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The use of passive sampling as a
potential compliance tool for the WFD
Andy Sweetman, Lancaster University
What's new in the analysis of complex environmental matrices?
Royal Society of Chemistry
Environmental Chemistry Group, Water Science Forum and the
Separation Science Group Joint Meeting
Friday 3rd March 2017
EU - Water Framework Directive
• Prevent deterioration and enhance status of
aquatic ecosystems & associated wetlands
• Promote sustainable water use
• Prevent deterioration/reduce pollution of
groundwater
• Contribute to mitigating effects of floods/droughts
• Reduce pollution from priority substances
The WFD, adopted in 2000, based on river basins and designed to
ensure all European waters in good condition.
Ecological and Chemical status
.
.
..
...
...
Hospital
Industry
Landfill
AquacultureFarm
STP
Domestic
Agriculture
Complexity of contaminant
sources, fate and behaviour
in a typical catchment
Policy decisions - Annex X of WFD.List of Priority Substances
Reduce to ‘zero’ Reduce to below EQS
Priority Hazardous
Substances Priority Substances Other specific pollutants
Anthracene 1,2-Dichloroethane DDT / p,p‘-DDT
Brominated diphenylethers Aclonifen Aldrin
C10-C13-Chloroalkanes Alachlor Dieldrin
Cadmium and its compounds Atrazine Endrin
Di(2-ethylhexyl)phthalate
(DEHP) Benzene Isodrin
Dicofol Bifenox Carbontetrachloride
Endosulfan Chlorfenvinphos Tetrachloroethylene
HCBDD Chlorpyrifos (ethyl) Trichloroethylene
Heptachlor and
heptachlorepoxide Cybutryne
Hexachlorobenzene (HCB) Cypermethrin
Hexachlorobutadiene (HCBD) Dichloromethane
Hexachlorocyclohexane Dichlorvos
Mercury and its compounds Diuron
Nonylphenols Fluoranthene
PCDD/Fs Isoproturon
Pentachlorobenzene Lead and its compounds
PFOS Naphthalene
Polyaromatic Hydrocarbons
(PAHs) Nickel and its compounds
Quinoxyfen Octylphenols
Tributyltin compounds Pentachlorophenol
Trifluralin Simazine
Terbutryn
Trichlorobenzenes
Trichloromethane
Watch list (monitored for up to 4 years)
diclofenac
17-Beta-estradiol (E2)
17-Alpha-ethinylestradiol (EE2)
Under discussion
Acetamiprid
Azithromycin
Clothianidin
Thiacloprid
Thiamethoxam
2-Ethylhexyl 4-methoxycinnamate
2,6-ditert-butyl-4-methylphenol
Erythromycin Clarithromycin
Imidacloprid
Methiocarb
Tri-allate
EU Survey: Frequency of detection of
selected substances in rivers and
groundwater – emerging contaminants
Wide range of contaminant groups
Industrial chemicals
Surfactants
Pharmaceuticals
Pesticides
Personal/household care ingredients
Sets out environmental quality standards (EQS) of certain
pollutants identified as priority on account of the substantial
risk they pose to or via the aquatic environment
• AA-EQS - the average value or concentration of the
substance concerned calculated over a one-year period.
• MAC-EQS the maximum allowable concentration of the
substance.
Environmental Quality Standards
(EQS) Directive 2008/105/EC
Member States must ensure compliance with these standards.
Difficult and expensive!
EQS setting for fluorinated surfactant in
European waters
PFOS added to Annex B of the Stockholm Convention (restriction on production
and use) in 2009 by the Conference of Parties
In 2010 the European Union has added PFOS to the POPs regulation (EC)
850/2004 (ensures compatibility with SC)
Selection of the protection goals is challenging.
Approach 1. Maximum Permissible Concentration for humans based on fish
consumption and Tolerable Daily Intake is 0.65 ng/L
Approach 2. The PNEC for the aquatic ecosystem was suggested by a UK report to
be 25 μg/L, (based on the mysid shrimp Americamysis bahia NOEC)
In-stream fate modelling for
persistent fluorinated surfactant PFOS
0
5
10
15
20
25
PF
OS
Co
nce
ntr
atio
n (
ng
/L)
Distance Downstream (km) and STPs
PFOS 2010
PFOS 2013
GLRM Pop @27µg/day ÷ 3
GLRM STP Adj @27ug/day
Predicted PFOS concentrations per EVnBETR box in European fresh (ng/L) and salt water (pg/L) environments. In freshwater, predicted concentrations were allocated to major rivers for demonstration purposes.
*EQS based on protection of human health via fish consumption
European Scale PFOS Modelling
– 90% exceeds 0.65 ng/l*
(even more challenging in
coastal waters 0.13 ng/l)
Andrew Johnson – Centre for Ecology and Hydrology
A comparison of a low protective value for a chemical (such as predicted no effect concentration –PNEC) with high measured environmental concentrations such as used in the 2016 EU –JRC monitoring based approach to chemical prioritisation
3-point scoring system that involves the 95%ile
of measured concentrations (MEC95) vs PNEC
This system picked out deltamethrin as
the number 1 new priority chemical
So why was this insecticide selected
as being of the highest risk?
Why was deltamethrin ranked as the highest risk by EU/JRC?1) A very low toxicity threshold PNEC 0.0031 ng/L
0.
0.
0.
0.
0.01
0.1
1.
10.
100.
1000.
10000.
100000.
1000000.
0 6 13 19 25
Deltamethrin ecotoxicity data (ug/L) and PNEC
PNEC set at a staggering 0.0031 ng/L!
Akerblom et al (2008) Chironomus riparius LC50 0.016 ng/L
But how often was deltamethrin quantified across 7 countries and 28,757 samples?
% deltamethrin above LOQ
% <LOQ % quantified
Answer = only 0.6%
Why was deltamethrin ranked as the highest
risk by EU/JRC?
2) A high exposure (MEC95) of 50 ng/L
How to demonstrate compliance?
Guidance on sampling strategy: location, frequencies and methods
Establishment of EQS values has been limited for the majority of priority
substances to water only. The principle matrix is whole water, or for metals,
the liquid fraction obtained by filtration of the whole water sample.
For most water bodies spot samples are likely to be appropriate. However,
situations, where pollutant concentrations are heavily influenced by flow
conditions and temporal variation flow-proportional or time-proportional
maybe preferable
Sampling frequency once-a-month for priority substances and once-per-three-
months for other pollutants
However, the guidance acknowledges that available analytical
methods are not sufficiently sensitive.
LOQ should be <30% of the EQS
• PFOS (AA EQS 0.65 ngL-1) this would be <0.2 ngL-1
• BaP (AA EQS 0.17 ngL-1) this would be <0.05 ngL-1
• Cypermethrin (AA EQS 0.08 ngL-1) this would be <0.02 ngL-1
How to demonstrate compliance?
Passive samplers (e.g., Semi-Permeable Membrane Devices
(SPMD), Polar Organic Chemical Integrative Samplers (POCIS),
Diffusion Gradient Thin Films (DGTs), Chemcatcher) are
exposed in the aquatic environment for several days or up to
weeks to yield time-integrated average concentrations for
organic contaminants and heavy metals.
PS are less influenced by short-term fluctuations in
concentrations than spot sampling.
PS sampling rates are in the range of litres per day for various
contaminants (e.g., organic compounds of medium
hydrophobicity, heavy metals), allowing analysis of trace
contaminant levels
What about passive sampling?
Importantly PS sample the freely-dissolved bioavailable water concentrations
which reflects the biologically available fraction but doesn’t provide total
water concentrations as required by the WFD.
However, if DOC, SPM and TOC content of the SPM are known, then
partitioning theory can be used to estimate the total concentrations.
TWO main types:
Hydrophobic chemicals: Can be biphasic e.g. SPMD or commonly monophasic
polymer strips e.g. silicone rubber, Low Density PolyEthylene (LDPE) strips
Requires knowledge of polymer-water partition coefficients and use of
performance reference compounds (PRCs)
What about passive sampling?
What about passive sampling?
Hydrophilic chemicals: Mostly adsorption based adsorption to a coated
disc protected by a membrane
POCIS A sorbent layer covered either side by porous polyethersulfone
membranes
Chemcatcher comprises a 47 mm 3M Empore disk as the receiving phase.
A range are available for different classes of chemicals class (e.g., non-
polar organic, polar organic, metals, radionuclides). A thin diffusion
limiting membrane can be placed over the receiving phase to restrict the
rate of uptake of pollutants.
PRCs can be used to account for variations in sampling rate.
Diffusion Gradients in thin-films (DGT) – two layers initially developed for
metals
19
Metals (Al, Cr, Cd, Cu, Co, Ni, Zn, Pb, Fe, Mn, Ca, Mg, Mo, As,
Se,W, V, Sb, Au, Hg)
Radionuclides (Cs, Sr, Tc, U)
Nutrients (SO42-
, NH4+)
Others (Ra, Pu)
Organics (current and in development)
• Wide range of antibiotics
• Personal/household product ingredients
• Pharmaceuticals
• Non-brominated flame retardants
• Pesticides
What Can DGT Measure?
Diffusion Gradients in Thin-films (DGT)
Davison W. and Zhang H., Nature, 1994.
Zhang H. and Davison W., Anal. Chem. 1995.
Passive sampling in rivers
and effluents
Agarose gel XAD or HLB
Diffusion Coefficient (D) Measurement
Cross-section through a diaphragm diffusion cell
Initially 50ml MQ
water containing
NaCl & Antibiotics
Initially 50ml MQ
water with NaCl
• Temperature: 20°C
• pH: 6.5
• Source part: 2ppm SMX
• Sampling: 0.4mL/15min
----HPLC-UV analysis
• De = k∆g/(CbA)
Cb = M∆g/(DAt)
DGT Development – diffusion rates
Measured masses (M, μg) of selected test chemicals in HLB-DGT deployed in well
stirred solution
bisphenol-A Propylparaben
• DGT accumulation with deployment time
• Most substances detected in INF, fewer in EFF
• 7-18 days accumulation (1-2 weeks recommended)
0
5
10
15
20
0 7 14 21 28
Ma
ss (
ng
)
Time (days)
BHA-INF
0
15
30
45
60
0 7 14 21 28
Ma
ss (
ng
)
Time (days)
TCS-INF
0
2
4
6
8
10
0 7 14 21
Ma
ss (
ng
)
Time (days)
BHA-EFF
0
5
10
15
20
0 7 14 21
Ma
ss (
ng
)
Time (days)
TCS-EFF
WWTP Field testing
• DGT (HLB) compared to auto-sampling & grab sampling)
• Comparable with auto-sample (TWA concentrations)
• 7 day sampling period (7 grabs, 7 24 hour composites from autosampler)
1
10
100
1000
10000
100000
ME
P
ET
P
PR
P
BU
P
PH
BA
BH
A
OP
P
TC
S
TC
C
BP
A E1
E3
4-T
-OP
NP
Cw
(n
g L
-1)
PPCPs
D7: INF DGT
Auto
Grab
0
1
10
100
1000
Cw
(n
g L
-1)
PPCPs
D7: EFF DGT
Auto
Grab
WWTP Field testing
Field testing – Liuxi river, Guangdong province
0
20
40
60
80
100
120
140
SDZ SPD TMP SMZ SMM SMX SQX NFX OFX CIP EFX LFX LIM LEM CLM ROM SAM FLO CHL
Co
nce
ntr
ati
on
, n
g/L
Passive & grab sampling in Liuxi River S2
S2-Grab
S2-DGT
Focussed on wide range of antibiotics
1
10
100
1,000
10,000
ME
P
ET
P
PR
P
UB
P
BE
P
HE
P
PH
BA
BH
A
BH
T
BP
A
DE
S
E1
E2
E3
EE
2
OP
P
TC
S
TC
C
4-T
-OP
NP
Co
nce
ntr
ati
on
(n
g/L
)
Chemicals
A: RI
1
10
100
1,000
10,000
ME
P
ET
P
PR
P
UB
P
BE
P
HE
P
PH
BA
BH
A
BH
T
BP
A
DE
S
E1
E2
E3
EE
2
OP
P
TC
S
TC
C
4-T
-OP
NP
Co
nce
ntr
ati
on
(n
g/L
)Chemicals
D: FE
� All 20 target chemicals detected in raw influent, 18 in final effluent
Chinese WWTP Fate Study
• Removal rates found to be very variable
Fate Study in Chinese WWTPs
-100
-50
0
50
100
150
ME
P
ET
P
PR
P
UB
P
BE
P
HE
P
PH
BA
BH
A
BH
T
BP
A
DE
S
E1
E2
E3
EE
2
OP
P
TC
S
TC
C
4-T
-OP
NP
Re
mo
va
l (%
)
Chemicals
-184% -183% -125% -466%
� Parabens: 81-100 %
� Estrogens: >50 % (not DES)
� BPA, OPP, TCS: > 50 %
� Antioxidants: < 50 %
� Alkyl-phenols: < 50 %
� DES and TCC: < 50 %
� PHBA: < 0 %
� DGT has been successfully applied for a wide range of organic
chemicals – most common configuration HLB resin as binding
agent
� Passive sampling has a wide range of applications - pre-
concentration and ‘clean-up’, sensitive, TWA concentrations,
provides bioavailable fraction.
� Needs further research and calibration/validation to define
sampling rates, operating range.
� Need to assess ability to predict ‘total concentrations’ for EQS
compliance for a wide range of chemicals
DGT and passive sampling