,000 for the purchase of a trace gas analyser through RDI’s Shared Equipment Enhancement Fund. Photosynthesis cannot be directly measured at the ecosystem or global scale, and traditional methods for partitioning observations of net carbon dioxide (CO 2 ) exchange into contributions from photosynthesis and respiration have known flaws. Independent tracers for photosynthesis are critical for reducing uncertainty in the responses of photosynthesis and respiration to global change and projecting the impacts of biosphere-atmosphere feedbacks. A number of promising tools have emerged for distinguishing respiration and photosynthesis processes on many scales, including carbonyl sulfide (COS), CO2 isotopes, and solar induced fluorescence (SIF). Yet, few studies have evaluated these carbon-cycle-tracers at the ecosystem scale. At Biosphere-2’ s Landscape Evolution Observatory they will test all three carbon cycle tracers simultaneously at the ecosystem scale for first time. This award from ORD of $141,328 will support the purchase of a COS trace gas analyzer to be seamlessly integrated into the LEO experimental infrastructure, thereby completing measurement capabilities of the carbon cycle tracer triad. Other faculty who will be making use of the equipment include Till Volkmann (Biosphere 2), Scott Saleska (EEB), Peter Troch (HWR), Greg Barron-Gafford (GEOG).