Korean J. Soil Sci. Fert. Vol.51, No.2, pp.101-110, 2018 Korean Journal of Soil Science and Fertilizer Article https://doi.org/10.7745/kjssf.2018.51.2.101 pissn : 0367-6315 eissn : 2288-2162 Effect of Soil Amendments on Arsenic Reduction of Brown Rice in Paddy Fields Dae-Won Kang 1, Da-Young Kim 2, Ji-Hyock Yoo 1, Sang-Won Park 1, Kyeong-Seok Oh 1, Oh-Kyung Kwon 3, Seung-Hwa Baek 4, and Won-Il Kim 1,3 * 1 Chemical Safety Division, National Institute of Agricultural Science, Wanju 55365, Korea 2 Department of Environmental Horticulture, University of Seoul, Seoul 02504, Korea 3 O-Jeong Eco-Resilience Institute, Korea University, Seoul 02841, Korea 4 Department of Biofood Science & Biotechnology, ChungBuk Provincial University, Okcheon 29046, Korea *Corresponding author: wikim0721@naver.com A B S T R A C T Received: October 22, 2017 Revised: May 24, 2018 Accepted: May 24, 2018 There is an increasing concern over arsenic (As) contamination in rice since Codex Committee on Contaminants in Food (CCCF) discuss on maximum levels for As in rice in 2010. This study was conducted to reduce As concentration in rice by soil amendment treatments in paddy field soils contaminated by As. The selected four amendments were poultry manure, agri-lime, steel slag, and gypsum with the addition of 3% or 5% (w/w) on a dry basis. The As reduction effect could not be verified, as a result of the pot test by adding poultry manure to the paddy soil around the mine located in Yesan. Among the agri-lime treated rice cultivated pots, the As concentration increased up to 32.1%. On the other hand, the content of As in the sample pots treated with steel slag and gypsum decreased by 65.4% and 63.4%, respectively. On the basis of the results of these pot experiments, the field test was carried out in the As polluted rice field around the mine located in Yesan, and when the four amendments were treated, the As content in the brown rice reduced in all the amendment treatments compared with the control plot. The As reduction in brown rice of the amendment was confirmed to be higher efficiency by the order of gypsum > steel slag > poultry manure > agri-lime. As a result of pot experiments using paddy soil around the mine located in Seosan, As stabilization efficiency in rice and As reduction effect could not be determined by comparison to the control. From the rice cultivated from agri-lime treated pot, As concentration increased by 15.8% in rice. On the other hand, the As content of the pots treated with steel slag and gypsum decreased by 39.1% and 60.2%, respectively. In conclusion, distinguished As reducing effectiveness could be expected by soil amendment treatments for rice cultivation. Keywords: Arsenic, Soil amendments, Brown rice, Paddy soil, Reduction Total As concentrations of brown rice grown in Yesan soil treated with 4 different soil amendments. C The Korean Society of Soil Science and Fertilizer. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non- Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
102 Korean Journal of Soil Science and Fertilizer Vol. 51, No. 2, 2018 Introduction 비소는맹독성발암물질로다양한경로를통하여하천이나농경지로유입되어오염을발생시킨다. 특히채광활동을중단하면서방치된폐기물내비소가다양한경로로유출되어인근하류주변농경지뿐만아니라재배작물의비소오염원으로작용할가능성이크다. 따라서휴 폐광지뿐만아니라인근농경지에이르기까지광범위한지역에대해효과적인오염복원기술개발이요구되고있다 (Bothe and Brown, 1999; Roman-Ross et al., 2006; Singh and Pant, 2006). 현재대부분의휴 폐광지주변에분포하는오염된농경지의복원사업은고형화보다는비소의용출을억제하기위한안정화를목적으로하는방법을적용한사례들이증가하고있다 (Kim, 2010; Lee and Jeon, 2010). 대표적인안정화제인가축분뇨와이를가공한축분퇴비와같은유기성자원은중금속과비소의오염농경지에적용하여함량을감소시킨사례가있다. 이들유기성자원은그표면에흡착및침전시키는기작을가지는넓은비표면적과많은작용기를가지는물질로서작물로의흡수이행을감소시키는역할은한다 (Ciccu et al., 2003; Kumpiene et al., 2008; Kim et al., 2010a; Oh et al., 2011). 농용석회는토양 ph를증가시키는대표적인안정제로중금속의유효도에영향을줄수있다. 토양 ph는중금속의유효도에영향을주어작물로의전이와생육저해에영향을줄수있다고알려져있다. 석회물질은토양의 ph를효율적으로조절할수있기때문에중금속또는비소로복합적으로오염된토양에적용이가능한물질로많이알려져있다. 현재우리나라에서는중금속안정화목적으로철강부산물도사용되고있으며, 그중제강슬래그와고로슬래그가가주로이용되고있다 (Yun et al., 2011). 제강슬래그의경우철광석의제련과정중발생되는물질선철을전로에서제련하여불순물인탄소, 인, 유황을제거하는과정에서생성되는물질이고, 불순물을제거하기위하여투입되는코크스, 석회와철광잔류물이서로결합된복합체로존재한다. 제강슬래그는주로도로기반제, 시멘트클링거, 토목용기초잡석으로사용되며최근에는토양중중금속안정화제물질로승인되어그활용도에대해서많은연구가진행되고있다 (Lee et al., 2010; Lim et al., 2011). 철강부산물의비소안정화기작으로다공성특징을이용한표면흡착, 물질에함유된황화물과의침전물형성, 다량으로존재하는 Ca 및 Fe와결합된 Ca-As-O 및 Fe-As-O 형태의침전물형성등이있다 (Kumpiene et al., 2008; Lee et al., 2011). 석고의대부분은시멘트원료, 석고보드, 자체활용등으로연간약 90만톤을재활용하고있으나이는전체발생량의약 58% 정도에불과하다. 석고를처리할경우칼슘작용에의해토양내용존유기탄소의응집체형성을증가시킬수있고그결과유기물- 중금속복합체형성에영향을주어토양내중금속이동성을변화시킬수있다고알려져있다 (Kim et al., 2010a; Koo et al., 2011). 우리나라비소오염농경지는상당수가폐광산인근에분포하고있다. 작물생산을위한영농활동이지속적으로이루어지고있고, 이러한지역에서생산된농산물의안전성문제가제기되고있어, 생산단계에서작물의비소흡수를저감시키기위한관리방안이필요한실정이다. 본연구는폐광산인근농경지의비소오염논토양의적절한관리방안을모색하기위해안정화제로계분퇴비, 농용석회, 제강슬래그, 석고의토양내비소의안정화및쌀의비소흡수저감효과에대해시험하고자하였다. 이를통해안전한농산물생산을위하여효율성, 경제성및 2차적인오염방지측면을고려한비소의토양환경내에서의이동성과생물유효도를저감시키기위한안정화제효율을제시하고자하였다. Materials and Methods 연구대상지역및토양시료연구대상지역은충청남도예산과서산에위치한폐광산인근지역으로중금속및
Effect of Soil Amendments on Arsenic Reduction of Brown Rice in Paddy Fields 103 비소로오염된것으로확인된논토양을대상으로하였다. 시험을위해토양은논토양의표토층 (0~20 cm) 에서채취하였고, 풍건후일반화학성분석을위하여 2 mm 체로통과된시료를균일하게혼합하여플라스틱용기에보관하였다. 또한동일방법으로채취하여풍건한토양은, 식물뿌리등을제거하고 4 mm체로균일하게체거름한뒤, 포트시험에사용하였다. 공시토양분석채취한토양의일반화학성분석은농촌진흥청분석법 (NAAS, 2010) 에근거하여실시하였다. 토양 ph와 EC분석은토양에 3차증류수를 1:5 비율로혼합하여한시간동안교반하여 ph 및 EC 측정기 (Orion 3 star, Thermo, England) 로측정하였다. 토양의교환성양이온함량 (Ca, Mg, K, Na) 은토양시료를 1 M NH 4 OAc (ph 7.0) 로 30분간진탕한후 Whatman No.42 여과지로여과하여 ICP-OES (720, Agilent technologies, USA) 로분석하였다. 공시토양의중금속전함량분석은토양오염공정시험법 (MOE, 2010b) 인환류냉각장치 (Kjeldatherm) (C. Gerhardt GmbH & Co., Northants, UK) 를이용하여토양 3 g에증류수 1 ml로적신후염산 21 ml, 질산 7 ml를가한후환류냉각장치를이용하여분해하였고분해용액을 Whatman No. 42여과지를이용하여여과한후여과액내중금속에대해 ICP-OES (720, Agilent technologies, USA) 로분석하였다. 안정화제선정본실험에사용된안정화제로는계분퇴비 (poultry manure), 농용석회 (agric-lime), 제강슬래그 (steel slag), 석고 (gypsum) 4종을선정하여사용하였다. 안정화제의 ph는각각의안정화제와 3차증류수를 1:5 비율로혼합하여한시간동안교반후 ph 측정기 (Orion 3 star, Thermo, England) 로측정하였다. 또한안정화제의중금속전함량분석은안정화제 3 g에증류수 1 ml로적신후염산 21 ml, 질산 7 ml를가한후환류냉각장치를이용하여분해하였고분해용액을 Whatman No. 42여과지를이용하여여과한후여과액내중금속에대해 ICP-OES (720, Agilent technologies, USA) 로분석하였다. 포트재배실험안정화제처리에따른비소저감효과를확인하기위해포트재배실험을수행하였다. 선정한공시토양 ( 예산, 서산 ) 3 kg에계분퇴비, 농용석회, 제강슬래그, 석고를 3, 5 % (w/w) 비율로처리하여잘혼합한후와그너포트 (1/5000 a) 에담아주었다. 이후일주일간담수상태로안정화시킨후어린모 ( 신동진벼 ) 를이앙하였다. 벼는 2015년 6월 1일에이앙하여 11월 3일에추수하여자연건조후탈곡하였다. 탈곡한벼는현미기 (FC2K, Kett, Japan) 를이용하여현미로만든후비닐지퍼팩에담아보관하였다. 현장포장재배실험안정화제의현장적용성과효과를파악하기위해오염현장에서포장재배실험을진행하였다. 선정된안정화제 ( 계분퇴비, 농용석회, 제강슬래그, 석고 ) 가처리된중금속오염농경지는과거채광활동으로인하여발생한광산폐기물등으로오염된충남예산지역논토양이다. 이논토양은비소, 카드뮴및다양한중금속들이복합적으로오염되어토양환경보전법의오염우려기준및대책기준을초과하는곳이었다. 각시험구는썬라이트를이용하여가로 1 m, 세로 1 m로구획을나눈후각각안정화제를토양깊이 15 cm의무게를대비하여 3, 5% (w/w) 로처리한후잘혼합하여충진하는방법으로진행하였다. 안정화제를처리한시험구에는농업용수를공급하여일주일간담수상태로안정화시킨후어린모 ( 신동진벼 ) 를이앙하였다. 이앙한벼는관행재배방법으로 2015년 5월 29일에이앙하여 10월 30일에추수하여자연건조후탈곡하였다. 탈곡한벼는현미기 (FC2K, Kett, Japan) 를이용하여현미
104 Korean Journal of Soil Science and Fertilizer Vol. 51, No. 2, 2018 로만든후비닐지퍼팩에담아보관하였다. 식물체분석현미로조제하여보관중인시료를마쇄한후시료 0.25 g, 7 ml의질산 (HNO 3 ) 과 1 ml 과산화수소 (H 2 O 2 ) 를 microwave 전용 vessel에넣고 microwave (Mars5, CEM, USA) 를이용하여분해하여 As 함량을 ICP-MS (7700e, Agilent technologies, USA) 를이용하여측정하였다 (MFDS, 2016). 현미의비소화학종분석현미중비소화학종의분리 분석을위해분말화한건조현미시료 1 g을 50 ml conical tube에넣어준후 5 mm malonic acid (ph 5.6) 10 ml를넣고 5분간균질화하여준다음 85 C water bath에서 30분간가열추출후 sonicator (Branson 8510, Bransonic, USA) 를이용하여 1분간초음파추출하였다. 앞의추출방법을총 4회실시한후마지막에는 5분간초음파추출하였다. 이를 4 C 이하냉장고에서 2시간동안냉각후원심분리기 (COMBI-514R, Hanil Science Industrial, Incheon, Korea) 를이용하여 3000 g로원심분리를실시하였다. 원심분리된시료의상등액을 0.45 µm membrane filter (Laboratory water purification system, Pall Life Science, USA) 로여과하여 15 ml conical tube에취하여보관하였다. 분석시료는 5 mm malonic acid, ph 5.6의 HPLC 조건으로분석하였다 (MFDS, 2016). 현미중비소종추출을위한각각의추출세트에는표준시료 (NIST 1568b) 를이용하여회수율을확인하였다. 통계처리포트및포장재배실험은처리구별 3반복으로진행하였다. 분석데이터에대해서는평균값과표준편차를이용하여표와그래프등으로나타내었으며, 처리별유의성분석은 SAS (SAS for Window v. 3.3, SAS Institute., Cary, NC) 를이용하여 ANOVA 검정으로수행하였다. Results and Discussion 토양안정화제처리에따른포트재배현미중비소함량실험에사용한토양과개량제 4종의일반화학성과중금속함량은각각 Table 1, 2, 3과같다. 본실험에서분석한현미시료의총비소함량은 0.11~1.40 mg kg -1 의범위로확인되었으며, 일반비오염농경지에서재배된쌀의평균총비소함량이 0.009~0.17 mg kg -1 의범위로봤을때 (Kim et al., 2000), 폐광산인근논토양에서재배된쌀의비소함량이높은것을확인할수있다. 또한광산주변지역쌀에대해분석한총비소농도도현재우리나라가적용하고있는 Codex ( 국제식품규격회 ) 의백미중무기비소허용기준농도인 0.2 mg kg -1 보다초과되는것으로확인되었다. 포트실험중안정화제를처리하지않은무처리구에서현 Table 1. Chemical properties of the soils used in this study. Area ph EC Available P Organic matter Exchangeable cations (cmol c kg -1 ) (1:5) (ds m -1 ) (mg kg -1 ) (g kg -1 ) Ca Mg Na K Yesan soil 6.3±0.06 0.15±0.01 63.97±4.17 38.9±0.7 8.4 18.9 0.2 0.27 Seosan soil 7.3±0.04 0.16±0.01 21.98±0.14 43.2±3.2 5.3 1.5 0.2 0.6 Optimal range 5.5~6.5 2.0 80~120 25~30 5.0~6.0 1.5~2.0-0.2~0.3 Electrical conductivity. Optimal range of chemical properties in the non-contaminated paddy soils (Kim et al., 2010b).
Effect of Soil Amendments on Arsenic Reduction of Brown Rice in Paddy Fields 105 Table 2. Total heavy metal concentration of the soils used in this study. Area Heavy metal (mg kg -1 ) As Cd Cu Pb Zn Yeasan soil 155.7±3.9 5.5±0.1 32.2±0.4 93.9±1.5 91.1±1.1 Seosan soil 209.1±8.4 49.2±1.4 142.9±1.9 5056.1±133.6 4291.6±111.0 Concern level 25 4 150 200 300 The Korean soil contamination concern level for agricultural land (MOE, 2010a). Data are means ± standard deviation (n=3). Table 3. Chemical properties of soil amendments used in this study. Amendments ph Heavy metal (mg kg -1 ) (1:5) Cd Pb Cu Zn As PM 7.2±0.4 0.03±0.01 0.46±0.11 0.63±0.05 2.73±0.36 N.D. AL 11.4±0.7 N.D. 0.06±0.01 0.16±0.01 1.09±0.07 N.D. SS 9.5±0.5 0.29±0.06 0.25±0.06 0.48±0.14 4.07±0.68 N.D GS 5.7±0.3 N.D. N.D. 0.01±0.02 N.D. N.D. PM, Poultry manure; AL, Agri-Lime; SS, Steel slag; GS, Gypsum. Data are means ± standard deviation (n=3). 미중비소함량은예산토양과서산토양에서각각 1.11±0.16, 0.28±0.01 mg kg -1 로토양중비소의총함량은서산토양의함량이높았지만현미중비소함량은예산토양에서재배한것이높은것을확인할수있었다. 이는토양화학성및수질등다른요인이관여하는것으로추정된다 (Tables 4 and 5). 예산지역폐광산인근논토양을이용한포트실험에서현미의비소함량은계분처리를 3% (w/w) 처리한포트에서무처리구보다 17.7% 저감하는것을확인하였고서산토양에서는계분퇴비처리시 5% (w/w) 처리구에서무처리구보다 8.3% 증가하는것을확인할수있었다 (Tables 4 and 5). 농용석회 3, 5% (w/w) 처리시예산토양에서는대조구에비해각각 20.4, 39.1% 비소의함량이높아지는것을확인할수있었고, 서산토양에서는 15.8, 4.7% 증가하는것을확인하였다 (Tables 4 and 5). 이러한증가는석회처리에의한토양 ph 상승으로식물유효태 As함량이증가했기때문으로추정된다 (Kim et al., 2010a; Lim et al., 2011). 제강슬래그 3, 5% (w/w) 처리구에서예산토양에서는무처리구대비비소의함량이각각 30.5, 64.7% 저감하는것을확인할수있었고, 서산토양에서는 29.1, 39.2% 저감하는것을확인하였다. 이는제강슬래그를처리함으로써토양중 ph가높아지면서비소의유효태함량은증가할수있지만제강슬래그의 Fe과토양의비소의결합후침전되어비소저감효과가나타난것으로추정된다. 현재까지연구된비소의안정화제들중철산화물은토양내비소와반응하여 FeAsO 4 H 2 O, FeAsO 4 2H 2 O, Fe 3 (AsO 4 ) 2 등의불용성의화합물이생성되어비소의이동성을매우효과적으로감소시켜가장좋은비소저감물질로보고되었다 (Carlson et al., 2002; Kumpiene et al., 2008). 또한제강슬래그를이용한비소오염토양의안정화연구는국내외적으로현재까지많이없는실정이다. 최근의관련연구들은검토해보면 Lee and Jeon (2010) 와 Lee et al. (2011) 은비소오염토양에대한효과적인제강슬래그의처리처리효과를보고하였다. 비소는토양의 ph에상관없이토양의철처리시안정화효율이가장높게나타났으며, 철이다른안정화제와복합적으로처리되었을때에도비소의안정화효과가나타났다. 이는비소가철표면의수산화기에서흡착이쉽게일어나
106 Korean Journal of Soil Science and Fertilizer Vol. 51, No. 2, 2018 안정화되었기때문이다 (Koo et al., 2011). 따라서본연구에서나타난제강슬래그의식물체전이비소저감효과는입자표면에포함된금속산화물에의해흡착되어안정화되는선행연구결과와일치하는것으로판단된다 (Lee et al., 2002; Oh et al., 2011). 석고 3,5% (w/w) 처리구는무처리구대비현미중비소의함량이예산토양에서 49.7, 67.7% 저감되었고, 서산토양에서는 60.1, 57.6% 로저감되었다. 이결과로볼때석고는석회와같이 Ca을공급하는역할을하지만황산기가있어토양 ph를높여주지않지만, 석고시용으로인해공급된 Ca이온은토양중공존유기탄소 (DOC, Dissolved organic carbon) 의응집제로작용하며 DOC와결합된비소가 Ca과의공침 (coprecipitation) 으로인한안정화로작물로의비소의저감효과가더욱뚜렷하게나타난것으로판단된다 (Kim et al., 2018). Table 4. Concentrations of arsenic species in brown rice grown in pot with Yesan soil as affected by amendments. Total As As (III) Percent of As (V) DMA MMA Amendments inorganic As mg kg -1 % Control 1.113±0.160bc 0.538±0.084a 0.013±0.001d 0.136±0.03a 0.005±0.001b 49.5 PM 3% 0.916±0.319cd 0.539±0.019a 0.027±0.006b 0.089±0.007b 0.002±0.000e 61.8 PM 5% 1.022±0.254bc 0.490±0.080ab 0.032±0.002a 0.158±0.050a 0.004±0.001c 51.1 AL 3% 1.340±0.162ab 0.513±0.020ab 0.015±0.002cd 0.158±0.008a 0.006±0.001b 39.4 AL 5% 1.548±0.303a 0.492±0.021ab 0.017±0.001c 0.156±0.009a 0.008±0.001a 32.9 SS 3% 0.773±0.226cd 0.477±0.030ab 0.012±0.001d 0.003±0.005b 0.003±0.000d 63.3 SS 5% 0.393±0.120e 0.232±0.007c 0.017±0.001c 0.029±0.003c ND 63.4 GS 3% 0.560±0.116de 0.445±0.064b 0.017±0.001c 0.061±0.004bc 0.002±0.000e 82.5 GS 5% 0.360±0.060e 0.273±0.031c 0.017±0.001c 0.029±0.007c 0.002±0.000e 80.6 PM, Poultry manure; AL, Agri-Lime; SS, Steel slag; GS, Gypsum; As (III), arsenite; As (V), arsenate; DMA, dimethylarsinate; MMA, monomethylarsonate; Means in each column followed by the same letter are not significantly different at p<0.05. Table 5. Concentrations of arsenic species in brown rice grown in pot with Seosan soil as affected by amendments. Total As As (III) Percent of As (V) DMA MMA Amendments inorganic As mg kg -1 % Control 0.278±0.013b 0.116±0.018a 0.015±0.001b 0.002±0.000e ND 47.1% PM 3% 0.287±0.009b 0.118±0.012a 0.014±0.003b 0.003±0.000e ND 46.0% PM 5% 0.301±0.008ab 0.127±0.008a 0.026±0.018a 0.004±0.000c 0.001±0.001 50.8% AL 3% 0.322±0.007a 0.114±0.008a 0.014±0.001b 0.007±0.000b ND 39.8% AL 5% 0.291±0.005b 0.119±0.016a 0.013±0.005b 0.008±0.000a ND 45.4% SS 3% 0.197±0.049c 0.089±0.004b 0.001±0.000c 0.002±0.000e ND 45.7% SS 5% 0.169±0.002c 0.086±0.009b 0.001±0.000c 0.002±0.000e 0.001±0.001 51.5% GS 3% 0.111±0.002d 0.060±0.007bc 0.001±0.000c 0.003±0.000d ND 55.0% GS 5% 0.118±0.002d 0.072±0.006c 0.001±0.000c 0.001±0.000f ND 69.1% PM, Poultry manure; AL, Agri-Lime; SS, Steel slag; GS, Gypsum; As (III), arsenite; As (V), arsenate; DMA, dimethylarsinate; MMA, monomethylarsonate; Means in each column followed by the same letter are not significantly different at p<0.05.
Effect of Soil Amendments on Arsenic Reduction of Brown Rice in Paddy Fields 107 포트실험과함께진행한포장실험은예산의폐광산인근논토양에서직접재배실험을실시하였다. 포장에서의실험은포트실험과달리모든안정화제처리구에서비소저감효과를나타내었는데안정화제를처리하지않고재배한현미에서는비소의총함량이 0.483±0.025 mg kg -1 로확인되었다. 포트실험에서의현미중비소함량인 1.113±0.160 mg kg -1 과비교하여크게감소함을보여주는데이는차단된포트의근권환경에서뿌리의분포가크게증가하고이에따른뿌리흡수의차이로추정된다. 계분퇴비를 3, 5% (w/w) 처리한처리구에서는현미중비소함량이각각 0.313± 0.001, 0.321±0.006 mg kg -1 로대조구보다 35.2, 33.5% 저감되었고, 농용석회를 3, 5% (w/w) 처리하였을때비소의함량은각각 0.26±0.008, 0.262±0.006 mg kg -1 으로대조구대비 46.2, 45.8% 저감되었다. 제강슬래그를 3, 5% (w/w) 처리하였을때현미중비소함량은 0.397±0.014, 0.408±0.002 mg kg -1 으로대조구대비각각 17.8, 15.5% 저감되었다. 이결과는비소오염논토양에제강슬래그 7.0 Mg kg -1 을처리하여무처리대조구에비해 40% 낮은함량을보인 Yoo et al. (2017) 결과와유사하였다. 이러한결과는제강슬래그를처리한토양에서 As는대조구와비교하여약 80% 이상용출농도가저감되었고이는제강슬래그내다량함유되어있는금속산화물들은 As의용출농도를저감시키는것으로보고한 Yun et al. (2011) 의결과와도관련이있음으로판단되었다. 마지막으로석고를 3, 5% (w/w) 처리하였을때현미중비소의함량은두함량처리구가각각 0.217±0.001, 0.218±0.001 mg kg -1 으로대조구대비 55.1, 54.9% 가저감되었다 (Table 6). Table 6. Concentrations of arsenic species in brown rice grown in field with Yesan soil as affected by amendments. Total As As (III) Percent of As (V) DMA MMA Amendments inorganic As mg kg -1 % Control 0.483±0.025a 0.167±0.010a 0.018±0.005a 0.055±0.004ab 0.004±0.00b 38.3 PM 3% 0.313±0.001c 0.135±0.010bc 0.002±0.000cde 0.046±0.002cd 0.005±0.00ab 43.8 PM 5% 0.321±0.006c 0.124±0.009c 0.002±0.000de 0.056±0.006a ND 39.3 AL 3% 0.260±0.008d 0.123±0.003c 0.005±0.000bc 0.040±0.002d ND 49.2 AL 5% 0.262±0.006d 0.149±0.002b 0.002±0.000de 0.048±0.008bcd 0.004±0.00b 57.6 SS 3% 0.397±0.014b 0.134±0.016bc ND 0.055±0.004ab 0.006±0.00a 33.8 SS 5% 0.408±0.002b 0.123±0.015c 0.005±0.000b 0.051±0.001abc 0.006±0.00a 31.4 GS 3% 0.217±0.001e 0.096±0.005d 0.004±0.000bcd 0.032±0.002e 0.001±0.00c 46.1 GS 5% 0.218±0.001e 0.074±0.010e 0.003±0.002e 0.015±0.004f ND 35.3 PM, Poultry manure; AL, Agri-Lime; SS, Steel slag; GS, Gypsum; As (III), arsenite; As (V), arsenate; DMA, dimethylarsinate; MMA, monomethylarsonate; Means in each column followed by the same letter are not significantly different at p<0.05. 토양안정화제처리에따른현미중비소화학종함량분석광산인근두지역 ( 예산, 서산 ) 을선정하여비소오염된논토양에서비소의저감을목적으로안정화제를처리하여재배한현미를대상으로비소화학종 ( 유기비소, 무기비소 ) 을분리하여분석하였다. 각분석시료중검출한계이하인값에대해서는 ND (not detected) 로표기하였다. 예산의광산인근논토양을이용한포트실험에서재배한현미의 As (III), As (V), DMA, MMA의 4가지비소화학종을분석실험의결과무기비소인 As (III), As (V) 의함량이각각 0.538, 0.013 mg kg -1 로총함량대비 49.5% 를차지하는결과를보였다. 또한비소저감목적으로처리한개량제처리구의경우농용석회 5% 처리구에서비소함량은무처리
108 Korean Journal of Soil Science and Fertilizer Vol. 51, No. 2, 2018 구대비 39.1% 증가하였지만비소화학종중무기비소 As (III), As (V) 의함량이각각 0.492, 0.017 mg kg -1 로오히려독성이강한 As (III) 의함량은조금줄어드는것을확인할수있었다. 비소화학종분석결과제강슬래그 3%, 5% 처리구에서는무기비소 As (III) 의함량이각각 0.477, 0.232 mg kg -1 로제강슬래그 5% 처리구에서 3% 처리구보다 43.1% 낮아졌고유기비소중 DMA는무처리구대비 78.6% 저감하는것으로확인되었다. 석고 3, 5% 처리구에서는무기비소인 As (III) 의함량이각각 0.445, 0.237 mg kg -1 로특히, 석고 5% 처리구에서무처리구대비 49.3% 낮아졌고유기비소인 DMA 역시 78.7% 저감되었다 (Table 4). 서산광산인근논토양을이용한포트실험에서재배한벼를가지고분석한현미의총비소함량은 0.278 mg kg -1 이었고비소화학종 As (III), As (V), DMA는각각 0.116, 0.015, 0.002 mg kg -1 이었으며 MMA는검출되지않았다. 서산폐광산인근논토양으로포트에서재배한벼의경우총비소대비무기비소의함량은 38.3% 를차지하였다. 안정화제를처리한후재배한벼의비소화학종을분석한결과계분퇴비와농용석회를처리하였을경우무처리구와비슷한함량을보였고, 제강슬래그 5% 를처리에서벼의 As (III) 와 As (V) 함량은각각 0.086, 0.001 mg kg -1 로무처리구에비해 25.9, 93.3% 감소하는것을확인할수있었다. 석고를처리구의경우 3% 처리하였을때 As (III) 와 As (V) 의함량이각각 0.06, 0.001 mg kg -1 로무처리구에비해 48.3, 93.3% 저감되었다 (Table 5). 이는앞의예산의광산인근논토양으로포트에서재배한쌀의총비소함량과비소화학종함량의경향과비슷한것을확인할수있었다. 안정화제를예산광산인근논에직접처리한후벼를재배하였고, 수확후현미중비소화학종을분석한결과, 대조구의 As (III), As (V), DMA, MMA의함량은각각 0.167, 0.018, 0.055, 0.004 mg kg -1 로총비소대비무기비소의비율은 38.3% 를차지하였다. 안정화제처리구에서 18.4~58.4% 저감하는효과를확인하였다. 현미중주요비소화학종인 As (III) 는무처리구대비안정화제처리구별 10.8~55.7% 저감하였는데특히석고 5% 처리구의경우무처리구에비해 55.7% 의가장높은저감효율을보였다. As (V) 는모든처리구에서무처리구대비 72.2~97.2% 저감하는효과를나타내었다. 유기비소인 DMA와 MMA는안정화제처리구에서대체적으로뚜렷한저감효과는보이지않았으나석고 5% 처리구에서는 DMA가 72.7% 까지저감되었다 (Table 6). 앞서실행하였던포트실험에서재배한쌀의총비소함량과포장실험의총비소함량은차이가있었지만안정화제처리구의비소저감효과의양상은서로비슷한경향이있음을확인하였고, 비소화학종의저감효과도비슷한양상을보이는것을확인하였다. Conclusion 쌀 ( 현미 ) 의비소저감을목적으로비소오염논토양에선정된안정화제를처리한포트와포장에서각각벼를재배하였고쌀중총비소와비소화학종을분석하여쌀비소저감을확인하였다. 계분퇴비, 농용석회, 제강슬래그및석고등선정된 4개의안정화제중동일농도로처리하였을경우포트및포장실험을통한결과로서석고와제강슬래그의효과가계분퇴비및농용석회보다우수한것으로확인되었다. 포장시험의경우에도석고를처리하였을때비소의저감효율이가장높았다. 이는석고처리시공급되는 Ca과토양용액중 As화학종과의공침, DOC의감소로인한비소이동성감소등복합적인기작으로 As의식물유효도가낮아진것이원인인것으로사료되며토양중이들안정화제처리에따른토양비소의생물학적유효태의형태전환과더불어작물의흡수이행에영향을미치는토양산도, 산화환원전위변화및토양의물리화학성등관련인자들의영향에관하여보다세밀한연구가지속되어야할것이다.
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