DOI: 10.6075/j0v985zz
title: Stack Gas and Plume Aerosol Measurements from Renewable Diesel and Ultra Low Sulfur Diesel in At-Sea Operation of Research Vessel Robert Gordon Sproul

description: Gas and particle emissions from the R/V Sproul were measured using two sets of real-time instruments, with gas analyzers sampling directly from the stack and particle instruments intercepting the “fresh” plume, directly after emission into the atmosphere. The first set of detailed emission measurements was carried out from 29 September to 3 October 2014 (2014 cruise). The second set was carried out in two parts: from 4 September to 7 September and from 26 September to 28 September 2015 (2015 cruise). In addition, stack gas concentrations were measured on 24 other cruises scheduled for oceanographic research studies on R/V Sproul during 2015. Measurement of Stack Gases CO, CO2 and NOx concentrations were measured from the stack using a custom-designed probe, heated inlet, and water-removal system (GK Associates, Simi Valley; Universal Analyzers, Carson City). The engine exhaust was sampled through a probe inserted into the main stack vent of the starboard engine. Particles were removed from the exhaust after the probe at the upstream end of the heated sampling line by a Teflon filter element with 2 μm nominal cut size (Universal Analyzers, Carson City, Nevada). The insulated line was 5 m long embedded with 1/2” OD Teflon tube and heating elements controlled to 150°C. The cooling unit chilled the line to ca. 20°C, removing condensed water to a trap and filtering any remaining particles. The flow was set to 4 L min-1, providing 850 cm3 min-1 to the CO Analyzer (Model: T300 with CO2 module, Teledyne API, San Diego), and 250 cm3 min-1 (diluted by a measured ratio of zero air) to the NOx analyzer (Model: T200M, Teledyne API, San Diego), with the excess vented. Particle Measurements in Aerosol Sampling Van During the dedicated 2014 and 2015 sampling cruises, cooled and diluted particle emissions from the R/V Sproul were measured using the plume intercept method with the inlet of the aerosol sampling van. Particles were measured in the plume approximately 20 m downwind of the engine stacks, heading directly into the wind. Atmospherically relevant dilution factors and temperatures were achieved by the time the plume was sampled. An isokinetic inlet with a motorized horizontal shroud mounted on the sampling van was used to sample the plume. Air pulled through the inlet was then distributed through a sampling plenum to the particle instruments housed in the van. Size distributions of sub-micrometer particles (0.01 - 1 μm) were measured with a Scanning Electrical Mobility Spectrometer (SEMS, Model 138 2002, Brechtel Manufacturing Inc., Hayward CA). Larger particles were measured using an Aerodynamic Particle Sizer (APS, Model 3321, TSI Inc., Shoreview MN; size range 0.5– 20 μm) and an Optical Particle Sizer (OPS, Model 330, TSI Inc., Shoreview MN; size range 0.3–10 μm). The Single Particle Soot Photometer (SP2, Model SP2-C, DMT, Boulder CO) was used to measure refractory Black Carbon (BC, or soot) mass and number concentrations, as well as size distributions in the 0.07 to 0.4 μm range. CO2 concentrations in the plume were measured using an infrared CO2 analyzer (Model LI-840, LI-COR, Lincoln, Nebraska). The chemical composition of the non-refractory components of the particle-phase was measured by High Resolution Time of Flight Aerosol Mass spectrometer (Model: HR-ToF-AMS with ET, Aerodyne, Billerica MA) after a PM1 size cut cyclone. The instrument was operated in two ion flight path modes. The shorter flight path (V-mode) provides better sensitivity at unit mass resolution (UMR), while the longer flight path (W-mode) provides sufficient mass spectral resolution (4300 at m/z 200) to determine empirical formulas of the ionized aerosol fragments. Characteristics of single-particles were also investigated by the Event Trigger Single Particle (ETSP) mode of the HR-ToF-AMS during the 2015 cruise. An event is defined as a single mass spectrum (MS) extraction or series of consecutive extractions containing signals corresponding to the detection of a particle. The ETSP mode was set to have three Regions of Interest (ROI), which is a continuous range of mass-to-charge values having signals associated with particles of interest. ROI1 was set to m/z 43 (C3H7+, hydrocarbon particles) with an event trigger level of 2 ions/extraction, ROI2 was set to m/z 46 (NO2+, nitrate particles) with an event trigger level of 1.5 ions/extraction, and ROI3 was set to m/z 48-150 (sulfate and organic particles) with an event trigger level of 4 ions/extraction. Single particle measurements were analyzed by Tofware version 2.5.3.b (developed by TOFWERK and Aerodyne Research, Inc.) and cluster analysis panel (CAP) version ETv1.2a (developed by Alex Lee and Megan Willis, University of Toronto). The HR-ToF-AMS was operated under a 5 min mode switching cycle (V-mode, 2-min; ETSP-mode (UMR), 2-min; W-mode, 1-min). The organic functional groups of submicron atmospheric particles were measured using Fourier transform infrared (FTIR) spectroscopy. Atmospheric particles were sampled on 37 mm Teflon filters using a 1 μm sharp-cut cyclone at a flow rate of 16.7 lpm. Back filters were used as a measure of sampling error. Samples were then frozen and transported to the laboratory for FTIR spectroscopy analysis. All samples were kept in a humidity and temperature-controlled room (RH = 35-45%, Temp = 20°C) for at least 24 hours prior to the analysis. Functional groups associated with carbon bond types, including alkane groups, alkene or aromatic groups, alcohol groups, carboxylic acid groups, carbonyl groups, and amine groups were characterized based on the absorbance of infrared wavelengths by each sample using Tensor 27 spectrometer (Bruker Optics). An automated algorithm including baselining, peak fitting, and integration was used to interpret the FTIR spectrum from each filter.
description: Reading data in ICARTT Format (.ict files): Dates and times in file names are in UTC. The date and time in the file name give the date/time at which the data within the file begin. For more information on reading and understanding the data in ICARTT format visit: http://www-air.larc.nasa.gov/missions/etc/IcarttDataFormat.htm If you are using Igor Pro, you should be able to use this software to read the files: http://cires1.colorado.edu/jimenez-group/wiki/index.php/Analysis_Software#ICARTT Alternatively, you can open the .ict files directly using the import data tool in excel.