Spatial Distribution Characteristics of Cadmium and Lead in Agricultural Soil of Typical Mining Area in Northern Guangdong and Its Pollution Assessment

doi:10.11924/j.issn.1000-6850.casb2025-0693

Abstract

Abstract:

This study investigated the spatial distribution and risk levels of cadmium (Cd) and lead (Pb) contamination in farmland soils within a typical industrial and mining area of northern Guangdong. An evaluation framework centered on “total content-chemical speciation-bioavailability” was constructed to provide a scientific basis for regional soil heavy metal pollution control and remediation. Taking the specific farmland area around typical industrial and mining industries in northern Guangdong as the research object, field sampling and laboratory analyses were conducted to determine the total concentrations and chemical speciation of Cd and Pb. The contamination degree, ecological risk, and bioavailability were systematically assessed. The results showed that: (1) both the contents and evaluation indices of Cd and Pb exhibit strong spatial variability. The spatial distributions of high-concentration areas differ between the two elements, indicating distinct pollution sources. Cd, in particular, displays significant point-source pollution characteristics. (2) Cd showed a high level according to the potential ecological risk index, whereas Pb was classified as uncontaminated based on both the single-factor index and the potential ecological risk index. However, the risk assessment code (RAC) and reduced partition index (RSP) evaluations for Cd both indicated high contamination levels. For Pb, RAC results suggested mainly low to moderate risk, while its RSP result indicated high contamination. The pollution grades derived from bioavailability-based assessment (using chemical speciation) were higher than those based on total heavy metal content. The soils in the study area were predominantly acidic, which could enhance Cd bioavailability and lead to a high contamination risk. Although Pb was considered safe based on total content evaluation, its potential ecological threat remained significant. Priority should be given to the remediation of Cd, while long-term monitoring of Pb should be strengthened to mitigate the composite pollution risk in the farmland ecosystem.

Key words: cadmium, lead, pollution risk assessment, bioavailability, spatial distribution

CLC Number:

S156

HUANG Wanyi, GAO Lin, QIU Tian, LIN Changhua, PAN Huirou, GUO Yinan, CHEN Leilei. Spatial Distribution Characteristics of Cadmium and Lead in Agricultural Soil of Typical Mining Area in Northern Guangdong and Its Pollution Assessment[J]. Chinese Agricultural Science Bulletin, 2026, 42(9): 82-91.

Figures/Tables 8

References 34

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污染指数	污染等级
单因子指数(P_i)	无污染	轻度污染	中度污染	重度污染
单因子指数(P_i)	P_i≤1.0	1.0<P_i≤2.0	2.0<P_i≤3.0	P_i>3.0
地累积指数(I_geo)	无	轻度—中等	中等	中等-强	强
地累积指数(I_geo)	I_geo≤0	0<I_geo≤1	1<I_geo≤2	2<I_geo≤3	3<I_geo≤4
潜在生态风险指数(Eⁱ_r)	轻微	中等	强	很强	极强
潜在生态风险指数(Eⁱ_r)	Eⁱ_r<40≤	40≤Eⁱ_r<80	80≤Eⁱ_r<160	160≤Eⁱ_r<320	Eⁱ_r>320
内梅罗综合指数(P_n)	无污染	尚未污染	轻度污染	中度污染	重度污染
内梅罗综合指数(P_n)	P_n≤0.7	0.7<P_n≤1.0	1.0<P_n≤2.0	2.0<P_n≤3.0	P_n>3.0
综合生态风险指数(RI)	低风险	中风险	重风险	危重风险
综合生态风险指数(RI)	RI<150	150≤RI<300	300≤RI<600	600≤RI<1200
风险评估编码法(RAC)	轻度风险	中等风险	高度风险	极高风险
风险评估编码法(RAC)	P≤0.1	0.1<P≤0.3	0.3<P≤0.5	P>0.5
次生相与原生相比值法(RSP)	无污染	轻度污染	中度污染	高度污染
次生相与原生相比值法(RSP)	P<1	1≤P<2	2≤P<3	P≥3

污染指数	污染等级
单因子指数(P_i)	无污染	轻度污染	中度污染	重度污染
单因子指数(P_i)	P_i≤1.0	1.0<P_i≤2.0	2.0<P_i≤3.0	P_i>3.0
地累积指数(I_geo)	无	轻度—中等	中等	中等-强	强
地累积指数(I_geo)	I_geo≤0	0<I_geo≤1	1<I_geo≤2	2<I_geo≤3	3<I_geo≤4
潜在生态风险指数(Eⁱ_r)	轻微	中等	强	很强	极强
潜在生态风险指数(Eⁱ_r)	Eⁱ_r<40≤	40≤Eⁱ_r<80	80≤Eⁱ_r<160	160≤Eⁱ_r<320	Eⁱ_r>320
内梅罗综合指数(P_n)	无污染	尚未污染	轻度污染	中度污染	重度污染
内梅罗综合指数(P_n)	P_n≤0.7	0.7<P_n≤1.0	1.0<P_n≤2.0	2.0<P_n≤3.0	P_n>3.0
综合生态风险指数(RI)	低风险	中风险	重风险	危重风险
综合生态风险指数(RI)	RI<150	150≤RI<300	300≤RI<600	600≤RI<1200
风险评估编码法(RAC)	轻度风险	中等风险	高度风险	极高风险
风险评估编码法(RAC)	P≤0.1	0.1<P≤0.3	0.3<P≤0.5	P>0.5
次生相与原生相比值法(RSP)	无污染	轻度污染	中度污染	高度污染
次生相与原生相比值法(RSP)	P<1	1≤P<2	2≤P<3	P≥3

指标		最大值	最小值	平均值	标准差	变异系数CV
pH		7.50	4.27	5.92±0.11	0.79	0.13
Cd/(mg/kg)	总量	3.76	0.11	1.42±0.11	0.80	0.56
	交换态	0.86	0.02	0.16±0.02	0.15	0.94
	碳酸盐结合态	2.29	0.08	0.90±0.07	0.50	0.56
	铁锰氧化物结合态	0.67	0.02	0.21±0.02	0.15	0.71
	强有机结合态	0.49	0.01	0.16±0.01	0.11	0.68
	残渣态	0.20	0.01	0.06±0.00	0.04	0.67
风险筛选值	pH≤5.5	0.3		风险管制值	pH≤5.5	1.5
	5.5<pH≤6.5	0.3			5.5<pH≤6.5	2.0
	6.5<pH≤7.5	0.3			6.5<pH≤7.5	3.0
Pb/(mg/kg)	总量	253.87	35.16	115.00±7.43	53.65	0.45
	交换态	7.47	0.87	3.40±0.20	1.51	0.44
	碳酸盐结合态	13.20	1.20	6.90±0.41	2.98	0.42
	铁锰氧化物结合态	232.95	29.62	99.82±6.87	49.61	0.48
	强有机结合态	17.27	3.11	9.11±0.44	3.18	0.34
	残渣态	8.70	1.25	3.99±0.22	1.63	0.41
风险筛选值	pH≤5.5	70		风险管制值	pH≤5.5	400
	5.5<pH≤6.5	90			5.5<pH≤6.5	500
	6.5<pH≤7.5	120			6.5<pH≤7.5	700

指标		最大值	最小值	平均值	标准差	变异系数CV
pH		7.50	4.27	5.92±0.11	0.79	0.13
Cd/(mg/kg)	总量	3.76	0.11	1.42±0.11	0.80	0.56
	交换态	0.86	0.02	0.16±0.02	0.15	0.94
	碳酸盐结合态	2.29	0.08	0.90±0.07	0.50	0.56
	铁锰氧化物结合态	0.67	0.02	0.21±0.02	0.15	0.71
	强有机结合态	0.49	0.01	0.16±0.01	0.11	0.68
	残渣态	0.20	0.01	0.06±0.00	0.04	0.67
风险筛选值	pH≤5.5	0.3		风险管制值	pH≤5.5	1.5
	5.5<pH≤6.5	0.3			5.5<pH≤6.5	2.0
	6.5<pH≤7.5	0.3			6.5<pH≤7.5	3.0
Pb/(mg/kg)	总量	253.87	35.16	115.00±7.43	53.65	0.45
	交换态	7.47	0.87	3.40±0.20	1.51	0.44
	碳酸盐结合态	13.20	1.20	6.90±0.41	2.98	0.42
	铁锰氧化物结合态	232.95	29.62	99.82±6.87	49.61	0.48
	强有机结合态	17.27	3.11	9.11±0.44	3.18	0.34
	残渣态	8.70	1.25	3.99±0.22	1.63	0.41
风险筛选值	pH≤5.5	70		风险管制值	pH≤5.5	400
	5.5<pH≤6.5	90			5.5<pH≤6.5	500
	6.5<pH≤7.5	120			6.5<pH≤7.5	700

	评价指数	最大值	最小值	平均值	标准差	变异系数CV	各等级比例/%
P_i							无污染	轻度污染	中度污染	重度污染
	Cd	1.878	0.073	0.722	0.457	0.634	75	25	0	0
	Pb	0.549	0.050	0.240	0.135	0.562	100	0	0	0
I_geo							无	轻度—中等	中等	中等—强	强
	Cd	3.720	-1.373	1.979	1.162	0.587	9.62	9.62	19.23	44.23	17.31
	Pb	2.297	-0.556	1.004	0.668	0.665	3.85	50.00	38.46	7.69
Eⁱ_r							轻微	中等	强	很强	极强
	Cd	592.89	17.368	224.92	127.23	0.566	5.77	11.54	19.23	42.31	21.15
	Pb	36.84	5.103	16.691	7.786	0.466	100	0	0	0	0
P							无污染	尚未污染	轻度污染	中度污染	重度污染
P		5.359	0.175	2.063	1.312	0.636	21.15	5.77	28.85	21.15	23.08
RI							低风险	中风险	重风险	危重风险
RI		603.88	34.815	241.61	125.91	0.521	28.85	34.62	34.62	1.92