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Hans Christian Bruun Hansen a, Lars H. Rasmussen b, Frederik Clauson- Kaas a, Ole Stig Jacobsen c, Rene K. Juhler c, Søren Hansen a, and Bjarne W. Strobel.

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Presentation on theme: "Hans Christian Bruun Hansen a, Lars H. Rasmussen b, Frederik Clauson- Kaas a, Ole Stig Jacobsen c, Rene K. Juhler c, Søren Hansen a, and Bjarne W. Strobel."— Presentation transcript:

1 Hans Christian Bruun Hansen a, Lars H. Rasmussen b, Frederik Clauson- Kaas a, Ole Stig Jacobsen c, Rene K. Juhler c, Søren Hansen a, and Bjarne W. Strobel a a Department of Plant and Environmental Sciences, KU- SCIENCE b Metropolitan University College c Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS) SOIL FATE AND LEACHING OF THE NATURAL CARCINOGEN PTAQUILOSIDE DWRIP 2014 KU-SCIENCE

2 Bracken form dense ”mats” Præstø Fed, Denmark Bracken is ”invasive” – and outcompetes other vegetation. Azores, Portugal

3 Why is this important? Bracken is one of very few plants known to cause cancer in animals Bracken is everywhere in Nature; 5 th most abundant plant on Earth The carcinogen in Bracken is produced in high amounts (up to 1 % dw) The carcinogen is very mobile in soil and water Several exposure routes for humans (air, milk, meat, drinking water) Little is known DWRIP 2014 KU-SCIENCE

4 A well known carcinogen in animals - Examples for cattle - Bovine enzootic haematuria (BEH): Tumours in the urinary bladder of cows and sheeps. Recognized worldwide. Test animals fed bracken produce similar symptoms. Upper digestive tract carcinomas: Ususally seen in conjunction with papillomavirus that infects the mucosa of the upper digestive tract in cattle. In presence of PTA papillomas transform to carcinomas DWRIP 2014 KU-SCIENCE

5 Exposure routes for humans DWRIP 2014 KU-SCIENCE Aranho, P (2013)

6 6 Bracken norsesquiterpene glycosides and hydrolysis products R 1 = H; R 2 = CH 3 Ptaquiloside R 1 = H; R 2 = CH 3 Isoptaquiloside R 1 = H; R 2 = CH 2 OH Ptesculentoside R 1 = CH 3 ; R 2 = CH 2 OHCaudatoside R 1 = CH 3 ; R 2 = CH 3 Ptaquiloside Z R 1 = H; R 2 = CH 3 Pterosin B R 1 = H; R 2 = CH 2 OH Pterosin G R 1 = CH 3 ; R 2 = CH 2 OH Pterosin A Hydrolysis products DWRIP 2014 KU-SCIENCE

7 PropertyData CAS Molecular formulaC 20 H 30 O 8 Mass Water solubility> 30 g L - -1 Melting point (acetone)85 – 89 o C Log K ow < 0 Soil sorption, K d < 0.25 L Kg -1 Half-life (25 o C), hydrol.hours - weeks Activation energy (pH 4.5), hydrolysis 74 kJ mol -1 Toxicitymutagenic, carcinogenic, clastogenic, genotoxic Threshold conc. drinking water (one hit model) µg L -1 Hydrophobic Hydrophilic PTA amphiphilic DWRIP 2014 KU-SCIENCE

8 Methods used for determination of PTA and PTB MethodConditionsLOD µg L -1 Reference HPLC-UVReverse phase, 214 nm for PTA; 220 nm for PTB Agnew & Lauren (1991) LC-MS/MSReverse phase;  (PTA)  (PTB) Jensen et al. (2008) GC-MSFormation of bromo- derivative of Pterosin B 0.3 Francesco et al. (2011) DWRIP 2014 KU-SCIENCE

9 PTA production, distribution and hydrolysis in soil and water DWRIP 2014 KU-SCIENCE

10 Bracken growth, PTA contents and PTA loads PTA contents in fronds during growing season at different sites in DK and UK PTA content in fronds per m 2 land surface during growing season at different sites in DK 300 mg m -2 = 3 kg ha -1 PTA in fronds (ug g -1 ) PTA load (mg m -2 ) Julian day number May Aug DWRIP 2014 KU-SCIENCE Rasmussen (2003)

11 PTA (min-max): (  g g -1 ) PTA (min-max): (mg m -2 ) Bracken Fronds 108 – 3,80015 – 500 Bracken Rhizomes 10 – 7,050N.D. Oi/Oe- horizons 0.09 – – 160 Oa/A- horizons 0.01 – – 57 High variation in PTA content between bracken populations DWRIP 2014 KU-SCIENCE Rasmussen (2003)

12 Hydrolysis of PTA k A = 25.7 h -1 M -1 ; k N = ; h -1 M -1 ; k B = h -1 M -1 - Half-lives at pH 4, 6 and 8 (25 o C): 8 d, 20 d, and 0.6 d - Low temperatures increase half-lives considerably DWRIP 2014 KU-SCIENCE Ayala et al. (2006)

13 Ovesen et al. (2008) Microbial contribution to PTA degradation open symbols: sterilized; closed symbols: untreated soil Degradation of PTA in soils at field moisture and 10 o C with initial PTA concentration of 25 g kg -1 Fast reaction: Abiotic Slow reaction: Biotic + Abiotic DWRIP 2014 KU-SCIENCE

14 Hydrolysis in soil solution Kinetics of PTA degradation in soil solutions from sandy and clayey top- and subsoils (10 o C). Open symbols represent solutions filtered (0.2 µm) before incubation; closed symbols unfiltered solutions. !! No significant hydrolysis PTA is stabilized in soil solution! Can degradation in soil be attributed to hydrolysis in solution phase? pH DWRIP 2014 KU-SCIENCE Ovesen et al. (2008)

15 Leaching DWRIP 2014 KU-SCIENCE

16 PTA and PTB in shallow groundwater at Bracken infested areas Location GroundwaterSurface water Soil type Water level (m) pH TOC (mM) pH TOC (mM) Gadevang Loamy sand PræstøSand RavnsholtOrganic Study sites Sampling in small inspection wells. Determination of PTA and PTB by a SPE-LC-MS/MS Clauson-Kaas et al. (2014) DWRIP 2014 KU-SCIENCE

17 PTA and PTB distribution in soil Clauson-Kaas et al. (2014) DWRIP 2014 KU-SCIENCE - PTA concentrations highest in the litter layer, but much higher total quantities in the mineral soil -Higher PTB than PTB concentrations in mineral soil -PTB as ”memory” effect of PTA? PTA w, PTB w : Extracted with water PTB a : Extracted with methanol

18 SoilJun.Jul.Aug.Sep.Oct.Nov.Dec.Jan. GadevangPTA T0.080bd T PTBbd xxbdT PræstøPTATT0.034bd TT PTB Tbd RavnsholtPTAnm Tbd 0.016bd PTBnm Observed groundwater concentrations of PTA and PTB (µg L -1 ) - PTA could be detected at all sites -Max. PTA concentration observed 0.09 ug L -1 ; max PTB observed 0.49 ug L -1. -Big variations over time! T = trace DWRIP 2014 KU-SCIENCE Clauson-Kaas et al. (2014)

19 SoilJun.Jul.Aug.Sep.Oct.Nov.Dec.Jan. GadevangPTAnd0.030nd Tnd PTB0.014ndT0.014nd PræstøPTAnd nd PTBnm 0.037Tnm RavnsholtPTAnm1.11nm nd PTBnm0.56nm 0.090nd Observed concentrations of PTA in pond water near Bracken stands (µg L -1 ) -PTA detected in all surface waters -max. PTA concentration 1.1 g L -1 ; max. PTB concentration 0.56 g L -1. -Large temporal and spatial variation T = trace DWRIP 2014 KU-SCIENCE Clauson-Kaas et al. (2014)

20 Modelling of PTA leaching from a sandy soil using the DAISY Plant-Soil-Water model - First attempt - PTA production: Biomass production data of Rasmussen and Hansen (2002) PTA in biomass: 200 g g -1 DM (low) PTAsoil transfer:Leaching from fronds (Rasmussen et al., 2003), and decaying plants (frost for 3 consecutive days) Soil: Sandy soil (Præstø), % of clay Hydraulic properties estimated according to Mualen and van Genuchten PTA degradation: Model from Ovesen et al. (2008) Climate data:Data for Zealand (Højbakkegaard) used. Modelling:Leaching modelled for the period , and for a selected 1-year period ( ). DWRIP 2014 KU-SCIENCE

21 Separate degradation rate constants have been used for O, A and B soil horizons for fast and slow degrading PTA pools Annual total PTA addition to soil 1.6 kg ha -1. Note the extremely variable soil contents and amounts of PTA leached Modelling results for the period DWRIP 2014 KU-SCIENCE

22 Conclusions PTA proven animal and suspected human carcinogen. PTA production of kg ha -1 y -1. High spatial and temporal variation. Initial PTA degradation due to hydrolysis; highly sensitive to pH and temperature. Apparent stabilization in soil water Fast abiotic and slower biotic degradation of PTA in soil; stabilization of PTA in soil by clays. Sorption of PTA in soil is insignificant  fast leaching PTA and PTB present in groundwater and surface water; µg L -1 to ng L -1 range Groundwater and surface water monitoring is strongly needed; high time and spatial resolution is critical. DWRIP 2014 KU-SCIENCE


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