树木年轮化学技术对典型汞污染区污染历史的重建

发布时间：2018-01-23 13:17

本文关键词： 汞污染年轮化学污染历史重建　出处：《贵州师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：汞是一种广泛分布于环境介质中且对人体具有严重生理和神经毒性的重金属污染物,其被视为六种最严重的污染物之一,是联合国环境规划署(UNEP)、世界卫生组织(WHO)和美国环保署(USEPA)等多个国际机构规定的优先控制污染物。汞是唯一主要以气态单质(Hg095%)形态存在于大气中的重金属元素,并且在大气中的居留时间长达数月至一年,能够随大气环流迁移到数千乃至上万公里后在偏远地区沉降,因此被认为是一种全球性污染物。我国是世界上第三大产汞国,排在西班牙和意大利之后,而贵州万山地区是我国最大的汞矿区。21世纪初期研究者对万山地区进行了系统的汞污染评估,发现土壤、表层水、粮食、蔬菜等超出国家标准数倍乃至数十倍之多,引起了我国政府对当地汞污染的重视。本文研究目的之一就是通过年轮化学技术重建该地区的污染历史,反映其历史开采强度的变化趋势,为当地的污染防治提供历史借鉴,同时为当地的汞污染研究评价提供数据支持。由于汞具有较高饱和蒸气压的特性,大气中的汞95%以上以气态单质汞(Hg0)的形态存在,大气中的汞可被植物吸收(尤其是植物的地上部分如叶片和木质部)从而固定在植物体内。因此,植物的生长过程可能记录了大气汞污染的历史变化特征。1975年Lepp首次将年轮化学方法用于检测环境中痕量金属元素的长期变化而获得成功,提出年轮化学的概念。年轮化学相比于沉积物、土壤等在标记时间序列上有其独特的优越性,比如年代分辨率高、活动稳定、时间跨度大、地理学分布广泛等。开展年轮化学重金属污染示踪研究具有多方面的意义,如再现高分辨率环境污染历史、判断树木生态系统重金属元素污染来源、研究重金属在大气-植物体和土壤-植物间的迁移过程等,为污染环境的修复治理及社会可持续发展建设等提供科学指导。本研究工作主要是通过采集典型汞污染区的树轮样品,分析不同年代树轮样品中汞含量,利用年轮化学理论重建重污染区历史汞污染特征;分析轮宽与汞积累强度的相关性,探究年轮生长速率对汞的年轮化学研究的影响;研究距离万山汞矿不同梯度的植物体汞累积含量,探讨万山地区汞污染的影响范围;应用汞的年轮化学技术成功重建了赫章县妈姑镇土法炼锌地区以及旬阳县红军乡青铜沟汞矿开采区的汞污染历史。通过研究得出以下主要结论:1、同一棵树同年的木质中,其木质总Hg量以及Hg浓度都没有呈现均匀分布的特点,其中木质总Hg量与该年份木质生长宽度相关性较好,相关系数在0.9以上,而木质Hg浓度与轮宽并未发现相关性。虽然木质Hg浓度在木质中不是均匀分布的,但是在各自方向上它们所反映出来的时间变化趋势是一致的。2、年木质Hg浓度只与污染区当年环境汞污染程度有关,因此可以作为当地污染历史的指示数据;而年木质的总Hg量由于与该年的气候特点和环境汞浓度都有相关关系,所以不能单独作为当地污染历史的指示数据。3、万山地区树木年轮的木质Hg浓度变化特点成功反映出当地的汞矿污染历史,证明汞的年轮化学研究的现实可行性。4、在树木指示汞污染方面,树叶的灵敏度是最高的,其次是土壤、树皮、木质。距离汞矿40公里以外的地区,其树木受到的汞污染影响已十分有限。5、应用汞的年轮化学技术成功重建赫章县妈姑镇黑坭寨土法炼锌地区近四十年来的汞污染历史,发现在1995-2010年间当地汞污染较为严重,尤其是2003-2006期间当地汞污染达到高峰。树皮与木质的Hg浓度具有显著相关性,表明大气是木质汞的主要来源。6.应用汞的年轮化学技术重建陕西省旬阳县红军乡青铜沟地区的汞污染历史,发现当地的环境汞污染有减缓趋势,这可能与当地冶炼公司对汞排放防治技术的改进有关;但是当地树叶、树皮和土壤仍然具有较高的汞浓度,表明当地汞污染仍然是十分严峻的环境问题。
[Abstract]:Mercury is a heavy metal is widely distributed in environment medium and has serious physiological and neurotoxic pollutants to human, which is regarded as one of the six most serious pollutant, the United Nations Environment Programme (UNEP), WHO (WHO) and the U.S. Environmental Protection Agency (USEPA) priority pollutants and other international institutions regulations. Mercury is the only major (Hg095%) in gaseous elemental speciation of heavy metals in the atmosphere, and in the atmosphere of the residence time for several months to a year, with the atmospheric circulation can migrate to thousands or even tens of thousands of kilometers of settlement in remote areas, so it is considered to be a global pollutant in our country is the world. The third mercury country, after Spain and Italy, and Guizhou mountains area is China's largest mercury mining area in the early.21 century researchers conducted the mercury pollution assessment system in the Wanshan area, found The soil, surface water, grain, vegetables exceeded the national standard several times or even ten times, the Chinese government attaches great importance to the mercury pollution in the local. One of the purposes of this paper is to rebuild the pollution history of the region by dendrochemistry, reflecting the trend of the history of mining intensity, to provide historical reference for the prevention and control of pollution of the local at the same time, to provide data support for the local assessment on mercury pollution. Because Mercury has the characteristics of high saturated vapor pressure, more than 95% of mercury in the atmosphere by gaseous elemental mercury (Hg0) form, mercury in the atmosphere can be absorbed by plants (especially parts such as leaves and xylem of plants on the ground) and fixed in plants. Therefore, the growth process of plants may be recorded the.1975 variation of atmospheric mercury pollution in Lepp for the first time dendrochemistry method for the long term variation of Trace Elements Detection in the environment But to succeed, put forward the concept of dendrochemistry. Dendrochemistry compared to sediment, soil has its unique superiority in the marked time series, such as in high resolution, stable activity, time span, geography is widely distributed. It has significance in many aspects to carry out the research on Heavy Metal Pollution Tracing chemical rings, such as high reproduction the resolution of environmental pollution history, sources of heavy metal pollution of heavy metal in the trees ecosystem, plant atmosphere plant body and soil between the migration process, to provide scientific guidance for environmental pollution remediation and sustainable development of the society construction. This research work is mainly through the acquisition of typical mercury contaminated area of the tree ring samples, analysis of mercury the content of tree ring samples of different ages, characteristics of mercury pollution in the heavily polluted area of historical reconstruction by means of dendrochemistry theory; analysis of wheel width and intensity related to accumulation of mercury Dendrochemistry, influence research on mercury into ring growth rate; distance of Wanshan mercury mine plants of different gradient mercury accumulation content, impact on the scope of mercury pollution in Wanshan area; dendrochemistry application of mercury successful reconstruction of Hezhang County town of Ma Gu area and Xunyang County Red zinc smelting Xiang qingtonggou mercury mine mining area of mercury pollution in history. The main results are as follows: 1. The wood with a tree in the same year, the total amount of Hg and Hg lignin concentration did not show uniform distribution characteristics, the total amount of the year and Hg wood wood growth width has good correlation, the correlation coefficient is above 0.9, and the concentration of Hg and the wooden wheel width did not find correlation. Although the concentration of Hg in wood wood is not evenly distributed, but the time trend in their respective directions reflect the consistent.2 year Hg concentration Only concerned with the pollution area year mercury pollution degree, so it can be used as indicator data of local pollution history; and the total amount of Hg in wood because with the climatic characteristics and environmental mercury concentration the year relationship, it is not alone as indicator data.3 local history of pollution, Hg concentration changes of wood in trees in mountains the ring success reflects the pollution history of mercury mine the feasibility of.4 that dendrochemistry study of mercury, mercury pollution indicator in trees, leaves the sensitivity is the highest, followed by soil, bark and wood. The distance of mercury mine 40 kilometers outside the area, the effect of mercury pollution is limited by the trees.5, dendrochemistry application of mercury successful reconstruction of Hezhang county. In the past forty years mercury pollution history Gu Zhen Hei Ni Zhai zinc smelting area, found in the 1995-2010 between local mercury pollution is serious 2003-2006, especially during the local mercury pollution. The peak was significantly correlated with the concentration of Hg bark and wood, wood is indicated that the atmospheric dendrochemistry mercury from mercury.6. application of the reconstruction of the Red Army Xunyang County township of Shaanxi province qingtonggou mercury pollution area history, found that when the mercury pollution has slowed down, the improvement this may be related to the local smelting company of mercury emission control technology; but the leaves, bark and soil mercury concentration was still high, indicating that mercury pollution of local environmental problems is still very serious.

【学位授予单位】：贵州师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X75;X142

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