Paths and degradation of PAHs in the Environment

Transcription

1 Paths and degradation of PAHs in the Environment Presentation at ISPAC 2013, Corvallis, Oregon, September 10 th 2013 Otto Andersen, Western Norway Research Institute, Norway Sergio Manzetti, Fjordforsk Institute for Science and Technology, Norway Jolanta Turek-Szytow, Silesian University of Technology, Poland

2 Background Why is there need for PAH environmental degradation rates? PAH removal from municipal wastewater treatment plants (sludge treatment) with biological and chemical methods Understanding the role of PAHs in the disappearance of fish in the Norwegian fjords Pollution entering the fjords Bio-availability of PAH in exhaust from bio-blended diesel How can we determine the degradation rates? The method approach Transformation Eco-accumulation Environmental fate MDS» PAH-FAME

3 The two main groups of PAH 1. Petrogenic (from petroleum and petroleum products) Small, 2-3 rings Acute toxicity and genotoxicity, low carcinogenicity Naphthalene Anthracene Phenanthrene 2. Pyrogenic (from combustion, volcanic eruption) Larger, 4-6 rings Lower acute toxicity, High mutagenicity and carcinogenicity Pyrene Benzo(a)pyrene Dibenzo(a,h)anthracene Dibenzo(a,l)pyrene Benzo(g,h,i)perylene Benzoanthracene

4 Environmental transformation of PAHs Slow transformation through chemical and biological processes Chemical reactions: Catalyzed by sunlight Volatilization Oxidation Nitration Others (interactions with air and water) Spontaneously occurring chemical processes:» Oxidation

5 Spontaneously occurring oxidation of anthracene PAH Peroxy-form Quinone form

6 Combustion-generated oxy-pahs Formed from partial combustion and cold-starts of diesel engines Through interaction with oxygen radicals during the combustion Act as precursors in combustion reactions leading to the formation of: Polychlorinated biphenyls (PCBs) Polychlorinated dibenzo-p-dioxins (PCDDs) Polychlorinated dibenzofurans (PCDFs)

7 Spontaneously occurring nitration of anthracene PAH Radical species Nitrohydroxyl-PAH Nitro-PAH

8 Combustion-generated nitro-pahs Fuel combustion, biomass incineration etc. Dinitro-PAHs 1,3-dinitropyrene 1,6-dinitropyrene 1,8-dinitropyrene Known to cause asthma, allergies and lung cancer Induce frame-shift mutations (reading frame shift) Account for % of the mutagenicity from diesel exhaust particles Form DNA-adducts in the form of: 1-N-(deoxyguanosin-8-yl) amino-6-nitropyrene Leading to: Guanine:Cytosine Adenine:Thymine transitions Guanine:Cytosine Thymine:Adenine transversions Single base deletion at Cytosine:Guanine sites

9 Common characteristics of various PAHs on oxy- and nitro-form Follow the same principles relating reactivity to molecular size Increasing size of molecule: Higher potential for absorbing UV-light (increasing its photo-reactivity) Higher aromaticity: More stable in the environment (less affected by biological activity), thus longer half-life Higher sp2-hybridization (i.e. peripheral carbon bonds): More rapid transformation rate of the PAH molecule into oxy- and nitro-form

10 Halogenation of anthracene catalyzed by fungal species

11 Transformation into methoxylated PAH in Trametes versicolor PAH Oxidized radical form Alcohol form Methoxy-PAH

12 Cellular Transformation of PAHs Oxy- and nitro-pahs: Transformed in cells mainly through the cytochrome P450 system Generation of diol-epoxide forms of PAHs, which are:» Mutagenic» Carcinogenic» Genotoxic The diol-epoxide PAHs form adducts with DNA, through covalently binding to guanine» Leading to steric hindrance of polymerase enzyme activity Halogenated PAHs: De-halogenation generates potentially genotoxic radical intermediates, e.g.: Arene-X-O (X=halogen)

13 Fluoranthene removal from soil, by use of calcium peroxide - setup Soil Soil + Fl Soil + Fl + CaO 2 (D1) Soil + CaO 2 (D1) Soil + Fl + CaO 2 (D2) Soil + CaO 2 (D2) physico-chemical analysis of soil sampled after 7 and 30 day of experiment HPLC analysis of soil extracts for fluoranthene concentation Fl fluoranthene CaO2 (D1) first dose of calcium peroxide 0.29 g/kg CaO (D2) second dose of calcium peroxide 0.58 g/kg

14 Fluoranthene removal from soil, by use of calcium peroxide results fluoranthene mg/kg % S S+Fl S+CaO2(D1) S+Fl+CaO2(D1) S+CaO2(D2) S+Fl+CaO2(D2) start after 30 days removal 0 - CaO 2 added to soil causes the PAH concentration determined by HPLC to increase - In soil w/o CaO 2 a 60% decrease in PAH after 30 days - Addition of 0.29 g CaO 2 per kg soil cause 65% decrease in PAH after 30 days - Addition of 0.58 g CaO 2 per kg soil cause 92% decrease in PAH after 30 days

15 PAHs in exhaust nanoparticles from bio-blended diesel (1) Atomic charges and electron density of Phe (a) OME (b). To the left the molecules are shown with the assigned atomic charges. The charges derive from the OPLS/AA (all-atom optimized potentials for liquid simulations) force field in the GROMACS molecular dynamics simulation package. All hydrogen atoms (in white) bound to sp3 carbon atoms between the methyl end and the double bonded (diene) carbons, and between diene carbons and the ester group, are given the charge 0.06 (not shown). Oxygen atoms are in red. In the electron density plots (to the right) the atomic charges are visualized in colours according to the legend (far right).

16 PAHs in exhaust nanoparticles from bio-blended diesel (2) Simulated aggregation of phenanthrene and Oleic Methyl Ester into nano initial configuration, right after short simulation.

17 PAHs in exhaust nanoparticles from bio-blended diesel (3) S imulated nanoparticles i n v acuum, each consisting of 512 O ME - molecules, plus 10 (a, b), 50 (c,d), and 100 (e,f) P he- molecules. T he P he- molecules are shown i n blue.

18 PAHs in exhaust nanoparticles from bio-blended diesel (4) Snapshots from a MD S of two nanoparticles i mmersed i n water. R ight containing PA H (Phe, shown i n blue- purple color) and FA ME (OME ), l eft containing O ME only. T he carbon atoms are shown i n g reen, oxygen i n red, hydrogen i n white.

19 PAHs in exhaust nanoparticles from bio-blended diesel (4) Model of PA H- FA ME nanoparticle located on top of a phospholipid bilayer membrane (lung cell wall)

20 PAHs in exhaust nanoparticles from bio-blended diesel (5)

21 Contact information: Name: Otto Andersen Phone: Vestlandsforsking / Western Norway Research Institute Postboks 163 NO-6851 Sogndal Norway Tel: