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Econ. Environ. Geol. 2022; 55(2): 209-217

Published online April 30, 2022

https://doi.org/10.9719/EEG.2022.55.2.209

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

The Alterations of Geochemical Behavior of Arsenic in Stabilized Soil by the Addition of Phosphate Fertilizer

Yong-Jung Jeon1, Bun-Jun Kim1, Ju-In Ko2, Myoung-Soo Ko1,3,*

1Department of Integrated Energy and Infra system, Graduate School, Kangwon National University, Chuncheon 24341, Republic of Korea
2Technology Research & Development Institute, Korea Mine Rehabilitation and Mineral Resources Corporation, Wonju 26464, Republic of Korea
3Department of Energy and Resources Engineering, Kangwon National University, Chuncheon 24341, Republic of Korea

Correspondence to : *Corresponding author : msko@kangwon.ac.kr

Received: April 8, 2022; Revised: April 26, 2022; Accepted: April 27, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

The purpose of this study was to confirm the dissolution of arsenic from the stabilized soil around abandoned coal mines by cultivation activities. Experimental soils were collected from the agricultural field around Okdong and Buguk coal mines, and the concentration of arsenic in the soil and the geochemical mobility were confirmed. The average arsenic concentration was 20 mg/kg. The soil with relatively high geochemical mobility of arsenic in the soil was used in the batch and column experiment. The limestone was mixed with soil for soil stabilization, and the mixing ratio was 3% of limestone, based on the soil weight. The phosphoric acid fertilizer (NH4H2PO4) was added to the soil to simulate a cultivation condition according to the Rural Development Administration's rules. Comparative soil without mixing limestone was prepared and used as a control group. The arsenic extraction from soil was increased following the fertilizer mixing amount and it shows a positive relationship. The concentration of phosphate in the supernatant was relatively low under the condition of mixing limestone, which is determined to be result of binding precipitation of phosphate ions and calcium ions dissolved in limestone. Columns were set to mix phosphoric acid fertilizers and limestone corresponding to cultivation and stabilization conditions, and then the column test was conducted. The variations of arsenic extraction from the soil indicated that the stabilization was effectible until 10 P.V.; however, the stabilization effect of limestone decreased with time. Moreover, the geochemical mobility of arsenic has transformed by increasing the mobile fractions in soil compared to initial soil. Therefore, based on the arsenic extraction results, the cultivation activities using phosphoric fertilizer could induce a decrease in the stabilization effect.

Keywords stabilization, cultivation activities, arsenic, phosphoric acid fertilizer, geochemical mobility

인산질 비료에 의한 안정화 적용 토양 내 비소의 지구화학적 거동 변화

전용중1 · 김범준1 · 고주인2 · 고명수1,3,*

1강원대학교 에너지·인프라 시스템 융합학과
2한국광해광업공단 기술연구원
3강원대학교 에너지자원공학과

요 약

경작을 위해 토양에 공급하는 인산질 비료가 석회석을 이용한 안정화 적용 토양에서 비소의 용출에 미치는 영향을 회분식 실험과 칼럼실험을 통해 확인하였다. 토양은 폐석탄광인 옥동, 부국 탄광 주변 경작지에서 채취하였으며, 채취한 토양의 평균 비소 농도는 20.0 mg/kg으로 나타났다. 연속추출을 통해 비소의 지구화학적 이동성이 상대적으로 높은 토양을 선택하여 실험에 사용하였다. 석회석(3 wt%)과 토양을 혼합하여 안정화 적용 토양을 준비하고 농촌진흥청에서 제시한 경작지 토양 내 유효인산기준을 바탕으로 인산질 비료(NH4H2PO4)를 토양과 혼합하였다. 이때, 석회석과 혼합하지 않은 비교토양을 준비하여 대조군으로 활용하였다. 토양으로부터 용출되는 비소의 농도는 인산질 비료의 공급량과 양의 상관관계를 나타냈다. 이러한 결과는 안정화 유무에 따라 큰 차이를 보이지 않았다. 용출액 내 인산염(PO43-)의 농도는 석회석을 혼합한 조건에서 상대적으로 낮은 결과를 보였는데, 이러한 결과는 PO43-와 석회석에서 용해된 칼슘 이온(Ca2+)의 결합침전에 의한 것으로 판단된다. 지속적으로 관개수를 공급하는 경작환경에서 인산질 비료가 비소의 용출에 미치는 영향을 확인하기 위해 칼럼실험을 진행하였다. 칼럼실험 초기 10 P.V.까지는 토양으로부터 비소의 용출량이 석회석 혼합조건에서 더 적었지만 이후에는 석회석 혼합조건과 상관없이 유출수의 비소 농도가 점차 증가하였다. 칼럼실험 이후 잔류토양을 건조시켜 연속추출을 실시한 결과 안정화 조건에 상관없이 실험 전 토양과 비교하여 상대적으로 이동 가능한 형태의 비소의 분율이 증가하였다. 이러한 결과는 석회석을 이용하여 토양 안정화 공법을 적용하여도 경작과정에서 공급하는 인산질 비료에 의해 토양 내 비소의 지구화학적 이동도가 증가하여 안정화 효과가 감소할 수 있음을 보여준다.

주요어 토양 안정화, 경작 활동, 비소, 인산질 비료, 지구화학적 이동도

Article

Research Paper

Econ. Environ. Geol. 2022; 55(2): 209-217

Published online April 30, 2022 https://doi.org/10.9719/EEG.2022.55.2.209

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

The Alterations of Geochemical Behavior of Arsenic in Stabilized Soil by the Addition of Phosphate Fertilizer

Yong-Jung Jeon1, Bun-Jun Kim1, Ju-In Ko2, Myoung-Soo Ko1,3,*

1Department of Integrated Energy and Infra system, Graduate School, Kangwon National University, Chuncheon 24341, Republic of Korea
2Technology Research & Development Institute, Korea Mine Rehabilitation and Mineral Resources Corporation, Wonju 26464, Republic of Korea
3Department of Energy and Resources Engineering, Kangwon National University, Chuncheon 24341, Republic of Korea

Correspondence to:*Corresponding author : msko@kangwon.ac.kr

Received: April 8, 2022; Revised: April 26, 2022; Accepted: April 27, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

The purpose of this study was to confirm the dissolution of arsenic from the stabilized soil around abandoned coal mines by cultivation activities. Experimental soils were collected from the agricultural field around Okdong and Buguk coal mines, and the concentration of arsenic in the soil and the geochemical mobility were confirmed. The average arsenic concentration was 20 mg/kg. The soil with relatively high geochemical mobility of arsenic in the soil was used in the batch and column experiment. The limestone was mixed with soil for soil stabilization, and the mixing ratio was 3% of limestone, based on the soil weight. The phosphoric acid fertilizer (NH4H2PO4) was added to the soil to simulate a cultivation condition according to the Rural Development Administration's rules. Comparative soil without mixing limestone was prepared and used as a control group. The arsenic extraction from soil was increased following the fertilizer mixing amount and it shows a positive relationship. The concentration of phosphate in the supernatant was relatively low under the condition of mixing limestone, which is determined to be result of binding precipitation of phosphate ions and calcium ions dissolved in limestone. Columns were set to mix phosphoric acid fertilizers and limestone corresponding to cultivation and stabilization conditions, and then the column test was conducted. The variations of arsenic extraction from the soil indicated that the stabilization was effectible until 10 P.V.; however, the stabilization effect of limestone decreased with time. Moreover, the geochemical mobility of arsenic has transformed by increasing the mobile fractions in soil compared to initial soil. Therefore, based on the arsenic extraction results, the cultivation activities using phosphoric fertilizer could induce a decrease in the stabilization effect.

Keywords stabilization, cultivation activities, arsenic, phosphoric acid fertilizer, geochemical mobility

인산질 비료에 의한 안정화 적용 토양 내 비소의 지구화학적 거동 변화

전용중1 · 김범준1 · 고주인2 · 고명수1,3,*

1강원대학교 에너지·인프라 시스템 융합학과
2한국광해광업공단 기술연구원
3강원대학교 에너지자원공학과

Received: April 8, 2022; Revised: April 26, 2022; Accepted: April 27, 2022

요 약

경작을 위해 토양에 공급하는 인산질 비료가 석회석을 이용한 안정화 적용 토양에서 비소의 용출에 미치는 영향을 회분식 실험과 칼럼실험을 통해 확인하였다. 토양은 폐석탄광인 옥동, 부국 탄광 주변 경작지에서 채취하였으며, 채취한 토양의 평균 비소 농도는 20.0 mg/kg으로 나타났다. 연속추출을 통해 비소의 지구화학적 이동성이 상대적으로 높은 토양을 선택하여 실험에 사용하였다. 석회석(3 wt%)과 토양을 혼합하여 안정화 적용 토양을 준비하고 농촌진흥청에서 제시한 경작지 토양 내 유효인산기준을 바탕으로 인산질 비료(NH4H2PO4)를 토양과 혼합하였다. 이때, 석회석과 혼합하지 않은 비교토양을 준비하여 대조군으로 활용하였다. 토양으로부터 용출되는 비소의 농도는 인산질 비료의 공급량과 양의 상관관계를 나타냈다. 이러한 결과는 안정화 유무에 따라 큰 차이를 보이지 않았다. 용출액 내 인산염(PO43-)의 농도는 석회석을 혼합한 조건에서 상대적으로 낮은 결과를 보였는데, 이러한 결과는 PO43-와 석회석에서 용해된 칼슘 이온(Ca2+)의 결합침전에 의한 것으로 판단된다. 지속적으로 관개수를 공급하는 경작환경에서 인산질 비료가 비소의 용출에 미치는 영향을 확인하기 위해 칼럼실험을 진행하였다. 칼럼실험 초기 10 P.V.까지는 토양으로부터 비소의 용출량이 석회석 혼합조건에서 더 적었지만 이후에는 석회석 혼합조건과 상관없이 유출수의 비소 농도가 점차 증가하였다. 칼럼실험 이후 잔류토양을 건조시켜 연속추출을 실시한 결과 안정화 조건에 상관없이 실험 전 토양과 비교하여 상대적으로 이동 가능한 형태의 비소의 분율이 증가하였다. 이러한 결과는 석회석을 이용하여 토양 안정화 공법을 적용하여도 경작과정에서 공급하는 인산질 비료에 의해 토양 내 비소의 지구화학적 이동도가 증가하여 안정화 효과가 감소할 수 있음을 보여준다.

주요어 토양 안정화, 경작 활동, 비소, 인산질 비료, 지구화학적 이동도

    Fig 1.

    Figure 1.Concentration of arsenic in soil by aqua-regia digestion and sequential extraction. (a) Okdong, (b) Buguk.
    Economic and Environmental Geology 2022; 55: 209-217https://doi.org/10.9719/EEG.2022.55.2.209

    Fig 2.

    Figure 2.XRD peak patterns of limestone sample.
    Economic and Environmental Geology 2022; 55: 209-217https://doi.org/10.9719/EEG.2022.55.2.209

    Fig 3.

    Figure 3.Concentration of As and PO43- in Okdong and Buguk soil with phosphoric fertilizer and limestone supply conditions. (a) As extraction from Okdong soil, (b) As extraction from Buguk soil, (c) PO43- extraction in Okdong soil, (d) PO43- extraction in Buguk soil.
    Economic and Environmental Geology 2022; 55: 209-217https://doi.org/10.9719/EEG.2022.55.2.209

    Fig 4.

    Figure 4.Variation of (a) As, (b) PO43-, and (c) pH in leachate from soil column.
    Economic and Environmental Geology 2022; 55: 209-217https://doi.org/10.9719/EEG.2022.55.2.209

    Fig 5.

    Figure 5.Variations of As concentration and fractionation in Okdong soil (a) before and (b) after column experiments.
    Economic and Environmental Geology 2022; 55: 209-217https://doi.org/10.9719/EEG.2022.55.2.209

    Fig 6.

    Figure 6.Concentration of As in Okdong soil by sequential extraction after column test.
    Economic and Environmental Geology 2022; 55: 209-217https://doi.org/10.9719/EEG.2022.55.2.209

    Table 1 . Sequential extraction process for arsenic in soil.

    StepFractionExtractantGeochemical Mobility
    1Non-specifically sorbed(NH4)2SO4High

    Intermediate

    Low
    2Specifically sorbed(NH4)H2PO4
    3Amorphous and poorly-crystaline hydrous oxides of Fe and AlNH4 oxaltate buffer (pH 3.25)
    4Well-crystallized hydrous oxides of Fe and AlNH4 oxalate buffer + ascorbic acid (pH 3.25)
    5ResidualAqua Regia

    Table 2 . Applied ratio of fertilizer in soils.

    SoilConditions for P2O5 (mg/kg)
    ControlSet 1Set 2Set 3Set 4Set 5
    Okdong96.5180341503664825
    Buguk35.0180341503664825

    Mixed amount of fertilizer (mg/kg) = {P2O5 Experimental conditions (mg/kg) - P2O5 concentration in the soil (mg/kg)}× 0.44a × 3.71b.

    *a: Conversion factor of P2O5 and P.

    *b: Conversion factor of NH4H2PO4 and P.


    Table 3 . Properties and results of sequential extraction in soils.

    PropertiesLocation
    OkdongBuguk
    pH5.60 ± 0.056.47 ± 0.01
    CEC (meq/100 g)9.1 ± 0.3011.9 ± 4.30
    LOI (%)2.73.1
    Step 1a (mg/kg)0.02 ± 0.00N.D.
    Step 2b (mg/kg)0.85 ± 0.000.33 ± 0.01
    Step 3c (mg/kg)10.03 ± 0.374.84 ± 1.62
    Step 4d (mg/kg)7.64 ± 0.733.02 ± 0.27
    Step 5e (mg/kg)5.74 ± 0.263.82 ± 0.80
    Sumf (mg/kg)24.27 ± 0.8612.01 ± 1.34
    Total Asg (mg/kg)26.75 ± 1.5613.09 ± 0.53
    Recoveryh (%)90.791.7

    a: Non-specifically sorbed.

    b: Specifically sorbed.

    c: Amorphous and poorly-crystalline hydrous oxides of Fe and Al.

    d: Well-crystallized hydrous oxides of Fe and Al.

    e: Residual.

    f: Sum of step 1 to step 5.

    g: As concentration in soil by aqua-regia digestion.

    h: Recovery (%) = Sum / Total As × 100.


    KSEEG
    Jun 30, 2024 Vol.57 No.3, pp. 281~352

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