锡林郭勒露天煤矿区土壤重金属分布特征与植被恢复研究

发布时间：2018-07-31 07:47

【摘要】：露天煤矿对干旱、半干旱地区原本脆弱的草地生态系统造成了巨大干扰。其开采过程中大量剥离废弃物所形成的众多排土场,不仅占压草原和破坏草原植被,且未经处理的排土场在雨水和风力作用下,导致矿区水土流失加剧,造成周边草原生态与环境质量下降。煤炭开采区生态与环境问题已成为区域经济可持续发展的重大问题之一。其中,准确了解矿区周边土壤重金属的污染状况与积累特征,对排土场进行植被恢复与重建,是防治矿区土壤重金属污染的基础,也是缓解矿区生态压力和解决环境问题的关键。因此,针对典型草原露天煤矿区进行土壤重金属污染特征和植被恢复研究,可为露天煤矿区土壤重金属防治和草原生态系统可持续发展提供科学理论依据,同时对促进国民经济又好又快健康发展具有重要意义。以锡林郭勒典型草原胜利煤田西一号和西二号露天矿为研究对象,采用样带野外取样和室内分析相结合的方法,以矿区为中心,向东、南、西和北,以及东北、东南和西南7个辐射方向各设置1条研究样带,并根据矿区实际情况,在矿区东向样带上,距矿区外围边界0km、0.5km、1km、2km和4km处各设置1个调查样地,在其余6个方向样带上,距矿区外边界0km、0.5km、1km、2km、4km、6km和8km处各设置1个调查样地。此外,在南向、西向和北向3条样线上的10km处增设调查样地,作为对照样地。2014年7-9月,在预先设置的样地上调查群落特征,并采集表层土样(0～10cm)。测定其铬(Cr)、铜(Cu)、锰(Mn)、镍(Ni)、锌(Zn)和铅(Pb)6种重金属元素的含量,综合运用多元统计分析法、GIS空间分析法、地统计学克里金插值法等分析方法,对矿区土壤重金属含量的空间分布、迁移扩散规律以及煤矿开采对典型草原土壤重金属影响范围进行了研究。同时,以国家土壤环境质量二级标准和内蒙古土壤背景值为基准,采用单因子指数法、内梅罗综合指数法、地积累指数法定量地评价了典型草原露天煤矿区周围土壤重金属污染现状,并采用潜在生态风险评价方法对试验区生态风险等级及其空间分布格局进行了研究。2015年7-9月,在露天煤矿外排土场生物笆植被恢复区和无生物笆植被恢复区,分别选择已恢复1年和5年的样地,进行植被群落特征调查,并采集表层土样,测定其重金属含量和养分含量(有机质、碱解氮、速效磷和速效钾),以分析不同植被恢复措施对土壤重金属含量、植被状况和土壤理化状况的影响。主要研究结果如下：(1)露天煤矿开采对周围土壤重金属空间分布有显著影响,其影响程度和范围受多种因素控制。土壤重金属元素含量、单因子污染指数、内梅罗综合污染指数和综合潜在生态风险指数在矿区中心处最高,并向四周逐渐降低。(2)矿区东北方向样带,土壤重金属含量高于内蒙古背景值,其所有采样点的综合污染指数和潜在生态风险指数都达到轻污染和中度生态危害等级。(3)以内蒙古土壤背景值为参比值,典型草原露天煤矿周围0.5km范围内土壤重金属含量均超过背景值；就综合污染指数和潜在生态风险指数而言,矿区开采对西向和南向的影响范围为2km,对东向和北向的影响范围可达4km。(4)以国家土壤环境质量二级标准为基准,典型草原露天煤矿区土壤Cr、Cu、Mn、Ni、Zn和Pb 6种重金属总体上属于清洁水平；以内蒙古土壤背景值为基准,单因子污染指数表明重金属Cu为轻污染水平,其余5种重金属元素为清洁水平,但距矿区0.5km内样点达到轻污染水平；内梅罗综合污染指数表明矿区周围土壤整体属于轻污染等级；地积累指数法表明露天煤矿区周围土壤重金属属于无污染水平。以10km对照样点为基准的潜在生态风险指数法表明,研究区土壤最高污染水平为中度生态危害等级,大部分区域处于轻度生态危害等级。(5)统计分析(相关分析、主成分分析和聚类分析)结果表明,典型草原矿区周围土壤重金属Cr、Cu、Mn、Ni和Zn来源相同,而Pb则有单独来源。(6)随着矿区植被恢复措施年限的增加,群落中物种数和多样性指数均逐渐增多(高)。一、二年生植物种所占比例减小,其生物量所占比例下降；多年生杂类草和灌木类逐渐成为优势植物种,具有较高物种多样性,在群落生物量中所占近70%。(7)露天煤矿排放的废弃土,随着在外暴露时间的增加,其重金属含量有增加趋势；采用人工种植植物的植被恢复技术方法,可增加土壤有机质、碱解氮、速效磷和速效钾的含量,并随着恢复年限的增加有显著提高,植被恢复措施可显著降低土壤中重金属含量(Pb除外)(p0.05)。植被恢复5年后重金属含量可达到矿区周围10km处水平,其中,生物笆植被恢复方法效果更为显著。
[Abstract]:The open-pit coal mine has caused great disturbance to the original fragile grassland ecosystem in arid and semi-arid areas. In the process of mining, a large number of dumps formed by the stripping of waste are not only occupied by the grassland and the grassland vegetation, but the soil and water loss in the mining area is aggravated by the rain and wind in the untreated dump. The ecological and environmental quality of grassland is declining. The ecological and environmental problems in the coal mining area have become one of the major problems in the sustainable development of the regional economy. It is the basis for the prevention and control of heavy metal pollution in the mining area, as well as the accurate understanding of the pollution and accumulation of heavy metals in the soil surrounding the mining area and the restoration and reconstruction of the vegetation. In order to alleviate the ecological pressure and solve the environmental problems in the mining area, the study on the characteristics of soil heavy metal pollution and the restoration of the vegetation in the typical open-pit coal mine area can provide scientific basis for the prevention and control of soil heavy metals and the sustainable development of the grassland ecosystem in the open pit coal mine area, at the same time, it can also promote the good and fast health of the national economy. The development is of great significance. Taking the XII and XII two open-pit mine of Shengli Coalfield of xilingogle as the research object, using the method of combining field sampling and indoor analysis, 1 research samples are set up in 7 radiation directions of East, South, West and North, northeast, Southeast and southwest, and according to the practice of mining area. On the east side of the mining area, 1 survey samples were set up at the periphery of the mining area 0km, 0.5km, 1km, 2km and 4km. On the other 6 direction samples, 1 survey samples were set up from the outer boundary 0km, 0.5km, 1km, 2km, 4km, 6km and 8km. Furthermore, the investigation plots were added to the 3 lines of southward, West and north as control. In 7-9 months of.2014, the characteristics of the community were investigated on the pre set plots and the surface soil samples were collected (0 ~ 10cm). The contents of 6 kinds of heavy metal elements, such as chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), zinc (Zn) and lead (Pb), were measured, and the analysis methods such as multivariate statistical analysis, GIS spatial analysis and geostatistical Kriging interpolation were applied to the mining area. The spatial distribution of heavy metal content, the law of migration and diffusion and the influence of coal mining on heavy metals in typical grassland soil are studied. At the same time, the single factor index method, Nemero comprehensive index method, and the land accumulation index method are used to evaluate the soil environmental quality of the typical grassland soil by the two grade standard of the national soil environmental quality and the soil background value of Inner Mongolia. The current situation of heavy metal pollution in the soil around the typical prairie open coal mine area, and using the potential ecological risk assessment method to study the ecological risk grade and its spatial distribution pattern in the experimental area for the 7-9 month of.2015 years, in the restoration area of the biologic fence vegetation in the outer dumping ground and the restoration area of the non biologically barred vegetation in the outside of the open pit coal mine, the selection has been restored for 1 years and 5 years respectively. The characteristics of the vegetation community were investigated, and the surface soil samples were collected and the contents of heavy metals and nutrients (organic matter, alkali hydrolysable nitrogen, available phosphorus and available potassium) were measured to analyze the effects of different vegetation restoration measures on the heavy metal content, vegetation status and the physical and chemical conditions of soil. The main results are as follows: (1) mining in open pit coal mine The spatial distribution of heavy metals in the surrounding soil has a significant influence, and the extent and extent of its influence are controlled by a variety of factors. The content of heavy metals in the soil, the index of single factor pollution, the Nemero comprehensive pollution index and the comprehensive potential ecological risk index are the highest in the center of the mining area, and gradually reduce to the four sides. (2) the northeast direction of the mining area and the heavy metal in the soil The content of the comprehensive pollution index and the potential ecological risk index of all the sampling points reached the level of light pollution and moderate ecological hazard. (3) the soil heavy metal content in the 0.5km range around the typical prairie open coal mine was higher than the background value, and the comprehensive pollution index and the potential of the latent energy were above the background value. (3) the soil background value of the Inner Mongolia soil was more than the background value. In terms of ecological risk index, the influence of mining mining on West and south direction is 2km, and the influence range of East and north direction can reach 4km. (4) based on national standard of two grade soil environmental quality. The soil Cr, Cu, Mn, Ni, Zn and Pb of typical prairie open coal mine area belong to the clean level, and the soil background value of Inner Mongolia is in the background value. The single factor pollution index indicates that heavy metal Cu is a light pollution level, the other 5 kinds of heavy metals are clean level, but it reaches the level of light pollution from the 0.5km sample in the mining area, and the comprehensive pollution index of inner Melo indicates that the soil around the mining area is a light pollution grade, and the soil accumulation index method shows the heavy metals around the open coal mine area. The potential ecological risk index method based on the 10km control point showed that the highest level of soil pollution in the study area was moderate ecological hazard grade and most of the region was in the mild ecological hazard grade. (5) statistical analysis (correlation analysis, principal component analysis and cluster analysis) showed that the soil around the typical steppe mining area The sources of Cr, Cu, Mn, Ni and Zn were the same, and Pb had a separate source. (6) the number of species and diversity index increased gradually (high) with the increase of vegetation restoration measures in the mining area. First, the proportion of the biennial plants decreased, the proportion of their biomass decreased, and the perennial grasses and shrubs gradually became dominant plant species. With the higher species diversity, the waste soil, which is nearly 70%. (7) in the community biomass, has increased the heavy metal content with the increase of external exposure time, and the method of vegetation restoration by artificial plants can increase the content of soil organic matter, alkali hydrolysable nitrogen, available phosphorus and available potassium. The heavy metal content in the soil was significantly reduced (except Pb) (P0.05). The heavy metal content could reach the level of 10km around the mining area after 5 years of vegetation restoration, among which the effect of the restoration method of the vegetation was more significant.
【学位授予单位】：内蒙古农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X53;X752;X173

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