Carbon monoxide (CO) emissions from corn silage were observed using Fourier Transform Infrared (FTIR) spectroscopy and laser spectroscopy. In the first experiment, corn silage was produced using laboratory bucket silo...Carbon monoxide (CO) emissions from corn silage were observed using Fourier Transform Infrared (FTIR) spectroscopy and laser spectroscopy. In the first experiment, corn silage was produced using laboratory bucket silos. Air samples were collected from the bucket silos during the first week of ensiling and analyzed using a low-resolution Bruker FTIR spectrometer coupled with a long optical path length White Cell. The CO concentration in the bucket silo gas, derived from the FTIR spectra using the LINEFIT program, was as high as 48.0 ppm. In the second experiment, air samples were collected through a flux chamber from an Ag-Bag silage pile on a commercial dairy that was opened several months after ensiling. The Ag-Bag air samples were analyzed using a high-resolution Bruker FTIR spectrometer, and CO concentrations were retrieved to be 6.83 ppm, corresponding to an area emission rate of 33.7 mg/(hour ·m<sup>2</sup>). An LGR N<sub>2</sub>O/CO gas analyzer based on infrared laser spectroscopy was also used to measure the CO concentrations from the same flux chamber. Elevated CO concentrations were observed from these silage sources. The present study revealed that CO was emitted by corn silage during different phases of ensiling. Annual CO emissions from the corn silage were estimated to be much lower than those from the well-known emission categories in San Joaquin Valley (SJV) and California, but comparable to those from food and agricultural sources in the SJV. It is also confirmed that FTIR spectroscopy is a viable method for measuring CO concentrations in complex gas mixtures, such as silage gas.展开更多
Nitrous oxide (N<sub>2</sub>O) is a greenhouse gas with about 300 times the global warming potential (GWP) of carbon dioxide (CO<sub>2</sub>). It is emitted from a wide range of sources and is ...Nitrous oxide (N<sub>2</sub>O) is a greenhouse gas with about 300 times the global warming potential (GWP) of carbon dioxide (CO<sub>2</sub>). It is emitted from a wide range of sources and is responsible for about 6% of anthropogenic US greenhouse gas emissions. Analytical techniques are needed that can measure concentrations of N2</sub>O rapidly and inexpensively in sources that are also emitting other compounds that may interfere with the analytical process. In this work, we demonstrate the use of Fourier Transform Infrared (FTIR) spectroscopy to analyze N2</sub>O in the complex mixture of gases produced during the early phase of the silage making process. Silage gas samples were collected into Tedlar bags from the bucket silos during the first week of corn ensiling. A bag of the silage gas was analyzed using a Bruker FTIR spectrometer coupled with a long optical path length White Cell. First, N2</sub>O infrared absorption bands were identified in the FTIR spectra of the silage gas by comparing them to both standard N2</sub>O gas and simulated infrared spectra which confirmed that N2</sub>O was present in the silage gas. Then, N2</sub>O concentration in the silage gas was derived from the FTIR spectra using LINEFIT program. It was demonstrated that FTIR spectroscopy is a viable method for measuring N2</sub>O concentrations in the silage gas.展开更多
文摘Carbon monoxide (CO) emissions from corn silage were observed using Fourier Transform Infrared (FTIR) spectroscopy and laser spectroscopy. In the first experiment, corn silage was produced using laboratory bucket silos. Air samples were collected from the bucket silos during the first week of ensiling and analyzed using a low-resolution Bruker FTIR spectrometer coupled with a long optical path length White Cell. The CO concentration in the bucket silo gas, derived from the FTIR spectra using the LINEFIT program, was as high as 48.0 ppm. In the second experiment, air samples were collected through a flux chamber from an Ag-Bag silage pile on a commercial dairy that was opened several months after ensiling. The Ag-Bag air samples were analyzed using a high-resolution Bruker FTIR spectrometer, and CO concentrations were retrieved to be 6.83 ppm, corresponding to an area emission rate of 33.7 mg/(hour ·m<sup>2</sup>). An LGR N<sub>2</sub>O/CO gas analyzer based on infrared laser spectroscopy was also used to measure the CO concentrations from the same flux chamber. Elevated CO concentrations were observed from these silage sources. The present study revealed that CO was emitted by corn silage during different phases of ensiling. Annual CO emissions from the corn silage were estimated to be much lower than those from the well-known emission categories in San Joaquin Valley (SJV) and California, but comparable to those from food and agricultural sources in the SJV. It is also confirmed that FTIR spectroscopy is a viable method for measuring CO concentrations in complex gas mixtures, such as silage gas.
文摘Nitrous oxide (N<sub>2</sub>O) is a greenhouse gas with about 300 times the global warming potential (GWP) of carbon dioxide (CO<sub>2</sub>). It is emitted from a wide range of sources and is responsible for about 6% of anthropogenic US greenhouse gas emissions. Analytical techniques are needed that can measure concentrations of N2</sub>O rapidly and inexpensively in sources that are also emitting other compounds that may interfere with the analytical process. In this work, we demonstrate the use of Fourier Transform Infrared (FTIR) spectroscopy to analyze N2</sub>O in the complex mixture of gases produced during the early phase of the silage making process. Silage gas samples were collected into Tedlar bags from the bucket silos during the first week of corn ensiling. A bag of the silage gas was analyzed using a Bruker FTIR spectrometer coupled with a long optical path length White Cell. First, N2</sub>O infrared absorption bands were identified in the FTIR spectra of the silage gas by comparing them to both standard N2</sub>O gas and simulated infrared spectra which confirmed that N2</sub>O was present in the silage gas. Then, N2</sub>O concentration in the silage gas was derived from the FTIR spectra using LINEFIT program. It was demonstrated that FTIR spectroscopy is a viable method for measuring N2</sub>O concentrations in the silage gas.
