天山北坡表层土壤及农作物重金属污染研究

发布时间：2019-06-01 20:27

【摘要】：随着西部大开发战略的实施,新疆的工业和农业都得到了飞速的发展。然而,工业的发展和农业的现代化不可避免的会造成周围环境的污染。农业是新疆经济的第一产业,保障土壤的安全才能保证农产品的安全,从而保障人们的安全。重金属是最难降解也是最常见的土壤污染物。本研究选择新疆的昌吉回族自治州以及乌鲁木齐市作为研究区域。对研究区表层土壤中Cd、Co、Cr、Cu、Ni、Pb、Zn和Hg的含量和土壤理化性质进行了测定,并研究区重金属污染风险程度进行了评估。此外对重金属污染来源采用数学方法进行了解析,对当地农作物进行了适当的采样并分析了重金属的分布以及转移规律。主要得出了如下结论:天山北坡的表层土壤呈碱性,肥力低,含水量较低,呈现出干旱区盐碱地的特点。Cd、Co、Cr、Cu、Ni、Pb、Zn和Hg的平均含量分别为1.27、14.55、44.63、33.79、22.96、7.95和63.37 mg·kg-1和0.10 mg·kg-1。Cd、Cu和Hg都已超过新疆的背景值,Cd甚至已超过国家二级标准。Co、Cr、Ni、Pb和Zn受到人类活动的影响较小,而Cd、Cu和Hg受到人类活动的影响较大。重金属Cd含量高的地方主要集中乌鲁木齐达坂城区的农业区和阜康的煤矿等小型工业区,Hg含量高的地方主要集中在煤矿和工业区周围,Pb主要集中在人口密度大交通发达的地区以及煤矿周边。Co、Cr、Ni和Zn的空间分布较为相似,含量高的地方集中在研究区矿场、景区和工业区。Cu含量高的位置集中在几个农业生产比较发达的位置。变异系数表明研究区的重金属可能受到人类活动的影响。以新疆土壤背景值作为标准对土壤进行重金属污染风险程度评价。富集系数显示,Pb和Ni处于无富集状态,Co、Cr、Cu、和Zn处于轻微富集状态,Cd和Hg均处于显著富集的状态。地积累指数显示,Co、Cr、Cu、Ni、Pb和Zn处于无污染的状态,Cd为3级中度-强度污染状态,Hg为2级中度污染状态,Cu有66.1%处于无污染状态,33.9%处于轻度-中度污染状态。Cd和Hg的潜在生态风险都很高是综合潜在生态风险的主要贡献因子。天山北坡综合潜在生态风险总体很高,有19.8%的样点有中等程度潜的在生态风险,30.5%的样点有较高的潜在生态风,49.3%的样点有很高的潜在生态风险。研究区土壤主要可分为三类,第一类样点主要集中在农田区域且受到Cu污染,;第二类样品主要集中在旅游区和工业区受到Hg和Cd的污染严重;第三类样品集中交通发达、工业也较多的地区Hg和Cd的污染也都很严重。重金属间的主成分分析和相关性分析进行综合得出Co、Cr、Cu、Ni和Zn来源相同为第一主成分(PC1),Cd和Hg来源相同为第二主成分(PC2),Pb为第三主成分(PC3),8种重金属元素所涵盖的信息基本上都可以由三个主成分解释。通过熵值法计算不同主成分PCi(i=1、2、3),并分析不同的主成分的空间分布得出,Co、Cr、Cu、Ni和Zn来源农业化合物和有机肥;Hg和Cd主要来源于工业和生活垃圾,可能具有通过河流污水灌溉传播的趋势;Pb主要来源与工业生产和汽车尾气的排放。棉花和玉米对重金属都不具备超富集能力,棉花对重金属的转运能力基本上比玉米强;棉花和玉米叶子对微量元素Cu、Zn的转运能力及富集能力强于其他部位;棉花和玉米的根对Cd、Co、Pb的富集能力强于其他的组织;棉花的根和茎对Cd和Pb的吸收具有协同作用,玉米根茎对Cd、Zn和Pb的吸收都具有协同作用;不同农作物之间以及不同组织间的重金属组成差别很大。
[Abstract]:With the implementation of the western development strategy, the industry and agriculture in Xinjiang have been developed rapidly. However, the development of industry and the modernization of agriculture will inevitably lead to the pollution of the surrounding environment. Agriculture is the first industry in the Xinjiang economy, and the safety of the soil can be guaranteed in order to guarantee the safety of the agricultural products. Heavy metals are the most difficult to degrade and are the most common soil contaminants. This study selected the Changji Hui Autonomous Prefecture of Xinjiang and the Urumqi City as the research area. The contents of Cd, Co, Cr, Cu, Ni, Pb, Zn and Hg in the surface soil of the study area and the physical and chemical properties of the soil were measured, and the risk degree of heavy metal pollution in the study area was evaluated. In addition, the method of heavy metal pollution is analyzed, the local crop is sampled and the distribution of heavy metals and the transfer rule are analyzed. The main results are as follows: the surface soil of the northern slope of the Tianshan Mountains is alkaline, the fertility is low, the water content is low, and the characteristics of the saline-alkali land in the arid area are presented. The average content of Cd, Co, Cr, Cu, Ni, Pb, Zn and Hg is 1.27, 14.55, 44.63, 33.79, 22.96, 7.95 and 63.37 mg 路 kg-1 and 0.10 mg 路 kg-1.Cd, Cu and Hg have exceeded the background value of Xinjiang, and Cd has even exceeded the national secondary standard. Co, Cr, Ni, Pb and Zn are less affected by human activity, and Cd, Cu and Hg are affected by human activity. The place where the content of heavy metal Cd is high is mainly in the small industrial areas such as the agricultural area of the Daqingcheng District of Urumqi and the coal mine of Fukang, where the content of Hg is mainly concentrated around the coal mine and the industrial area, and the Pb is mainly concentrated in areas with high population density and large traffic and the periphery of the coal mine. The spatial distribution of Co, Cr, Ni and Zn is similar and the content of Co, Cr, Ni and Zn is concentrated in the field, scenic area and industrial area of the research area. The location of high Cu content is in a relatively developed position in several agricultural production. The coefficient of variation indicates that the heavy metals in the study area may be affected by human activity. The risk degree of heavy metal pollution was evaluated in the soil background of Xinjiang as the standard. The enrichment factor shows that Pb and Ni are in an unenriched state, and the Co, Cr, Cu, and Zn are in a slightly enriched state, and both Cd and Hg are in a state of significant enrichment. The accumulation index shows that Co, Cr, Cu, Ni, Pb and Zn are in a pollution-free state, Cd is 3-grade moderate-intensity pollution, Hg is 2-grade moderate pollution, Cu has 66.1% in pollution-free state, and 33.9% is in mild-moderate pollution state. The potential ecological risk of Cd and Hg is very high, which is the main contribution factor of the comprehensive potential ecological risk. The comprehensive potential ecological risk of the northern slope of the Tianshan Mountains is very high. There are 19.8% of the samples with medium-level latent ecological risk, 30.5% of the samples have high potential ecological wind, and 49.3% of the spots have a high potential ecological risk. The soil in the study area can be divided into three types, the first type of sample is mainly concentrated in the farmland area and is polluted by Cu, the second type of sample is mainly concentrated in the tourist area and the industrial area, and the pollution of Hg and Cd is serious; the third type of sample is concentrated in traffic, The pollution of Hg and Cd in the industry is also very serious. Co, Cr, Cu, Ni and Zn sources are the same as the first main component (PC1), and the source of Cd and Hg is the same as the second main component (PC2). Pb is the third main component (PC3), and the information covered by the 8 heavy metal elements can be basically explained by the three principal components. The different principal components, PCi (i = 1,2,3), are calculated by the entropy method, and the spatial distribution of different principal components is analyzed to obtain the agricultural compound and the organic fertilizer from the sources of Co, Cr, Cu, Ni and Zn; the Hg and Cd are mainly from the industrial and domestic wastes, and may have the tendency to spread through the river sewage irrigation; The main source of Pb is the emission of industrial production and automobile exhaust. the cotton and the corn do not have the super-enrichment capacity for heavy metal, the transport capacity of the cotton to the heavy metal is substantially higher than that of the corn, the transport capacity and the enrichment ability of the cotton and the corn leaves on the trace elements Cu and Zn are stronger than other parts, and the root of the cotton and the corn is Cd and Co, The concentration of Pb is stronger than that of other tissues; the roots and stems of cotton have a synergistic effect on the absorption of Cd and Pb, and the absorption of Cd, Zn and Pb by the rhizomes of the corn has a synergistic effect; and the heavy metal composition among different crops and between different tissues is very different.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;X173

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