Soil Environment Monitoring by Multi-frequency Electromagnetic Sounding

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1 J. Jpn. Soc. Soil Phys. No. +*3, p. - +.,**2 * * * * ** Soil Environment Monitoring by Multi-frequency Electromagnetic Sounding Yuuya H IRAI*, Yasushi M ORI*, Hiroaki S OMURA*, Naokazu E GUSA* and Taihei M ORISAWA** * Faculty of Life and Environmental Science, Shimane University, +*0* Nishikawatsu, Matsue 03* 2/*., Japan ** The United Graduate School of Agricultural Sciences, Tottori University,. +*+ koyama-minami, Tottori 02* 2//-, Japan Abstract Surface soil environment was surveyed and characterized using a multi-frequency electromagnetic wave (EM) sensor. Traditional resistivity method needs multiple point electrodes in the field to investigate the deeper points, however, this method uses broadband electromagnetic data to obtain the apparent conductivity from di# erent depth, i.e., the higher the frequency, the shallower data we can obtain. It is non-invasive and rapid, therefore, appropriate for wide area environmental survey. Five frequencies of,-+*, -21*, 13/*,,./+* and.131* Hz were applied so that we obtained vertical profile of the domain. Forest under di# erent management, winterponded paddy field, orchard and tea farm in hilly mountainside and orchard in plain field were investigated using a broadband electromagnetic wave sensor sounding. Surface electrical conductivity (EC) obtained by Wenner array has the highest correlation with.131* Hz data, showing it is the appropriate frequency for surface soil investigation. Moreover, EC in the order of several tens milli-siemens obtained by EM sounding corresponded very well with the EC obtained by traditional method. Conductivity data successfully showed management induced changes in soil environment by conductivity map along with vertical conductivity profile, which is advantage of broadband EM survey. Water content changes in forest after rainfall, e# ect of ponding management in paddy field, and the di# erences in fertilizer application practice in hilly farm, were clearly demonstrated by the broadband EM sensor. Key words : Electromagnetic wave sounding, nondestructive investigation, Electrical conductivity ,**0 * 03* 2/*. +*0* ** 02* 2//-. +*+ :

2 4 +*3,**2,,+ Geophex GEM-, broadband EMI sensor Corwin et al.,,**- H H,+. h, + r +00. m --* Hz.1, 31* Hz +/ - /,**/ f m s az e a + z e *.-02 z + e -1 d skin depth skin depth d + +** ms m,**/ d w, pf +,*** Huang,,**/ d : m w m s ms m : rad s : H m : + Mitsuhata et al.,,**0 S m f : Hz + ms m f m s m + m depth of investigation, DI Huang,**/ DIad : z : a, b *3.. */-. r h b H s p p

3 : 5 Fig. + + Schematic representation of multi-frequency electromagnetic wave sensor measurement. H + Won et al., +330 Hs r -, l R lexp, l hj * l rd l H p Rl s,,,, +, m Hs : Hp : +* m r : m h : m J* : f :,,-+* -, 21* 1, 3/*,.,/+* Hz : H m : S m.1, 31* Hz / m s m s Huang and Won,***, - GPS BR- -//, SiRFstarIII, GlobalSat CSV RS-,-, C In-phase, Quadrature Surfer 2, Golden software Huang and Won,,***

4 6 +*3,**2 Table + + Soil physical properties of examined field4 Land Management Forest West Forest South Paddy field Tea farm Orchard (hilly) Orchard (plain) Soil Brown forest Brown forest Gley paddy Red-Yellow Red-Yellow Red-Yellow soils soils soils soils soils soils Sampling point Sampling Depth (cm) + EC + : / (ms m ) + Moisture ratio (g g ) - - VWC (m m ) - Bulk density (Mg m ), Soil Hardness (kg cm ) VWC ; Volumetric water content ; Standard Deviation,*,+,+,/,+ +, +* +* +* +* +* +* , /4*1-4,3.+4/ *4-1 -4*/ *4*3 *4-2 *4+2 *4.0 *4+* *4.+ *4*/ *4/- *4+0 *4-+ *4*+ *4-- *4*. *4-3 *4+. *4.- *4++ *4., *4++ *4/2 *4+/ *4,3 *4*/ *4-, *4*. +4*1 *43/ +4., *43/ *43/ +4*2 +4*3 *40/ +431 *43, +400 *4.0-40, +4.. / , + : / + : / PIA-+*** Shimadzu Wenner array +3+0 / +* cm, GPS + a, / b +* -* +, ++ +,,,,+. Wenner array, Wenner array +*2 m, 0/ m,, -m c.1, 31* Hz *. 31/*

5 : 7 Fig.,, Appropriate frequency for surface soil monitoring..1, 31* Hz -, Wenner array.1, 31* Hz.1, 31* Hz - Wenner array, Wenner array,, - -.1, 31* Hz - / m *. 31/* + m Wenner array Wenner Array, +* m +.1, 31* Hz ms m

6 8 +*3,**2 Table,, Depth of investigation estimated from soil conductivity4 Land Management Electrical + conductivity(ms m ) Forest West Forest South Paddy field Tea farm Orchard (hilly) Orchard (plain) *4,+, /3 143*.042, Frequancy (Hz) Unit : m.131* ,0 /4,1.40*.4.2-4,3,./+* +04/, ,3 /4/* /4-/ /*,,4, ,+ /4,3-21*,043/ *4, , 04.+,-+* -* , *4,2 +*4** 14-. Fig. - - Comparison of EC between traditional Wenner array measurement and multi-frequency EM survey + ms m Wenner array --.1, 31* Hz *. 31/* -...1, 31* Hz /

7 : 9. a b c d e f Fig.. Horizontal EC map obtained by multi-frequency EM survey. (a) Forest West, (b) Forest South, (c) Tea farm, (d) orchard (plain), (e) orchard (hilly), (f) Paddy field 0 c d + / a / b b,**0 m TOC TN,**, 0. - m - / 0 a b

8 10 +*3,**2 / a b c d e f g Fig. / Vertical EC map obtained by multi-frequency EM survey. (a) Forest West, (b) Forest South, (c) Tea farm, (d) orchard (plain), (e) orchard (hilly), (f) Paddy field (Before Inundation), (g) Paddy field (After Inundation) Wenner Array -+. 1,0 -/. a b. a b +. b. f,,+ 2 +, msm - +, ++ +,,,,+ +

9 : 11 0 a b c Fig. 0 Vertical EC map of before and after rain in the forest obtained by multi-frequency EM survey. (a) Forest West (Before rain), (b) Forest West (After rain), (c) Forest South (Before rain), (d) Forest South (After rain) Table - - Volumetric water content changes before and after rainfall4 Sampling GEM-, EC data at q - - Site Rainfall [m m ] + Depth (cm).131* Hz [ms m ] West South before after before after +* *4+20 *4+10 *4,*1 *4,2- +* *4,,3 *4+-* *4.1* *4/23 +* *4,*1 *4*/+,4-0,,4*0. +* *4,/- *4*03,40,0,4*-+ ; Standard Deviation - Wenner array / f g. f +* -* / f +, ++ / + g,/. ms m

10 12 +*3,**2. + : / Table. Ion chromatography of + : / soil extracted water4 Sampling Depth (cm) Forest West Forest South Paddy field Tea farm Orchard (hilly) Orchard (plain) +* +* +* +* +* +* PO -. F N D N D N D N D N D Cl + NO, Unit : mg L N D N D N D N D Br ND ND NO SO -,. +243, +343+,-4*/ 2-4/ *4-04., /4+, +4.,42 +4/ *4/ +41* 4 4 *4, *4.2 *4/2 4 4 *4- * /410 *4., +/41,/4. *40,4/ +*421,*4/-,.4,./ ,41-1 +* -+ +, ++ Corwin et al.,,**- Roades et al / c e. c. / +* a 3* kg -* kg.* kg - / c / c 2 m - / d +,. Wenner array - - Wenner - / m array *. 31/* + m

11 : 13.1, 31* Hz Corwin, D.L., Ka# ka, S.R., Hopmans, J.W., Mori, Y, Wenner array van Groenigen, J.W., van Kessel, C., Lesch, S.M. and Oster, J.D. (,**-) : Assessment and field-scale Wenner mapping of soil quality properties of a salinearray sodic soil, Geoderma, ++. (-) :,-+,/3. msm Huang, H. (,**/) : Depth of investigation for small + broadband electromagnetic sensors, Geophysics, 1* ( 0 ) : G+-/ -G +.,. Huang, H. and Won, I. J. (,***) : Conductivity and susceptivility mapping using broadband electromagnetic sensors, Journal of Environmental and Engineering Geophysics, / (.) : Mitsuhata, Y., Uchida, T., Matsuo, K., Marui, A. and Kusunose, K. (,**0) : Various-scale electromagnetic investigations of high-salinity zones in a coastal plain, Geophysics, 1+ ( 0 ) : Rhoades, J.D., P.A.C. Raats and R. J. Prather. ( +310) : E# ects of liquid-phase electrical conductivity, water content, and surface conductivity on bulk soil electrical conductivity. Soil Sci. Soc. Am. J..* : 0/+ 0//. Wenner, F. ( +3+0) : A Method of Measuring Earth Resistivity, Bulletin of the US Bureau of Standards Science Paper +, (-). Won, I. J., Keiswetter, D.A., Fields, G.R.A. and Sutton, L.C. ( +330 ) : GEM-, : A new multifrequency electromagnetic sensor, Journal of Environmental and Engineering Geophysics, + (,) : +, ,*+*+1 +2/+**1.,**0 :.2 1, 1-.,**, :,00 : : : /10-. Kwou Hyoung Seok,**/ : GREEN Report,**/ 1, 1-.

12 14 +*3,**2 msm + :,** :,**2 - -+

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