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1 Korean Journal of Environmental Agriculture Korean J Environ Agric. 2016;35(2): Korean Online ISSN: Published online 2016 June Print ISSN: Short Communication Open Access 중금속오염농경지토양에서바닥재시용에의한카드뮴식물이용성저감효과 김성은 1, 김용균 1, 이상몽 1, 박현철 1, 김근기 1, 손홍주 1, 윤성욱 2, 김상윤 3, 홍창오 1* 1 부산대학교생명자원과학대학생명환경화학과, 2 농촌진흥청국립농업과학원농업공학부 3 농촌진흥청국립농업과학원농업생명자원부 The Effect of Bottom ash in Reducing Cadmium Phytoavailability in Cadmium-contaminated Soil Sung Un Kim 1, Yong Gyun Kim 1, Sang Mong Lee 1, Hyean Cheal Park 1, Keun Ki Kim 1, Hong Joo Son 1, Sung Wook Yun 2, Sang Yoon Kim 3 and Chang Oh Hong 1* ( 1 Department of Life Science and Environmental Biochemistry, College of Natural Resource and Life Sciences, Pusan National University, Miryang 50463, Korea, 2 Department of Agricultural Engineering, National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Korea, 3 Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Wanju 55365, Korea) Received: 4 May 2016 / Revised: 23 June 2016 / Accepted: 26 June 2016 Copyright c 2016 The Korean Society of Environmental Agriculture This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ORCID Chang Oh Hong Sung Un Kim Abstract BACKGROUND: Since bottom ash (BA) contains considerable amounts of CaO and MgO, it could be a useful amendment to increase soil ph and to immobilize cadmium (Cd). This study was conducted to evaluate effect of BA application in reducing Cd phytoavailability. METHODS AND RESULTS: Bottom ash was applied at the rate of 0, 20, 40, and 80 Mg/ha to Cd contaminated soil, and then lettuce was cultivated under field condition. soil ph and net negative charge increased slightly with increasing BA application; however, there was no statistical difference among the rates. Water soluble, exchangeable+acidic, reducible, and oxidizable fraction of Cd decreased with increasing bottom ash application rate, whereas residual fraction of Cd increased with increasing *Corresponding author: Chang Oh Hong Phone: ; Fax: ; soilchem@pusan.ac.kr bottom ash application rate. Lettuce yield increased with rate of bottom ash up to 40 kg/ha. Visual evidences of cadmium toxicity and growth inhibition were not found during lettuce cultivation. CONCLUSION: Bottom ash was effective to reduce phytoextractability of Cd and to increase lettuce yield. Conclusively, BA could be a good soil amendment to reduce Cd phytoavailability in contaminated arable soil. Key words: Bottom ash, Cadmium, Phytoabailability 서론 토양내카드뮴은이동성이높아작물에의해쉽게이용되어지며작물에흡수된카드뮴은직접적으로인간과동물에영향을미치기보다는먹이연쇄를통해인간과동물에게간접적으로영향을미친다 (Bolan et al., 2003). 그리고토양내카드뮴은용탈수에의해지하수로유입되어환경적으로도많은문제를유발하고있다 (Cai and Ma., 2003). 이러한카드뮴은저농도에서도인간과동물에강한독성을나타내어심각한문제를일으키는데대표적인예로이따이이따이질병이 152

2 Effect of Bottom Ash on Cadmium Phytoavailability 153 Table 1. Selected chemical properties of the studied soil ph (1:5 with H 2O) Organic matter (g/kg) Total nitrogen (g/kg) Available phosphorus (mg/kg) Cation exchange capacity (cmol c/kg) Exchangeable cation (cmol c/kg) K Ca Mg Na Total Cd (mg/kg) Item Concentration Warning criteria* *Means warning criteria of each heavy metals established by Korean Soil Environmental Conservation Act. 있다 (Tsuchiya, 1978). 석탄회는화력발전소에서석탄이화로에서고온으로연소될때발생하는잔류물로석탄회에대한재활용방안이더확대되어야한다는주장이제기되고있다. 현재우리나라에서는비산재 (fly ash) 의경우포집해레미콘 / 콘크리트혼화재나시멘트연료로재활용하고있으나바닥재 (bottom ash) 의경우대부분폐기물관리법시행규칙에의해매립지성토재로활용하고있는데이는오히려운송비등의지출에대한부분을재활용으로볼수있는지에대해의문시하고있다. 또한정부의전력수급계획에따라향후화력발전소의추가계획돼있고석탄재발생량도지속적으로증가해 2020년이후석탄재발생예상량은매년 1,6000만톤으로 2015년대비약 2배이상많을것으로예산되어지나사회간접시설이점진적으로줄어들고있기때문에단순히건설용으로재활용되는석탄재에대한수요는계속해서줄어들전망이다. 하지만바닥재를농업적으로재사용시바닥재의텍스쳐, 용수량, 용적밀도, ph 등의우수한물리적특성은좋은토양개량제로서의높은잠재력을가지고있어작물생산에농업적활용가치가높을뿐아니라바닥재의 95% 를차지하는칼슘, 철, 마그네슘, 칼륨, 실리콘은식물의필수영양소로작물생산시식물영양공급원으로서의가치평가를위한연구가진행되어져왔다 (Wearing et al., 2004; Hong et al., 2006; Singh et. al., 2011). 뿐만아니라바닥재고유의큰입자크기, 마이크로크기의많은기공및넓은표면적을가지는특성때문에최근중금속으로오염된다양한환경분야복원에있어바닥재를흡착제로사용에관한관심이증가되고있는실정이다 (Shim and Lee, 2001; Kim et al., 2002; Shim et al., 2003). 일부연구에서는비산재를이용하여토양내중금속을부동화하기위한시도가이루어졌으며비산재는토양의 ph를증대시켜중금속의용출성을감소시킨다고보고됐다 (Knox et al., 2000). 그러나현재까지바닥재의시용에따른토양의이화학적특성개선에대한연구는실시되었으나 (Mukhtar et al., 2003; Mukhtar et al., 2008) 바닥재시용에의한카드뮴의용출성과식물이용성에대해미치는효과에대한연구는전무한실정이다. 따라서본연구는중금속으로오염된 토양에바닥재를시용하여토양내카드뮴의용출성및카드뮴의식물이용저감에대한영향을조사하기위하여실시되었다. 재료및방법 현장시험공시토양으로는경남합천군술곡리의봉산광산 ( N E) 인근밭토양을공시토양으로선정하였다. 대상지역의토양은칠곡통에속하는토양이었으며점토 6.1%, 미사 35.0%, 모래 58.9% 를포함하는사질양토 (sandy loam) 이었다. 자세한공시토양의이화학적특성은 Table 1에타나냈다. 공시토양내조사된중금속중카드뮴 (Cd) 의총함량은 9.1 mg/kg으로토양오염우려기준을 2배이상초과하였다. 공시재료인바닥재는경남하동에위치한화력발전소에서채취되었다. 채취된바닥재는 CaO와 MgO를각각 7.82% 와 3.60% 포함하고있었으며 ph는 8.75이었다 (Table 2). 토양내카드뮴의농도변화와작물의카드뮴흡수특성을조사하기위해포장시험조건으로 2015년 4월에청치마상추 (Lactuca sativa L. var. crispa cv. Chungchima)( 흥농종묘사 ) 를파종하여 90일간재배후수량및식물체내카드뮴농도를조사하였다. 처리구는 3반복난괴법으로배치되었으며바닥재 (bottom ash) 를 0, 20, 40, 80 Mg/ha으로처리하였다. 토양과식물체이화학적특성및카드뮴함량조사공시토양의이화학적분석방법은다음과같은방법을따랐다 : ph(1:5 토양 : 물 ), 유기물함량 (Wakley and Black method; Allison 1965), 총질소함량 (Kjeldahl method; Brenner, 1965), 치환성양이온 K +, Ca 2+, Mg 2+, Na + (1 M NH 4-acetate, ph 7.0 ICP-OES, Inductively Coupled Plasma Absorption Emission Spectrophotometer, Perkin Elmer model DV 4300, Shelton, CT, USA). 유효인산의함량은 Lancaster method (RDA, 1988) 를이용하여분석하였다. 유효태카드뮴의함량은토양 : 용액비 1:5의

3 154 Kim et al. Table 2. Chemical and physical properties of bottom ash used in this study Item ph (with KCl 1:5) Electrical conductivity (ds/m, with H 2O1:5) Total content (g/kg) C N P K XRF1)analysis(%,wt/wt) Al 2O 3 CaO Fe 2O 3 K 2O MgO Na 2O P 2O 5 SiO 2 SO 3 TiO 2 Bulk density (g/cm 3 ) Particel density (g/cm 3 ) Porosity (%) Content 비로 1M NH4OAc로 1시간침출한후여과하여 ICP-OES 로 Cd의함량을분석하였다. 토양의음하전도를측정하기위하여토양 5 g을 centrifuge tube에담고 1M NaCl 30 ml 을가하여 1시간동안교반한후원심분리하여상등액을따라내고남아있는토양에 ethyl alcohol 20 ml을가하여남아있는침출액을 3회반복하여씻어냈다. Ethyl alcohol을분리시킨후상등액은따라내고남은토양에 1M NH4OAc 30 ml을가하여 1시간동안침출하였다. 침출수여과시켜여과액내의나트륨 (Na) 의함량을 ICP-OES로분석하여음하전도를구하였다. 카드뮴형태별함량은연속추출법에의해조사하였다.(Ure et al., 1993).Total Cd fraction ( 카드뮴총함량 ) 은왕수 (HNO3:HCL, 1:3) 분해법에의해측정되었다. 각형태의중금속을침출후상등액을 0.2 μm cellulose acetate membrane filter로여과후 ICP-OES로중금속함량을측정하였다. 상추내중금속함량은상추를 70 에서 48시간건조후분쇄하였다. 분쇄된시료 1 g을채취하여 ternary solution 으로분해시킨후 ICP-OES로 Cd의함량을측정하였다. 통계분석통계분석을위한 ANOVA는 Statistix 9 (Analytical Software, 2009) 을사용하여바닥재처리간에따른토양의 ph, 음하전도및식물체내중금속함량및수량의유의성을검증하였으며, p < 0.05 수준에서 LSD를이용하여처리구내평균간의차이를검정하였다. Soil ph (H2O 1:5) Net negative charge (cmol c /kg) NS NS Bottom ash application (Mg/ha) Fig. 1. Changes of ph and negative charge of soil amended with different rate of bottom ash. 결과및고찰 토양내화학적특성본연구에서는바닥재시용량증가에따른 ph 및음하전도값의통계적유의차는없었으나바닥재시용량이증가할수록토양의 ph 및음하전도가각각 4.90에서 5.10, 4.83에서 4.98 cmol c/kg까지증가하였다 (Fig.1). Hong et al. (2014) 은바닥재를처리한토양에알타리무를재배하여수확후토양의 ph를측정하였을때바닥재시용량이증가할수록토양의 ph가 5.97에서 6.22까지증가하였다고보고하였으며, Singh et al. (2011) 은병아리콩 (Cicer arientinum), 녹두 (Phaseolus aureus), 흑녹두 (Phaseolus mungo) 재배를위해비산재를토양볼륨의 0에서 50% 까지처리하였을때 ph가 6.65에서 6.96까지증가하였다고보고하였다. 토양내카드뮴의분획특성본연구에서바닥재처리에따른토양내카드뮴의분획특성을조사한결과, 바닥재처리량이증가할수록토양내수용성 (Water soluble), 치환성및 carbonate 결합태 (Exchangeable + Acidic), 유기물결합태형태 (Oxidizable) 의카드뮴함량이감소되었으며, 특히바닥재를 80 Mg/ha 으로처리하였을때 Fe/Mn 결합태 (Reducible) 의카드뮴의함량은무처리의 37.1% 에서 31.0% 로감소하였다. 반면, 광물내고정태 (Residual) 카드뮴의경우바닥재의처리량이 80 Mg/ha까지증가하였을때무처리의 9.2% 에서 20.7% 로증가하였다 (Table. 3). 토양내존재하는카드뮴분획들의이동성은 Water soluble > Exchange+Acidic > Reducible > Oxidizable > Residual의순으로높다. 토양내수용성이나

4 Effect of Bottom Ash on Cadmium Phytoavailability 155 Table 3. Distribution of Cd fractions in soils amended with the different rates of bottom ash Bottom ash application (Mg/ha) Water soluble Exchangeable + Acidic Cd fraction (%) Reducible Oxidizable Residual LSD 0.05 ns ns 1.24 ns 5.39 치환성의형태로존재하는양분들은식물에의해흡수되어지는반면에광물내고정태로존재하는양분은식물에의해거의흡수되어지지못한다 (Adriano, 2001). 따라서 Table 3과같은결과는바닥재의처리가카드뮴의식물이용성을저감시킬가능성이있음을보여준다. 토양내존재하는 Residual 형태카드뮴은광물내고정된형태이거나침전반응을통해이동성이낮은광물형태로생성된것이다. 바닥재의처리에의해생성될수있는카드뮴광물은 octavite (CdCO 3), Cd(OH) 2, Cd 3(PO 4) 2 로예상된다. CdCO 3 와 Cd(OH) 2 는알카리성토양에서생성되어카드뮴의이동성을낮추게된다. CdCO 3 의침전은토양의 ph가 9.0 이상인조건에서발생될수있으며 (Hong et al., 2014) Cd(OH)2의침전발생은토양의 ph가 10이상인조건에서발생된다 (Naidu et al., 1994). 본연구에서바닥재의처리에의한토양의 ph는 5.10이었으므로바닥재처리에의한 CdCO 3 와 Cd(OH) 2 의형성을발생하지않은것으로판단된다 (Fig. 1). 시험에사용된바닥재내포함된인산이 0.69% 포함되어있어바닥재의처리에의해카드뮴과인산이반응하여 Cd 3(PO 4) 2 를형성할가능성이있다. Hong et al. (2015) 은총카드뮴의함량이 5.57 mg/kg인토양에서카드뮴이 Cd 3(PO 4) 2 의형태로침전하기위해서는인산을 16,000 mg/kg이상처리하여야한다고보고하였다. 본연구에서공시토양내카드뮴의총함량은 9.1 mg/kg이고바닥재를최고처리양인 80 Mg/ha로처리하였을때첨가되는인산의양은약 300 mg/kg( 용적밀도 1.25 g/cm, 표토 15 cm 깊이토양무게기준 ) 에해당되어바닥재의처리에의한 Cd3(PO4)2의침전은발생되지않는것으로판단된다. 따라서바닥재의처리에따른 Residual형태카드뮴함량의증대는침전반응을통해서보다는바닥재의물리적표면특성에의한것으로판단된다. Table 2에제시된바와같이바닥재는다공성이어서토양에바닥재를처리함에따라카드뮴이바닥재의기공에흡착되거나끼어들어이동성이낮은형태의카드뮴으로전환되어진것으로판단되어진다. 하지만바닥재에의한카드뮴의부동화기작을명확하게하기위해서는추가적인연구가이루어져야할것으로판단된다. 상추수량및카드뮴흡수특성상추의재배기간동안가시적인독성현상은관찰되지않 았다. 바닥재처리에따른상추의수량은 Fig. 2와같다. 바닥재의시용량을 40 Mg/ha까지증가시킴에따라상추의수량은증가하는경향을나타내다가 40 Mg/ha 이상처리함에따라다소감소하는경향을나타냈다. 하지만바닥재처리량에따른상추수량간의통계적유의차는나타나지않아바닥재시용에따른상추의생육저해현상은발견되지않았다. 바닥재를 41.6 Mg/ha로처리하였을때상추의최대수량인 11.7 Mg/ha에도달하였으며무처리에비해 15% 증수의효과를보였다. Wearing et al. (2004) 의연구결과에따르면땅콩재배토양에바닥재를 198 Mg/ha까지처리하였을때식물에필요한양분을공급할수있었으며토양의포장용수량및토양공극내기상을증가시켜땅콩의수확량이무처구에비해 2배정도높았다고보고하였다. 바닥재의물리적및화학적구성특성은바닥재가발생되는화력발전소의처리과정및석탄의원료에따라달라질수있다. 따라서채취된바닥재의종류에따라작물의수량증대를나타내는데필요한바닥재의처리량에차이가나타날수있는것으로판단된다. 바닥재처리에따른상추의카드뮴흡수특성은 Fig. 3에나타낸바와같다. 바닥재의처리량이증가할수록상추내카드뮴의농도는감소하였다. 바닥재시용량이 0, 20, 40, 80 kg/ha로증가할수록상추내카드뮴의농도는 72.0, 68.4, 62.3, 53.7 mg/kg로, 이는무처리구와비교하였을때 5.0, 13.5, 25.4% 감소되었음을알수있었다. 바닥재의시용에따른상추내카드뮴의농도에대한 2차회귀곡선식을이용하여상추의최대수량을나타내었던 41.6 Mg/ha의바닥재시용시상추카드뮴의흡수농도는 62.9 mg/kg으로무처리에비해약 13% 감소되는것을확인하였다. 이러한결과는카드뮴오염농경지토양에바닥재를약 40 Mg/ha으로시용하면상추내카드뮴함량을저감시킴과동시에수량의증대효과를얻을수있다는것을나타낸다. 바닥재의처리량증가에따른상추내카드뮴함량의저감은바닥재처리에따른토양내 Reducible형태의카드뮴함량감소와 Residual형태의카드뮴함량증대와관련이있는것으로판단된다. 상추내카드뮴의함량에대하여 Exchangeable + Acidic와 Reduciable형태의카드뮴은유의한정의상관관계를나타내었으며 Oxidizable과 Residual 형태의카드뮴은유의한부의상관관계를나타냈다 (Table 4). 본연구와유사한연구결과로 Hong et al. (2010) 은카드뮴

5 156 Kim et al. Lettuce yield (Mg ha -1 ) Y = X x10-4 X 2, R 2 =0.999 *** NS Cd content in lettuce (mg/kg) a ab Y = X x10-4 X 2, R 2 = *** ab b Bottom ash application (Mg ha -1 ) Bottom ash application (Mg/ha) Fig. 2. Response of lettuce yield to different rate of bottom ash application. Fig. 3. Changes of Cd concentration in lettuce with different rate of bottom ash application. Table 4. Correlation coefficients between Cd concentration in lettuce and concentration of Cd fractions in soil Cd fraction Water soluble Exchangeable+ Acidic Reducible Oxidizable Residual Correlation coefficient *** 0.511*** * *** *, **, and *** denotes significance at 95%, 99%, and 99.9%, respectively. 오염농경지에패화석을처리하면 Residual형태의카드뮴의함량이증대하여알타리무내카드뮴의함량이감소한다고보고하였다. 본연구에서바닥재의처리에의한카드뮴의식물이용성저감기작은명확히구명할수없어추후추가적인연구가수행되어져야할것으로판단된다. 요약 바닥재에의한토양내카드뮴의부동화기작구명및바닥재시용에의한상추의카드뮴흡수량저감효과를확인하고자카드뮴으로오염된토양에바닥재를 0, 20, 40, 80 kg/ha 로처리한후상추내카드뮴흡수특성과토양내카드뮴의특성을조사하였다. 바닥재시용량증가에따른 ph 및음하전도값의통계적유의차는없었으나바닥재시용량이증가할수록토양의 ph 및음하전도가증가하였다. 바닥재처리에따른토양내카드뮴의분획특성을조사한결과수용성카드뮴의경우바닥재처리량이증가할수록토양내수용성, 치환성및 carbonate 결합태, 유기물결합태형태의카드뮴함량이감소되었으며, 특히 Fe/Mn 결합태의카드뮴의경우바닥재처리량이증가할수록유의하게감소되어졌다. 반면, 바닥재의처리량이증가할수록광물내고정태카드뮴의경우유의하게증가하였다. 상추의재배기간동안가시적인독성현상및생육저해현상은나타나지않았다. 바닥재의처리량이증가할수록상추내카드뮴의농도는감소하였다. 이는토양내카드뮴분획특성에서나타난것처럼바닥재시용량이증가할수록식물이이용가능한카드뮴의형태가감소됨에따 라상추내캄드뮴의농도역시감소되었다고판단된다. Acknowledgment This work was supported by a 2-Year Research Grant of Pusan National University References Adriano, D. C., (2001). Trace elements in terrestrial environments; biogeochemistry, bioavailability and risks of metals, p. 866, second ed. Springer, New York. Allison, L. E., (1965). Organic carbon, in: Black C. A. (Eds), Methods of Soil Analysis. Part Ⅱ. Am. Soc. Agron. Inc. Publ,. Madison, WI, pp Bolan, N. S., Adriano, D. C., Mani, P. A., & Duraisamy, A. (2003). Immobilization and phytoavailability of cadmium in variable charge soils. II. Effect of lime addition. Plant and Soil, 251(2), Bremner, J. M., (1965). Total nitrogen, in: Black C. A. (Eds), Methods of Soil Analysis. Part Ⅱ. Am. Soc. Agron. Inc. Publ., Madison, WI, pp Cai, Y., & Ma, L. Q. (2003). Metal tolerance, accumulation, and detoxification in plants with emphasis on arsenic in terrestrial plants. In ACS symposium Series (Chapter 8, pp ). Washington, DC, USA.

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THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. 2018 Oct.; 29(10), 799 804. http://dx.doi.org/10.5515/kjkiees.2018.29.10.799 ISSN 1226-3133 (Print) ISSN 2288-226X (Online) Method