拉萨市城区土壤重金属分布特征及生态风险评价

李伟; 高海涛; 张娜; 孙晶; 巴桑; 吕学斌; 熊健

doi:10.12153/j.issn.1674-991X.20210191

拉萨市城区土壤重金属分布特征及生态风险评价

doi: 10.12153/j.issn.1674-991X.20210191

西藏大学理学院

基金项目: 国家重点研发计划“固废资源化”重点专项（2019YFC1904100）；2021年第二次青藏科考支撑服务与成果转化项目（XZ202101ZD0014G）；2021年西藏自治区科技厅重点研发计划项目（XZ202101ZY0012G）；中央支持地方高校专项资金(藏财预指〔2020〕01，〔2021〕01)；环境化学与生态毒理学国家重点实验室开放基金(KF2017-07)；西藏大学培育基金（ZDQMJH18-14，ZDCZJH18-08）；西藏经济社会发展与高原科学研究共建创新基金(lzj2020002，lzt2020002）

详细信息

作者简介:
李伟（1986—），男，副教授，硕士，主要研究方向为土壤化学，li_wei05416@163.com

通讯作者:
熊健（1987—），女，副教授，硕士，研究方向为生态学，568284825@qq.com

中图分类号: X826
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- 文章访问数: 368
- HTML全文浏览量: 168
- PDF下载量: 30
- 被引次数: 0
出版历程
- 收稿日期: 2021-05-20
- 录用日期: 2021-08-30
- 网络出版日期: 2022-06-07

Distribution characteristics and ecological risk assessment of heavy metals in soil of Lhasa City

College of Science, Tibet University

摘要

摘要:
为了解拉萨市土壤重金属污染情况和空间分布特征，对其主城区20个表层土壤样品中8种重金属浓度进行测定，利用内梅罗综合污染指数法和潜在生态风险指数(RI)法对其环境质量和生态风险进行评价。结果表明：土壤中的Cu、Zn、Cr、Ni、Pb、Cd、As、Hg浓度均值分别是拉萨市土壤背景值的0.92、1.02、0.85、0.83、0.73、0.83、1.28、0.8倍，但均符合GB 15618—1995《土壤环境质量标准》二级标准，其中Zn、As超标率较高，分别为45%、95%；重金属元素空间分布呈现一定规律，大部分元素呈点状格局，其中Ni分布均匀，其他元素均有高值区出现，重金属累积状态与人为活动轨迹相似；除Zn和As的单项污染指数为轻度污染外，其他元素均为无污染，内梅罗综合污染指数均值为1.24，属于轻度污染；RI均值为85.96，为低生态风险，Hg和Cd为主要风险因子。拉萨市土壤中Cu、Zn、Pb和Cd的累积以自然源为主，部分受到交通运输活动的影响；As的累积主要源于较高的自然背景值，Hg的累积受到自然源和工业源共同影响，Ni和Cr的累积受自然因子控制。
- 拉萨市 /
- 土壤 /
- 重金属 /
- 环境质量 /
- 生态风险评价
Abstract:
In order to study the pollution and spatial distribution characteristics of soil heavy metals in Lhasa, the contents of 8 heavy metals in 20 surface soil samples in the main urban area were analyzed and determined. And the Nemerow comprehensive pollution index and potential ecological hazard index were used to evaluate the environmental quality and ecology risk. The research results showed that the average values of Cu, Zn, Cr, Ni, Pb, Cd, As, and Hg in the soil are 0.92, 1.02, 0.85, 0.83, 0.73, 0.83, 1.28, and 0.8 times of the Lhasa background values, All of them meet the grade Ⅱ standard of National Soil Environmental Quality Standard (GB 15618-1995), among which Zn and As have a higher rate of exceeding the standard, 45% and 95% respectively. From the spatial distribution map of heavy metals, the distribution of elements presents a certain pattern, which mostly presents a dot pattern. Among them, Ni was evenly distributed, and other elements have high value areas. The accumulation status of heavy metals in the study area was similar to the track of human activities. Except for the single pollution index of Zn and As, which was slight pollution, all other elements are non-pollution. The average value of Nemerow comprehensive pollution index was 1.24, which belongs to slight pollution; The mean value of RI was 85.96, which was low ecological hazard, and Hg and Cd were the main risk factors. The accumulation of Cu, Zn, Pb, and Cd were mainly from natural sources, partly affected by transportation activities; the accumulation of As were mainly due to the high natural background value; the accumulation of Hg was affected by both natural sources and industrial sources; the accumulation of Ni and Cr were controlled by natural factors.
- Lhasa City /
- soil /
- heavy metal /
- environment quality /
- ecological risk assessment

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图 1 拉萨市主城区土壤重金属浓度空间分布

Figure 1. Spatial distribution of heavy metal concentrations in soil in the main urban area of Lhasa City

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图 2 内梅罗综合污染指数评价结果空间分布

Figure 2. Spatial distribution of assessment result of Nemerow comprehensive pollution index

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图 3 土壤重金属RI评价结果空间分布

Figure 3. Spatial distribution of RI evaluation results of soil heavy metals

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表 1 拉萨市主城区土壤重金属浓度统计

Table 1. Statistics of heavy metal concentrations in soil in the main urban area of Lhasa City

重金属	浓度/(mg/kg)				标准差/(mg/kg)	变异系数	超标率/%	拉萨市背景值^[23]/(mg/kg)	GB 15618—1995 二级标准^[24]/(mg/kg)
重金属	最小值	最大值	中值	均值	标准差/(mg/kg)	变异系数	超标率/%	拉萨市背景值^[23]/(mg/kg)	GB 15618—1995 二级标准^[24]/(mg/kg)
Cu	15.00	36.00	20.00	20.25	4.87	0.24	20	22.00	100
Zn	50.80	87.30	64.85	66.07	10.10	0.15	45	65.00	250.0
Cr	27.00	54.00	33.50	35.90	6.64	0.18	10	42.00	200
Ni	12.00	22.00	18.00	17.35	3.05	0.17	5	21.00	50
Pb	18.50	41.90	21.25	22.70	5.71	0.25	10	31.00	300.0
Cd	0.07	0.22	0.10	0.10	0.03	0.30	5	0.12	0.30
As	18.50	48.90	22.70	25.64	7.83	0.31	95	20.00	30.0
Hg	0.010	0.220	0.052	0.074	0.067	0.91	30	0.092	0.500

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表 2 土壤重金属单因子污染指数评价结果

Table 2. Assessment results of single factor index of heavy metals in soil

评价标准	重金属	P_i 均值	采样点数量占比/%
评价标准	重金属	P_i 均值	无污染	轻微污染	轻度污染	中度污染	重度污染
拉萨市土壤环境背景值	Cu	0.92	80	20	0	0	0
	Zn	1.03	55	45	0	0	0
	Cr	0.86	90	10	0	0	0
	Ni	0.83	95	5	0	0	0
	Pb	0.73	90	10	0	0	0
	Cd	0.85	95	5	0	0	0
	As	1.28	5	85	10	0	0
	Hg	0.81	70	20	10	0	0
GB 15618—1995 二级标准	Cu	0.20	100	0	0	0	0
	Zn	0.27	100	0	0	0	0
	Cr	0.18	100	0	0	0	0
	Ni	0.35	100	0	0	0	0
	Pb	0.08	100	0	0	0	0
	Cd	0.34	100	0	0	0	0
	As	0.85	90	10	0	0	0
	Hg	0.16	100	0	0	0	0

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表 3 土壤重金属潜在生态风险评价结果

Table 3. Evaluation results of potential ecological risk of soil heavy metals

项目	E_rⁱ
项目	最大值	最小值	均值
Cu	8.20	3.40	4.60
Zn	1.34	0.78	1.03
Cr	2.58	1.28	1.71
Ni	5.25	2.85	4.13
Pb	6.75	3.00	3.66
Cd	54.90	17.40	25.64
As	24.50	9.30	12.84
Hg	96.40	4.00	32.36
RI	155.94	45.91	85.96

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表 4 土壤重金属元素之间的相关系数

Table 4. Correlation coefficients between heavy metals in the soils

重金属	Cu	Zn	Cr	Ni	Pb	Cd	As	Hg
Cu	1
Zn	0.799**	1
Cr	0.284	0.201	1
Ni	0.235	0.273	0.09	1
Pb	0.679**	0.651**	−0.032	0.257	1
Cd	0.754**	0.659**	−0.07	0.221	0.818**	1
As	0.138	0.173	0.104	−0.049	−0.256	−0.027	1
Hg	−0.001	0.27	0.286	−0.143	0.116	0.084	0.055	1
注：**表示在0.01水平上相关性显著。

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表 5 土壤重金属主成分分析

Table 5. Principal component analysis of soil heavy metals

重金属	第一主成分	第二主成分	第三主成分
Cu	0.903	0.090	0.180
Zn	0.884	0.210	0.046
Cr	0.185	0.708	0.036
Ni	0.370	−0.218	0.469
Pb	0.866	−0.291	−0.250
Cd	0.882	−0.211	−0.077
As	0.018	0.567	0.608
Hg	0.178	0.620	−0.617
方差百分比/%	41.590	17.947	13.435
累计贡献率/%	41.590	59.537	72.972

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