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Heinz Rüdel, Karlheinz Weinfurtner Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) Schmallenberg, Germany

Andrea Körner, Jan Koschorreck German Federal Environment Agency Dessau-Rosslau, Germany Contact: heinz.ruedel@ime.fraunhofer.de

Use of archived suspended particulate matter from rivers for the retrospective monitoring of polar compounds

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Overview Use of archived suspended particulate matter from rivers for the retrospective monitoring of polar compounds

motivation - why is SPM an interesting matrix for ESBs? what is SPM? how is SPM sampled? characteristics of SPM

- binding properties - long-term comparability

what are polar compounds? case studies on retrospective SPM monitoring of chemicals conclusions

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Why is SPM an interesting matrix for ESB concepts?

Most polar compounds have a low rate of bioaccumulation and cannot be detected sensitively in biota. However, these compounds bind to suspended particulate matter (SPM) by other mechanisms (e.g., ion exchange, adsorption)

Biota samples are most appropriate for monitoring lipophilic compounds which bioaccumulate in fatty fractions of tissue. The German environmental specimen bank programme covers two freshwater species, i.e. fish (bream) and mussels (zebra mussel)

Although polar compounds are not completely bound to SPM it can be assumed that the relative bound fraction remains quite similar over years (provided that the SPM quality does not change significantly)

Thus the retrospective SPM analysis may allow for trend monitoring of polar chemicals in rivers – for example many pharmaceuticals, personal care products, biocides…

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What is suspended particulate matter (SPM)? Definition according to the standard ISO 5667-17 (2008) -

Guidance on sampling of bulk suspended solids: suspended solids are solids with a diameter greater than 0.45 µm that are suspended in water and can be removed by filtration, settling or centrifuging under specified conditions

German ESB glossary: - SPM is the third important structural and functional element in aquatic ecosystems next to the water phase and the sediment

- Origin, quantity and quality of the SPM are site-specific, dependent on geology, land use, urbanisation, state of waste water treatment technology, etc. of the respective catchment

- The chemical and biological composition of SPM is also influenced by season, nutrient supply, water outflow, weather…

Factors characterising the binding characteristics of SPM for organic chemicals are, e.g., particle size distribution, specific surface area, cation exchange capacity, pH, total organic carbon content, redox potential, and mineral constituents

5 Routine SPM sampling in the German ESB started in 2005;

currently 16 sites in large rivers are covered SPM is collected passively with stainless steel traps:

operated from buoys in the open water or as flow-through systems in measuring stations (German ESB guideline)

Sampling of Suspended Particulate Matter (SPM)

freezing device for SPM

polystyrene insulation

source for pictures/schemes: FU Berlin

Sampling by Hydrogeology, FU Berlin

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Preparation of SPM for ESB storage sieving < 2 mm

and freezing at -150°C

Long-term sampling since 2005 at 16 German river sites; currently about 140 different pooled annual SPM samples with about 25,000 sub-samples are kept in the ESB archive

freeze-drying crushing of agglo-merates with a pestle

pooling of 12 monthly samples homogenisation with a stirrer preparation of up to 200 sub-samples final storage at < -150 °C

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Monitoring strategy for chemicals in SPM Monitoring guidance No. 25 (EU 2010)

rule of thumb for monitoring: - compounds with a log Kow > 5 preferably in sediments or SPM - compounds with a log Kow < 3 preferably in water

However, this rule strongly only applies to non-ionising compounds and sorption to (non-polar) organic carbon; if compounds have polar functional groups or are acids or bases (or both), a binding to SPM also occurs by other mechanisms

Even for a compound with a log Kow < 3 an SPM monitoring may be interesting in the context of archiving for an ESB: Trends can be detected, levels in the water phase can be estimated and compared to effect levels although only a fraction of the compound is bound to SPM

Types of interactions between SPM and chemicals: van der Waals interactions, hydrophobic bonding, hydrogen bonding, charge transfer, ligand-exchange and ion bonding, direct and induced ion-dipole and dipole-dipole interactions, chemisorption (covalent bond)

Kow - n-octanol water partition coefficient

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Characteristics of annual pooled SPM samples SPM parameters: variation between sites

at each site: long-term comparability seems possible example: SPM from Saar river, site Guedingen clay (%) pH total organic carbon (%)

German ESB data available for download at www.umweltprobenbank.de

TOC pH boxplots: clay

key parameters may change slightly over longer periods - if TOC or clay show trends, a normalisation of target compounds concentrations to a defined TOC or clay content may be considered

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What are polar compounds? the following chemicals are regarded here as polar compounds

- compounds with a log Kow < 3 - compounds with a log Kow > 3 which are ionisable under environmental conditions, i.e. in the pH range 5 - 9

Kow - n-octanol water partition coefficient pKa - logarithmic acid dissociation constant D - distribution coefficient

the Kow is not appropriate to describe the polarity of ionisable compounds; for these the distribution coefficient D value is a better descriptor D = [non-ionised]octanol / ([non-ionised]water + [ionised]water)

The extent of ionisation can be viewed as the fraction of neutral species present - fraction of neutral (protonated) acid = (1 + 10pH - pKa)- 1

- fraction of neutral (non-protonated) base = (1 + 10pKa - pH)- 1 Example: Triclosan has a log Kow of 4.76; it is a weak acid with a pKa of 7.9 - 8.1; at pH 8 about 50 % of the Triclosan molecules are ionised and at pH 7 about 9 %

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Dissociation of ionisable compounds fraction of neutral species (US EPA) 1.00 = 100 %

for compounds with pKa between 5 and 9 the fraction of the neutral molecule is significantly influenced by the ambient pH

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Examples for monitoring of polar compounds in SPM Tris(2-chloroisopropyl)phosphate (TCPP), CAS no. 13674-84-5

log Kow (exp.) 2.59 (not ionisable) phosphorus flame retardant

months (period 01-1998 - 12-2000) months (period 01-1998 - 12-2004)

Tris(2-chloroethyl)phosphate (TCEP), CAS no. 115-96-8 log Kow (exp.) 1.44 (not ionisable) phosphorus flame retardant

Data for Elbe river and tributary sites; source: FGG Elbe 2015 (www.fgg-elbe.de)

months (period 01-1998 - 12-2004)

months (period 01-1998 - 12-2000)

months (period 01-1998 - 12-2000) months (period 01-1998 - 12-2000)

sampling mainly bi-monthly; not continuously

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monitoring of polar compounds in suspended particulate matter from the German ESB

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Retrospective monitoring of biocides in ESB SPM samples Irgarol: Saar / Rehlingen Rhine / Bimmen Elbe / Blankenese Cybutryn CAS no. 28159-98-0 log Kow (exp.) 2.8 / (est.) 4.07 pKa = 4.12 Saar / Rehlingen Rhine / Koblenz Rhine / Bimmen

Data source: Schulz 2013; contract study for Umweltbundesamt

Elbe / Zehren Saale / Wettin Elbe / Blankenese

Cybutryn (Irgarol) is a biocide; currently it is only used in antifouling coatings for ships - the use as preservative in construction materials (e.g., façade coatings) and other products was phased out in 2011

[µg/kg dw]

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Retrospective monitoring of biocides in ESB SPM samples Tebuconazole CAS no. 107534-96-3 log Kow (exp.) = 3.70 pKa = 5.0 Saar / Rehlingen Rhine / Koblenz Rhine / Bimmen

Data source: Schulz 2013; contract study for Umweltbundesamt

Elbe / Zehren Saale / Wettin Elbe / Blankenese

[µg/kg dw]

Tebuconazole is used as a biocide for several applications, e.g., as preservative for construction materials, wood and other products; it was assumed to be a potential substitute for cybutryne (Irgarol), especially in façade coatings

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Elbe / Zehren Saale / Wettin Elbe / Blankenese

Retrospective monitoring of biocides in ESB SPM samples Propiconazole CAS no. 60207-90-1 log Kow (exp.) = 3.72 pKa = 1.09 Saar / Rehlingen Rhine / Koblenz Rhine / Bimmen

Data source: Schulz 2013; contract study for Umweltbundesamt

[µg/kg dw]

Propiconazole is used as a biocide for several applications, e.g., as preservative for wood and other materials; it was assumed to be a potential substitute for cybutryne (Irgarol)

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to SPM organisms by chemicals

Use of SPM monitoring data for risk assessments

SPM monitoring data may be used to assess (retrospectively) the potential risks posed to pelagic organisms Calculation of water concentrations for chemicals detected in SPM if

(estimated) partitioning coefficients are available and comparison with aquatic PNECs

A direct comparison of detected concentrations of chemicals in SPM with ecotoxicological effect levels of organisms is not possible due to a lack of effect data measured with SPM organisms

However, effect concentrations for SPM organisms can be estimated from the aquatic predicted no effect concentrations (PNECs) on the basis of partitioning of chemicals between solids and water - equilibrium partitioning approach (ECHA, 2010)

Ksusp-water - SPM-water partitioning coefficient (estimated) RHOsusp - bulk density of SPM

PNECsusp = * PNECwater * 1000

[chemical]water = [chemical]susp * RHOsusp / (Ksusp-water * 1000)

17 Archived SPM samples enable the German ESB programme

to cover polar organic compounds in freshwater monitoring First retrospective monitoring studies are promising:

data for biocides - cybutryn, azole fungicides - allow trend analyses and discussion in relation to policy measures (here phase-out of certain uses, possible use of substitutes)

Conclusions

Normalisation of concentration data may be applicable to consider temporal changes of TOC or clay in SPM (other parameters may be also considered, e.g., cation exchange capacity)

SPM monitoring data may also be used to assess the potential risks for SPM organisms (equilibrium partitioning approach if aquatic effect data are available) or pelagic organisms (calculation of water concentrations with respective partitioning coefficients for PNEC comparison)

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Acknowledgements

Many thanks for the excellent cooperation

- to all colleagues of the Environmental Specimen Bank (ESB) team of the German Environment Agency (Umweltbundesamt)

- to all team members involved in the German ESB program at: Fraunhofer IME

Hydrogeology, Freie Universität Berlin

Many thanks to Jörg Wellmitz, German Federal Environment Agency, for kindly providing the Excel-based LOESS-Trend tool 1.1 which was applied for trend analysis