【作者】 黎炜；

【导师】 陈龙乾；

【作者基本信息】 中国矿业大学 ， 土地资源管理， 2011， 博士

【摘要】 作为我国重要的煤炭工业基地,淮南市为我国经济和社会发展提供了大量能源。建国以来近半个多世纪的煤炭开采,对矿区生态环境造成了严重影响,特别是由于煤炭开采引起地表沉陷,使地表变形,坡度加大,土壤侵蚀加重,造成了土地资源严重破坏,引起土壤质量下降。土地复垦是恢复矿区生态环境的重要途径,而复垦区土壤肥力质量的恢复状况以及地下水的安全性是矿区土地复垦成功与否的关键。本研究针对淮南矿业集团矿区生态环境建设的需求,以张集矿复垦区土壤和地下水为研究对象,通过相关资料收集、室外现场调查和室内分析,采用时空对比法,系统研究了张集矿复垦区土壤的理化性质变化规律和地下水重金属污染特征,对复垦土壤肥力质量、煤矸石对地下水重金属累积特征影响和地下水潜在生态风险进行了评价,主要研究结果如下: (1)复垦土壤物理特性变化特征不同层次土壤容重随复垦时间增加呈现下降趋势。0～20 cm土层容重降低幅度最大,20～40 cm次之,而40～60 cm土层最小;与对照土壤容重相比,各土层土壤容重偏高。0～20 cm土层团粒结构(0.25～2 mm)组成呈现增加趋势,与复垦初期相比提高27.73%;而20～40 cm和40～60 cm土层土壤则变化不大,各层土壤团粒结构组成低于对照水平。复垦土壤孔隙度变化规律与土壤容重相似。不同土层土壤含水量变化存在一个相似之处,即在复垦0.5 a、1.5 a和2.5 a时,土壤含水量较复垦1.0 a、2.0 a和3.0 a时要高,其变化趋势呈现波浪式变化。(2)复垦土壤化学特性变化特征复垦土壤有机质含量在复垦的3.0 a内有明显的改善,特别是0～20 cm土层土壤,较初期提高了148.00%,而20～40 cm和40～60 cm土层土壤增幅降低,分别为30.54%和25.05%,各层复垦土壤有机质含量低于对照水平。0～20 cm土层复垦土壤pH值在复垦的3.0 a内有明显的改善,与对照土壤pH值差异较小。而20～40 cm和40～60 cm土层土壤pH值则远高于对照农田土壤水平。复垦土壤全氮、全磷和全钾在复垦期内变化不一致,仅0～20 cm土层全氮、全磷和全钾含量均为提高,分别为28.29%,3.07%和7.63%。而20～40 cm土层和40～60 cm土层全氮、全磷和全钾则升降幅度不一。原因在于复垦土壤的全量养分水平主要受土壤母质影响,复垦后的耕作措施对其影响较小。复垦土壤速效N、速效P和速效K随复垦时间增加而递增。总体而言,速效养分随土壤深度增加增幅下降,0～20 cm土层提高幅度最大,复垦措施较好地提高土壤速效养分水平,同时各层复垦土壤含量低于对照相应层次农田土壤含量水平,今后应加强复垦土壤培肥措施,以提高土壤养分水平。复垦土壤微量元素有效态Cu, Zn, B和Mo的含量变化规律不一。总体而言,0～20 cm土层土壤微量元素随着复垦时间增加有所提高;而20～40 cm和40～60 cm土层微量元素则随复垦时间增加呈现一定的波动性变化。(3)复垦区土壤肥力质量变化综合评价主成分分析法和模糊数学法被引入复垦土壤肥力质量评价中,结果表明:复垦土壤肥力质量随深度增加而下降,与对照正常农田土壤肥力变化规律一致;此外,与对照相应土层土壤肥力质量相比,复垦土壤各层肥力质量略低,土层由上到下分别达到正常农田土壤肥力的92.68%,90.63%和88.33%,复垦土壤在耕作措施和人工施肥的作用下,土壤肥力质量已经达到正常农田肥力水平的90%左右,复垦取得了良好的效果。(4)煤矸石对复垦区地下水重金属累积特征影响评价复垦区地下水重金属含量在复垦期内有不同程度的提高,其中金属Cd, Hg,和Pb的含量超过了对照家用井水的重金属含量水平,而只有As的含量较对照含量水平低。尼梅罗综合污染评价指数表明:复垦的3.0 a内煤矸石对地下水重金属累积影响持续增强。复垦3.0 a时监测井Ⅰ和监测井Ⅱ的综合污染指数分别为3.044和3.109,这一结果表明煤矸石对地下水重金属的累积作用达到了“强烈影响”状态。而监测井Ⅲ的综合污染指数为2.779,煤矸石对地下水重金属的累积作用为“适度影响”状态。(5)复垦区地下水潜在生态风险评价复垦区Ⅰ和复垦区Ⅱ地下水重金属的潜在生态风险水平较高,达到了“强”的生态风险等级,而复垦区Ⅲ地下水生态风险等级略低,为“中等”生态风险等级。其原因在于煤矸石中的Cd和Hg的富集程度较大,分别达到了“很高”和“中等”富集水平;同时它们的毒性系数较大,从而引起了地下水重金属潜在生态风险水平较高。基于地下水质量标准(GBT14848-93),在复垦的3.0 a内,复垦区地下水重金属的含量全部优于Ⅱ级标准,因此,地下水符合各类用水标准。更多还原

【Abstract】 Huainan, an important city of coal industrial base, provided lots of energy for the development of China’s national economy and society. As one of the most important coal producing bases, Huainan coal mine area has been explored for more than 50 years since P. R. C. was founded, which led to some inevitable impacts on the ecological environment of coal mine area. Especially, large amounts of arable land are changed into non-agricultural land use. Ground subsidence not only induce surface deformation, slope steep and serious erosion, which made a damage to land resources, but also lower the soil quality. Land reclamation is an important way to rebuild the ecological environment of coal mine area, so soil fertility quality restoration and security of groundwater of reclamation area are the key for the success of land reclamation. In this dissertation, aimed at the requirement of eco-environment construction of coal mine area of Huainan Coal Group, the reclamation soil and groundwater of Zhangji reclamation mine area were collected as research objects and the field investigation and the indoor tests were introduced to analyze the reclaimed soil. With the application of space and time correlation method, the physical and chemical properties of reclamation soil in Zhangji reclamation area were studied systematically. The reclamation soil fertility quality,the impacts of coal gangue on the accumulation characteristics and the potential ecological risk of heavy metal in the groundwater were also evaluated. The main conclusions are showed as follows:(1)The change characteristics of physical properties of reclamation soilIt shows a descending trend in soil bulk density of different layers with the reclamation time increasing. The layer of 0-20 cm reclaimed soil has a largest degree of decline in soil bulk density, secondly is layer of 20-40 cm reclaimed soil, which is 7.50%, and last is layer of 40-60 cm reclaimed soil. In addition, reclaimed soil bulk density of all layers is higher than control soil. The soil aggregate structure (0.25-2 mm) of layer 0-20 cm is increased by 27.73% after reclamation for 3 years; however, there are no significance change for layers of 20-40cm and 40-60cm. The law of reclaimed soil porosity is the same as the soil bulk density. There is a same place between different layers of reclaimed soil in content of water. That is higher content of water at reclamation time 0.5 a, 1.5 a and 2.5 a than those at 1.0 a, 2.0 a and 3.0 a, in other words, the content of water in reclaimed soil shows a“wave”change.(2) The change characteristics of chemical properties of reclamation soil There is a significance improvement of organic matter of reclaimed soil after reclamation for 3 years. Organic matter of layer 0-20 cm is increased by 148%, and 30.54%, 25.05% for layers of 20-40 cm and 40-60 cm, respectively. Furthermore, the content of organic matter in reclaimed soil is lower than that of in control soil. The pH value of reclaimed soil layer 0-20 cm also improvs after 3 year’s reclamation, which is a little different while comparing to control soil. However, the pH values of reclaimed soil layer of 20-40 cm and 40-60 cm are much higher than control soil.The laws of TN, TP and TK of contents in reclaimed soil vary in different lays, there is an enhancement trend in TN, TP and TK contents after reclamation for 3 years for layer 0-20 cm, and the increasing rates are 28.29%、3.07% and 7.63%, respectively. However, the fluctuation scopes of TN, TP and TK contents in reclaimed soil of layer 20-40 cm and 40-60 cm are different. The main reason is that the total N、P and K mainly come from soil parent material, while there are a few impacts by the cultivation measures. The contents of available N, available P and available K in reclaimed soil show an increasing tread along with the reclamation time going up. The results indicate that all available nutrients have the same law, that is, increasing rate become lower with the depth increasing, in other words, the available nutrients in top layer soil improve more than those in subsoil. However, compared to the available nutrients in control soil, contents in reclaimed soil are much lower. As a result, it should be take some measures to improve the reclaimed soil in future.The laws of the trace elements of Cu, Zn, B and Mo in reclaimed soil are different. Overall, the contents of trace elements in layer 0-20 cm have an enhancement trend with the increasing of reclamation time, while there is a fluctuation change during the same period in layers of 20-40 cm and 40-60 cm.(3) Evaluation characteristics of fertility quality of reclaimed soilThe principal component analysis and fuzzy mathematics method were introduced to evaluate the law of fertility quality of reclaimed soil. The results show that: The fertility quality of reclaimed soil decreased with depth, which is the same as control soil. Furthermore, compared with the control soil, the fertility quality of reclaimed soil is lower, which is up to 92.68%, 90.63% and 88.33% of control soil from top layer to subsoil. The fertility quality of reclaimed soil has been up to about 90% of normal farmland’s fertility quality level under the impact of cultivation measures and artificial fertilization for 3 years.(4) The evaluation of accumulation characteristics of heavy metal in groundwater of reclamation areaThe contents of heavy metal in groundwater of reclamation area increase to a different extent. Among the selected heavy metals, the Cd, Hg and Pb contents exceed the background values of water from individual well, while the content of As in groundwater of reclamation area is lower than background values of water from individual well. The Nemerow index values are 3.044 for Monitor wellⅠ, 3.109 for Monitor wellⅡand 2.779 for Monitor wellⅢafter reclamation for 3.0 years, respectively, which means that the acculumation of heavy metal in groundwater of reclamation areaⅡandⅢare strongly affected by coal gangue, while moderately affected by coal gangue for reclamation areaⅠ.(5) The evaluation of potential ecological risk of heavy metal in groundwater of reclamation areaThe degree of potential ecological risk of heavy metal in groundwater of reclamation areaⅠandⅡis so high and it is up to“strong”, while the degree of risk of reclamation areaⅢis lower, which is“moderate”. The reason for the higher potential ecological risk of heavy metal in groundwater of reclamation area is that it is so enrichment for Cd and Hg in coal gangue, which are up to“very high”and“moderate”, respectively. And the toxicity coeffifient of them are so big that resulted in a high degree of risk of potential ecological risk.Based on The Quality Standard of Groundwater (GBT14848-93), groundwater in reclamation area is not contaminated and could be of usage as agricultural irrigation and drinkable interests after reclamation for three years.更多还原