the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 13 Feb 2024
Emission characteristics of reactive organic gases from industrial volatile chemical products (VCPs) in China
Abstract. Volatile chemical products (VCPs) have become an important source of reactive organic gases (ROGs) in urban areas worldwide. Industrial activities can also utilize a large amount of VCPs and emit many organic gases into the atmosphere. Due to multiple sampling and measurement challenges, only a subset of ROG species is usually measured for many industrial VCP sources. This study aimed to investigate the emissions of ROGs from five industrial VCP sources in China, including shoemaking, plastic surface coating, furniture coating, printing, and ship coating industries. More comprehensive speciation of ROG emissions from these industrial VCP sources was developed by the combination of the proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) along with gas chromatography-mass spectrometer/flame ionization detector (GC-MS/FID). Our study identified oxygenated ROG species (OVOCs) as representative ROGs emitted from these sources, which are highly related to specific chemicals used during the industrial activities. Moreover, mass spectra similarity analysis revealed significant dissimilarities among the ROG emission sources, indicating substantial variations between different industrial VCP sources. Except for the ship coating industry utilizing solvent-borne coatings, the proportions of OVOCs range from 67 % to 96 % in total ROG emissions and 72 % to 97 % in total OH reactivity (OHR) for different industrial sources. The industrial VCP sources associated with solvent-borne coatings exhibited a higher ozone formation potential (OFP), reaching as high as 5.5 and 2.7 g O3·g-1 ROGs for ship coating and furniture coating industries, primarily due to contributions from aromatics. The fractions of the ten most abundant species in total ROG emissions, OHR, and OFP indicated a highly centralized of ROG emissions from various industrial VCP sources. Our results suggest that ROG treatment devices may have limited effectiveness for all ROGs, with treatment efficiencies ranging from -12 % to 68 %. Furthermore, we found that ROG pairs (e.g., methyl ethyl ketone (MEK) /C8 aromatics ratio) could serve as effective indicators for distinguishing industrial VCP sources, particularly for measurements in industrial areas. Our study demonstrated the importance of measuring a large number of ROGs using PTR-ToF-MS for characterizing ROG emissions from industrial VCP sources.
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RC1: 'Comment on egusphere-2024-380', Anonymous Referee #1, 15 Mar 2024
The authors present comprehensive speciation of ROG emissions from industrial VCP sources, including shoemaking, plastic surface coating, furniture coating, printing, and ship coating industries. They use the combination of a PTR-ToF-MS in H3O+ and NO+ to capture OVOCs and long chain alkanes, respectively, alongside a GC-MS to identify individual molecules and smaller alkanes. They highlight the important contribution of OVOCs not only to the overall emissions but also to the reactivity, ozone, and SOA formation potential. Finally, they evaluate the performance of ROG treatment devices used to reduce ineffectively emissions from these VCP sources. This paper provides unique insights on the emission fingerprint of VOCs and OVOCs from industrial VCPs in China and is suitable for publication after the following minor comments.
Comments:
I recommend that the authors thoroughly proofread and improve the English, especially in the supplement and captions.
Line 38-39: The meaning of this sentence is unclear to me.
Line 66: Delete the word "on."
Lines 97-98: This sentence feels somewhat out of place.
Line 100: Add "...attributed to a VCP-dominated..."
Line 126: I'm unsure about the definition of ROG treatment devices. It would be helpful to define this term early on, as it is used extensively throughout, including in figure captions.
Line 149: These sampling lines are quite long. Is there any treatment for wall losses, especially for sticky OVOCs?
Line 188: Remove the double dot.
Lines 221-223: This sentence is unclear. Please rephrase it.
Lines 235-238: One could argue that this agreement is not ideal when both axes are in logarithmic scale. The differences are often greater than a factor of 2. More discussions on these differences would be great, especially considering the fragmentation interferences for both ionization methods.
Section 3.1: The current organization of the paper, with frequent references to Figures 1 and 2, makes it difficult for the reader to follow. I suggest reconstructing the paper to address each emission source separately, with overview graphs that combine information from both (or more) figures. The comparison of all sources could be presented in a separate figure.
Lines 251-252: Please provide more elaboration on what is meant here. Is it that the angle θ approach was previously only used for AMS spectra, which have substantial fragmentation compared to PTR?
Lines 260-262: It's unclear what is meant by collection devices and collection and treatment devices, as well as their differences.
Lines 263-264: How do these treatment devices work? How do they ensure fewer ROG emissions?
Lines 265-266: I'm unsure about the meaning of this sentence. Please define what stacked emissions are.
Line 327: Replace "are" with "have".
Lines 327-331: Did the authors measure outside air and consider its influence on the measured spectra? Could there be any influence from outside air on the factory spectra? Given that later on, ambient measurements are discussed, it might be worth comparing the two in more detail.
Line 354: Change to "a quantification."
Line 427: Delete the word "in."
Lines 453-457: It would be helpful to provide a more detailed description of how O3 sensitivity was calculated here, rather than limiting it to previous citations.
Lines 536-530: The definition of treatment devices should be introduced earlier and discussed at the beginning of the paper.
Section 3.3: This discussion is based on a double logarithmic graph that shows a highly variable scatter by a factor of 10 to 100. In many cases, most compounds are increasing, not just the ones highlighted by the authors. It would be beneficial for the authors to provide a more detailed analysis for this section. They should describe the trends by group of compounds and dive into the reasons for the observed differences, supported by clear graphs indicating the efficiency of the treatment devices e.g., histogram percentage differences per source category.
Line 591: Delete the word "in."
Lines 612-614: It would be valuable if the authors could verify these ratios by running a PMF on the ambient data. Observing whether they can separate different sources and extract the aromatic to MEK ratio would provide more confidence in using this ratio as an indicator of different VCP emissions. Was the site downwind of the industry? Meteorological data could also help narrow the influence of the different industrial sectors.
Line 623: Add "that have been..."
Citation: https://doi.org/10.5194/egusphere-2024-380-RC1 -
RC2: 'Comment on egusphere-2024-380', Anonymous Referee #2, 19 Mar 2024
This work investigated the emissions of ROGs from five industrial VCP sources in China, including shoemaking, plastic surface coating, furniture coating and shipping coating industries. PTR-ToF-MS and GC-MS/FID are combined together to develop comprehensive speciation of VOC from these industrial sources in PRD, China. The manuscript is generally well organized. Some statements are unclear and need to be clarified. I also suggest authors polish English and grammar throughout the manuscript. Please see below for my detailed comments.
- Abstract: This work is only for PRD, China, instead of the whole nation. Please clarify this in the title and abstract to avoid misunderstanding.
- Line 30: Not sure what this sentence means. Please keep in mind that this study doesn’t cover all emission sources. Please clarify this sentence to avoid misunderstanding.
- Line 32: so, what's the proportion of OVOCs for ship coating industry then? Does it make big difference using solvent-borne coatings or waterborne coatings for OVOC proportion?
- Line 37-39: please improve the statement.
- Line 41: Why is the treatment efficiency negative?
- Line 74: Not accurate statement. The substitution of solvent-borne VCPSs by water-borne ones are for several sources., e.g., interior wall painting.
- Line 159: I’m curious how to combine PTR-ToF-MS with GC-MS/FID measurements when they overlap? How to handle the un-known species?
- Line 299: have you found any additional important OVOCs using PTR-ToF-MS? Please list them or at list some examples here.
Citation: https://doi.org/10.5194/egusphere-2024-380-RC2
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