Ammonia removal properties of lightweight aggregates from Si-Al-Fe and Si-Ca rocks

Lightweight aggregates commonly used as construction materials contain high percentages of metal oxides and thus are potential sorbents in aqueous systems. Here, ammonia is used as the model compound to be removed by aggregates since it is toxic for the aquatic life and is regulated in physical systems. The point of zero charge of aggregates is determined at pH values higher than 9. The aggregates made with raw materials from Larisa, Milos, and Samos presented ammonia sorptive capacities of 210, 220 and 400 μmol/kg, respectively. However, the LWA made from wollastonite (Samos) resulted in high pH (10.6) solutions and thus, production of toxic unionized ammonia. Thus, a combination of high sorptive uptake and neutral pH in solution is desired and can be achieved in future studies by selecting the appropriate raw materials for the preparation of aggregates. © 2009 Springer-Verlag

A coupled groundwater-flow-modelling and vulnerability-mapping methodology for karstic terrain management

A coupled groundwater-flow-modelling and vulnerability-mapping methodology for the management of karst aquifers with spatial variability is developed. The methodology takes into consideration the duality of flow and recharge in karst and introduces a simple method to integrate the effect of temporal storage in the unsaturated zone. In order to investigate the applicability of the developed methodology, simulation results are validated against available field measurement data. The criteria maps from the PaPRIKa vulnerability-mapping method are used to document the groundwater flow model. The FEFLOW model is employed for the simulation of the saturated zone of Palaikastro-Chochlakies karst aquifer, in the island of Crete, Greece, for the hydrological years 2010–2012. The simulated water table reproduces typical karst characteristics, such as steep slopes and preferred drain axes, and is in good agreement with field observations. Selected calculated error indicators—Nash-Sutcliffe efficiency (NSE), root mean squared error (RMSE) and model efficiency (E′)—are within acceptable value ranges. Results indicate that different storage processes take place in different parts of the aquifer. The north-central part seems to be more sensitive to diffuse recharge, while the southern part is affected primarily by precipitation events. Sensitivity analysis is performed on the parameters of hydraulic conductivity and specific yield. The methodology is used to estimate the feasibility of artificial aquifer recharge (AAR) at the study area. Based on the developed methodology, guidelines were provided for the selection of the appropriate AAR scenario that has positive impact on the water table

Application of EPIK and KDI methods for identification and evaluation of karst vulnerability at Intervales State Park and surrounding region (Southeastern Brazil)

Between the Guapiara Plateau and the Paranapiacaba Range, Southern Brazil, there are karst systems that are under constant pressure from anthropic advancement of various natures, such as mining of carbonate rocks, forestry, agriculture, and human settlement itself. Karst systems develop differently in both geomorphological compartments. At the Guapiara Plateau the karst is not very expressive with scattered and rare karst features in all carbonate bodies covered by this study. The most cushioned relief, with relatively low hydraulic gradients and the short time of exposure of the carbonate rocks did not allow the full development of a karst system at the plateau. At Paranapiacaba Range, the most rugged relief, associated with high hydraulic gradients, purer carbonates and longer exposure of the carbonate rocks, allows karst features to be more concentrated, and greater development in relation to the plateau. This study presents the karst vulnerability and environmental zonation based on geologic and geomorphologic aspects, using EPIK and KDI methods. At the Guapiara Plateau, the karst vulnerability is low and human settlement is more expressive, with little risk to the system and the people who settled there. At Paranapiacaba Range the presence of karst features is constant and concentrated so the vulnerability is very high, but the presence of protected areas to guarantee the preservation of this type of system and the low occupancy and human interference. This study can contribute to public policies for future land use, minimizing any impacts on the karst region

Human impacts on Karst aquifers of Albania

Albania is situated in the western part of the Balkan Peninsula, on the eastern coast of the Adriatic and the Ionian Sea. The karst landscape in Albania covers about 6750 km2, approximately 24 % of the Albanian territory. There are 25 karst regions in the country, 23 in carbonate rocks and 2 in evaporites. The total renewable karst water resources are estimated about 227 m3/s, representing 80 % of the groundwater resources of Albania. About 70 % of the population of the cities, including also part of the capital Tirana, obtains the water from karst springs. However, the negative human impacts often are threatening the karst groundwater resources of Albania. Several bad experiences in Albania have demonstrated that the main human negative impacts on karst water are related to: (a) urbanised areas, (b) agriculture activities, and (c) quarrying activities. Understanding the vital importance of karst waters and the necessity for intensive scientific investigations and monitoring, to evidence their high vulnerability, are still at a low level in Albania

Anticipating and managing engineering problems in the complex karst environment

Karst environments are characterized by distinctive landforms and a peculiar hydrologic behavior dominated by subsurface drainage. Karst systems can be extremely complex, heterogeneous, and unpredictable due to the wide range of geological and hydrological controlling factors. The great variability results in serious problems for engineers, and in difficulties to characterize the karstified rock masses, and in designing the engineering works to be performed. The design and development of engineering projects in karst environments require specific approaches aimed at minimizing the detrimental effects of hazardous processes and environmental problems. Further, karst aquifers (that provide approximately 20–25 % of the world’s drinking water) are extremely vulnerable to pollution, due to the direct connection between the surface and the subsurface drainage, the rapidity of the water flow in conduit networks, and the very low depuration capability. Sinkholes are the main source of engineering problems in karst environments, and may cause severe damage in any human structure. The strategies and solutions that may be applied to mitigate sinkhole problems are highly variable and largely depend on the kind of engineering structure, the karst setting, and the typology and size of the sinkholes. A sound geological model, properly considering the peculiarities of karst and its interactions with the human environment, is essential for the design of cost-effective and successful risk reduction programs. Due to the unique direct interaction between surface and subsurface environments, and the frequent ground instability problems related to underground karstification, management of karst environments is a very delicate matter. Disregarding such circumstances in land-use planning and development inevitably results in severe problems with high economic impacts. Karst environments require specific investigation methods in order to properly manage and safeguard the sensitive geo-ecosystems and natural resources associated with the

State of the art of karst vulnerability assessment: overview, evaluation and outlook

The study gives an overview of the evolution of the concepts and approaches to karst groundwater vulnerability, its connections to previous vulnerability evaluations and of the steps proposed for the assessment. The majority of the methods are based on prerequisites derived from the basic processes of shallow karst systems in the form of transferred parameters. A systematic survey of existing methods and their applications highlights the significance of scale, parameters, its intrinsic or specific and source or resource nature. Revealing the relationships between methods helps to understand their innovations, advantages, disadvantages and the data need. Based on the literature study, the critical examination of the physical reliability of the resulting vulnerability maps and the necessity of their validation is also highlighted. The paper considers the possible and desirable directions for further research, including the development of process-based methods and involvement of an understanding of the flow and transport processes of karstified carbonates. However, the various aspects of water management are not discussed in the present study