OECD Global Forum on the Environment dedicated to Per- and Polyfluoroalkyl Substances: Spatial and Temporal Trends of PFAS in Oceans, Coastal Areas, and Air on a Global Scale | Amila O. De Silva 2024
PFAS, which stands for per- and polyfluoroalkyl substances, are a diverse group of chemicals that include PFCAs, PFOA, PFSAs, PFHxS, and thousands of others. These chemicals have been in commercial production since the 1950s and are now widely used in consumer and industrial applications. One characteristic of PFAS is their persistence in the environment, as they are extremely resistant to degradation. PFAS have emerged as contaminants of global concern because of their potential to accumulate in the human body and food chains.
On 12-13 February 2024, a wide range of stakeholders, including governments, industry, non-governmental organisations (NGOs), and academics came together to discuss various topics related to PFAS. These topics covered areas such as country risk management approaches, innovation challenges for finding safer alternatives, effective risk communication strategies, monitoring techniques, waste management, and approaches to managing contamination.
Eu actions to regulate Per- and Polyfluoroalkyl Substances
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Proposed Amendments to Chapter 15, Article X: Wetland Conservation Areas
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OECD Global Forum on the Environment dedicated to Per- and Polyfluoroalkyl Substances: Spatial and Temporal Trends of PFAS in Oceans, Coastal Areas, and Air on a Global Scale | Amila O. De Silva 2024
1. Spatial and Temporal Trends of PFAS in
Oceans, Coastal Areas, and Air
on a Global Scale
Amila O. De Silva
Research Scientist
Environment and Climate Change Canada
Burlington, ON, Canada
Robert Letcher, Tom Harner,
Hayley Hung, Amandeep Saini
2. โข 2005 paper โA Global Survey of Perfluorinated Acids in Oceansโ by Yamashita et al.
โข picogram per litre detection limits PFBS, PFHxS, PFOA, PFNA, PFOS, FOSA
โข International research cruises in Pacific Ocean, Atlantic Ocean, South China Sea, coastal seawater
from Japan, China, Korea
PFAS in the Marine Environment
โข 2021 Review
Nobuyoshi Yamashita et al. 2005. A global survey of perfluorinated acids in oceans. Mar Pollut Bull; 51(8-12):658-68
3. PFAS in the Marine Environment โ Slow to Change
โข Twenty years of PFAS data in oceans and coastal waters
โข Perfluoroalkyl acids (PFAA): Persistence, high water solubility, and low partitioning to
organic matter
โข Very slow removal in oceans:
outflow to other oceans,
vertical eddy diffusion, deep water
formation, and settling particles
Modeled Removal
Half-Life (years)1
North Atlantic
PFOS 5.8
PFOA 3.0
1 Zhang, X. et al. 2017. Global Biogeochemical Cycles. 31:1332-1343; Gonzalez-Gaya, B. et al. 2014. Environ. Sci. Technol.
48:13076-13084; Lohmann, R. et al. 2013. Environ. Pollut, 179:88-94.
Depth [PFAA]
mixed
layer
depth
(z)
4. Spatial Trends in PFAS in Oceans, 2010-2019
Sum of perfluorocarboxylic acids (PFBA to PFDoDA)
Sum of perfluorosulfonic acids (PFBS, PFHxS, PFOS, PFDS)
Muir and Miaz. 2021. Environ. Sci. Technol. 55, 9527-9537
โข Results are lacking from coastal
areas:
โข North America
โข South America
โข Africa
โข India
โข Australia
5. Casas, Gemma et al. (Dachs) 2023. Inputs, amplification, and sinks of perfluoroalkyl substances at coastal Antarctica. Environ. Pollut. 338: 122608.
PFAS in coastal Antarctica 2018
โข Total PFAAs 50-1020 pg L-1
โข Higher total concentrations in a few sites that also had PFUnDA, PFDoDA, PFTrDA (C11-13 PFCAs)
PFBS
PFOS
30 m
6. Casas, Gemma et al. (Dachs) 2023. Inputs, amplification, and sinks of perfluoroalkyl substances at coastal Antarctica. Environ. Pollut. 338: 122608.
PFAS in coastal Antarctica 2018
โข Higher total concentrations in a few sites that also had PFUnDA, PFDoDA, PFTrDA (C11-13 PFCAs)
โข Penguin colonies and likely guano wash off are a source of PFCA amplification
PFBS
PFOS
30 m
7. โข 91 river estuaries sampled for surface waters
along the entire coast of China in 2018
โข Measured concentrations (Criver, ng L-1 )and
discharge rate (Qriver, m3 year-1) to calculate
mass loading
PFAS in coastal China in 2018
Du, D. et al. (Yonglong Lu) 2022. Perfluoroalkyl acids (PFAAs) in water along
the entire coastline of China. Environ. International. 169: 107506.
8. Total mass loading (all rivers)
= 131 tonnes โPFAA in 2018
Du, D. et al. (Yonglong Lu) 2022. Perfluoroalkyl acids (PFAAs) in water along the entire coastline of China. Environ. International. 169: 107506.
โPFAA concentrations:
1.6 to 620 ng L-1
Mean: 40 ng L-1 PFOA
17 ng L-1 PFBA
12 ng L-1 PFBS
โข 7013 fluorochemical industries in
mainland China; 69% are in coastal
provinces;
9.
10.
11. Han, T. (Xiuping He) et al. 2022. Spatial distribution, vertical profiles and transport of legacy and
emerging per- and polyfluoroalkyl substances in the Indian Ocean. J. Hazardous Materials, 437:
129264
Spatial Distribution of PFAAs in Indian Ocean
Northwest
Pacific Ocean
Joint -Asian-
Indian-Pacific
Southwest
Indian Ocean
Northeast
Indian Ocean
โข Sampling in 2019-2020
โข 92 surface water
samples
โPFAA
(pg L-1)
โข NEIO 44
โข SWIO 24
โข JAIPO 64
โข NWPO 219
โข PFOS detection frequency was
< 20% in all regions except
northwest Pacific (80% d.f.)
โข Mostly PFHxA and PFHpA
โข Data quality? PFBA and PFPeA
12. Spatial Distribution of PFAAs in Canadian Arctic Ocean
Barrow Strait Lancaster Sound
Devon Island
Cornwallis
Island
Bathurst
Island
Ellesmere
Island
Somerset
Island
Prince of
Wales
Island
Jones Sound
Melville
Sound
Resolute
Bay
Grise
Fiord
โข Under ice sampling in May
โข Barrow Strait near Resolute Bay, Nunavut,
Canada
โข PFBA is the major PFAA unless you include
shorter PFAAs
De Silva, Kirk, Muir et al. Northern Contaminants Program M-15
13. โข Sea spray aerosols are enriched in
PFAAs
โข 48 hours of aerosols collected over 2
years
โข Two coastal locations in Norway
โข Highest concentrations were PFOA
and PFNA
โข Mechanism for delivering PFAS from
ocean to land
14. Tom Harner, Amandeep Saini, and Hayley Hung
Air Quality Research Division, Science and Technology Branch
Environment and Climate Change Canada (ECCC)
Measurements of PFASs in Air:
Globally (GAPS Network), Arctic
(AMAP, NCP) and in the Great Lakes
Basin
15. 15
The Global Atmospheric Passive Sampling (GAPS)
โข Address needs under Canadaโs Chemicals Management Plan and the Global Monitoring Plan
โข Currently ~60 sites under core GAPS network (since 2005) and 23 sites under GAPS-Megacities
(since 2018)
polar
background
rural
agricultural
urban
megacities
19. PFASs (2017)
Latest Paper - Saini et al., Environ. Pollut. 2023
LC-PFASs
(2017)
Saini et al., Environ. Pollut. 2023
Passive air samples in GAPS-2017
PFAS congener distribution
21. ร
Seasonal cycle Trend Measured
โข Active air sampling using PUF-XAD-PUF
โข Observe declines but lagging behind industry shifts and
regulatory decisions
โข Presence in landfills and in existing products may prolong
emissions
โข Similar to ice core deposition results.
Alert, Nunavut
PFAS Monitoring in Arctic Air โ Alert, Nunavut
Northern Contaminants Program (NCP)
PFOA PFOS
ln
concentration
(pg
m
-3
)
22. โข 2014 polar bear livers samples from Arctic Canada
โข Western Hudson Bay (WHB), n= 17; Southern Hudson Bay (SHB), n=24
โข Apex marine mammal, year-round resident to Arctic
PFAA in an Arctic Apex Predator: Polar Bears
โข Long chain C8-16PFCAs consistently
detected
โข Most ocean measurements are C4-
C10 PFCA with low concentrations
of PFNA and PFDA
โข Wildlife monitoring demonstrate
the presence of long chain PFCAs in
the marine environment
Letcher, R.J. et al. 2018. Sci. Tot. Environ. 610-611: 121-136.
23. ๏ฑ Continue to track PFAS on spatial and temporal scales
๏ฑ Assess effectiveness of international control measures (e.g., Stockholm
Convention)
๏ฑ Air: Extend target lists to include novel PFASs and ultra-short chain PFASs
๏ฑ Air: Are there other volatile precursors? Total organofluorine methods or
TOP assays?
๏ฑ Water: Aqua-GAPS to achieve full spatial extent
๏ฑ Wildlife: Consider short chain and ultrashort chain ecotoxicity using
environmentally relevant concentrations
๏ฑ Wildlife: Monitor fluorotelomer precursors x:3 FTCA
๏ฑ All media: fluoropolymers?
๏ฑ Include PFASs hotspots for air (e.g. cities) and water and linkages to
ecosystem and human toxicity (assays)
Future Directions
Amila.desilva@ec.gc.ca
28. Application of Passive Samplers to the
Marine Environment
โข Successful in deploying passive samplers for PFAS but not PFBA
โข PFAAs detected in very deep water.
29. SHB
WHB
Temporal Trends of PFAAs in Hudson Bay Polar Bears
WHB; PFNA
2005 2010 2015 2020
0
250
500
750
1000
6.1 % yr-1
SHB; PFNA
2005 2010 2015 2020
0
500
1000
1500
2000
0.80 % yr-1
2005 2010 2015 2020
0
20
40
60
80
100
120
SHB; PFOA
-2.7 % yr-1
WHB; PFOA
2005 2010 2015 2020
0
20
40
60
80
1.5 % yr-1
2005 2010 2015 2020
0
1000
2000
3000
4000
5000
6000
SHB; PFOS
Medians: -5.8 % per yr
Subadults, 15N adj - 8.7 % per yr
WHB; PFOS
2005 2010 2015 2020
0
500
1000
1500
2000
2500
median + 0.30 % per yr
Subadults, 15N adj + 4.4 % per yr
(Letcher et al. 2024. Environ.
Pollut. In prep.)
โข PFOS declining or no
change
โข PFNA increasing or no
change.
โข Similar trends in ringed
seals
โข Climate change food
web shifts
32. PFOS and PFOA in Precipitation and Surface Water in Great Lakes
ln
(C/
ng
L
-1
)
Volume
of
Precipitation
(L)
Gewurtz et al., EST2019
PFOS
PFOA
33. Great Lakes Basin (GLB) Monitoring & Surveillance Program
โข Canada/US Great Lakes Water Quality Agreement (GLWQA)
๏ Air and precipitation monitoring for POPs started in late 80s.
๏ PFAS monitoring in precipitation since 2006
๏ Monitoring in air started 2018 at Point Petre and 2019 in Evansville
Air Concentrations of PFASs
34. PFAS Analysis Difficulties
INCORPORATION OF POLAR ANALYTES
INTO LCMS METHOD
MATRIX EFFECTS AND RECOVERY
Improvement of retention of short-chain ionic PFAS (TFA,
PFPrA, TFMS, PFPrS, PFBA, PFBS) with a switch of LC column
and separation conditions
Recovery issues found in select PUF samples, by examining the injection
and surrogate standards one can get a hint to if the issue was
inappropriate spiking, ionization suppression, or both
13C4-PFOA Surrogate
0
20
40
60
80
Relative
Abundance
5.4 5.6 5.8 6.0 6.2
Time (min)
Very low
recovery in the
PUF extract
(< 10 %)
100
0
20
40
60
80
100
Relative
Abundance
GFF MeOH extract
PUF/XAD/PUF MeOH extract
13C8-PFOA Injection Standard
Injection
standard area
counts within
+/- 20 %,
therefore not an
ionization
suppression
issue