Natural Sources of Volatile Organic Compounds to the Summer Arctic Troposphere by Emma L ...

193 Pages·2017·23.16 MB·English

Natural Sources of Volatile Organic Compounds to the Summer Arctic
Troposphere
by
Emma L. Mungall
A thesis submitted in conformity with the requirements
for the degree of Doctor of Philosophy
Graduate Department of Chemistry
University of Toronto
(cid:13)c Copyright 2018 by Emma L. Mungall
Abstract
Natural Sources of Volatile Organic Compounds to the Summer Arctic Troposphere
Emma L. Mungall
Doctor of Philosophy
Graduate Department of Chemistry
University of Toronto
2018
Due to chemistry-climate coupling, observations of chemical processes in the atmosphere are crucial
to improving understanding of the Earth system and enabling future climate predictions. Quantifying
the effect on climate of current and future anthropogenic influence requires first understanding natural
processes. This task is complicated by the interactions between natural and anthropogenic emissions.
Because the summer Arctic experiences limited anthropogenic influence, it is considered an analog for
somepre-industrialatmospheres. Duetoitsremoteness,observationsintheregionarescarce. Thegoals
of this thesis were to 1) make observations of the tropospheric composition of the summer Canadian
Arctic Archipelago and 2) improve understanding of the sources of volatile organic compounds (VOCs)
in the region. To achieve the first goal, two new datasets were collected by field deployment of chemical
ionization mass spectrometers. The second goal was addressed through analysis of the newly collected
data sets, modeling experiments, and laboratory experiments. This work confirmed that local marine
sources are the major contributors to high levels of dimethyl sulfide (DMS) in the summer Arctic, and
supported the hypothesis that DMS emissions from melt ponds on top of the sea ice may be significant.
Unexpectedly,wefoundthatheterogeneouschemistryattheseasurfacemicrolayeremitslargequantities
of formic acid to the atmosphere, as well as smaller amounts of many other OVOCs, some of which may
play a role in the formation of secondary organic aerosol. Methane sulfonic acid in aerosol particles,
which has traditionally been considered a conservative tracer for DMS, was shown to be degraded by
heterogeneous oxidation during atmospheric transport. Finally, the presence of high levels of formic
and acetic acids in the summer Arctic calls into question the current understanding of the sources of
these acids. In summary, this thesis begins to paint a clearer picture of the chemical composition of
the summerArctic tropospherewhile emphasizing thatfurther measurements are badly needed tobring
that picture into focus.
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To Cyrille, who kept me going.
iii
Acknowledgements
Thank you, first and foremost, to my supervisor, Jon Abbatt, for giving me the opportunity to be part
of NETCARE and work on this amazing project. Getting to go the Arctic, not once, but twice, was an
incredibleexperience,andI’mverygrateful. Thankyouforyourkindanddedicatedsupervision. Thanks
to my committee, Jennifer Murphy and Frank Wania, for their thoughtful comments at committee
meetings over the years.
Most of my PhD work was field-based, and field campaigns are made possible by the hard work
and enthusiasm of a whole lot of people. Thanks to Jennifer Murphy, Maurice Levasseur, and Richard
Leaitch for their wisdom and guidance. Thanks to Luis Ladino and Alex Lee for sending me off from
Quebec city with all the particle instruments working. Thanks to the friends and colleagues who kept
mesane(moreorless)ontheship: VickieIrish,MartineLizotte,TonyaBurgers,HeatherStark,Lauren
Candlish, and Joannie Charette. Thanks to the EC crew at Alert for the fun and the hikes: Dana
Stephenson, Kevin Rawlings, Justin Wagenaar, and Melody Fraser. Thanks most particularly to Greg
Wentworth for listening to far too many complaints and keeping me laughing.
I’d like to acknowledge that Nunavut, the province in which I carried out my field research, is the
traditional and current territory of the Inuit. It was a privilege to study the land, one which I am
very grateful for. I wish to acknowledge this land on which the University of Toronto operates. For
thousandsofyearsithasbeenthetraditionallandoftheHuron-Wendat, theSeneca, andmostrecently,
theMississaugasoftheCreditRiver. Today,thisplaceisstillthehometomanyIndigenouspeoplefrom
across Turtle Island and I am grateful to have the opportunity to live and study on this land.
Thank you to all the members of the Abbatt group, past and present. I’ve learned so much from all
ofyou,andithasbeenapleasuretobeyourcolleague. SpecialthankstoDanaAljawharyandRanZhao
for getting me started in the lab and with the CIMS, and to Jenny Wong for shepherding me through
my first (and as it turned out, last) days as an experimentalist. Thanks for John Liggio at Environment
Canada for letting me work in your lab and borrow not one but two of your CIMS. Thanks also to
Jeremy Wentzell at Environment Canada, without whose mentorship none of this data would have been
collected, and without whose company the data collection would have been much more boring. Finally,
thankstoRandallMartinandBettyCroftforhostingmeatDalhousieforaninterestingandproductive
exchange.
Thanks to the GCAC (formerly ELWS) for their excellent classes and workshops on everything
writing-related. In particular, I am very grateful to Rachael Cayley for her invaluable advice on both
the craft of writing and overcoming the inertia of sitting down to write.
I feel very fortunate to have landed in the tight-knit group of Environmental Chemistry. All the
science discussions at lunch were both fun and helpful. Thanks to everyone in the division whose years
in the department overlapped with mine for listening to my science woes – and sharing yours. The
lunches, clothing swaps, and book clubs were an integral part of my experience and truly enriched
my life. Thanks to Shira Joudan, Lisa D’Agostino, Jennifer Faust, Doug Collins, Nicole Combe, Jessica
Clouthier,LauraStirchak,AlysonNeufeld,JacquieJakobi-Hancock,KatieBadali,andRaminaAlwarda.
A huge thank you to my friends and family, near and far. In particular, thanks to Sarah Kavassalis
and Alex Tevlin for the beers and the love, to Angela Hong for the food (and of course the company),
and to Rachel Hems for listening to my endless productivity tips and being an excellent office-mate
and friend. Thank you to Megan Willis for all the dinners; long talks about science, the Arctic, and
the future; and the postcards from the field. I can’t imagine what this degree would have been like
iv
without you. Thanks to Clara del Junco for keeping me grounded (one of these days I’ll make it out to
Chicago). Thanks to all my cousins, aunts, and uncles for making me feel at home in this world and
takingagenuineinterestinmyresearch. ParticularthanksareduetoJoan,Alfred,andSusieforputting
me up in Halifax during my exchange at Dalhousie. Thanks to my mother, Fiona MacKinnon, for the
family dinners, the support, and that time you picked me up in Quebec City and drove me out east so I
could spend a few days at the beach before the Amundsen left port. Thanks to my brother Thomas for
delicious meals and erudite conversation. Thanks to my brother Sean, the wisest 21-year-old out there,
for your listening ear and excellent advice. Thanks to my father, Jim Mungall, for sending me all those
letters from the field. The squashed mosquitoes and bits of lichen seemed unutterably glamorous and
I knew I needed to get myself north somehow, someday. Thanks also to my step-mother Julie for the
chats, and to both dad and Julie for the family dinners, the science talk around the dinner table, and
the career advice. Thanks to my baby sister Dalia for being a pure delight and source of joy.
Thanks to all the authors of all the books that brought magic into my world. In particular, Phillip
Pullman’s Northern Lights set me dreaming fifteen years ago. Fantasy books might not seem like an
essential component of a PhD in Chemistry, but for me they assuredly were.
Finally, thanks to Cyrille for the emotional support and the laughs (the technical support was nice
too). I literally couldn’t have done it without you.
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Contents
Acknowledgements iv
Table of Contents vi
List of Tables xi
List of Figures xii
Contributions xv
1 Introduction 1
1.1 Chemistry-climate coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 VOCs and tropospheric chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Carbon cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Oxidation capacity & methane lifetime . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.2 VOCs and aerosol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Aerosol-climate interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 The summer Arctic troposphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.1 Seasonal changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.2 Summer Arctic as pre-industrial analog . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.3 The changing Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3 Moving across interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.1 Equilibrium partitioning approaches . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.2 Flux parameterizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Surface-atmosphere exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Air-water transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.3.3 Direct flux measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.4 Sources of VOCs to the summer Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.4.1 Formation of secondary VOCs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.4.2 Production at interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4.3 Terrestrial VOC emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4.4 Marine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
DMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
vi
The CLAW hypothesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
DMS sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
OVOCs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Isoprene & terpenoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.4.5 Snow & Ice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.4.6 Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Biomass burning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Terrestrial & Oceanic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.5 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.5.1 Chemical Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Online techniques vs offline techniques . . . . . . . . . . . . . . . . . . . . . . . . . 20
Satellite remote sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
CIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
1.5.2 Source apportionment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Molecular tracers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Isotopic methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Statistical methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Discussion of methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2 Dimethyl sulfide in the summertime Arctic atmosphere: Measurements and source
sensitivity simulations 45
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.2.1 Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
DMS mixing ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Surface seawater DMS concentrations . . . . . . . . . . . . . . . . . . . . . . . . . 49
Meteorological data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Sea surface temperature and salinity . . . . . . . . . . . . . . . . . . . . . . . . . . 50
2.2.2 Model Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
FLEXPART-WRF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
GEOS-Chem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Seawater DMS values in GEOS-Chem . . . . . . . . . . . . . . . . . . . . . . . . . 50
2.2.3 Flux estimate calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.3 DMS mixing ratio observations and estimated fluxes . . . . . . . . . . . . . . . . . . . . . 52
2.4 Source sensitivity studies with GEOS-Chem and FLEXPART-WRF . . . . . . . . . . . . 54
2.4.1 Model-Measurement Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
2.4.2 Seawater sources: Baffin Bay and Lancaster Sound as principal oceanic DMS source 56
2.4.3 Transport from a seawater source: role of Hudson Bay System as an additional
oceanic DMS source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
2.4.4 Investigation of possible missing sources . . . . . . . . . . . . . . . . . . . . . . . . 57
Emissions from melt ponds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Emissions from coastal tundra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
vii
Emissions from lakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Other potential DMS sources for the study area. . . . . . . . . . . . . . . . . . . . 59
2.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3 Heterogeneousoxidationofparticulatemethanesulfonicacidbythehydroxylradical:
kinetics and atmospheric implications 70
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
3.2 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.2.1 Aerosol generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.2.2 Flow tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.2.3 Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.3 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.3.1 Calculation of the uptake coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.3.2 Uncertainties in the uptake coefficient . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.4.1 Interpretation of the uptake coefficient . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.4.2 Rates of MSA loss in the atmosphere. . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.4.3 Atmospheric implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4 Microlayer source of oxygenated volatile organic compounds to the summer marine
Arctic boundary layer 87
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
4.2 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
4.4 Atmospheric Implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
4.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.6 Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
5 High gas-phase mixing ratios of formic and acetic acid in the High Arctic 104
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
5.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.2.1 Field site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.2.2 Gas-phase measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
5.2.3 Precipitation measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
5.2.4 Ancillary data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
5.2.5 Soil data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5.2.6 FLEXPART-ECMWF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5.3 Results & Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5.3.1 Role of meteorology in determining FA and AA mixing ratios . . . . . . . . . . . . 109
Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Diurnal variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
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5.3.2 Precipitation data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.3.3 Possible sources of FA and AA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Anthropogenic emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Heterogeneous chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Snowpack emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Soil emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Plant emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
5.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
6 Conclusion 128
6.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
6.2 Future directions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
6.2.1 Missing link to SOA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
6.2.2 Episodic contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
6.2.3 Unknown sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
6.2.4 Solving the access problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
6.3 Final thoughts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
6.3.1 The need for more observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
6.3.2 What are we missing? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Appendix A SI Appendix for Chapter 2: Dimethyl sulfide in the summertime Arctic
atmosphere: Measurements and source sensitivity simulations 137
A.1 HR-ToF-CIMS data processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Appendix B SI Appendix for Chapter 4: Microlayer source of oxygenated volatile
organic compounds in the summertime marine Arctic boundary layer 143
B.1 Correlation with particle volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
B.2 Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
B.2.1 Aerosol particle measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
B.2.2 Chlorophyll-a measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
B.2.3 Acetate HR-ToF-CIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
B.2.4 Benzene HR-ToF-CIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
B.2.5 DOC measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
B.3 Relationship of Ocean Factor to wind speed . . . . . . . . . . . . . . . . . . . . . . . . . . 146
B.4 Residence times over land and water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
B.5 Traditional precursors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
B.5.1 Correlations with DMS and isoprene . . . . . . . . . . . . . . . . . . . . . . . . . . 146
B.5.2 Sum of monoterpenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
B.5.3 Box model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
B.6 Preparation of data for PMF analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
B.6.1 Analysis using Tofware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
B.6.2 Data analysis in R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
B.7 PMF solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
B.7.1 4 factor solution in detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
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B.7.2 Line Contaminant Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
B.7.3 Combustion Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
B.7.4 3 factor solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
B.7.5 5 factor solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
B.7.6 Quality of fit parameter Q/Q . . . . . . . . . . . . . . . . . . . . . . . . . . 149
expected
B.7.7 Bootstrap results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
B.7.8 4 factor PMF solution run without HNCO or HCOOH . . . . . . . . . . . . . . . . 149
B.8 Ship track . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Appendix C SI Appendix for Chapter 5: High gas-phase mixing ratios of formic and
acetic acid in the High Arctic 172
C.1 Calibration data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
C.2 Mixing height analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
C.3 Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
C.3.1 Amount of precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
C.3.2 Deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
C.3.3 Scavenging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
x