Porella : features, morphology, anatomy, reproduction etc.
Ph.D. Dissertation Defense final version
1. Water-soluble organic gases in
residential indoor air, and
the potential for aqueous chemistry
indoors to alter exposures
Sara Duncan
February 23, 2018
Dissertation Defense
2. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Motivation: time spent indoors
2
Klepeis et al., JEAEE 2001
3. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 3
Paciência et al. JTEH 2016
I/O:
150-
10-
1-
0.5-
VOCs (n=38)
Motivation: enhanced exposure to (nonpolar) VOCs
4. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Motivation: dampness in homes
• 18 - 50% of homes are damp
• Associated with adverse health
outcomes
• Unsure of causal agents
• Microbial exposures – most
commonly explained culprit,
but may not be the whole
picture
• What else is occurring?
Mendell et al., EHP 2011
4
5. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 5
Presence and characteristics
of liquid water
Composition and
concentrations of oxidized
VOCs aka. water-soluble
organic gases
Critical knowledge gaps in indoor air chemistry
6. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Hypothesis
I hypothesize that water-soluble organic
gases (WSOG) are ubiquitous and abundant
in homes, and their subsequent aqueous
uptake and processing alters the chemical
composition of indoor air.
6
7. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Objectives
• Synthesize literature: determine previously measured
WSOG and hypothesize additional WSOG
• Collect WSOG in homes: characterize integrated
composition of WSOG
• Characterize sampling method
• Characterize WSOG in real-time in one home
• Postulate the presence of liquid water indoors and
subsequent occurrence of aqueous chemistry
7
8. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
What do we already know about WSOG in
homes? Which ones have been measured?
What else do we expect to be there?
Conduct literature search:
determine WSOG previously
measured and hypothesize
others expected to be present
8
9. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 9
Compound Structure
Henry's law
constant (M/ atm)
Mean (and range) Gas phase
concentrations (ppb)
Glyoxal 4,000,000 1 (0.5 – 1.8)
Methylglyoxal 32,000 0.9 (0.4 – 1.6)
Formaldehyde 3,000 22 (4 – 100)
Acetone 31 16 (0.4 – 280)
2-Butanone 18 2 (BDL* – 8.4)
Acetaldehyde 15 7.4 (0.7 – 23)
Propionaldehyde 13 1 (BDL – 7.3)
2-Hexanone 11 0.13 (NA* – 0.8)
Tetrahydrofuran 10 0.44 (NA – 83)
Acrolein 10 0.25 (BDL – 2.4)
Examples of WSOG previously measured
*BDL = below
detection limit
*NA = not
available
Duncan et al., IA 2017 & refs therein
10. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Examples of WSOG likely to be emitted
10
Emission source WSOG emitted
Building occupants Acids
Ketones
AlcoholsCooking
Fireplace
Oxidized aromatics
Aldehydes
Ketones
Dicarbonyls
Microbial VOCs
Aldehydes
Acids
Ethers
Esters
Ketones
Duncan et al., IA 2017 & refs therein
11. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 11
Low solubility precursor Oxidant Soluble product
C5-C8 n-alkanes (attached garages) OH· Hydroxycarbonyls
Monoterpenes (cleaning products, wood
floors, e.g. α-pinene, β-pinene, limonene)
O3
Aldehydes
Acids
OH·
Aldehydes
Ketones
Alkylbenzenes (building materials,
furniture, attached garages)
OH·
Oxidized aromatics
Hydroxyl dicarbonyls
Squalene (human skin lipid) O3
Ketones
Acids
Alcohols
Isoprene (indoor plants, people)
OH·
Carbonyls
Hydroperoxides
Epoxides
NO3·
Organic nitrates
Hydroxycarbonyls
Examples of WSOG likely to form through gas phase chemistry
Duncan et al., IA 2017 & refs therein
12. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
WSOG in literature: summary
12
• Some WSOG have been measured indoors
• These compounds have well developed analytical
methods
• Many more WSOG are emitted from common
indoor sources
• Many more WSOG are likely to be formed indoors
13. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Are WSOG also elevated indoors?
What are their characteristics?
Conduct integrated
measurements of WSOG in
real homes and perform
subsequent chemical analysis
13
14. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Collect WSOGs
14
Mist chambers
(MCs) collect
water-soluble
organic gases
Mist
25 L/min
25 mL
Scrubbed air
(to pump)
Sampled air
(particle filtered)
Refluxing liquid
Cofer et al., ES&T 1985
15. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Sampling parameters
15
•Sampled 13 real
homes (1x each)
•June – October 2015
•Sampling time:
~ 10:00AM – 2:00PM
Sample for 2 hours x 2
Inside homes
Outsidehomes
16. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Characterize homes
16
Parameter Average (range)
Measured in home
Temperature (˚C) 23 (20-26)
Relative Humidity (%) 60 (53-67)
Carbon dioxide (ppm) 930 (620-1390)
Reported from
nearby outdoor
monitoring site
Ozone (ppb) 40 (8-60)
Temperature (˚C) 25 (15-33)
Calculated
Floor area (m2
) 140 (40-230)
Air exchange rate (h-1
) 0.5 (0.3-0.8)
17. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Compare indoor and outdoor WSOG
concentrations
17
Total organic carbon
analyzer
Conduct carbon analysis
18. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Water-soluble organic gas concentrations are
significantly higher indoors than outdoors
18
Paired t-test, α=0.05,
p < 0.001
Indoor gas-phase
concentration – mean (range):
145 µg-C/m3 (84-215)
Outdoor gas-phase
concentration – mean (range):
11 µg-C/m3 (4-16)
Estimate of WSOG of indoor
origin: 86%
19. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Predictors of WSOG indoors
19
Step-wise multiple linear regression
p-value of <0.05
Indoor WSOG
Outdoor WSOG
Indoor T
Outdoor T
∆ T
Indoor RH
Outdoor O3
Indoor CO2
Occupants
Year built
Home area
p=0.008
R2 = 0.61
20. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Total WSOG decreases with air exchange rate
20
Equation 11, Chan et al., AE 2005:
H = building height (m)
NL = normalized leakage (function
of year built and floor area)
F = scaling factor = 16
𝐴𝐸𝑅 (ℎ−1
) = 48
2.5 𝑚
𝐻
0.3
𝑁𝐿
𝐻 × 𝐹
21. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Quantify organic acid portion of WSOG
21
Ion chromatography
Detect anions
22. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Organic acids constitute a significant portion of WSOG
22
Acetic + lactic acids
(quantified as acetic):
18 to 53% of total
WSOG - carbon
Formic acid:
3 to 12% of total
WSOG - carbon
What can
ESI-MS tell us
about the remainder?
23. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Identify molecular formulas for the
remainder of WSOG
23
Electrospray ionization
mass spectrometry
(positive mode)
Obtain precise molecular
weights of compounds
24. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Most compounds contain oxygen, many contain nitrogen
24
Compound type Average (%)
CHO 67
CHON 11
CHN 11
Other 11
98 total molecular formulas
25. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
1 2 3 4 5 6 7 8 9 10 11 12 13
WSOG in homes varies greatly and is quite complex245m/z+59Home
#:
25
Diethylene glycol
Diethylene glycol
butyl ether
157.0835 – C4H10O3
163.1328 – C8H18O3
Not detected
in sample
Detected in
sample
29. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Integrated measurements: summary
29
• WSOGs are elevated indoors (15 x higher in sampled homes)
• Organic acids account for approximately 50% of collected
WSOG
• 98 distinct molecular formulas were identified in homes
• Inter-home variability is high
30. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
What are the chemical dynamics of
WSOG indoors?
Conduct real-time, high resolution
molecular identification of
residential WSOG
30
31. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 31
Iodide chemical ion mass
spectrometry (I-CIMS)
High resolution m/z- →
elemental composition
In real time →
2 second intervals
Detects: organic acids, alcohols,
ketones, organic peroxides,
amines, and organic nitrates
Conduct real-time measurements
in one home under
various conditions
32. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Sampling schedule
32
Date Perturbation
7/18/17 Background
7/19/17 No occupancy
7/20/17 High occupancy
7/21/17 Windows open/ AC off
7/22/17 Cleaning
7/23/17 Cooking
7/19, 8-hour max outdoor O3 = 51 ppb
Supporting measurements
33. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Schematic of air sampled by CIMS instrument
33
Inside home Inside homeInside home
Instrument Instrument Instrument
Instrument inlet Sampling line (1 meter)
Sampling inside air Sampling outside air Sampling inside air
20 min at ~ 8 AM and 2 PM 20 min, after outdoor air samplingNormal sampling
34. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 34
Organic acids cycle approximately hourly
Acetic acid ↓: 31-38% Formic acid ↓: 47-53%
35. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 35
Cycling on of central air conditioning unit leads to scrubbing
of organic acids from air
36. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Other compounds cycle with the air conditioning system as well
36
↑ O:C suggests ↑ uptake into
AC system
37. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
A look at forced air conditioning systems in homes
37
Acetic + lactic acid = ~ 1000 μM
Formic acid = ~ 350 μM
39. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 39
Lactic acid concentrations increase from
increased occupancy and cooking events
40. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Other compounds also spike with cooking events
40
41. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Real-time measurements: summary
41
• Central air conditioning systems take up WSOGs
• Likely due to condensation in the condensate tray and/
or duct work
• Some compounds are dominated by indoor sources, some
outdoor sources
• Cooking events are a substantial source of WSOG indoors
42. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
WSOG are elevated indoors; what
happens to them if liquid water is
present?
Making the case for aqueous
chemistry in homes
42
43. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Cloud
evaporation
SOA
·OH
·OH
·OH
NOx
·OH
·OH
·OH
NOx
NOx,
alkenes,
aromatics
O
O
O
O
·OH O3
·OH
Isoprene
Utilize insights from outdoor aqueous chemistry
43
• Atmospheric water is found
in clouds, fogs, wet aerosol
• Changes composition of
gases, particles, and
oxidants
• Faster and different
products
44. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Provide evidence for liquid water in homes
44
Surface-to-volume ratios:
~ 3 m2/m3 indoors
vs. < 0.01 m2/m3 outdoors
Liquid water condensed in AC
= 2.2 ± 0.2 L
RH = 80%RH = 70%
(↓ 10%)
Water uptake = 3 mL/m2
Künzel et al., ASHRAE 2004
45. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Postulate on subsequent aqueous chemistry
45
• Radical reactions, acid-base, nucleophilic and hydrolysis
reactions
• Surface films – similar chemistry to that of wet particles
• Bulk water – similar chemistry to that of clouds and fogs
• Some products will remain in the condensed phase, while
others volatilize back into the gas phase
• Magnitude of reactions will likely act as significant source
and compete against air exchange
46. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Identify the critical unknowns
46
•Contributions by compound class and
molecular structure to WSOG
•Hygroscopicity of indoor surfaces
•Characteristics of liquid water on indoor
surfaces
•Dominant chemistry in indoor liquid water
47. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Aqueous chemistry: summary
47
• Liquid water is present in homes, especially damp homes
• There are many WSOG indoors that can partition into liquid
water if present
• Aqueous chemistry substantially alters outdoor air composition
• Aqueous chemistry is also likely to alter indoor air composition
48. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Overall conclusions
48
1. Some WSOG have been identified previously indoors, more are
likely present
2. Much more WSOG indoors than outdoors (mean = 15x)
3. WSOG chemical makeup is quite complex and varied between
homes (98 molecular formulas identified in integrated samples)
4. Air conditioning systems are a large sink for WSOG (30-50% for
acetic and formic acids)
5. Most WSOG originate indoors, some outdoors
6. With the ubiquitous presence WSOG indoors and evidence for
liquid water, aqueous chemistry is likely to occur
49. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Hypothesis
49
I hypothesize that water-soluble organic
gases (WSOG) are ubiquitous and abundant
in homes, and their subsequent aqueous
uptake and processing alters the chemical
composition of indoor air.
50. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Final thoughts
50
•First broad look at WSOG in homes
•WSOG merit further identification and quantification
•Evidence that liquid water is indoors
•Aqueous chemistry is likely to happen
•Occupants will be exposed to WSOGs and products
of aqueous chemistry. What are the health
implications?
51. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Future work
51
• Further identify and quantify WSOG indoors
• Explore WSOG uptake and subsequent
chemistry in liquid water indoors
• Conduct exposure studies to determine health
effects
52. Thank you and acknowledgements!
52
Sara Duncan, email: saraduncan31@gmail.com
Adviser: Dr. Barbara Turpin
Committee: Dr. Clifford Weisel, Dr.
Gediminas Mainelis, Dr. Charles Weschler
Lab group: Dr. Neha Sareen, Dr. Jeff
Kirkland, Dr. Natasha Hodas, Ronald
Lauck, Dr. Kenneth Sexton, Dr. Sophie
Tomaz, Marc Webb
Other scientists: Dr. Jason Surratt, Dr.
Glenn Morrison, Leonard Collins, Yuzhi
Chen, Rutgers exposure science group
Support staff at both Rutgers and UNC
Research volunteers in New Jersey and
North Carolina
My family (especially my parents)
Many friends (especially those that I’ve
met during my time at Rutgers and UNC)
Funding: National Institute of
Environmental Health Sciences and Sloan
Foundation
53. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Mist chamber characterization - collection time
53
1hr
8hr
MC: 1 2 3 4
7.5 min
15 min
30 min
1 hr
7.5 min
7.5 min
15 min
7.5 min
7.5 min
15 min
30 min
7.5 min
7.5 min
15 min
7.5 min
1 hr
2 hr
4 hr
8 hr
1 hr
1 hr
2 hr
1 hr
1 hr
2 hr
4 hr
1 hr
1 hr
2 hr
1 hr
MC: 1 2 3 4
54. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 54
10 min: KH>103 M/atm
η = 80-100% 1
(glyoxal, hydroxyacetone,
formaldehyde)
Spaulding et al., ES&T 2002
H-law equilibrium at
t=?
Increasing sample time allows for collection of a larger
range of water-soluble compounds
Further collection
of less soluble
compounds,
1<KH<103 M/atm
56. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions
Cleaning produces many chlorinated compounds
56
57. Introduction WSOG in literature Integrated measurements Real-time measurements Aqueous chemistry Conclusions 57
2NO2 + H2O → HONO + HNO3
early study of 10 homes by Spengler and Brauer, who found
HONO concentrations ranging from 2 to 8 ppb (Spengler et al.,
1993). Recently, measured indoor OH radical concentrations of
1.8 x 106 molecules/m3 were linked to HONO photolysis on
windows (Gómez Alvarez et al., 2013).
high relative humidity (RH), presence of mold, presence of standing water, and damp building materials
2-butanone, lactic acid, acrolein,
Overall presence of water on indoor surfaces
Hydrolysis, acid-base, and oxidation-reduction reactions may occur
https://www.angieslist.com/articles/how-fix-condensation-windows.htm
http://www.owasa.org/What-Is-A-P-Trap
1. Conduct literature search for WSOG previously measured
- Example search terms: “volatile,” “organic compounds,” “indoors,” “air,” “concentration,” “measured”
- Identify compounds with Henry’s law constants > 1 M/atm
Henry’s law = concentration in gas phase over concentration in aqueous phase at equilibrium
Some WSOG have been measured: HPLC, GC-MS
With help of Dr. Ken Sexton
Red arrow flying in to mix
Sampling device: Cofer Scrubber or Mist Chamber
MCs filter out particles. Pressure drop pulls water up capillary tube and sprays into mist. Increases surface area between water and air. Water-soluble organic gases partition into water
Advantage: MCs collect all WSOG. Collected into media that can be used for further analysis/ experimentation
Mist chamber sampling inlets:
2 sampling in parallel indoors
2 sampling in parallel outdoors
Conducted technician and participant survey to characterize homes
3 in NJ, 10 in NC during more or less summertime. No notable difference between the two.
Lower ozone concentrations on rainy/ cloudy days. Summer time ozone can make WSOG
Conducted technician and participant survey to characterize homes
3 in NJ, 10 in NC during more or less summertime. No notable difference between the two.
Lower ozone concentrations on rainy/ cloudy days. Summer time ozone can make WSOG
Accurate-Mass Quadrupole Time-of-Flight Liquid Chromotography/Mass Spectrometry with an Electrospray Ion Source (ESI Q-TOF LC/MS)
Positive mode, soft ionization (fragmentor voltage = 40V)
step-wise multiple linear regression
Accurate-Mass Quadrupole Time-of-Flight Liquid Chromotography/Mass Spectrometry with an Electrospray Ion Source (ESI Q-TOF LC/MS)
Positive mode, soft ionization (fragmentor voltage = 40V)
Accurate-Mass Quadrupole Time-of-Flight Liquid Chromotography/Mass Spectrometry with an Electrospray Ion Source (ESI Q-TOF LC/MS)
Positive mode, soft ionization (fragmentor voltage = 40V)
Why higher N indoors?
Iodide CIMS, negative mode
Calibrated for formic, acetic, lactic acids, imidazole
What does it measure?
WSOGs with high Henry’s Law Constant likely to partition into liquid water
Water films likely to be highly concentrated with salts and organics
Although many will be slow, some reactions are likely to be fast and can compete with air exchange
Acetaldehyde lifetime with respect to OH in aqueous phase = 50 minutes
Prior work in Turpin lab shows that outdoor collected WSOGs react with OH in minutes
Svenningsson et al., 2006, Lim et al. 2013, Sareen et al. 2016
Liquid chromatography method development
Structural identification using MS-MS and confirmation with authentic standards
Collection efficiency determination for specific compounds collected with mist chambers
Thin films on surfaces
bulk AC condensate and other bulk water
2 mist chambers in series and sampled for 2 hours (10 x)