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IJ Allan, C Harman & NW Green 1
Passive sampling in the regulatory context (WFD)
Ian J. Allan, Christopher Harman & Norman W. Green
IJ Allan, C Harman & NW Green 2
Message
• Provide reasons for the incorporation of passive sampling into regulatory monitoring
• Identify some of the challenges regarding its implementation in the WFD regulatory context
IJ Allan, C Harman & NW Green 3
Recent steps forward
2006 BSI PAS 61:2006 Passive sampling for priority pollutants in surface waters
2007 ISO 17402:2008 Measurement of contaminant bioavailability in soils and sediments*
2009 WFD CMA Guidance 19
PSDs mentioned as «complementary» tools for chemical quality monitoring of water
2010 WFD CMA Guidance 25
Listed in the guidance for sediment and biota monitoring
2010 Norman Network position paper
PSDs for screening for emerging substances and contaminants
2011 ISO 5667-23:2011 Passive sampling in surface waters
*Harmsen et al. (2007)
Passive sampling
20 years of research and developments
Passive sampling measures a concentration of contaminant Dissolved or labile in water
Based on diffusive processes
In/ex situ measurements of trace contaminants: Dissolved/labile in water Dissolved/labile in sediment/soil pore waters That are bioaccessible
Passive sampling-PRC vs. biomonitoring Standardised method
Integrative monitoring over periods of days to months
Improved limits of detections and simplified matrix composition
IJ Allan, C Harman & NW Green 4
IJ Allan, C Harman & NW Green 5
Passive sampling
• Focus on surface waters, but should consider other matrices (air, sediments…etc)
Applicable to:
• Nonpolar organic substances (e.g. PAHs, PCBs & PBDEs)
• Polar compounds (e.g. pharmaceuticals and pesticides)
• Metals, metalloid and radionuclides
• Organo-metallics (e.g. TBT)
Advantages of passive sampling
Continuous sampling
Low variability (particularly when compared with biomonitoring)
No need for normalisation such as for sediments
Control over blanks
Ability to standardise uptake (e.g. with PRCs)
Extremely low limits of detection (low pg/L level)
Measurement of a relevant fraction of contaminants in water
Simplified matrix composition
IJ Allan, C Harman & NW Green 6
IJ Allan, C Harman & NW Green 7
Sampler deployment
Sampler Retrieval
Sampler Extraction
and analysis Calculation of
concentration, CW
Exposure for days-months
Modelling…
Sampler selection
Passive sampling
Environmental
variability
-Biofouling
-Temperature
-Salinity Uptake rates (reproducibility, bias)
-Calibration rig set-up (tank, carousel, analyte delivery)
-Control over temperature/turbulences
-Water sample collection, prep., analysis
-DOC/TOC/biofouling
-Sampler prep., deployment, extraction & analysis
IJ Allan, C Harman & NW Green 8
Passive sampler-measured
TWA
Concentration
Sampler extraction
-Contamination
-Recoveries
Extract analysis
for analytes and PRCs
-Calibration, linearity
-LOD/LOQ … etc
TRUE TWA
Concentration
Modelling of TWA concentrations (e.g. for NP)
-Sampler characteristic (Vs, Surface area…)
-Contaminant characteristics (Log Kow, …etc)
-Rs estimation procedure
-Model selection
-Ksw
Sampler storage &
transport
-Stability
-Temperature
-PRC/analyte stability
-Contamination (cross-)
Sampler preparation
-Membrane thickness
-Surface
-Vs
-PRC concentration
-Contamination
Sampler deployment & retrieval
-Clean cage!
-Standard equipment
-Contamination
-Site survey
-Deployment technique
IJ Allan, C Harman & NW Green 9
QA/QC for PSDs for nonpolar substances
At equilibrium:
• Required time to equilibrium
• Level of fluctuations in analyte concentrations
• Ksw values
Integrative mode:
• Ksw for analytes of interest and PRCs
• Method for Rs estimation from PRC (e.g. nonlinear least square method*)
• Model to calculate Rs for nonpolar substances within a wide range of hydrophobicity
*Booij and Smedes (2010)
IJ Allan, C Harman & NW Green 10
QA/QC for PSDs for nonpolar substances
Ksw values
• Mostly available for LDPE or PDMS
• Uncertainty of 0.2-0.5 log units
• Effect of temperature can be modelled but impact is generally minor
• Effect of salinity can be modelled using the Setschenow constant*
*Jonker and Nuijs (2010)
Application to regulatory monitoring
EU Water Framework Directive monitoring:
- Surveillance monitoring
- Operational and investigative monitoring
More specifically:
Testing for compliance with EQS
Monitoring long-term trends in contaminant levels
Measurements of transboundary fluxes
Sources tracking/spatial distribution
Linking exposure and effects
Contaminant speciation
Support to more common monitoring methods (bottle sampling and biomonitoring)
IJ Allan, C Harman & NW Green 11
IJ Allan, C Harman & NW Green 12
Compliance checking with PSDs?
• EQS are set for the «whole water» i.e. substances dissolved as well as fractions sorbed to dissolved/particulate matter
• PSDs measure only the dissolved concentration!
• Nonpolar substances cannot be measured practically and reliably in the water column by other means!
• Which alternatives exist?
– Suspended particulate matter (SPM) monitoring,
– Biomonitoring (e.g. Musselwatch),
– Freshly deposited bed-sediment monitoring?
How do we reconcile «whole water»-based EQS with dissolved phase
PSD data?
IJ Allan, C Harman & NW Green 13
Compliance checking with PSDs?
1. From the Deltares report: Calculate Cw EQS from «whole water» EQS and:
1. Equilibrium partioning theory (EqP)
2. Pre-set DOC/SPM levels
2. Calculate «whole water» concentrations from PSD data and:
1. Measured DOC and SPM levels and EqP
2. Site/water-body specific partitioning data
3. Combine PSD data with SPM data?
How do we reconcile «whole water»-based EQS with dissolved phase
PSD data?
IJ Allan, C Harman & NW Green 14
Compliance checking when Cw are low
• SPMD/Sil measurement near Bear Island
• > 100d exposures
• Integrative sampling for compounds with logKow > 6
• Sampling at Andøya, Bear Island & Jan Mayen
• Ksw values not corrected for salinity or temperature
IJ Allan, C Harman & NW Green 15
SPMD/Sil measurement near Bear Island
PAHs
LogKow
3 4 5 6
CP
S/C
"wh
ole
wa
ter"
0.01
0.1
1
10
0.1 mg L-1
OC
1.0 mg L-1
OC
10 mg L-1
OC
PCBs/OCs
LogKow
4 6 8 10
CP
S/C
"wh
ole
wa
ter"0.001
0.01
0.1
1
10
0.1 mg L-1
OC
1.0 mg L-1
OC
10 mg L-1
OC
• Partitioning to OC (Schwarzenbach et al. 2003)
• Most PAHs present in the dissolved phase
IJ Allan, C Harman & NW Green 16
SPMD/Sil measurement near Bear Island
Priority substances
AA-EQS
(ng L-1)
Bjørnøya Period 1
(ng L-1)
Bjørnøya Period 2
(ng L-1)
Anthracene 100 0.043 0.053
Pentabromodiphenylether 0.2 0.001-0.008 0.0002-0.007
Fluoranthene 100 0.95 0.60
Hexachlorobenzene 10 0.12 0.078
Pentachlorobenzene 7 0.029 0.016
Benzo[a]pyrene 50 <0.02 <0.009
Benzo[b+k]fluoranthene* 30 0.12 0.088
Benzo[ghi]perylene & indeno[1,2,3-cd]pyrene**
2 <0.04 a 0.025
p,p’-DDT 10 <0.012 <0.008
*Sum of benzo[b]fluoranthene and benzo[k]fluoranthene **Sum of Benzo[ghi]perylene and indeno[1,2,3-cd]pyrene aBoth values were below LODs
IJ Allan, C Harman & NW Green 17
Compliance checking with PSDs?
How do we reconcile «whole water»-based EQS with dissolved phase
PSD data?
• For most PAHs, estimated «whole water» concentrations << EQS values
• What is the risk of false negative? How do we reduce it?
• How do we build in safety factors?
IJ Allan, C Harman & NW Green 18
Compliance checking with PSDs?
(How) Can we combine passive sampling and SPM monitoring?
• Contaminant partitioning in Norwegian rivers – Sandvikselva, Alna and Akerselva
– Drammenselva and Glomma
• PAHs, PCBs, OCs and PBDEs
• Passive samplers: LDPE, silicone and SPMDs
• SPM monitoring: Centrifuge, in-situ samplers
• What about DOC?
IJ Allan, C Harman & NW Green 19
The tools
• Continuous flow centrifuge
• In situ samplers (SPM)
• LDPE membranes, silicone strips and SPMDs
IJ Allan, C Harman & NW Green 20
Monitoring on the Glomma River
IJ Allan, C Harman & NW Green 21
SPM-water partitioning for PAHs
logKOW
4 5 6 7 8 9
logK
PO
C
4
5
6
7
8
9
Exposure 1, 2010
Exposure 2, 2010
Exposure in 2009
PAH partitioning in the Glomma river
For 2009:
LogKpoc= 0.97logKow+1.11
(R2=0.958, se = 0.08)
ocPAHw
PAHSPMpoc
fC
CK
IJ Allan, C Harman & NW Green 22
Evaluation of PSDs through intercomparisons
2005 SWIFT-WFD project Tank calibration and field exposure of 7 types of PSDs for polar/nonpolar substances and metals
2006-2007
PSTS water/sed (ICES)
12 laboratories
2009-2011
Eclipse project Tank calibration and field exposure of 5 types of PSDs for nonpolar substances
2010 Aquaref intercomparison
Field exposures involving 25 laboratories, polar and nonpolar substances
2011 Norman Network intercomparison
Intercomparison of PSDs for emerging substances
SWIFT-WFD: intercomparison
First intercomparison of passive samplers* Meuse river (NL), 2005 Overlapping exposures of 7, 14 and 28 days Evaluation of 7 types of passive samplers:
- Chemcatcher - MESCO I (m), MESCO II - LDPE membrane - Silicone rods and strips - SPMDs
Analysis performed in three laboratories - PAHs - PCBs and some organochlorines
(Too?) many dimensions…
IJ Allan, C Harman & NW Green
*Allan et al. (2009)
SWIFT-WFD intercomparison
X Data
Che
mca
tche
r
LDPE m
embr
ane
MESC
O I
(m)
MESC
O II
Silico
ne ro
d
Silico
ne stri
p
SPM
D
(N/A
)/(N
/A) L
DP
E m
em
bra
ne
0.0
1.0
2.0
3.0
4.0
7.0(A)
8
6
1623
70
63
X Data
Che
mca
tche
r
LDPE m
embr
ane
MESC
O I
(m)
MESC
O II
Silico
ne ro
d
Silico
ne stri
p
SPMD
CT
WA / M
ean C
TW
A
0.1
1
10(B)
84
262
200
99
101
50
264
X Data
Che
mca
tche
r
LDPE m
embr
ane
MESCO I
(m)
MESCO II
Silic
one
rod
Silic
one
strip
SPM
D
10
Sta
ndard
Devia
tion
1.0
1.5
2.0
2.5
3.3 (C)
27
87
88
36
3817
88
Comparison of: Contaminant masses accumulated
CW
Standard deviations
Variation in CW caused by: PRC data
Sampler-water partition coefficient, KSW
Use of CW estimator models
Analysis in three different labs
IJ Allan, C Harman & NW Green
IJ Allan, C Harman & NW Green 25
ECLIPSE: Intercomparison
IJ Allan, C Harman & NW Green 26
ECLIPSE: Intercomparison
IJ Allan, C Harman & NW Green 27
AQUAREF: Intercomparison
• Metals, PAHs and polar pesticides
• 3 sites in France – Charente River (Pest)
– Ternay/Rhone River (PAHs/metals)
– Thau Lagoon (Pest/PAHs/Metals)
IJ Allan, C Harman & NW Green 28
Norman Network: Intercomparison
Interlaboratory calibration study in 2011
• present variability in data by comparing results from various passive samplers sent by participating laboratories exposed to water at a single (reference) site
• Target substances:
– polar pesticides - 19 participants
– Pharmaceuticals – 17 participants
– steroid hormones – 14 participants
– Triclosan - 8 participants
– bisphenol A - 11 participants
– PFOA, PFOS - 8 participants
– PBDE -16 participants
• 28 participants from commercial, academic and regulatory laboratories
Silicone strips CONTACT: branovrana@gmail.com
IJ Allan, C Harman & NW Green 30
Intercomparisons
• A wide range of field-based intercomparisons/tank calibrations (2005-2011)
• Much work already undertaken
• Increasing level of testing and complexity of the trials
• QC solutions
• PSDs by participants and organisers
• Trials have yet to include deployment/exposure procedures
Should we focus our effort on a restricted number of samplers?
IJ Allan, C Harman & NW Green 31
Reference material/matrix spikes
• Reference to the ISO standard (2011)
• A need for reference materials/matrix spikes
• Straightforward production
• Relative standard deviation on PRC spikes in LDPE/Sil/SPMDs: < 10% for sampler batches ~ 100
• What about scaling up?
• A challenge is the many types of passive sampling devices available today!
Should we aim to reduce the number of passive sampling devices on the
market?
IJ Allan, C Harman & NW Green 32
Costs of passive sampling
• Two field trips are needed
• Deployment equipment is needed
• Replication
• Need for enough preparation and trip control samplers
For a similar level of information, are passive sampling costs higher than for
conventional bottle sampling?
IJ Allan, C Harman & NW Green 33
Moving forward
• How do we reconcile «whole water»-based EQS and dissolved phase passive
sampling data?
• Will water-based EQS translated into sediment EQS? How will this be done? and
can this be of benefit to us?
• Have other fields attempted such a move towards regulatory use? Can we benefit
from the experience of others?
• Who can/will undertake regulatory passive sampling?
• Can we simplify passive sampling?
• Can we demonstrate that passive sampling costs are lower than for other
monitoring methods for a similar level of information? Is this level of information
needed, wanted?
IJ Allan, C Harman & NW Green 34
Moving forward
• Should we establish «PSDbanks»?
• AQUA-GAPS?*
• What about setting up sampling networks using ferry routes?
• Should we be interested in highly hydrophobic substances in the dissolved phase
(e.g. BDE209)?
*Lohmann & Muir (2010)
IJ Allan, C Harman & NW Green 35
Acknowledgement
Sissel Ranneklev (NIVA)
Guttorm Christensen (Akvaplan-NIVA)
Klif: Norwegian Climate and Pollution Agency
*Lohmann & Muir (2010)
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