Mapping the soil gas radon concentration and soil permeability and their relation to pedological and geological background

Transcription

1 VII. Hungarian Radon Forum and Radon in Environment Satellite Workshop május , Veszprém, Hungary Mapping the soil gas radon concentration and soil permeability and their relation to pedological and geological background Katalin Zsuzsanna Szabó 1, Gyozo Jordan 2, Ákos Horváth 3, László Pásztor 2, Zsófia Bakacsi 2, Csaba Szabó 1 1 Lithosphere Fluid Research Lab, Department of Petrology and Geochemistry, Eötvös University, Budapest, Hungary ([email protected]) 2 Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences 3 Department of Atomic Physics, Eötvös University, Budapest, Hungary

2 Aims Take the first steps towards Hungarian geogenic radon potential mapping Describe the geological formations from radon, permeability and radon potential point of view Understand the spatial variation of these variables Understand the relationship between these variables and geological/pedological features Compile a geogenic radon potential map for the studied area Selection of measurement sites Geological background Populated areas km 2 grid net

3 Study area and measurement sites Middle Hungary (~5400 km 2 ) Geological background Mesozoic sedimentary rocks (limestone,dolomite) Tertiary volcanic rocks (andezite, dacite) Tertiary sedimentary rocks (marl, clay, sandstone) Quaternary sediments (loess, sand, fluvial sediment)

4 Study area and measurement sites Middle Hungary (~5400 km 2 ) Geological background Mesozoic sedimentary rocks (limestone,dolomite) Tertiary volcanic rocks (andezite, dacite) Tertiary sedimentary rocks (marl, clay, sandstone) Quaternary sediments (loess, sand, fluvial sediment) Populated areas Budapest

5 Study area and measurement sites Middle Hungary (~5400 km 2 ) Geological background Mesozoic sedimentary rocks (limestone,dolomite) Tertiary volcanic rocks (andezite, dacite) Tertiary sedimentary rocks (marl, clay, sandstone) Quaternary sediments (loess, sand, fluvial sediment) Populated areas Grid net km 2 Budapest

6 Study area and measurement sites Middle Hungary (~5400 km 2 ) Geological background Mesozoic sedimentary rocks (limestone,dolomite) Tertiary volcanic rocks (andezite, dacite) Tertiary sedimentary rocks (marl, clay, sandstone) Quaternary sediments (loess, sand, fluvial sediment) Populated areas Grid net km 2 Measurement sites average 3 sites per cell altogether 192 sites

7 Measurement methods Soil gas radon concentration and soil permeability RAD7 radon monitor (soild state semiconductor detecto, radon daughter detection) + soil gas probe GRAB protocol (30 min) 5 min pumping (1l/min) 5 min waiting for radioactive equilibrium 4 5 min counting ( 218 Po) RADON - JOK permeameter Sampling depth is generally 0.8 m RADON - JOK permeameter RAD7 + soil gas probe 15 cm

8 Calculation of geogenic radon potential Geogenic radon potential (GRP) Neznal et al. (2004) GRP log c 10 k 10 where c is the equilibrium soil gas radon concentration at a definite depth (0.8 m) (kbq m -3 ) k is the soil permeability (m 2 ) GRP<10 LOW GRP 10<GRP<35 MEDIUM GRP GRP>35 HIGH GRP

9 percentage cumulative probability frequency frequency Results Box-and-Whisker Plot Soil gas radon concentration (kbq m -3 ) Count 192 Average 14.1 Median 10.9 Standard deviation 10.2 Coeff. of variation 71.9 % MAD 5.7 Minimum 1.0 Maximum 47.1 Range 46.2 Lower quartile 6.8 Upper quartile 19.2 Interquartile range radon_1 Histogram for radon Histogram Distribution Lognormal Khi-squared and Kolmogorov-Smirnov tests data follow lognormal distribution radon radon Normal Quantile Probability probability Plot Plot plot radon Distribution Lognormal

10 Results Legend (kbq m -3 ) Soil gas radon concentration Outliers >36 kbq m -3 Tertiary sedimentary rock: clay Quaternary sediments Proluvial-deluvial sediments Fluvial sediment Sandy loess Loess

11 median median Soil gas radon concentration on different geological formations 41 geological formations median of the measured soil gas radon concentrations of the geological formations 3 groups 5 geological formations have >8 data Median Median Gr2 Gr Tozeg 1 Buda rsi Dolomit Formßci= 1 Fut=homok 9 Tinnyei Formßci= 3 Foly=vfzi nledtk (V. terasz) 2 Mtsziszap 2 Nagyalf ldi Tarkaagyag Formßci= (befogla 7 Dobog=koi Andezit Formßci= (B rzs ny-vis 2 Drift sand 9 Fluvioeolic sand 27 Gr3 Fodolomit Formßci= 1 Foly=vfzi agyag 1 Fluvioeolikus homok 27 Mßnyi Formßci= 1 Foly=vfzi homok 14 V r sagyag 3 Foly=vfzi-proluvißlis nledtk 1 Mßnyi Ts T r kbßlinti Formßci= ßtmenete 1 Zagyvai Formßci= 1 Szilßgyi Agyagmßrga Formßci= 1 Cs=dihegyi Dßcit Tagozat 1 Dorogi Ts Csolnok Formßci= sszevontan 2 Fluvial sand 14 L sz s homok 3 Kavics, lejtot rmeltk 2 Egyhßzasgergei Ts Garßbi Formßci= sszev 1 Homokos l sz 7 Homokos l sz, l sz s homok 2 L sz 30 Nagyalf ldi Tarkaagyag Formßci= 3 SzTpv lgyi MTszko F. 3 GEO_név geological formation Folyovizi aleurit 6 Foly=vfzi aleuritos homok 2 Hßrshegyi Homokko Formßci= 2 Loess 30 T r kbßlinti Homokko Formßci= 3 Hidroeolikus agyagos l sz 3 Fluvial sediment 27 Deluvißlis aleurit 2 Foly=vfzi nledtk 27 Egyhßzasgergei Formßci= 1 Dachsteini mtszko F. 1 Kiscelli Agyag Formßci= 2 Nagyv lgyi Dßcittufa Formßci= (B rzs ny- 4 Deluvißlis agyag, homok 1 Proluvißlis-deluvißlis nledtk 3

12 Soil gas radon concentration on different geological formations Legend Gr1 (>28 Bq m -3 ) Quaternary proluvial, deluvial sediments (3) Püspökhatvan Galgagyörk Pilisszentlászló Galgamácsa

13 Soil gas radon concentration on different geological formations Gr1 (med soilrn >28 Bq m -3 ) Quaternary proluvial, deluvial sediments (4) Gr2 (med soilrn : Bq m -3 ) Tertiary (Miocene) dacite (1) Tertiary sedimentary clay (4) Mesozoic limestone (2) Tertiary sandstone (1) Quaternary fluvial sediment (27) Gr3(med soilrn < 20 Bq m -3 ) Quaternary loess (30) Quaternary fluvial sand (14) Quaternary fluvioeolic sand (27) Quaternary drift sand (9) etc. n>8

14 Soil gas radon concentration (kbq m-3) Soil gas radon concentration in case of different soil texture Median Sand 68 Rocky 5 Light loam 44 Loam 63 Heavy loam clay 4 soil texture

15 Soil gas radon concentration (kbq m-3) Soil gas radon concentration in case of different chemical behaviour median Rocky, gravelly 3 mainly acid, upper soil is unsaturated with chalk, lower soil contains carbonated chalk 29 mainly neutral or alkalescent, unsaturated with chalk 143 mostly acid, upper soil is unsaturated with chalk, lower soil do not contains carbonated chalk 9

16 frequency Eredmények Box-and-Whisker Plot Soil permeability Count 192 Average Median Standard deviation 1.8 Coeff. of variation -6.9% MAD 1.4 Minimum Maximum Range 9.2 Lower quartile Upper quartile Interquartile range log(permea) Histogram log(permea) ln(permea)= (=2.5E-12 m 2 )

17 Eredmények Soil permeability

18 Eredmények Soil permeability Categorization (Neznal et al., 2004) high k medium k low k >4E-12 4E-12>k>4E-13 <4E-13

19 med(log((permea)) med(log((permea)) Soil permeability on different geological formations med(permea) -27 Loess 30 Fluvial sand 14 Fluvial sediment 29 Fluvioeolic sand 31 Drift sand 9 geological formation geonev

20 Soil gas radon concentration and soil permeability on different geological formations R 2 = soil radon permea Drift sand 9 Fluvioeolic sand 31 Fluvial sand 14 Loess 30 Fluvial sediment 29 Geo_nev R 2 = -0.92

21 GRP (geogenic radon potential) Eredmények Count 192 Average 11.9 Median 8.7 Standard deviation 14.6 Coeff. of variation 121.9% MAD 4.7 Minimum Maximum 73.9 Range Lower quartile 4.7 Upper quartile 15.5 Interquartile range 10.7 GRP<10 low 10<GRP>35 medium GRP>35 high

22 Results Geogenic radon potential (GRP) Neznal et al. (2004) c GRP log k where c is the equilibrium soil gas radon concentration at a definite depth (0.8 m) (kbq m -3 ) k is the soil permeability (m 2 ) Based on Czech data (Barnet and Pacherova, 2010) GRP Low (<10) Medium (10-35) High (>35) Indoor radon concentration <200 Bq m Bq m -3 >400 Bq m -3

23 Results GRP in case of different geological formations Folyóvízi-proluviális üledék 1 Mésziszap 2 Tozeg 1 Dobogókoi Andezit Formáció 2 Vörösagyag 3 Mányi és Törökbálinti Formáció átmenete 1 Nagyalföldi Tarkaagyag Formáció 7 Csódihegyi Dácit Tagozat 1 Folyóvízi homok 14 Futóhomok 9 Budaörsi Dolomit Formáció 1 Folyóvízi aleurit 7 Homokos lösz, löszös homok 2 Löszös homok 3 Fodolomit Formáció 1 Egyházasgergei és Garábi Formáció összev 1 Törökbálinti Homokko Formáció 3 Hidroeolikus agyagos lösz 3 Nagyalföldi Tarkaagyag Formáció 3 Mányi Formáció 1 Fluvioeolikus homok 28 Folyóvízi üledék (V. terasz) 2 Homokos lösz 7 Lösz 30 Folyóvízi aleuritos homok 3 Deluviális aleurit 2 Zagyvai Formáció 1 Folyóvízi üledék 27 Dachsteini mészko F. 1 Kavics, lejtotörmelék 2 Tinnyei Formáció 3 Kiscelli Agyag Formáció 2 Dorogi és Csolnok Formáció összevontan 2 Hárshegyi Homokko Formáció 2 Nagyvölgyi Dácittufa Formáció (Börzsöny- 4 Proluviális-deluviális üledék 3 Szilágyi Agyagmárga Formáció 2 Egyházasgergei Formáció 1 Szépvölgyi Mészko F. 2 Deluviális agyag, homok border of medium-high GRP border of low-medium GRP median of GRP values n>8

24 100% 0.03 Geogenic radon 90% potential 80% 0.28 map of the 70% study area 60% 50% 40% 30% 20% 10% 0% Based on our 192 data Percentage of low, medium and high GRP sites on the different GRP areaslegend LOW MEDIUM HIGH 1.0 GRP low medium high no data HIGH MEDIUM LOW GRP of the area Low (<10) Medium (10-35) High (>35) GRP of sites 69% low 28% medium 3% high 29% low 58% medium 13% high 0% low 0% medium 100% high

25 Summary Soil gas radon concentration data soil gas radon concentration data follow lognormal distribution it has spatial pattern and relationship to geological background, soil texture and soil chemical behaviour Soil permeability data there is no pattern in the soil permeability spatial distribution it has relationship to geological background there is negative linear correlation between soil gas radon concentration and soil permeability Geogenic radon potential it has relationship to geological background most of the study area has low and medium GRP medium GRP: Quaternary fluvial sediment high GRP in case of proluvial-deluvial sediments

26 Thank you very much for your attention! Acknowledgement Anna Dömök Tamás Gábner Zsuzsanna Szabó Roland Helf Hédi Nagy (ELTE TTK) Péter Völgyesi (ELTE TTK) Doctoral School for Environmental Sciences, Eötvös University The research was founded by the European Union and Hungary in the framework of the TÁMOP A/ National Excellence Program - National Program for elaboration and run a system for personal support for Hungarian students and researchers