The role of passive sampling. Branislav Vrana

Transcription

1 The role of passive sampling Branislav Vrana

2 Pollution of surface water by chemical pollutants

3 Outline Motivation why passive sampling? Working principles of passive sampling Bosna river survey results

4 Need for monitoring data of pollutants in the aquatic environment Information to assess the effectiveness of measures taken to reduce emissions long term data Compliance with legislative requirements Concentrations in surface water are linked to pollutant bioconcentration and bioaccumulation in the food-chain exposure assessment Monitoring data supports modelling of transport and distribution of pollutants

5 Current monitoring practice Currently the method used for measuring chemical pollutants in water is spot (bottle/grab) sampling and laboratory analysis Disadvantages: costly (manpower/transport) provides only a snapshot of pollution at the instant of sampling may not be representative where levels of pollutants fluctuate required sensitivity often not achieved Alternative monitoring methods needed to overcome these problems

6 Representative methods for monitoring Frequent sampling Automatic sequential sampling to provide composite samples over a period of time (usually 24 hours) Continuous, on-line monitoring systems, sensors, biological early warning systems) Biomonitoring (sentinel organisms) Passive samplers

7 Passive sampling Sampler selection Sampler deployment Exposure for days-weeks Sampler retrieval Calibration Parameters (sampling rates R s, partition coefficients K sw ) Exterior cleanup Discard Dialysate Models Sealed in a can Transport Dialytic extraction Biotest battery Gel permeation chromatography (GPC) Calculation of water concentration C w SPMD - Exposure GC/MS - analysis Extraction and analysis

8 Advantages of passive sampling Non-mechanical devices Measurement of a freely dissolved concentration of contaminants in water Continuous sampling measurement of TWA concentrations Extremely low limits of detection (low pg/l level)

9 Principle of a hydrophobic passive sampler: sampler as a communicating vessel C w - concentration in the water system K sw - sampler-water partition coefficient V s volume of sampler C s concentration in the sampler C w C s /K sw V w = infinite Sampling rate - R s equivalent volume of water extracted per unit of time [L/d] sampler capacity -V s K sw maximum volume of water extracted [L] V s K sw

10 Principle of a passive sampler: uptake process from water Diffusional path δ Chemical activity C w /S w Diffusion C S /S S Bulk water Mass transfer coefficients: Water Membrane boundary layer (WBL) D W D M K MW δ δ W W Sorbent or solvent (Receiving phase) D δ S K SW S

11 Variation in pollution over time Concentrations In individual Spot samples TWA = time-weighted average WFD: annual average Environmental Quality Standards AA-EQS 7 14 Time in days

12 Passive samplers: extremely low limits of quantification thanks to integrative sampling 300 C w = 1 ng / L N (ng) weeks 100 Graph by Kees Booij log K ow

13 Need for methods with very low limits of quantification Analytical Methods for the new proposed Priority Substances of the European Water Framework Directive (WFD) methods limits of quantification (LOQs) are compared with one third (1/3) of the EQS, mandatory for WFD compliance monitoring Example EQS: Cypermethrin 80 pg/l (8 pg/l for coastal salt waters) Dichlorvos 60 pg/l in coastal waters Dicofol 32 pg/l in coastal waters 17-alpha-ethinylestradiol 35 pg/l (7 pg/l in coastal waters) 17-beta-estradiol 80 pg/l in coastal waters Heptachlor/epoxide 0.2 pg/l (10 fg/l in coastal waters) BDEs 49 fg/l (2.4 fg/l in coastal waters)

14 Sampler selection: Available technology Sampler Construction Compounds SPMD POCIS MESCO Ceramic Dosimeter DGT Chemcatcher Silicone rubber Semi-permeable membrane devices; flat tube of LDPE filled with triolein Solid sorbent material enclosed in a polyethersulphone membrane PDMS rod enclosed in a membrane made of regenerated cellulose or LDPE Ceramic tube filled with a solid-phase sorbent material, closed with PTFE lids Two layers of acrylamide gel mounted in a holder device A housing made of inert plastic, containing a disk of solid sorbent and a disk of diffusion membrane. Sheets from poly-dimethylsiloxane (PDMS) and many more Hydrophobic semivolatile organic compoundswith K ow > 3 Polar pesticides and Pharmaceuticals with log K ow < 3 Hydrophobic semivolatile organic compounds with log K ow > 3 Groundwater contaminants with a broad range of physico-chemical properties Metallic elements including the common heavy metals, phosphorous, sulphide, 99 Tc Many taylor-made versions; polar and nonpolar organics, metals, organometallic compounds Hydrophobic organic compounds, organometallic compounds.

15 Method: passive sampling of POPs Semipermeable membrane device SPMD Polyetylene membrane filled with triolein Integrative sampling days Target compounds: PAHs, PCBs, OCPs

16 Method: passive sampling of polar compounds Polar Organic Chemical ntegrative Sampler (POCIS) Adsorbent OASIS HLB 2 layers of PES membrane Application: polar organic compounds Integrative sampling days

17 Method: passive sampling of metals Diffusion gradient in thin films: DGT Two layers of acrylamide gel (diffusion gel + chelating resin) in a plastic holder Integrative sampling days Target compounds: Ni,Cd,Pb,Cu

18 Passive sampling: Bosna river survey sampling sites on the Bosna river Organic compounds: (PAHs,PCBs, OCPa) Heavy metals: Ni,Cd,Pb,Cu Polar pesticides Passive samplers: SPMD, DGT,POCIS Campaign: October - November 2012 Sampling: days

19 Sampler deployment Buoy Attachment To a bridge pillar by a rope 1 m Deployment device with samplers Anchor

20 Sampler deployment

21 Sampler deployment

22 Sampler deployment

23 Sampler deployment

24 Sampler retrieval after one month

25 Sampler processing

26 SPMD processing Discard Exterior cleanup Dialysate Sealed in a can Transport Dialytic extraction Gel permeation chromatography (GPC) GC/MS - analysis SPMD - Exposure

27 Data interpretation: Calculation of TWA concentration M s R t = C K V 1 exp s w sw s K V sw s Sampling rate R S [L d -1 ] equivalent volume of water cleared of the target analyte per unit of time Sampler/water partition coefficient K sw [L/L]

28 Correlation between uptake and offload Performance reference compound (PRC concept) Both uptake and offload are governed by the same mass transfer law isotropic exchange kinetics. Concentration Uptake Offload Time M S (0) = 0 C w = const. M S (0) 0 C w = 0

29 Performance reference compounds SPMD9 1.2 fraction PRC retained Rs=5.9 (±0.6) f-measured f-calc log(k pw /M )

30 Results: Free dissolved concentrations of PAHs using SPMDs Free dissolved PAH concentrations in water from SPMDs Spring of Bosna Sarajevo, downstream Visoko, upstream Visoko, downstream Lasva confluence, upstream Zepce, upstream Maglaj, upstream Doboj, upstream Modrica, upstream Modrica, downstream Concentration [pg/l] 0 Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthracene Chrysene Benzo[b]fluoranthene Benzo[k]fluoranthene Benzo[a]pyrene Indeno[1,2,3-cd]pyrene Dibenz[a,h]anthracene Benzo[ghi]perylene

31 Results: Free dissolved concentrations of PAHs using SPMDs Free dissolved concentrations of light PAHs in water from SPMDs Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Concentration [pg/l] Spring of Bosna Sarajevo, downstream Visoko, upstream Visoko, downstream Lasva confluence, upstream Zepce, upstream Maglaj, upstream Doboj, upstream Modrica, upstream Modrica, downstream

32 Results: Free dissolved concentrations of PAHs using SPMDs Free dissolved concentrations of heavy PAHs in water from SPMDs Benz[a]anthracene Chrysene Benzo[b]fluoranthene Benzo[k]fluoranthene Benzo[a]pyrene Indeno[1,2,3-cd]pyrene Benzo[ghi]perylene Concentration [pg/l] Spring of Bosna Sarajevo, downstream Visoko, upstream Visoko, downstream Lasva confluence, upstream Zepce, upstream Maglaj, upstream Doboj, upstream Modrica, upstream Modrica, downstream

33 Results: Free dissolved concentrations of PCBs using SPMDs Free dissolved PCB concentrations in water from SPMDs Concentration [pg/l] Spring of Bosna Sarajevo, downstream Visoko, upstream Visoko, downstream Lasva confluence, upstream Zepce, upstream Maglaj, upstream Doboj, upstream Modrica, upstream Modrica, downstream PCB 28 PCB 52 PCB 101 PCB 118 PCB 153 PCB 138 PCB 180

34 Results: Free dissolved concentrations of PCBs using SPMDs 80.0 Free dissolved PCB concentrations in water from SPMDs PCB 28 PCB 101 PCB 118 PCB 153 PCB 138 PCB 52 PCB 180 Concentration [pg/l] Spring of Bosna Sarajevo, downstream Visoko, upstream Visoko, downstream Lasva confluence, upstream Zepce, upstream Maglaj, upstream Doboj, upstream Modrica, upstream Modrica, downstream

35 Results: Free dissolved concentrations of OCPs using SPMDs Free dissolved OCP concentrations in water from SPMDs Concentration [pg/l] Spring of Bosna Sarajevo, downstream Visoko, upstream Visoko, downstream Lasva confluence, upstream Zepce, upstream Maglaj, upstream Doboj, upstream Modrica, upstream Modrica, downstream PeCB HCB a-hch b-hch Lindane o,p'- DDE p,p'- DDE o,p'- DDD p,p'- DDD o,p'- DDT p,p'ddt

36 Practical implications for compliance checking with EQS Direct comparison of PS-derived free dissolved concentrations with EQS not possible for hydrophobic compounds derived for whole water Possibility to predict concentrations in BIOTA from passive samplers and check compliance to EQS for biota an initial survey before starting to monitor in biota

37 Predicting concentrations in biota from passive samplers PS data is very relevant for assiessing organism exposure Smedes et al. demonstrated a perfect correlation of concentrations in mussels to PSderived free dissolved concentration Transfer to lipid basis in biota possible

38 Predicting concentrations in biota (containig 5% lipid) from passive samplers EXAMPLE OPTION 1: from BCF Cl = Cw BCF OPTION 2: from lipid/water partition coefficient C l = C w K Lip w

39 Predicting concentrations in biota (containig 5% lipid) from passive samplers EXAMPLE FLUORANTHENE Calculated from literature BCF in fish Fluoranthene Calculated from C(BAFmussel)flt literature BAF in mussel Calculated from Series3 equilibrium lipid concentration Series2 Proposed EQS for biota (fish), normalised on 5% lipid Sarajevo, downstream Visoko, upstream Visoko, downstream Lasva confluence, upstream Zepce, upstream Maglaj, upstream Doboj, upstream Modrica, upstream Modrica, downstream Spring of Bosna Estimated steady state concentration in biota[ug/kg lipid]

40 GC/MS screening of SPMD extracts Abundance 3.2e+07 TIC: SPMD_2c.D\ data.ms TIC: SPMD_blank3c.D\ data.ms (*) 3e e e e e+07 2e e e e e+07 1e Time--> Large volume injection (20 µl), thermal desorption (Gerstel TDU)/cryofocusation (Gerstel CIS4) GC/MS Agilent 6890N + Agilent 5973 mass spectrometer GC/MS EI ionisation, retention time locked chromatography according to Agilent application note EN Blank subtraction AMDIS automated mass spectral deconvolution and indentification MS library search (NIST, Wiley)

41 Results: Free dissolved concentrations of metals using DGT Ni new proposed AA-EQS Concentration (ug/l) spring of bosna Sarajevo, down-stream Visoko, up-stream Visoko, down-stream Lasva confluence,up stream Zepce, up stream Maglaj,up stream Doboj,up stream Modrica,up stream Modrica,down stream

42 Results: Free dissolved concentrations of metals using DGT Pb new proposed AA-EQS Concentration (ug/l) spring of bosna Sarajevo, down-stream Visoko, up-stream Visoko, down-stream Lasva confluence,up stream Zepce, up stream Maglaj,up stream Doboj,up stream Modrica,up stream Modrica,down stream

43 Results: Free dissolved concentrations of metals using DGT Cu Concentration (ug/l) spring of bosna Sarajevo, down-stream Visoko, up-stream Visoko, down-stream Lasva confluence,up stream Zepce, up stream Maglaj,up stream Doboj,up stream Modrica,up stream Modrica,down stream

44 Results: Free dissolved concentrations of metals using DGT Cd new proposed AA-EQS Concentration (ug/l) spring of bosna Sarajevo, down-stream Visoko, up-stream Visoko, down-stream Lasva confluence,up stream Zepce, up stream Maglaj,up stream Doboj,up stream Modrica,up stream Modrica,down stream

45 CONCLUSIONS Passive samplers (PS) identify spatial concentration gradients and patterns of ultra-trace pollutants in Bosna river PS results indicate PAHs originate from point sources and their concentrations likely exceed the EQSs at all profiles except Spring of Bosna PCBs and OCPs originate from diffusion sources and their concentrations are low A good agreement with PS data on POPs reported earlier (Harman et al., Environ Monit Assess DOI /s ) Concentrations of priority metals at some profiles are close to the new proposed AA-EQSs Concentrations of monitored polar pesticides are very low (low ng/l range)

46 An overview of passive sampling techniques R. Greenwood, G. A. Mills and B. Vrana Comprehensive Analytical Chemistry, Volume 48 Passive Sampling Techniques in Environmental Monitoring Elsevier, Amsterdam, 2007