Can co2 O C O & o2 o/o can pass through a membrane lipid bilayer by diffusion?

Author links open overlay panelMatthäusKielaPersonEnvelopeAnnmarieElderingaDustin D.RotendJohn C.LindShaFengbjRuixueLeibThomasLauvauxcTomohiroOdaefgColeen M.RoehlhJean-FrancoisBlavieraLaura T.Iracii

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https://doi.org/10.1016/j.rse.2021.112314Get rights and content

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Abstract

NASA's Orbiting Carbon Observatory-3 (OCO-3) was designed to support the quantification and monitoring of anthropogenic CO2 emissions. Its Snapshot Area Map (SAM) and target mode measurements provide an innovative dataset for carbon studies on sub-city scales. Unlike any other current space-based instrument, OCO-3 has the ability to scan large contiguous areas of emission hot spots like cities, power plants, and volcanoes. These measurements result in dense, fine-scale spatial maps of column averaged dry-air mole fractions of carbon dioxide (XCO2). For the first time, we present and analyze XCO2 distributions over the Los Angeles megacity (LA) derived from OCO-3 SAM and target mode observations. Urban XCO2 enhancements range from 0 − 6 ppm (median enhancements ≃ 2 ppm) relative to a clean background and show excellent agreement with nearby ground-based TCCON measurements of XCO2. OCO-3's dense observations reveal intra-urban variations of XCO2 over the city that have never been observed from space before. The spatial variations are mainly driven by the complex fossil fuel emission patterns and meteorological conditions in the LA Basin and are in good agreement with those from co-located TROPOMI measurements of co-emitted NO2. Differences between measured and simulated XCO2 enhancements from two models (WRF-Chem and X-STILT) are typically below 1 ppm with larger differences for some sub regions. Both models capture the observed intra-urban XCO2 gradients. Further, OCO-3's multi-swath measurements capture about three times as much of the city emissions compared to single-swath overpasses. OCO-3's frequent target and SAM mode observations will pave the way to constrain urban emissions at finer, sub-city scales.

The process is a genuine Carbon Capture and Utilisation (CCU) process. During the process, significant volumes of carbon dioxide are permanently captured as stable carbonates.

The process has further benefit in the valorisation of thermal wastes as construction products. At the three commercial facilities in the UK, carbonated thermal wastes are blended with binders and fillers and then pelletised to form a rounded aggregate (M-LS or Manufactured-LimeStone) that has many applications in construction.

The finished M-LS has captured more carbon dioxide than is emitted in its manufacture, resulting in the World’s first carbon negative aggregate.

The principal science objective of the OCO-2 mission is to retrieve a global geographic distribution of carbon dioxide (CO2) sources and sinks. However, the OCO-2 mission does not directly measure CO2 sources and sinks. Instead, sophisticated computer-based data assimilation models that use column averaged dry air CO2 mole fraction (XCO2) data infer the location of these sources and sinks.

To get the representative values of XCO2, or the amount of CO2 in the measured space, the OCO-2 instrument measures, at a given location, the intensity of reflected sunlight off the Earth's surface at specific wavelengths. Gas molecules in the atmosphere absorb the sunlight at specific wavelengths. So, when light passes through the Earth's atmosphere, the gases that are present leave a distinguishing fingerprint that can be captured. The OCO-2 spectrometers, working like cameras, detect these molecular fingerprints. Then the absorption levels shown in these spectra, like a captured image, tells us how many molecules were in the region where the instrument measured. The OCO-2 measurement approach concentrates on gathering data near the Earth's surface, where almost all of the CO2 sources and sinks are located.

One of the challenges to get to these sources and sinks is that the light detected by the instrument must penetrate through all of the atmosphere. If you can picture the image of Earth from space, that image will always include white swirls over the land and ocean. The presence of clouds and optically thick aerosols or uneven terrain such as mountains can block the light and create an incomplete measurement of the complete atmospheric column. To reduce any uncertainties, the OCO-2 instrument acquires a large number of densely-spaced samples. Each sample covers an area of about 3 km2 when the instrument is looking straight down (nadir), along the spacecraft's ground track. The OCO-2 instrument can gather as many as 72,000 soundings on the sunlit side of any orbit. With measurement footprints of this size and density, the OCO-2 instrument acquires an adequate number of high quality soundings, even in those regions where clouds, aerosols and topographic variations are present.

To make sure that we have an accurate derivation of XCO2, we also do a comparative absorption measurement of a second atmospheric gas, oxygen (O2). The concentration of molecular oxygen O2 is constant, well known, and uniformly distributed throughout the atmosphere. Therefore, O2 is the best candidate for reference measurements. The O2 A-band wavelength channel, in the vicinity of 0.76 µm, provides the required absorption spectra. The O2 A-band spectra indicate the presence of clouds and optically thick aerosols that preclude full column measurements of CO2. Observations from this band are used to infer the total atmospheric pressure, as well as to measure the solar light path length as it passes through the atmosphere. OCO-2 mission designers selected three specific Near Infrared (NIR) wavelength bands – O2 (Oxygen), A-band Weak CO2, and Strong CO2. The OCO-2 instrument measures intensity over all three of these bands at the same location on the Earth's surface simultaneously. Each of the three selected wavelength bands provides specific information to measurement accuracy. The weak CO2 band wavelength, in the vicinity of 1.61 µm, is most sensitive to the CO2 concentration near the surface. Since other atmospheric gases do not absorb significant energy within this spectral range, the 1.61 µm band measurements are relatively clear and unambiguous.

Last, but not least, the strong CO2 wavelength channel, in the vicinity of 2.06 µm, provides a second and totally independent measure of the CO2 abundance. The 2.06 µm band spectra are very sensitive to the presence of aerosols. The ability to detect and mitigate aerosol presence enhances the accuracy of XCO2. The 2.06 µm band measurements are also sensitive to variations in atmospheric pressure and humidity along the optical path. These variations in pressure and humidity have a known impact on XCO2.

OCO-2 flies in a polar, sun-synchronous orbit, providing global coverage with a 16-day repeat cycle. On each orbit, the Observatory path crosses the equator at approximately 1:35 PM local time. Acquisition at this time of day is ideal for spectroscopic observations of CO2 that use reflected sunlight, as the high sun maximizes the measurement signal-to-noise ratio. Furthermore, since XCO2 measurements tend to be near their daily average value at this time of day, the Observatory data will be highly representative of the region where they were acquired. Coordination of the orbit with the A-train facilitates carbon cycle science by integrating OCO-2 observations with those of other instruments that fly aboard the Aqua and Aura spacecraft. Among these measurements are the temperature, humidity, and CO2 retrievals from Atmospheric Infrared Sounder (AIRS), the cloud, aerosol and ocean color observations as well as carbon source and sink measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS), and the CH4 and CO retrievals from Tropospheric Emission Spectrometer (TES).

Is OCO a carbon dioxide?

How does OCO

What gas is OCO?

What are the limitations of the OCO measurements?