Potential for remediation of acidic mining lakes evaluated by hydrogeochemical modelling: Case study Grünewalder Lauch (Plessa 117, Lusatia/Germany)     

Brigitte Nixdorf  Wilfried Uhlmann 《Limnologica》2010,40(2):167-174

About one third of several hundred mining lakes in Eastern Germany are highly acidified, and there is a need to restore them to neutral conditions because they constitute an environmental hazard for water resources and downstream environments. The aim of this study is to evaluate the efficiency of three different acid pit lake water remediation treatments: dilution with alkaline (river) water, limestone treatment and biological neutralization by organic carbon-driven alkalinity generation. The efficiency is evaluated for the acidic mining lake Grünewalder Lauch by adjusting input values into a geochemical model and making future projections. Current approaches, such as flooding with neutral surface water or extensive liming, are not suitable for many lakes because of a limited supply of alkaline water or high lime immobilizing potential of Fe- and Al-rich water in acidic lakes, respectively. Further treatment methods are, therefore, designed to combine water supply and biological measures with the management of water quality by the application of in-lake microbial processes. These processes are focused on the metabolic response of aquatic ecosystems to nutrient enrichment (enhancement of primary production and thereby organic carbon supply) and the microbial decomposition of organic matter and their effects on the gain or loss of alkalinity.The results and comparisons of different neutralization measures will be generalized by the application of hydrogeochemical models for alkalinity production showing

a)

the long term efficiency of the measures, depending on carbon turnover at the sediment/water interface,

b)

the development of bicarbonate buffering capacity as a consequence of biological measures,

c)

the importance of pyrite formation instead of FeS.

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Geochemical modelling and speciation studies of metal pollutants present in selected water systems in South Africa     

《Physics and Chemistry of the Earth》2016

Metal pollutants in water poses great threats to living beings and hence requires to be monitored regularly to avoid loss of lives. Various analytical methods are available to monitor these pollutants in water and can be improved with time. Modelling of metal pollutants in any water system helps chemists, engineers and environmentalists to greatly understand the various chemical processes in such systems. Water samples were collected from waste water treatment plant and river from highlands close to its source all the way to the ocean as it passing through areas with high anthropogenic activities. Pre-concentration of pollutants in the samples was done through acid digestion and metal pollutants were analysed using inductively coupled plasma-optical emission spectra (ICP-OES) to determine the concentration levels. Metal concentrations ranged between 0.1356–0.4658 mg/L for Al; 0.0031–0.0050 mg/L for Co, 0.0019–0.0956 mg/L for Cr; 0.0028–0.3484 mg/L for Cu; 0.0489–0.3474 mg/L for Fe; 0.0033–0.0285 mg/L for Mn; 0.0056–0.0222 mg/L for Ni; 0.0265–0.4753 mg/L for Pb and 0.0052–0.5594 mg/L for Zn. Modelling work was performed using PHREEQC couple with Geochemist’s workbench (GWB) to determine speciation dynamics and bioavailability of these pollutants. Modelling thus adds value to analytical methods and hence a better complementary tool to laboratory-based experimental studies.  相似文献   

A Coupled Calibration and Modelling Approach to the Understanding of Dry-Land Lake Oxygen Isotope Records     

Matthew D.?JonesEmail author  Melanie J.?Leng  C. Neil?Roberts  Murat?Türke?  Rana?Moyeed 《Journal of Paleolimnology》2005,34(3):391-411

Comparisons between climate proxies and instrumental records through the last two centuries are often used to understand better the controls on palaeoarchives and to find relationships that can be used to quantify changes in pre-instrumental climate. Here we compare an 80-year-long annually resolved oxygen isotope record from Nar Gölü, Turkey, a varved lake sequence, with instrumental records of temperature, precipitation, wind speed, relative humidity and calculated values of evaporation, all of which are known to be possible controls on lake oxygen isotope systems. Significant relationships are found between the isotope record and summer temperatures and evaporation suggesting these are dominant controls on the isotope hydrology of this non-outlet lake. Modelling the stable isotope hydrology of the lake system allows these relationships to be tested independently. We show that the isotope record follows the same trends in the temperature and evaporation records but that, even when combined, these two climatic factors cannot fully explain the magnitude of change observed in the isotope record. The models show the lake system is much less sensitive to changes in evaporation and temperature than the climate calibration suggests. Additional factors, including changes in the amount of precipitation, are required to amplify the isotope change. It is concluded that proxy-climate calibrations may incorrectly estimate the amplitude of past changes in individual climate parameters, unless validated independently.  相似文献   

A syn-eruptive ground deformation episode measured by GPS,during the 2001 eruption on the upper southern flank of Mt Etna   总被引：4，自引：0，他引：4  

Alessandro?BonforteEmail author  Francesco?Guglielmino  Mimmo?Palano  Giuseppe?Puglisi 《Bulletin of Volcanology》2004,66(4):336-341

Ground deformation occurring on the southern flank of Mt Etna volcano during the July–August 2001 eruption was monitored by GPS measurements along an E–W profile crossing the fissure system. This profile was measured eight times during the eruption, using the 'stop and go' semi-kinematic technique. Horizontal and vertical displacements between GPS surveys are reported for each station. The most significant event is a deformation episode occurring during the first week of the eruption, between 25–27 July. Displacements were measured on benchmarks close to the eruptive fissure and the tensile 1989 fracture. Data inversions for measured displacements were performed using the Okada model. The model shows the narrowing of the 2001 dyke accompanied by a dextral dislocation along an east-dipping fault, parallel to the 1989 fracture.Editorial responsibility: T. Druitt  相似文献   

耗散结构论中的模型方法及其意义     

李德义  刘松涛 《成都信息工程学院学报》1997,(1)

耗散结构理论是系统科学的新兴学科之一。它研究系统演化的一般条件、机制，并把对系统的研究推进到动态阶段。作者探讨了建立耗散结构理论所使用的模型方法，分析了从原型实例到耗散结构概念的提出及其反应模型——布鲁塞尔器（Ｂｒｕｓｓｅｌａｔｏｒ）的建立过程。在此基础上进而分析了模型与原型的相似性，指出了该模型的合理性与科学性。最后提出了运用耗散结构理论的五条原则  相似文献   

On the dynamics of the jovian ionosphere and thermosphere.: IV. Ion-neutral coupling     

George Millward  Steve Miller  Tom Stallard  Alan D. Aylward 《Icarus》2005,173(1):200-211

We use the fully coupled, three-dimensional, global circulation Jovian Ionospheric Model (JIM) to calculate the coupling between ions in the jovian auroral ovals and the co-existing neutral atmosphere. The model shows that ions subject to drift motion around the auroral oval, as a result of the E×B coupling between a meridional, equatorward electric field and the jovian magnetic field, generate neutral winds in the planetary frame of reference. Unconstrained by the magnetic field, these neutral winds have a greater latitudinal extent than the corresponding ion drifts. Values of the coupling coefficient, k(h), are presented as a function of altitude and cross-auroral electric field strength, for different incoming electron fluxes and energies. The results show that, with ion velocities of several hundred metres per second to over 1 km s⁻¹, k(h) can attain values greater than 0.5 at the ion production peak. This parameter is key to calculating the effective conductivities required to model magnetosphere-ionosphere coupling correctly. The extent to which angular momentum (and therefore energy) is transported vertically in JIM is much more limited than earlier, one-dimensional, studies have predicted.  相似文献   

New evidence for the dominance of vapour diffusion during the re-saturation of compacted bentonite     

Klaus-Peter Kröhn 《Engineering Geology》2005,82(2):127-132

The established codes for modelling the re-saturation of compacted bentonite are based on the assumption that the hydraulic processes can be described as a two-phase flow of liquid water and air. Some models additionally take vapour flow into account. Recent investigations suggest, though, that compacted bentonite in contact with liquid water does not re-saturate via the liquid water phase but exclusively by evaporation in the pore space and subsequent vapour diffusion. The present paper adds further evidence to support this hypothesis.Under certain conditions a balance equation for the water vapour in the bentonite can be transformed into the well-known Fickian approach that has been empirically derived from observations of uptake experiments with liquid water. This transformed balance equation allows to interpret the so-called “diffusion coefficient” as a product of several simple physical parameters. An exemplary set of parameters for compacted MX-80 bentonite yields a value that lies within the narrow band of empirically determined “diffusion coefficients”.  相似文献   

Evaluating sustainability transitions pathways: Bridging analytical approaches to address governance challenges     

《Global Environmental Change》2015

The paper sets out a proposal for bridging and linking three approaches to the analysis of transitions to sustainable and low-carbon societies: quantitative systems modelling; socio-technical transition analysis; and initiative-based learning. We argue that each of these approaches presents a partial and incomplete picture, which has implications for the quality and usefulness of the insights they can deliver for policy and practice. A framework for bridging these different approaches promises to enrich each of the approaches, while providing the basis for a more robust and complete analysis of sustainable transitions pathways that serves better to address questions and dilemmas faced by decision-makers and practitioners. We elaborate five key challenges for the analysis and governance of transitions pathways, and compare the three approaches in relation to each of these. We suggest an integration strategy based on alignment, bridging, and iteration, arguing that a structured dialogue between practitioners of different approaches is needed. In practical terms, such a dialogue would be organised around three areas of joint knowledge production: defining common analytical or governance problems to be tackled through integration; establishing shared concepts (boundary objects); and establishing operational bridging devices (data and metrics, pathways evaluation and their delivery). Such processes could include experts and societal partners. We draw conclusions about future research perspectives and the role of analysis in transitions governance.  相似文献   

厦门湾海洋塑料垃圾的运动特性及输移机理     

宁德志  袁泽林  潘钟  陈丽芬  张崇伟  马嘉骏 《海洋与湖沼》2022,53(4):838-851

作为新型海洋污染物,海洋塑料垃圾入海通量计算过程中涉及的源汇过程、迁移途径、输运过程等尚未完全清楚,需进一步研究完善。以工业高速发展的厦门湾为研究对象,考虑潮流、入海径流、风等因素的影响,基于MIKE3软件的生物仿真模拟技术(Agent Based Modelling),模拟研究了漂浮及悬浮塑料垃圾的分布特征和迁移规律,并提出经验公式对沉积塑料垃圾的通量进行了预测。结果表明漂浮塑料垃圾在不利风、常风向和最大风的作用下集中堆积于岸线处。而悬浮塑料垃圾由海面向下呈现指数式下降的分布特征,且其水平迁移分布与潮流运动密切相关;流速小的区域悬浮塑料垃圾更容易堆积使局部浓度升高。悬浮塑料垃圾的扩散速率也与塑料颗粒的物理性质有关,沉降速度小的塑料颗粒在水中悬浮的时间更长,更容易被传输到距离污染源更远的地方。同时,研究发现沉积微塑料通量的增长规律近似为线性变化,通量大小与厦门塑料产量和厦门湾的水动力特性相关。  相似文献