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Bioavailability and Bioaccumulation as crucial factor to link contamination and ecological status

Bioavailability and Bioaccumulation as crucial factor to link contamination and ecological status.

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Bioavailability and Bioaccumulation as crucial factor to link contamination and ecological status

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  1. Bioavailability and Bioaccumulationas crucial factor to link contamination and ecological status Bert van Hattum, Pim Leonards, Jussi Kukkonen, Arto Sormunen, Anita Tuikka, Sander Van Vliet, Joop Bakker, Foppe Smedes, Paul van Noort, Georg Streck, Werner Brack, Nicole Bandow, Anton Kocan, Miren Lopez de Alda, Rikke Brix, Isabel Muñoz, Eric de Deckere, Chris van Liefferinge, Vicky Leloup, Pavel Jurajda, Zdenek Adamek, Mirek Machala, Jos van Gils, Yenory Morales, Dick de Zwart DG Environment, Brussels 20 January 2010

  2. Emission Transport Transformation Partitioning Exposure Bioavailability Bioaccumulation Biotransformation Effects Pollutants Sediment Linking exposure to effects

  3. Air Air Biota Biota Freely dissolved Freely Dissolved DOC DOC SPM SPM DOC Sediment Sediment Porewater Porewater (FD) Aqueous environment Bioavailable Total water concentration Working with total concentrations may lead to overestimation of toxicity Inorganic ligands

  4. Dissolved Organic Carbon - Cu Corrections in Modelkey effect studies: hardness, pH, sorption to SPM Other factors: pH, speciation Problem: metal-specific corrections required Kramer et al. (2004) Environmental Toxicology and Chemistry, Vol. 23, No. 12, pp. 2971–2980

  5. Sediment properties –speciation e.g., Organic Carbon Content, Organic Carbon Composition, Black carbon Particle Size Distribution, Cation Excange Capacity (CEC), Sulphides (AVS/SEM), Fe-hydroxides porewater composition: dry wt, DOC Contaminant Characteristics e.g., pKa, hydrophobicity (log Kow), sorption characteristics (Koc, Kd, Kbc), planarity Bioavailability – Controlling Factors

  6. Organism Physiology e.g., digestive fluid composition, life span of organism, organism size, seasonal changes in biochemistry, respiration, metabolism, growth, egestion, repoductional losses Physical Changes e.g., seasonal stochastic events, inundation, seasonal temperature changes, ageing Bioavailability – Controlling Factors

  7. Black carbon traffic oil Binding affinity to BC 1-2 order of magnitude higher compared to regular OC for many compounds graphite M.T.O. Jonker and A.A. Koelmans, 2002, Environ. Sci. Technol., 36:3725-3734.

  8. Sediment - equilibrium partitioning • Classical EqP: • The freely dissolved pore water concentration (Cw) is in equilibrium with the concentration in sediment organic carbon • Concentration organism in equilbrium with Cw • “Revised” EqP • Fractions with rapid-slow-very slow exchange • The freely dissolved concentration in pore water (Cw) is at equilibrium with rapidly desorbing fraction (Fr) • Fr can be estimated with different methods: for example by passive sampling or by Tenax desorption. Organic carbon particle Rapid fraction (Fr) Pore Water (Cw) Animal (lipid)

  9. Modelkey desorption studies (Tenax) Lab studies 49-d desorption study to estimate rapidly, slowly and very slowly desorbing fractions and corresponding desorption rates

  10. BSAF and Fr Lumbriculus variegatus The relationship between BSAF and rapidly desorbing fractions (Fr) in various sediment treatments with several organic compounds (thesis: Sormunen 2008).

  11. Cw measured with POM-SPE (Polyoxymethylene) BSAF and freely dissolved concentration Modelkey sediments PCB-77 BDE-47

  12. Other factors investigated in lab studies • Contact time and ageing • Role of feeding activity • Sediment properties • Compound properties • Concentration dependency Important for most compounds: Freely dissolved concentration rapidly desorbing fraction Properties: OC, BC, lipid likes Understanding of the biological factors is incomplete

  13. Silicon-rubber IVPS • Determination of: • Freely dissolved concentration • Field Koc (Example: Schijn – Eenhoorn) • Exchangeable fraction Benz[a]anthracene (pg/l) Field Koc values higher compared to experimental Koc In field bioavailability may be limited Method: Smedes et al., 2009, in preparation

  14. Measurement in biota Measurement of in-situ exposure and internal concentrations Bioassays (toxicity, bioaccumulation) with field sediments Freely dissolved concentration - measurement Biomimetic (SPMD,SPME, POCIS, POM, pore-water peepers, C18 SPE porewater): freely dissolved conc. Freely dissolved concentration - predicted EQP-based estimation from: total sed, Org-C, DOC. lipid content organism EQP-extended with BC, exchangeable fractions Desorption Characterisation of desorption profiles: rapid-slow-very slow fractions (Tenax, XAD, Silicon,....) Gut-juice extractions (for mobilisation in dietary tract) Operational methods Measuring or predicting bioavailability

  15. Elbe, Llobregat, Schijn, Scheldt Fresh water food web water, sediment, biofilm (2), invertebrates (7), fish (8) 165 parameters PCBs, OCPs, polar pesticides Dioxins, PCNs, PFCs, PBDEs Alkylphenols, Polar pest. Organo-metals, etc. Western Scheldt, Terneuzen Food web of common tern 71 parameters PCBs, dioxins, PAHs, PBDEs, PFCs, alkylphenols, Organotins, metals DR-CALUX Food web field studies

  16. Biota-Sediment Accumulation Factor (BSAF) BSAF <0.1-1: reduced bioavailability, biotransformation: PAHs, PCDDs, PCDFs High BSAFs >10: PFOS, PFBS, Alkyl phenols, MeHg+ Biofilms: increased BSAFs

  17. 1000 Trophic magnification factor (TMF): 3 tern eel 100 sole shrimps worms Concentration (ng/g lw or TOC) herring 10 SPM 1 0 1 2 3 4 5 6 Trophic level (δ15N) Trophic magnification PFOS Western Scheldt, Terneuzen Compounds that biomagnify: PFOS PFBS PCBs TBT PBDEs DDT

  18. Pyrene Elbe, Prelouc 1000000 Schijn, Eenhoorn Anoia, Martorell Biotransformation 100000 10000 Concentration (ng/g lw) 1000 100 10 1 -2 0 2 4 6 8 10 12 14 16 18 Trophic level (d15N)

  19. TMF>1 air-breathing organisms with limited metabolic transformation Which compounds biomagnify ? 20 18 16 14 logKow5-9, Koa>5 logKow>9 logKow2-5, Koa 6-12 12 10 LogKoa 8 6 4 logKow2-5, Koa <6 2 0 0 2 4 6 8 10 12 LogKow Key-toxicant EDA studies Food web compound

  20. Safe level seal** Eel Terneuzen Effect levels top predators dioxin-like compounds Marine food web Fresh water food web 50 Vitamin A reduction tern* Vitamin A reduction tern* 40 30 TEQ concentration (ng TEQ/kg ww) 20 Safe level tern* Safe level tern* 10 Safe level otter*** 0 Eel Scheldt Temse Carp Anoia Martorell Chub Elbe Prelouc Sprat/ herring Sole Sandeel *Murk et al., 1994, Bosveld et al., 1995; Everts, et al., 1996 **Reijnders, 1986; Brouwer et al., 1989; Ross, 1995; de Swart, 1995 ***Leonards, 1997; Murk et al., 1998; Smit et al., 1996; Traas et al., 2001

  21. EXPOBASIN Food web structure

  22. Validation trials • Estimation of Cw-freely dissolved (TOC, BC) from measured sediment concentrations (>165 comp) • Validation set covered: 148 compounds, 6 locations, 3 rivers, 14 species, • Example: Predictions within 1-2 orders of magn. of measured concentrations Best match: persistent compounds (PCBs) in biofilms and eel BC important factor bioavailability; without: overestimation of risks Inclusion of biotransformation to improve predictions of PAHs

  23. C l C l C l O O H Application Triclosan (EDA studies) Bioavailability

  24. Conclusions and recommendations • Considering bioavailability and bioaccumulation is essential in clarifying possible linkages between exposure to toxics and ecological status • Ignoring bioavailability & bioaccumulation may lead to over or underestimation of risks, as well as false-positive or false-negative conclusions. • Although current assessment methods for bioavailability still involve considerable uncertainties, it is obvious that management decisions can best be based on extractable concentrations and freely dissolved concentrations rather than on total water or total sediment concentrations. These methods can also be useful for investigative monitoring studies. • Prediction and assessment of bioaccumulation and trophic transfer is essential for the assessment of risks of secondary poisoning. It may reveal unexpected properties of emerging compounds. • A combination of modeling partitioning to different organic carbon phases and application of assessment methods to estimate freely dissolved (pore) water concentrations or exchangeable sediment concentrations seems to be the most cost-effective approach for risks assessment

  25. Research needs • Sorption mechanisms of surfactants and other polar compounds and factors driving bioavailability and bioaccumulation are currently not well understood • The current knowledge of biotransformation is insufficient for predictive models. • There is a need for a generic approach to account for the bioavailability of trace metals in monitoring and risk assessment. • Ecological or biological factors on bioavailability not well understood; when possible in investigative monitoring we recommend to use bioassays and studies with field organisms: “Let the organisms tell us the bioavailability”

  26. Thank you for your attention. Modelkey Contract-No. SSPI-CT-2003-511237-2

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