Abstract. We present the development and assessment of a new flight system that uses acommercially available continuous-wave, tunable infrared laser directabsorption spectrometer to measure N2O, CO2, CO, andH2O. When the commercial system is operated in an off-the-shelfmanner, we find a clear cabin pressure–altitude dependency forN2O, CO2, and CO. The characteristics of this artifactmake it difficult to reconcile with conventional calibration methods. Wepresent a novel procedure that extends upon traditional calibrationapproaches in a high-flow system with high-frequency, short-duration samplingof a known calibration gas of near-ambient concentration. This approachcorrects for cabin pressure dependency as well as other sources of drift inthe analyzer while maintaining a ∼90% duty cycle for 1Hz sampling.Assessment and validation of the flight system with both extensive in-flightcalibrations and comparisons with other flight-proven sensors demonstrate thevalidity of this method. In-flight 1σ precision is estimated at0.05ppb, 0.10ppm, 1.00ppb, and 10ppm for N2O,CO2, CO, and H2O respectively, and traceability to WorldMeteorological Organization (WMO) standards (1σ) is 0.28ppb,0.33ppm, and 1.92ppb for N2O, CO2, and CO. We showthe system is capable of precise, accurate 1Hz airborne observations ofN2O, CO2, CO, and H2O and highlight flightdata, illustrating the value of this analyzer for studying N2Oemissions on ∼100km spatial scales.
Abstract. Physiological aspects like heat balance, gas exchange, osmoregulation, and digestion of the early Permian aquatic temnospondyl Archegosaurus decheni, which lived in a tropical freshwater lake, are assessed based on osteological correlates of physiologically relevant soft-tissue organs and by physiological estimations analogous to air-breathing fishes. Body mass (M) of an adult Archegosaurus with an overall body length of more than 1m is estimated as 7kg using graphic double integration. Standard metabolic rate (SMR) at 20°C (12kJh−1) and active metabolic rate (AMR) at 25°C (47kJh−1) were estimated according to the interspecific allometry of metabolic rate (measured as oxygen consumption) of all fish (VO2 = 4. 8M0. 88) and form the basis for most of the subsequent estimations. Archegosaurus is interpreted as a facultative air breather that got O2 from the internal gills at rest in well-aerated water but relied on its lungs for O2 uptake in times of activity and hypoxia. The bulk of CO2 was always eliminated via the gills. Our estimations suggest that if Archegosaurus did not have gills and released 100% CO2 from its lungs, it would have to breathe much more frequently to release enough CO2 relative to the lung ventilation required for just O2 uptake. Estimations of absorption and assimilation in the digestive tract of Archegosaurus suggest that an adult had to eat about six middle-sized specimens of the acanthodian fish Acanthodes (ca. 8cm body length) per day to meet its energy demands. Archegosaurus is regarded as an ammonotelic animal that excreted ammonia (NH3) directly to the water through the gills and the skin, and these diffusional routes dominated nitrogen excretion by the kidneys as urine. Osmotic influx of water through the gills had to be compensated for by production of dilute, hypoosmotic urine by the kidneys. Whereas Archegosaurus has long been regarded as a salamander-like animal, there is evidence that its physiology was more fish- than tetrapod-like in many respects.
more » « less- Award ID(s):
- 1655756
- NSF-PAR ID:
- 10082078
- Date Published:
- Journal Name:
- Fossil Record
- Volume:
- 20
- Issue:
- 2
- ISSN:
- 2193-0074
- Page Range / eLocation ID:
- 105 to 127
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/fr-20-105-2017
