The Statistical Study on the Effects of Physicochemical Properties of Soil on Single Extraction Methods for Heavy Metals

Hyeop-Jo Han; Chang-Woo Song; Jong-Un Lee

doi:10.9719/EEG.2021.54.2.259

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Econ. Environ. Geol. 2021; 54(2): 259-269

Published online April 30, 2021

https://doi.org/10.9719/EEG.2021.54.2.259

The Statistical Study on the Effects of Physicochemical Properties of Soil on Single Extraction Methods for Heavy Metals

Hyeop-Jo Han, Chang-Woo Song, Jong-Un Lee^*

Author Info. +

Department of Energy and Resources Engineering, Chonnam National University, Gwangju 61186, Korea

Correspondence to : jongun@jnu.ac.kr

Received: March 24, 2021; Revised: April 8, 2021; Accepted: April 9, 2021

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 effects of the physicochemical properties of soil such as soil pH, cation exchange capacity, and organic matter content on single extraction of Cd, Cr, Cu, Ni, Pb, and Zn using CaCl₂, HOAc, HNO₃, and DTPA were statistically investigated for 69 agricultural soils in Korea. Correlation analysis and multiple regression analysis were applied for soil samples which were grouped on the basis of average values of the physicochemical properties of the soil. Diluted HNO₃ extracted higher concentrations of Cr, Cu, Ni, and Pb when compared with the other extractants, however, similar amounts of Cd and Zn were extracted by HOAc with HNO₃. The results of correlation analysis indicated that DTPA extraction showed a high correlation with other single and pseudo-total extraction methods, and the physicochemical properties of soil influenced the concentrations of heavy metals leached by the single extraction methods. In the case of Zn, high correlations between pseudo-total and the studied single extraction methods were observed. As a result of regression analysis, it was found that the physicochemical properties of the soil could explain up to 74% of variances of the single extraction results. These results indicate that the physicochemical properties of the soil can have a direct influence on the concentrations of heavy metals extracted by the single extraction methods.

Keywords soil, heavy metal, single extraction, correlation, regression analysis

토양의 물리화학적 특성이 중금속 단일용출법에 미치는 영향에 대한 통계학적 연구

한협조 ∙ 송창우 ∙ 이종운^*

전남대학교 에너지자원공학과

요 약

국내 69개 농경지 토양 내 Cd, Cr, Cu, Ni, Pb, Zn을 대상으로 하여 토양 pH, 양이온교환능력, 유기물 함량 등의 물리화학적 특성이 CaCl₂, HOAc, HNO3, DTPA 등을 이용한 중금속의 단일용출 결과에 미치는 영향을 통계학적으로 조사하였다. 통계학적 분석은 토양의 물리화학적 특성의 평균값을 기준으로 높고 낮은 두 표본으로 구분한 후 이에 대해 상관분석과 다중회귀분석을 수행하였다. Cr, Cu, Ni, Pb의 경우 HNO₃를 적용하였을 때 다른 추출제에 비하여 높은 함량이 추출되었으나, Cd, Zn의 경우 HOAc를 이용한 추출에서도 유사한 함량이 추출되었다. 상관관계 조사 결과, DTPA 추출이 다른 단일용출 및 전함량과 상관관계가 높았으며, 토양의 물리화학적 특성이 단일용출 결과에 영향을 미치는 것으로 나타났다. Zn의 경우, 전함량과 모든 단일용출법들에 의한 추출 함량이 상호 높은 상관관계를 보였다. 회귀분석 결과, 토양의 물리화학적 특성은 최대 74%에 이르는 단일용출 결과의 분산을 설명할 수 있는 것으로 나타났다. 이러한 결과는 토양의 물리화학적 특성이 단일용출 결과에 직접적인 영향을 미칠 수 있음을 나타낸다.

주요어 토양, 중금속, 단일용출, 상관관계, 회귀분석

Article

Research Paper

Econ. Environ. Geol. 2021; 54(2): 259-269

Published online April 30, 2021 https://doi.org/10.9719/EEG.2021.54.2.259

The Statistical Study on the Effects of Physicochemical Properties of Soil on Single Extraction Methods for Heavy Metals

Hyeop-Jo Han, Chang-Woo Song, Jong-Un Lee^*

Department of Energy and Resources Engineering, Chonnam National University, Gwangju 61186, Korea

Correspondence to:jongun@jnu.ac.kr

Received: March 24, 2021; Revised: April 8, 2021; Accepted: April 9, 2021

Abstract

Keywords soil, heavy metal, single extraction, correlation, regression analysis

토양의 물리화학적 특성이 중금속 단일용출법에 미치는 영향에 대한 통계학적 연구

한협조 ∙ 송창우 ∙ 이종운^*

전남대학교 에너지자원공학과

Received: March 24, 2021; Revised: April 8, 2021; Accepted: April 9, 2021

요 약

주요어 토양, 중금속, 단일용출, 상관관계, 회귀분석

Fig 1.

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Figure 1.Ranges of the heavy metals extracted from the soil samples with the studied single extraction methods. Refer to the text for each symbol.

Economic and Environmental Geology 2021; 54: 259-269https://doi.org/10.9719/EEG.2021.54.2.259

Fig 2.

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Figure 2.Extraction ratio of the heavy metals with the studied single extraction methods over aqua regia (AR) extraction. Refer to the text for each symbol.

Economic and Environmental Geology 2021; 54: 259-269https://doi.org/10.9719/EEG.2021.54.2.259

Table 1 . Sample number, mean, median, standard deviation, and range of pH, cation exchange capacity, organic matters, and the studied elements extracted with aqua regia and 0.01 M CaCl₂, 0.11 M HOAc, 0.5 M HNO₃, and 0.005 M DTPA + 0.01 M CaCl₂ + 0.1 M TEA.

		Sample number	Mean	Median	Standard deviation	Range
pH		69	6.5	6.3	0.9	4.8~8.6
Cation exchange capacity (meq/100 g)		69	20.0	18.8	7.4	6.0~40.2
Organic matters (%)		69	4.2	3.5	2.6	1.0~15.0
Cd (mg/kg)	Aqua regia	50	1.3	1.2	0.5	0.7~2.9
	0.01 M CaCl₂	50	0.2	0.2	0.0	0.1~0.3
	0.11 M HOAc	50	0.7	0.7	0.1	0.5~1.0
	0.5 M HNO₃	45	0.4	0.3	0.3	0.2~1.3
	DTPA*	50	0.3	0.3	0.1	0.2~1.0
Cr (mg/kg)	Aqua regia	69	72.2	51.7	58.3	22.3~259.6
	0.01 M CaCl₂	0	n.d.
	0.11 M HOAc	0	n.d.
	0.5 M HNO₃	66	1.7	1.4	1.5	0.0~7.3
	DTPA	53	0.2	0.2	0.1	0.1~0.5
Cu (mg/kg)	Aqua regia	69	36.0	25.7	40.8	3.6~273.6
	0.01 M CaCl₂	39	0.2	0.1	0.0	0.1~0.3
	0.11 M HOAc	9	1.1	0.6	1.1	0.1~3.2
	0.5 M HNO₃	69	7.9	7.1	6.4	1.2~43.9
	DTPA	65	3.4	2.8	2.6	0.2~13.8
Ni (mg/kg)	Aqua regia	69	43.0	36.4	22.3	15.1~118.8
	0.01 M CaCl₂	8	0.1	0.1	0.1	0.0~0.4
	0.11 M HOAc	1	0.6	0.6		0.6
	0.5 M HNO₃	69	2.0	1.6	1.5	0.2~7.8
	DTPA	58	0.9	0.7	0.8	0.1~4.2
Pb (mg/kg)	Aqua regia	69	71.1	69.7	15.1	28.1~122.3
	0.01 M CaCl₂	16	1.4	1.4	0.2	1.0~1.6
	0.11 M HOAc	34	3.9	3.8	1.0	2.4~6.0
	0.5 M HNO₃	69	12.5	11.3	5.5	4.0~33.8
	DTPA	55	4.1	3.4	2.3	1.6~11.3
Zn (mg/kg)	Aqua regia	68	119.1	116.9	43.6	52.7~330.9
	0.01 M CaCl₂	56	2.7	2.6	1.2	1.7~9.4
	0.11 M HOAc	28	21.0	14.4	13.5	11.1~59.8
	0.5 M HNO₃	67	18.4	11.9	17.5	2.7~84.8
	DTPA	47	12.9	8.8	10.0	5.3~45.6

The values lower than detection limits were excluded..

DTPA* : 0.005 M DTPA + 0.01 M CaCl₂ + 0.1 M TEA.

Table 2 . Pearson correlation coefficients higher than 0.6 among pseudo-total and each single extraction method.

Cd	Soil condition		DTPA	pH < 6.6, CEC > 20.0, **OM > 4.6
	low pH*	log AR	0.701 (28)
	high CEC**	log HNO₃	0.630 (24)
	high OM***	log HNO₃	0.651 (22)

Cr	Soil condition		log HNO₃	*OM < 4.2
Cr	low OM*	log AR	0.703 (37)	*OM < 4.2

Cu	Soil condition		log HNO₃	log DTPA	AR > 36.0, pH < 6.5, CEC > 20.0, **OM > 4.2
	Total	log CaCl₂		0.644 (39)
	high AR*	log CaCl₂		0.669 (22)
	low AR	log AR	0.637 (36)
	low pH**	log AR		0.613 (34)
	low pH**	log CaCl₂		0.767 (19)
	high CEC***	log AR	0.629 (31)
		log CaCl₂		0.675 (18)
		log HNO₃		0.657 (28)
	low CEC	log CaCl₂		0.659 (21)
	high OM****	log CaCl₂		0.650 (16)
	low OM	log CaCl₂		0.637 (23)

Ni	Soil condition		log HNO₃	log DTPA	AR < 43.0, pH < 6.5, CEC > 20.0, **OM < 4.2
	Total	log HNO₃		0.617 (58)
	low AR*	log HNO₃		0.658 (29)
	low pH**	log HNO₃		0.733 (30)
	high CEC***	log HNO₃		0.724 (21)
	low OM****	log AR	0.641 (39)
	low OM****	log HNO₃		0.666 (39)

Zn	Soil condition		log HOAc	log HNO₃	log DTPA	AR > 119.1, pH > 6.5, CEC > 19.9, **OM > 4.3
	Total	AR	0.802 (28)	0.646 (67)	0.613 (47)
		log HOAc		0.767 (28)	0.887 (20)
		log HNO₃			0.767 (47)
	high AR*	AR	0.686 (13)
		log HOAc		0.870 (13)	0.865 (12)
		log HNO₃			0.813 (24)
	low AR	AR			0.689 (23)
	high pH**	AR	0.808 (12)	0.634 (31)
		log HOAc		0.885 (12)	0.847 (9)
		log HNO₃			0.827 (26)
	low pH	AR	0.791 (16)	0.690 (36)	0.737 (21)
		log HOAc		0.636 (16)	0.910 (11)
		log HNO₃			0.713 (21)
	high CEC***	AR	0.753 (13)	0.838 (30)	0.713 (19)
		log HOAc		0.843 (13)	0.912 (9)
		log HNO₃			0.796 (19)
	low CEC	AR	0.883 (15)	0.628 (37)	0.621 (28)
		log HOAc		0.831 (15)	0.895 (11)
		log HNO₃			0.738 (28)
	high OM****	AR	0.816 (15)	0.627 (30)	0.762 (17)
		CaCl₂			0.672 (15)
		log HOAc		0.706 (15)	0.892 (10)
		log HNO₃			0.786 (17)
	low OM	AR	0.881 (13)	0.724 (37)	0.605 (30)
		log HOAc		0.892 (13)	0.886 (10)
		log HNO₃			0.768 (30)

For Pb, no Pearson correlation coefficient higher than 0.6 existed. The numbers in brackets represent the number of samples. CEC: cation exchange capacity (meq/100 g), OM: organic matter content (%), AR: aqua regia extraction (mg/kg).

Table 3 . The results of multiple regression analyses for each heavy metal.

Metals	Soil condition	Variable input	Multiple regression analysis	R²	p value
Cd	low pH	enter	DTPA = 0.053 pH – 0.001 CEC – 0.130 logOM + 0.858 logAR – 0.003	0.561	0.001
Cd	low pH	stepwise	DTPA = 0.882 logAR + 0.205	0.491	< 0.001
Cu	low pH	enter	logDTPA = 0.183 pH + 0.003 CEC – 0.023 logOM + 0.739 logAR – 1.812	0.413	0.003
Ni	low pH	enter	logHNO₃ = 0.262 pH + 0.005 CEC – 0.190 logOM + 0.886 logAR – 2.711	0.404	0.001
Zn	all pH	enter	logHOAc = -0.015 pH – 0.001 CEC + 0.003 logOM + 0.003 AR + 0.935	0.648	< 0.001
		stepwise	logHOAc = 0.003 AR + 0.835	0.643	< 0.001
		enter	logHNO₃ = -0.022 pH + 0.012 CEC + 0.317 logOM + 0.005 AR + 0.224	0.554	< 0.001
		stepwise	logHNO₃ = 0.005 AR + 0.012 CEC + 0.314 logOM + 0.101	0.55	< 0.001
		enter	logDTPA = -0.015 pH + 0.010 CEC + 0.168 logOM + 0.003 AR + 0.419	0.478	< 0.001
		stepwise	logDTPA = 0.003 AR + 0.010 CEC + 0.398	0.459	< 0.001
	high pH	stepwise	CaCl₂ = 0.058 CEC – 0.962 logOM + 2.025	0.487	< 0.001
		stepwise	logHOAc = 0.003 AR + 0.868	0.652	0.001
		enter	logHNO₃ = 0.045 pH + 0.018 CEC + 0.206 logOM + 0.005 AR – 0.357	0.631	< 0.001
		stepwise	logHNO₃ = 0.005 AR + 0.019 CEC + 0.048 0.593 < 0.001	0.593	< 0.001
		enter	logDTPA = 0.046 pH + 0.016 CEC –0.144 logOM + 0.004 AR – 0.076	0.525	0.003
		stepwise	logDTPA = 0.004 AR + 0.015 CEC + 0.237	0.508	< 0.001
	low pH	enter	logHOAc = 0.046 pH – 0.014 CEC + 0.034 logOM + 0.005 AR + 0.669	0.748	0.003
		stepwise	logHOAc = 0.004 AR – 0.014 CEC + 0.955	0.737	< 0.001
		enter	logHNO₃ = 0.124 pH + 0.007 CEC + 0.367 logOM + 0.006 AR – 0.623	0.591	< 0.001
		stepwise	logHNO₃ = 0.006 AR + 0.369 logOM + 0.224	0.55	0.005
		enter	logDTPA = -0.025 pH – 0.001 CEC + 0.216 logOM + 0.004 AR + 0.550	0.584	0.005
		stepwise	logDTPA = 0.004 AR + 0.478 0.543 < 0.001	0.543	< 0.001

Oct 29, 2024 Vol.57 No.5, pp. 473~664

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The Statistical Study on the Effects of Physicochemical Properties of Soil on Single Extraction Methods for Heavy Metals

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토양의 물리화학적 특성이 중금속 단일용출법에 미치는 영향에 대한 통계학적 연구

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Research Paper

The Statistical Study on the Effects of Physicochemical Properties of Soil on Single Extraction Methods for Heavy Metals

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토양의 물리화학적 특성이 중금속 단일용출법에 미치는 영향에 대한 통계학적 연구

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