Spatial and Temporal Distribution Characteristics of Heavy Metals in Surface Sediments of Niulan River (Kunming Section) and Potential Ecological Risk Assessment

doi:10.11988/ckyyb.20230632

Abstract

Abstract:

In order to explore the characteristics of heavy metal pollution in surface sediments of Niulan River (Kunming Section), the surface sediments of 20 points in the basin were collected ;and the contents of 8 metals (Cu, Zn, Cr, Cd, Ni, Pb, Hg and As) were determined in three water periods (wet period, dry period and normal period). Water stage and regional difference analysis, potential risk assessment and heavy metal source analysis were also carried out. The results showed that the content of Cd (1.45 mg/kg) and Hg (0.23 mg/kg) of heavy metals in sediments of Niulan River (Kunming Section) was 6.7 times and 4.0 times that of the background values 0.218 mg/kg and 0.058 mg/kg in Yunnan Province, respectively. It indicates that Cd and Hg pollution are relatively serious. The soil accumulation index showed that Cd had the highest pollution level in the three water periods of Niulan River (Kunming Section), followed by Hg. The average pollution levels reached moderate pollution and moderately moderate pollution, respectively. Therefore, Cd and Hg are the main ecological risk contributing factors of heavy metal pollution in surface sediments of Niulan River (Kunming Section). At the same time, the potential ecological risk coefficient showed that the distribution of potential ecological risk was higher in the main stream than in the tributaries, higher in the lower stream than in the upper stream and higher in the north than in the south.

Key words: surface sediment, heavy metal, ground accumulation index, potential ecological risk, Niulan River (Kunming section)

CLC Number:

X522河流

LI Xin-yue, YANG Yan, HONG Chang-hai, ZHI Guo-qiang, YANG Jian, HAN Zhen-yang, WAN Zheng-fen, LU Shao-yong. Spatial and Temporal Distribution Characteristics of Heavy Metals in Surface Sediments of Niulan River (Kunming Section) and Potential Ecological Risk Assessment[J]. Journal of Changjiang River Scientific Research Institute, 2024, 41(11): 32-40.

Figures/Tables 13

Fig.1 Distribution of sampling points

Table 1 Classification of heavy metal pollution levels

I_geo	分级	污染程度	I_geo	分级	污染程度
<0	0	无污染	[3,4)	Ⅳ	偏重度污染
[0,1)	Ⅰ	轻度污染	[4,5]	Ⅴ	重度污染
[1,2)	Ⅱ	偏中度污染	>5	Ⅵ	严重污染
[2,3)	Ⅲ	中度污染

Table 2 Grading of E r i and RI calculated values

$E r i$	RI	潜在生态风险等级	$E r i$	RI	潜在生态风险等级
<40	<150	低风险	[160,320]	>600	高风险
[40,80)	[150,300)	中风险	>320	—	极高风险
[80,160)	[300,600)	较高风险

Table 2 Grading of E r i and RI calculated values

$E r i$	RI	潜在生态风险等级	$E r i$	RI	潜在生态风险等级
<40	<150	低风险	[160,320]	>600	高风险
[40,80)	[150,300)	中风险	>320	—	极高风险
[80,160)	[300,600)	较高风险

Table 3 Statistics of heavy metal content in sediments of three water periods

水期	重金属	重金属含量ω/(mg·kg^-1)					变异系数
水期	重金属	背景值	最小值	最大值	平均值	标准差	变异系数
枯水期	Cu	46.3	31.50	115.58	79.44	38.48	0.48
	Zn	89.7	93.22	2 133.07	287.95	500.69	1.74
	Cr	65.2	59.62	156.16	96.03	28.27	0.29
	Cd	0.218	0.09	7.54	1.89	2.23	1.18
	Ni	42.5	26.23	82.00	44.75	17.50	0.39
	Pb	40.6	2.72	110.12	52.62	31.66	0.60
	Hg	0.058	0.07	0.47	0.21	0.12	0.58
	As	18.4	3.61	22.64	10.69	5.16	0.48
丰水期	Cu	46.3	30.00	130.93	76.16	30.03	0.39
	Zn	89.7	80.53	606.36	204.33	132.31	0.65
	Cr	65.2	69.42	165.74	102.36	25.53	0.25
	Cd	0.218	0.17	6.66	1.29	1.50	1.16
	Ni	42.5	28.34	87.00	50.21	17.46	0.35
	Pb	40.6	2.54	111.57	59.90	24.17	0.40
	Hg	0.058	0.07	0.46	0.24	0.12	0.51
	As	18.4	3.32	28.32	9.84	6.06	0.62
平水期	Cu	46.3	12.52	167.47	78.16	36.89	0.47
	Zn	89.7	82.86	542.66	196.03	138.61	0.71
	Cr	65.2	61.75	143.00	90.62	20.46	0.23
	Cd	0.218	0.20	6.82	1.17	1.53	1.31
	Ni	42.5	25.18	141.51	48.93	25.71	0.53
	Pb	40.6	9.97	107.49	57.18	23.85	0.42
	Hg	0.058	0.07	0.47	0.25	0.14	0.55
	As	18.4	4.35	31.18	11.01	6.46	0.59

Table 4 Heavy metal content in surface sediments of different rivers in China

河流	年份	重金属含量/(mg·kg^-1)
河流	年份	Cu	Zn	Cr	Cd	Ni	Pb	Hg	As
牛栏江昆明段(本研究)	2021	77.92	229.44	96.34	1.45	47.97	56.57	0.23	10.51
长江流域武汉段^[19]	2005	51.64	140.27	87.82	1.53	—	45.18	0.15	15.85
长江上游^[19]	2014	65.80	141.85	80.04	0.93	—	51.01	0.10	8.79
长江中下游^[19]	2017	28.48	104.12	—	0.67	—	27.28	0.03	20.10
辽河^[20]	2017	28.08	36.59	38.13	—	26.88	17.49	—	17.30
松花江^[21]	2016	5.62	26.32	15.15	0.89	—	21.77	—	80.50
淮河江苏段^[22]	2019	27.83	109.17	53.05	0.07	36.60	26.80	—	10.55
海河^[23]	2013	34.47	86.47	104.53	0.31	29.03	34.92	—	—
金沙江攀枝花段^[24]	2018	42.60	91.10	—	0.20	—	17.00	—	5.70
湘江流域衡阳段^[25]	2019	51.40	264.10	47.80	5.41	—	157.70	—	86.70
黄河^[26]	近年	26.32	87.11	90.31	0.50	26.50	20.99	—	18.91
珠江^[26]	2013	134.80	313.90	76.40	1.50	115.10	7.03	—	56.70

Fig.2 Difference of heavy metals in sediments of main stream and tributaries

Table 5 Evaluation results of heavy metal pollution in sediments of Niulan River (Kunming Section)

水期	重金属		I_geo						污染程度					单因子危害指数 $E r i$			单项潜在风险程度
水期	重金属		平均值		干流		支流		平均值		干流		支流	平均值	干流	支流	干流	支流
枯水期	Cu	0.18		0.21		0.15		轻度		轻度		轻度		8.45	8.69	8.34	低	低
	Zn	1.01		0.73		1.30		偏中度		轻度		偏中度		3.32	2.48	3.69	低	低
	Cr	-0.04		-0.06		-0.01		无		无		无		2.94	2.88	2.97	低	低
	Cd	2.64		3.06		2.21		中度		偏重度		中度		259.13	376.47	208.84	极高	高
	Ni	-0.54		-0.62		-0.46		无		无		无		5.28	4.88	5.45	低	低
	Pb	-0.17		-0.09		-0.26		无		无		无		6.51	7.05	6.28	低	低
	Hg	1.44		1.93		0.95		偏中度		偏中度		轻度		150.05	229.04	116.19	高	较高
	As	-1.28		-1.09		-1.47		无		无		无		5.92	7.07	5.43	低	低
丰水期	Cu	0.16		0.24		0.08		轻度		轻度		轻度		8.22	8.88	7.94	低	低
	Zn	0.72		1.17		0.27		轻度		偏中度		轻度		2.28	3.37	1.81	低	低
	Cr	0.01		-0.11		0.14		轻度		无		轻度		3.14	2.77	3.30	低	低
	Cd	2.10		2.74		1.47		中度		中度		偏中度		177.39	301.22	124.32	高	较高
	Ni	-0.39		-0.49		-0.29		无		无		无		5.91	5.34	6.15	低	低
	Pb	0.02		0.15		-0.11		轻度		轻度		无		7.38	8.32	6.97	低	低
	Hg	1.60		2.06		1.14		偏中度		中度		偏中度		167.29	249.38	132.11	高	较高
	As	-1.47		-1.42		-1.52		无		无		无		5.35	5.60	5.24	低	低
平水期	Cu	0.25		0.49		0.01		轻度		轻度		轻度		8.44	10.52	7.55	低	低
	Zn	0.67		1.21		0.13		轻度		偏中度		轻度		2.19	3.46	1.64	低	低
	Cr	-0.12		-0.16		-0.09		无		无		无		2.78	2.69	2.82	低	低
	Cd	1.96		2.69		1.23		偏中度		中度		偏中度		160.89	289.61	105.72	高	较高
	Ni	-0.32		-0.14		-0.50		无		无		无		5.76	6.80	5.31	低	低
	Pb	-0.04		0.09		-0.18		无		轻度		无		7.04	7.99	6.63	低	低
	Hg	1.62		2.08		1.15		偏中度		中度		偏中度		169.75	254.10	133.61	高	较高
	As	-1.36		-1.42		-1.29		无		无		无		5.98	5.59	6.15	低	低

Table 5 Evaluation results of heavy metal pollution in sediments of Niulan River (Kunming Section)

水期	重金属		I_geo						污染程度					单因子危害指数 $E r i$			单项潜在风险程度
水期	重金属		平均值		干流		支流		平均值		干流		支流	平均值	干流	支流	干流	支流
枯水期	Cu	0.18		0.21		0.15		轻度		轻度		轻度		8.45	8.69	8.34	低	低
	Zn	1.01		0.73		1.30		偏中度		轻度		偏中度		3.32	2.48	3.69	低	低
	Cr	-0.04		-0.06		-0.01		无		无		无		2.94	2.88	2.97	低	低
	Cd	2.64		3.06		2.21		中度		偏重度		中度		259.13	376.47	208.84	极高	高
	Ni	-0.54		-0.62		-0.46		无		无		无		5.28	4.88	5.45	低	低
	Pb	-0.17		-0.09		-0.26		无		无		无		6.51	7.05	6.28	低	低
	Hg	1.44		1.93		0.95		偏中度		偏中度		轻度		150.05	229.04	116.19	高	较高
	As	-1.28		-1.09		-1.47		无		无		无		5.92	7.07	5.43	低	低
丰水期	Cu	0.16		0.24		0.08		轻度		轻度		轻度		8.22	8.88	7.94	低	低
	Zn	0.72		1.17		0.27		轻度		偏中度		轻度		2.28	3.37	1.81	低	低
	Cr	0.01		-0.11		0.14		轻度		无		轻度		3.14	2.77	3.30	低	低
	Cd	2.10		2.74		1.47		中度		中度		偏中度		177.39	301.22	124.32	高	较高
	Ni	-0.39		-0.49		-0.29		无		无		无		5.91	5.34	6.15	低	低
	Pb	0.02		0.15		-0.11		轻度		轻度		无		7.38	8.32	6.97	低	低
	Hg	1.60		2.06		1.14		偏中度		中度		偏中度		167.29	249.38	132.11	高	较高
	As	-1.47		-1.42		-1.52		无		无		无		5.35	5.60	5.24	低	低
平水期	Cu	0.25		0.49		0.01		轻度		轻度		轻度		8.44	10.52	7.55	低	低
	Zn	0.67		1.21		0.13		轻度		偏中度		轻度		2.19	3.46	1.64	低	低
	Cr	-0.12		-0.16		-0.09		无		无		无		2.78	2.69	2.82	低	低
	Cd	1.96		2.69		1.23		偏中度		中度		偏中度		160.89	289.61	105.72	高	较高
	Ni	-0.32		-0.14		-0.50		无		无		无		5.76	6.80	5.31	低	低
	Pb	-0.04		0.09		-0.18		无		轻度		无		7.04	7.99	6.63	低	低
	Hg	1.62		2.08		1.15		偏中度		中度		偏中度		169.75	254.10	133.61	高	较高
	As	-1.36		-1.42		-1.29		无		无		无		5.98	5.59	6.15	低	低

Fig.3 Distribution of combined potential ecological risk levels of multiple heavy metals in various periods

Fig.4 Contribution value of each metal in different potential ecological risk degrees in different water periods

Table 6 Data range of hydrology, hydrodynamics, human activities and land use types in the catchment

水期	水文水动力				人类活动		不同用地类型面积/km²
水期	有效宽度/m	有效水深/m	流速/ (m·s^-1)	流量/ (m³·s^-1)	人口数量/人	道路密度/ (km·km^-2)	草地	耕地	建设用地	林地	裸地及水域
枯水期	2.5~35	0.1~1.1	0.1~0.4	0.1~8.1
丰水期	3~40	0.25~1.3	0.1~0.5	0.4~22	9 295.33~ 93 284.09	0.78~3.65	0.31~ 188.68	6.83~ 123.33	2.71~25.09	0.3~ 54.60	0.14~5.27
平水期	2.5~35	0.15~1.2	0.1~0.4	0.1~0.9

Fig.5 Analysis of impact factor of heavy metals risk in surface sediments during different water periods

Table 7 Correlation analysis of heavy metals in sediment during dry season

重金属	Cu	Zn	Cr	Cd	Ni	Pb	Hg	As
Cu	1
Zn	-0.086	1
Cr	0.423^*	-0.240	1
Cd	-0.259	0.457^*	-0.295	1
Ni	0.517^*	-0.280	0.776^**	-0.103	1
Pb	-0.045	0.547^**	0.120	0.234	0.109	1
Hg	-0.093	0.036	-0.128	0.062	-0.240	0.327	1
As	-0.298	0.254	-0.486^*	0.334	-0.594^**	0.221	0.197	1

Fig.6 Distribution of major industrial enterprises in the basin

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