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石生苔藓组织氮含量和氮同位素指示贵阳地区大气氮沉降与迁移的研究 总被引：1，自引：0，他引：1
利用苔藓组织氮含量和氮稳定同位素研究了贵阳市大气氮沉降的来源、沉降和迁移。结果表明,贵阳地区苔藓氮含量的变化特征很好地指示了区内大气氮沉降的空间变化。贵阳市区苔藓氮同位素与郊区或农村地区差异明显,区内城市与农村有不同的氮源。苔藓氮同位素从市区往外逐渐偏正(-8.87‰~-2.48‰),说明来自市区的铵在逐渐减少,而来自农村的铵的贡献逐渐增加。贵阳地区从市区往外苔藓氮含量随距离指数降低(y=1.5e-0.13x+1.26),而氮同位素随距离对数升高[y=2.54ln(x)-12.227],揭示了源自市区的大气铵(NHx)向周边的扩散迁移呈指数降低的变化规律。运用极限法求解苔藓氮含量和氮同位素组成随距离变化的函数,发现市区铵沉降的影响范围小于41 km,在17.2 km以外的地区,市区铵沉降低于背景农业铵沉降值。 相似文献
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通过实验室土柱模拟实验,研究垃圾渗滤液污染晕中不同污染物的迁移转化规律和生物地球化学降解作用。实验结果表明:微生物在前28 d的增长速度较快,平均每天增长1.7×105个;TOC在土壤中以“梭形”向前迁移,而且微生物的增长对其衰减具有明显的影响;NH4 -N在土壤中以“活塞式”向前推进,其衰减和微生物的增长在短期内未见明显的关系;TOC在土壤中的迁移速度比NH4 -N的迁移速度快,TOC的迁移速度约为3.0 cm/d,而NH4 -N的迁移速度约为2.4 cm/d。 相似文献
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两种废物材料在地下水环境治理中的应用 总被引：2，自引：1，他引：1
实验利用粉煤灰和矿化垃圾两种废物材料作为反应屏障的反应介质用于修复受渗滤液污染的地下水环境。所设计的两个反应器A、B分别填充矿化垃圾和粉煤灰,利用它们的吸附能力、阳离子交换能力以及微生物的作用去除污染质。试验结果表明:A、B两柱COD的去除率最高可达66%和59%,对铵氮的去除率柱A明显优于柱B,最高可达92.7%,并在81%左右保持稳定。另外柱A对硝酸盐氮和亚硝酸盐氮的去除效果也优于柱B。说明矿化垃圾作为反应屏障介质更加经济可行,可以达到以废治废的目的。 相似文献
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蒸汽注射法是一种新近发展起来并对包气带非水相液体（NAPLs）污染修复具有较好应用前景的修复方法。为了探讨热蒸汽在非饱和多孔介质中的运移特征和蒸汽注射技术修复氯苯污染土壤的效果,本文通过一维模拟柱分别开展了热蒸汽在多孔介质中的迁移规律实验和蒸汽注射修复氯苯实验。研究表明：模拟柱中给定点处温度随时间变化可分为环境温度段、升温段和饱和蒸汽温度段3个阶段,随着温度锋面向下迁移,其迁移速度逐渐减小;模拟柱中的压力分布在蒸汽覆盖区域且空间分布呈线性规律,给定点处的压力随时间先增加后趋于平稳;实验结束后测得的水饱和度随蒸汽迁移距离的增加逐渐增加。在注入蒸汽质量流量为0.3 kg/h和氯苯初始质量分数为56.8 mg/kg的条件下,热蒸汽修复细砂中氯苯3.5 h后去除率达98.0%。模拟柱底部因蒸汽冷凝水达到饱和而产生出流液,出流10 min时出流液中氯苯最大质量浓度达到152.98 mg/L,70 min后出流液中氯苯质量浓度低于7.00 mg/L;介质中氯苯质量分数随距离的增加而增加,最大残留量为0.36 mg/kg。蒸汽注射法有效地改善了SVE（土壤气相抽提）法"拖尾"现象。 相似文献
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贵阳地区主要大气氮源的沉降机制与分布：基于石生苔藓氮含量和氮同位素的证据 总被引：5，自引：0，他引：5
对贵阳市区到农村地区4个方向的175个石生苔藓样品氮含量和氮同位素(δ15N)进行了分析.苔藓δ15N表明贵阳地区大气氮沉降以铵沉降为主,主要来源为城市废水氨释放以及农村地区的农业氨挥发.苔藓氮含量从市区往外随距离呈指数降低,而δ15N随距离对数升高,揭示了城市来源的铵沉降随距离指数降低,该变化模式与其他点源氨的沉降分布以及点源氨附近苔藓氮含量的变化规律相同.因此,贵阳市区可以看成整个研究区的一个点状氨源.不同方向苔藓氮含量和δ15N随距离的变化梯度存在差异,表明城市铵向周边不同方向的扩散迁移具有非均一性,其原因可能与地形条件、植被状况、风向、城市化程度等有关.苔藓δ15N平均值在15 km以外没有明显差异,反映了农业面源氨的影响.此外,运用极限法计算,苔藓氮含量随距离的变化关系(y=1.5e-o.13x 1.26)表明城市铵的影响范围总体小于41 km,而苔藓δ15N的变化(Y=2.54lnx-12.23)反映了在17.2 km以内的地区,大气氮沉降以城市铵为主,17.2 km以外的地区主要受农业铵沉降的控制.本研究为城市氮沉降的变化提供了新的证据,促进了苔藓氮含量和δ15N方法研究大气氮沉降从定性向定量的发展. 相似文献
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随着我国经济的快速发展,加大了滨海地区的开发强度,化工、医药、农药等行业在滨海地区迅猛发展。滨海地区复杂的地下水、地表水与海水之间的水力联系使地下水环境影响评价成为项目环评的难点。本文以某化工企业为例,通过构建研究区地下水数值模拟模型,利用观测水位校正模型,耦合污染物运移方程模拟预测评价了滨海地区地下水环境影响。同时针对评价过程中弥散度尺度效应现象,提供了一种评价方法。研究表明随时间的增加,污染物COD和甲苯中心浓度逐渐升高,迁移距离逐渐增加,污染范围不断扩大。随着弥散度的不断增加,污染物COD和甲苯中心浓度逐渐下降,迁移距离和超标范围不断扩大。通过模拟不同弥散度下污染物迁移规律,有利于企业加强地下水管理和判断可能发生的污染现象。 相似文献
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吉林市地下水中"三氮"迁移转化规律 总被引：9，自引：0，他引：9
通过对吉林市1988~2004年地下水水化学资料进行分析,认为地下水中“三氮”的分布、随时间变化的特点与其来源有极为密切的关系,农灌区地下水中“三氮”含量在空间上分布比较均匀,丰水期含量升高、枯水期含量降低;工业污染导致地下水中“三氮”含量变化较大,年内丰枯水期变化表现不明显;多年基本表现为地下水中“三氮”不断增高。地下水中“三氮”的增加是土壤和地表水中污染源的增加与补给地下水的渗流共同作用的结果。污染源不同、地表水污染、水文地质条件、水土流失、地下水中Fe2 含量较大对“三氮”迁移转化及其空间分布都有一定的影响。 相似文献
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垃圾填埋场对周边地质环境影响与防治对策 总被引：5，自引：0，他引：5
垃圾填埋场对周边地质环境的污染越来越受到研究人员的重视,其影响因素复杂,不仅与MSW的性质有关,还与垃圾填埋场的类型及其所处地质环境有密切关系。为分析垃圾填埋场中的渗滤液、重金属以及其他有害物质对周边地质环境(地下水环境、土壤环境)的影响规律,对大量相关文献和实验资料进行研究分析。研究结果表明:渗滤液是垃圾填埋场影响周围地质环境最为重要的因素,对渗滤液污染地表水及地下水情况和防治方法进行了探讨;同样渗滤液也是重金属污染土壤的载体,重金属在土壤剖面中的滞留量一般随深度的增加而逐渐减少;重金属对土壤的污染具有积累性和滞后性特点,随着填埋时间的延长污染加重。最后,根据其污染途径和污染规律,提出了相应具体防治对策。 相似文献
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柴油污染对人类健康和生态环境具有很大危害。自然衰减以其经济、易操作、对人危害小和降解污染物彻底等优点,成为国内外比较常用的水土污染修复方式之一。采用室内实验的方式,以柴油作为修复对象,模拟了含水层系统中柴油污染物随地下水迁移转化的过程,以自然衰减作为修复方式,研究其修复机理。通过分析计算总石油烃(TPH)污染晕的变化规律,计算修复时间和截留率等方法,研究了柴油污染含水层中的自然衰减强度及修复效能。结果显示,柴油进入含水层后,逐渐形成了稳定的污染晕,并在地下水流场中沿各个方向不断迁移并衰减,其迁移速率由快变慢,并趋于稳定,且沿流向上的迁移作用最强,垂向上次之;"断源"后,含水层中的TPH浓度随时间呈明显的下降趋势,自然衰减作用变得明显;结合一阶反应动力学方程,计算出下部含水层的修复时间为1.0~1.5a,表层注油点位置地下水的修复时间约为2.6a;含水层对柴油具有截留作用,截留作用初期较为稳定,近饱和后作用渐弱,停止注油后,截留作用重新渐变明显;自然衰减可作为修复地下水柴油污染的有效方式。 相似文献
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开封市垃圾场污染物运移模拟与控制 总被引：3，自引：0，他引：3
在对开封市某典型垃圾场进行野外调查的基础上,应用Visual Modflow建立了该垃圾场污染场地的水流和溶质运移耦合模型并进行数值模拟预测,预测了20年后该污染场地垃圾渗滤液污染羽运移范围、途径及方式等特点。模拟了应用防渗墙和抽水井两种方式控制地下水污染的措施和方案,并利用计算机模型对污染控制的效果进行了模拟分析。模拟结果表明,模拟初期污染羽覆盖了3个抽水井,污染羽前缘距离村庄688 m。模拟20年后污染羽已经覆盖了7个抽水井,其中浓度超标井有3口,污染羽前缘距离村庄605 m。建议在加强污染物监测的同时协助开展其他的污染控制措施,进一步控制污染羽的扩散。 相似文献
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Huan-Xin Weng Feng Zhang Yang-Ming Zhu Ya-Chao Qin Zhong-qiang Ji Charles Cheng 《Environmental Earth Sciences》2011,64(6):1675-1681
Because domestic landfill leachate concentrates complex organic pollutants, effective treatment of landfill leachate has gained
increasing attention in recent years. In this paper, three-stage physicochemical and biochemical technology for treatment
of domestic landfill leachate is presented. Based on an eight-month pilot operation, over 96% of the main pollutants, for
example CODCr, BOD5, SS, NH4
+–N, coliform, and chrominance, can be removed, among which the removal efficiency of CODCr was 89.5, 8.6, and 1.7% in stages 1, 2, and 3, respectively, and the removal efficiency of BOD5 was 90.3, 8.3, and 1.4%. In the treatment, the biochemical process played a principal role on the removal of pollutants from
the leachate. The treatment efficiency depends on how the syntheses of physicochemical, anaerobic, and hydrolytic procedures
pave the way for biochemical treatment. Application of a combined efflux and mixed-flow aerator enhanced the removal efficiency
during each procedure. 相似文献
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Study on numerical simulation of organic pollutant transport in groundwater northwest of Laixi 
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下载免费PDF全文 The construction and hydrogeological area in the low hill, which is northwest of Laixi City and in the east of Shandong Province more precisely, is one of Dagu River’s groundwater source. Regarding COD as the typical pollutant according to general situation of groundwater pollution in aforementioned area, a three-dimensional advection-dispersion model was established to simulate the transport of organic pollutants under two accident conditions. In addition, the effect of corresponding dispersity was analyzed. The results show that COD transport is mainly in accordance with the direction of groundwater flow, pollutant concentration and its gradient as well as the rule of narrower pollution range in deeper stratum. Moreover, COD is mainly transported and diffused in groundwater of sandy soil in the first and second layers. However, under accident condition II, the pollutant concentration begins to decay gradually after its transport and diffusion tends to be stable. Besides, in terms of dominance, dispersion is to transverse transport of pollutants what advection is to longitudinal transport. If considering random dispersion, the final results see higher peak concentration of COD and longer transverse distance from pollution center compared to transport route. What’s more, the pollution plume changes and concentration isocline becomes slightly irregular. 相似文献
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Nikos Depountis Charles Harris Michael C. R. Davies George Koukis Nikos Sabatakakis 《Environmental Geology》2005,47(7):907-914
Electrical imaging (resistivity tomography) is increasingly used as a geophysical exploration technique in contaminated land research. The present work demonstrates the efficiency of electrical imaging in monitoring pollution plume evolution under both in-situ and model conditions. The in-situ campaign was done at an unlined landfill site situated in the city of Patras, Hellas. A partially saturated zone of alluvial fan deposits underlies the site, which retards leachate percolation to the underlying water table. Electrical imaging provided details of the internal structure of the waste tip, and confirmed the presence of a leachate plume beneath the base of the landfill. This field data component provided the constraints for the design of a generic model of contaminant infiltration into partially saturated sand. The aim was to study leachate plume evolution in a laboratory environment. For this purpose, a miniaturised resistivity tomography technique, developed at Cardiff University, was used to image the resistivity distribution before during and after contaminant infiltration. Comparison of resulting two-dimensional tomography with observed plume geometry at the end of the test showed the miniaturised electrical imaging technique to be highly effective. Experiment showed that contaminant evolution taking place in the model was gravity-driven, with capillary water in the vadose zone being displaced by the denser contaminant solution. 相似文献
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Landfilling is a common practice worldwide for solid waste management. The leachate generated at landfill sites contains various organic and inorganic pollutants while it should be treated properly. In this study, the electrocoagulation (EC) process was recognized for its simplicity and effectiveness which was used for the treatment of leachate from the Djebel Chakir landfill site in northern Tunisia. In addition, we investigated the effect of microorganisms (e.g., bacteria, fungi, spore) on sludge production by the application of autoclaving treatment on raw leachate. The application of low current density (15 mA/cm2) within 2 h of treatment and using Al-Al electrodes revealed significant improvement of performance when autoclaving was applied. The chemical oxygen demand (COD) and nitrogen removal increased from 39 to 64% and from 13 to 30%, respectively. The sludge volume was reduced from 40 to 10%, and thus, its handling and disposal costs would be significantly decreased. The energy consumption rate was stable after 40 min of treatment at about 0.8 kWh/kg COD removed. Our study shows that removal of microorganisms by autoclaving prior to the EC process is promising for landfill leachate treatment. However, since autoclaving is far from being practical and cost-effective at full-scale plant, research on coupling EC with an alternative disinfecting process might be of great interest. 相似文献
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The Burwood landfill, which serves the city of Christchurch, New Zealand, is situated on coastal sands underlain by a sequence
of aquifers and aquitards. Groundwater flow is toward the coast, located approximately 700 m from the landfill boundary. Shortly
after completion of the first phase of the landfill, an array of wells was installed to detect any contaminant from the landfill.
Leachate was detected in the wells closest to the landfill. A shallow electromagnetic (EM31) survey was carried out between
the landfill and the coast, in order to delineate any leachate plume that may be present. On the basis of the geophysical
results, a contaminant plume and buried channels connected to the coast were identified. Leachate flow initially occurs in
what is probably a channel or pair of channels. Downgradient, the plume spreads out to the north and south as it moves eastward
toward the coast. Using the geophysical results as a guide, a new set of wells was installed to confirm the presence of high
leachate concentrations. Pore-water sampling confirms the presence of a leachate plume.
Received, June 1998 /Revised, March 1999, January 2000/Accepted, January 2000 相似文献
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在阐述膨润土的矿物学特性、类型及其改性方法（包括酸活化、焙烧、无机盐,有机铵盐）的基础上,探讨了其在废水处理、垃圾填埋场和土壤改良中的应用现状,并以膨润土作为反应介质,COD（化学需氧量）、Cr6+和NH4+为靶污染物,进行垃圾渗滤液对地下水污染的渗透反应格栅（PRB）实验研究,结果表明：pH值和DO（垃圾渗滤液中的溶解氧）对靶污染物的去除效果有一定的影响,且反应介质对COD、Cr6+和NH4+的去除率分别为53%、51%和53%,此结果说明了以膨润土作为PRB的反应介质是可行的. 相似文献