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61.
水生观赏植物在湿地建设中的应用   总被引:1,自引:0,他引:1  
水生观赏植物的利用是湿地恢复工作的重要内容之一,直接关系到湿地景观整体效果。在湿地的池边水畔、岩石缝隙、水面等不同的环境中种植各种水生观赏植物能给人一种自然美的感觉。水生观赏植物的姿态、色彩及清香,加强了水体的空间感和美感,并具有净化水体的生态作用。如北京翠  相似文献   
62.
Vanadium, improving mechanism and jointing capacity of steel products, is a kind of excellent additive during steel-making and its industry gets support from national industry policy. On account of shallow buried depth and low technique request of exploitation, there is much exploitation by local people lacking system management and technique guidance in area rich in vanadium since years ago, which damages regional environment dramatically. Accordingly, taking stone coal-vanadium as an example, the paper focuses on environment impact on water environment and eco-environment caused by exploitation in open air. Impact of exploitation on surface water mainly includes mining drainage and eluviated water of stock yard. According to civilian exploitation in the area, the rock suffers man-made disturbance, therefore, water quality indicators of mining drainage like heavy metal, permanganate, CI, SO4^2-, F are able to be analogies of ground water quantity in the region since the primary component of drainage is surrounding rock ground water. Water monitoring result of local well shows as follows: pH 6.68, SO4^2- 5.76 mg/L, F- 0.005 mg/L, Fe 0.025 mg/L, Mo 8.08 μg/L, Ni 5.91 μg/L, Co 0.61 μg/L, and all of them reach corresponding standard of water quality. Ground water turns into acid mine water by oxygenation after it discharges and with the help of sulfur the acid water contains nocuous elements which permeate in groundwater and surface water arousing pollution. The value of pH in the range of standard indicates that the acidification of mine water is relatively weak in the diggings. Eco-environment damage is another aspect that cannot be ignored, it acts as: (1) peeling work and establishment construction destroy landform; (2) stack of waste soil and rock occupies amounts of land; (3) various exploitation activities like vegetation peeling, landform change will enlarge the scope or enhance the intensity of soil erosion, which destroys eco-environment by leading water and soil loss;  相似文献   
63.
Selenium (Se) is an essential micronutrient to biota, but can become a potent toxicant at elevated concentrations. The natural sources and chemical properties of Se species make the boundary between deficiency and toxicity narrow for some biota, with both phenomena common around the globe. Large areas of farmland in the Colorado River Basin (CRB) generate salinized drainage water with Se concentrations much higher than 5 μg/L, the U.S. Environmental Protection Agency chronic water-quality criterion for the protection of aquatic life. We have carried out detailed field and laboratory studies to investigate Se geochemistry and remediation in two of these areas: the Middle Green River Basin, Utah and the Salton Sea Basin, California, located respectively in the Upper and Lower CRB. Results from these and other studies show that approximately 90% of the dissolved Se in the Colorado River and its tributaries originally is derived from the Upper Cretaceous Mancos Shale and equivalent pyritic marine units that outcrop in the Upper CRB. Selenium is mobilized commonly by biogeochemical oxidation of this pyritic shale and is concentrated mainly as selenate (SeO4^2-) in soils and agricultural drainage water of dry climates by evaporation. Minor (0%-5%) amounts of Se are present as the selenite species (HSeO3^-) and (SEO3^2-), but these species and the more reduced species, elemental Se (SeO) and selenide (Se^2-), have much lower solubility and/or have high sorptive affinity towards organic matter, clay minerals and iron oxyhydroxides. The concentration of dissolved Se (-2.5 μg/L) and salinity in the Lower Colorado River water are among the highest of the world major rivers. Because of low precipitation (7 cm/a) and extreme evapotranspiration (-1.8 m/a) rates in the Salton Sea Basin, California, Se values in irrigation water imported from the Colorado River increase to 〉300 μg/L in drainage wastewater. Removal of Se from contaminated wastewater by nanofiltration membranes was demonstrated in laboratory and pilot-scale field experiments.  相似文献   
64.
An appropriate concentration of fluoride in drinking water is required to prevent dental cavities, but long-term ingestion of water that contains more than a suitable level of fluoride can cause bone disease and mottling of the teeth. Fluoride ions can be found in wastewater from the fluoride chemical industry, as well as the semiconductor, metal processing, fertilizer, and glass-manufacturing industries. The discharge standard for fluoride in industrial wastewater in China is 10 mg/L. Efficient treatment of fluoride-containing wastewater is therefore of major concern in China, following the rapid development of the fluoride chemical industry. Several methods have been used to remove fluoride from water, such as adsorption, chemical precipitation, electrodialysis, ion exchange and electrochemical processes. Layered double hydroxides (LDHs) are anionic clays with high anion exchange capacities which are effective adsorbents for removal of a variety of anionic pollutants. LDHs have been studied as potential adsorbents for removing toxic anionic species such as CrO4^2-, TcO4^-, SeO3^2-, pesticides, and anionic surfactants from aqueous systems. One of the main attractions of using LDHs for fluoride removal, is that unlike other chemical treatment methods, no chemical sludge should be produced. In the present study, an attempt was made to investigate the mechanism of fluoride removal by LDHs under different conditions using batch methods. In addition, the release of fluoride adsorbed on LDHs by treatment with an aqueous solution of Na2CO3 was studied. The residual fluoride was found to be 10 mg/L in a solution with an initial concentration of 1000 mg/L, which meets the discharge standard for fluoride in industrial wastewater in China.  相似文献   
65.
湿地公园(Wetland Park)的概念类似于小型保护区.但又不同于自然保护区和一般意义公园的概念。根据国内外目前湿地保护和管理的趋势.兼有物种及其栖息地保护.生态旅游和生态环境教育功能的湿地景观区域都可以称之为“湿地公园”,  相似文献   
66.
根据生态系统服务功能理论,利用RS和G IS技术,以土壤含水量为基础因子,对青藏高原区草地生态系统的土壤水分保持功能及其价值的动态变化过程进行有效评价,以直接的货币形式反映出青藏高原主要草地类型的土壤水分保持功能的大小。通过计算和分析发现:(1)由于草地类型分布面积、单位面积保持量的影响,各种类型草地提供的土壤水分保持功能及其价值贡献率有较大差异,按照大小依次为:高寒草原类、高寒草甸类,高寒荒漠类、高寒草甸草原类和温性山地草甸类;(2)草地对土壤水分保持量及其价值呈现出较强的阶段性变化过程;(3)由于各种草地类型所处地理区域不同、草地本身各种自然特点和整体生态功能的不同,青藏高原草地生态系统提供的土壤水分保持功能及其经济价值呈现出明显的地域分布规律:自西北至东南逐渐降低。应该说,由于青藏高原地域、地理和独特气候等原因所致,本文计算得出的青藏高原草地生态系统土壤水分保持功能及其价值的具体数值不一定十分准确,但是能在一定程度上反映出土壤水分保持功能的强大及其在生长季中随时间变化的动态过程和基本规律(这种规律性结论与前人研究结论一致),这是一种在区域尺度上揭示草地生态系统土壤水分保持功能及其价值动态变化过程的方法尝试,这也是对动态评估生态服务功能的一种有益尝试。  相似文献   
67.
塔里木河源区冰川系统变化趋势预测   总被引:1,自引:0,他引:1  
塔里木河源区是我国冰川分布最集中的地区之一,总面积达17 745.51 km2,占全国冰川总面积的30%;同时本区又属于我国升温幅度最大的地区之一。应用冰川系统变化的功能模型,对塔里木河源区冰川系统在本世纪对气候变化的趋势进行预测。结果表明:到2050年,如气温比1961~1990年高出1.9~2.3℃,本区冰川面积将减少4%~6%,冰川径流将增加22%~34%,零平衡线将上升62~94 m;如此升温率持续到本世纪末,则本区冰川面积将减少10%~16%,冰川径流将会回落,但仍比本世纪初多11%~13%,零平衡线将上升156~233 m。  相似文献   
68.
湿地功能快速评价中的若干理论问题   总被引:9,自引:5,他引:9  
针对目前湿地功能快速评价中存在的不足之处,分析了产生这些不足的原因及湿地功能快速评价过程中存在的一些基本理论问题。分析表明:湿地功能快速评价方法是为了达到“湿地功能无净损失”目的,是在需要评价的湿地如此之多而从事湿地功能评价的专业人员又极其缺乏的情况下发展起来的。它对于湿地恢复与重建以及湿地受人类活动干扰程度的评价是非常有效的;在湿地功能快速评价过程中,把相对未受人类干扰的参照湿地的功能指数规定为1,这就使得快速评价方法不能对参照湿地的功能进行评价,而目前最需要评价其功能的湿地往往就是这些相对未受人类活动干扰的湿地;在相同水文地貌的湿地类型内评价湿地功能之间的差异,这使得快速评价方法不能评价湿地的水文地貌功能;由于快速评价的结果都是相对的功能指数,并不能说明湿地所提供的功能量是否满足人们的需求,因而在决策中不能单独使用;快速评价都是“一次调查就获得结果”,同时由于快速评价过程中指标选择的主观性、指标赋值的主观性、采样点空间设置的主观性以及采样时间的主观性,对于具有时空变化特征的湿地功能的评价结果的可重复性和科学性是很低的。为了使湿地功能评价的结果对管理和决策具有指导意义,基于湿地功能量计算的、定量的评价湿地功能的方法必须开发出来。针对不同的评价目的,湿地功能评价可采用双重参照标准:一是以自然为参照来评价湿地功能受人类活动影响的程度以及湿地恢复与重建成功与否;二是以人类需要为标准来评价湿地提供的功能量是否满足了我们的期望,以便采取措施改进湿地功能来满足人类的需求。  相似文献   
69.
1990~2003年洪湖水体环境质量演变分析   总被引:16,自引:0,他引:16  
以详细的水质监测资料为基础,采用标准指数法并结合实地调查,分析了1990~2003年洪湖水质的变化状况。结果表明,14 a间,洪湖水质类别以Ⅲ类和Ⅳ类为主。水质恶化的驱动因子是氮、磷及其它有机污染物。1991年到1994年期间,水体中氨氮(NH4 -N)占溶解无机氮(D IN)的比例逐年增高;1995~2003年,以氨氮和硝酸盐(NO3--N)同时作为水体中溶解无机氮的主要存在形式,与1990~1994年的水质状况相比,亚硝酸盐(NO2--N)所占的比例呈增加之势。氨氮、硝酸盐和亚硝酸盐的年际变化表明,洪湖水体自净能力在逐渐降低。以总磷(TP)、总氮(TN)和溶解无机氮(D IN)作为评价指标,洪湖水体已属中富营养型湖泊。洪湖水质演变与该区域人类活动(围湖造田、围网养殖等)以及江湖连通的变化对水环境的作用相耦合。  相似文献   
70.
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