Geochemical Markers as a Tool for the Characterization of a Multi-Layer Urban Aquifer: The Case Study of Como (Northern Italy)

The analysis of geochemical markers is a known valid tool to explore the water sources and understand the main factors affecting natural water quality, which are known issues of interest in environmental science. This study reports the application of geochemical markers to characterize and understand the recharge areas of the multi-layer urban aquifer of Como city (northern Italy). This area presents a perfect case study to test geochemical markers: The hydrogeological setting is affected by a layered karst and fractured aquifer in bedrock, a phreatic aquifer hosted in Holocene sediments and connected with a large freshwater body (Lake Como); the aquifers recharge areas and the water geochemistry are unknown; the possible effect of the tectonic setting on water flow was overlooked. In total, 37 water samples were collected including water from two stacked aquifers and surface water to characterize hydrochemical features. Moreover, six sediment samples in the recent palustrine deposits of the Como subsurface were collected from cores and analyzed to understand the main geochemistry and mineralogy of the hosting material. The chemical analyses of water allow to observe a remarkable difference between the shallow and deep aquifers of the study area, highlighting different recharge areas, as well as a different permanence time in the aquifers. The sediment geochemistry, moreover, confirms the differences in trace elements derived from sediment-water interaction in the aquifers. Finally, an anomalous concentration of As in the Como deep aquifer was observed, suggesting the need of more detailed analyses to understand the origin of this element in water. This study confirms the potentials of geochemical markers to characterize main factors affecting natural water quality, as well as a tool for the reconstruction of recharge areas.

Influence of Injection Well Location on CO2 Geological Storage Efficiency

An analysis of the influence of injection well location on CO2 storage efficiency was carried out for three well-known geological structures (traps) in deep aquifers of the Lower Jurassic Polish Lowlands. Geological models of the structures were used to simulate CO2 injection at fifty different injection well locations. A computer simulation showed that the dynamic CO2 storage capacity varies depending on the injection well location. It was found that the CO2 storage efficiency for structures with good reservoir properties increases with increasing distance of the injection well from the top of the structure and with increasing depth difference to the top of the structure. The opposite is true for a structure with poor reservoir properties. As the quality of the petrophysical reservoir parameters (porosity and permeability) improves, the location of the injection well becomes more important when assessing the CO2 storage efficiency. Maps of dynamic CO2 storage capacity and CO2 storage efficiency are interesting tools to determine the best location of a carbon dioxide injection well in terms of gas storage capacity.

How Leaders Can Shape the Oil & Gas Industry – Accelerating Innovations Through Business & Environmental Intelligent Systems

One of the harms to climate brought about by anthropogenically instigated environmental change is the overabundance creation of CO2 because of industrialization. Research and development endeavors so far have been focused on the improvement of CCS (Carbon Capture and Sequestration), with the fundamental spotlight on the best way to eliminate CO2 from vent gases and how to cover it perpetually in deep aquifers or depleted oil and gas reservoirs to save the environment from the detrimental effects of CO2. At one side, the alarming situation due to excess emission of CO2 from industries has been bulled out and simultaneously, there is higher potential for CO2 in the depleted oil fields which can aid to the Enhanced Oil Recovery (EOR) through the prolonged CO2 injection in depleted oil fields. It is currently turning out to be certain that CCS technology could advance the utilization of fossil fuels than in any case recently thought. This paper discusses the integration of Carbon Capture and Sequestration (CCS) technology with the progressive strategy of Enhanced Oil Recovery (EOR). CCS includes various advances that can be utilized to catch CO2 from point sources. Countries that are badly affected by the harmful effects of global warming with depleting oil reserves in the very near future can be the most viable target of the CCS Project. The scope and potential of different techniques of CCS along with the opportunities and challenges and the real case scenarios happening in the world are discussed in detail. The economics, process cycle and case studies of this futuristic technology intend to give valuable insight to the implementation of this integrated technique to the prevalent depleting oil fields around the globe.

Designing Aquifer Model for the Banks of the Serayu River, Sokawera, Somagede, Banyumas, Indonesia by Means of 1D-Electrical Resistivity Data

A geoelectric survey using the 1D-electrical resistivity method was applied to design a groundwater aquifer model for the banks of the Serayu River in Sokawera Village, Somagede District, Banyumas Regency, Indonesia. The aim of this research was to identify the characteristics of aquifers in the research area based on resistivity log data. Acquisition, modeling, and interpretation of resistivity data were carried out and the results were lithological logs at seven sounding points. Correlation between the lithological logs resulted in a hydrostratigraphic model. This model is composed of several hydrological units, i.e. shallow aquifer, aquitard, and deep aquifer. The shallow aquifers are composed of sandy clay (10.81-18.21 Wm) and clayey sand (3.04-7.43 Wm) with a depth of groundwater from the water table to 27.51 m. The deep aquifers are composed of sandstone with variation of porosity (2.24-12.04 Wm) at a depth of more than 54.98 m. Based on this model, potential shallow aquifers were estimated to be at sounding points Sch-5, Sch-6, and Sch-7. This hydrostratigraphic model shows that the two types of aquifers are separated by an aquitard layer, allowing groundwater infiltration from the shallow aquifer to the deep aquifer and vice versa. Moreover, the Serayu riverbanks in this research area are estimated to be a groundwater discharge area.

El rol de la exploración geofísica en acuíferos profundos en ambientes semiurbanos y rurales en cuencas de ante arco Andino, caso de estudio en acuífero del río Ñuble, Valle Central de Chile

The hydric resource coming from groundwater has a strategic nature at global scale, within a context of overpopulation and over exploitation of the resource and climate change. Chile doesn’t scape to it, where climate models predict a drought for most of the country, including partially, the agriculture region of the Central Valley between Santiago and Puerto Montt. The adaption process to global change demands the exploration new sources of provisions of this resource, being strategic the one coming from aquifers. To date, the knowledge of these resources is limited to depths below 200 m in each aquifer. However, in the Central Valley between Santiago and Chiloé, the geophysical evidences allow to infer the existence of a thick volcano-sedimentary basin growing in thickness southward well above 500m, with good potential for occurrence of large groundwater resources. The characterization of deep aquifers, 200-1,000 m of depth, demands to have an exploration tool economic, non-invasive, and reliable, able to be applied in semi-urban and rural environments, where the water resource need is higher. The geophysical methodologies meet these characteristics and have been applied in Chile and elsewhere as an exploration tool of ground water resources. However, its application have not been described in Andean environments, of large population and/or agro-industrial activity. In consequence, the present work raises a methodological strategy for the characterization of groundwater resources, in particular for the detection of deep resources. We propose the application of a combination of complementary geophysical techniques, including electrical, electromagnetic, and gravimetric methods (to determine the aquifer geometry) along with complementary techniques, like magnetometry, to reduce interpretation ambiguity and , constrained by hydrogeological information and petrophysics of rocks and sediments of the basin and basement. Complementary, we include an analysis of the potential effects of cultural noise and its effects on geophysical observations, given the focus of exploration in semi-urban and rural places. With the aim to validate the proposed methodology we use as a case study the aquifer of Ñuble river, in the Ñuble region, Chile. This aquifer properly represents an Andean forearc environment in rural and semi-urban condition, and potentially hosting a deep seated aquifer. The results allow the characterization of an aquifer with hydrogeological potential between 50 and 300-500 depth, overlying a sedimentary basin of more than 1,000 m thickness. The application of the proposed methodology for the exploration of groundwater resources will provide, in consequence, the recognition of a vital relevance resource for the sustainability of Chile during the following decades.

Challenges of groundwater pollution and management in transboundary basins at the African scale

We address the significant knowledge gap for groundwater pollution in Africa methods by assessing groundwater pollution risk at the African scale. To do so, we compiled the most recent continental-scale information on soil, land use, geology, hydrogeology, and topography in a Geographical Information System at the resolution of 15 × 15 km and the 1:60 000 000 scale. We produced a vulnerability map by using the generic DRASTIC vulnerability indicator. This map revealed that groundwater is highly vulnerable in Central and West Africa groundwater basins, where the water table is shallow. In addition, very low vulnerability classes are found in the large sedimentary basins of Africa deserts where groundwater is situated in very deep aquifers. The generic groundwater pollution risk map is obtained by overlaying the DRASTIC vulnerability indicator with current land use. The northern, central, and western parts of the African continent are dominated by high vulnerability classes and very strongly related to water table depths and the development of agricultural activities. Given the availability of data, we concentrate first on nitrate vulnerability mapping. To this end, groundwater nitrate contamination data are compiled in literature using meta-analysis technic and used to calibrate as well linear and nonlinear statistical models; the latter performing much better as compared to simple linear statistical models. This study will help to raise awareness of the manager's International Basin Authorities or Transboundary Basin Organizations in Africa and in particular on transboundary groundwater pollution issues.

Stable Isotope and Hydrochemical Evolution of Groundwater in Mining Area of the Changzhi Basin, Northern China

The Changzhi Basin of China is an economically and ecologically important area with intensive human activities. To foster the sustainable development of groundwater resources and the economy, a total of 117 groundwater samples were collected in shallow and deep aquifers, including 91 2H and 18O isotope samples, to improved understanding of the natural geochemical processes and the impacts of anthropogenic activities on the groundwater chemistry. Synthetical application of the stable isotopes, Piper diagram, Gibbs diagram, ionic ratios and saturation indices to data analysis led to identification of hydrochemical zones for both aquifers from west to east of the basin. Isotopic analyses suggested that the groundwater recharge mainly comes from infiltration of rain water, hydraulic interaction between surface water and shallow groundwater, and lateral recharge from fissure water at the edge of the basin. The predominant natural geochemical processes include mineral dissolution in conjunction with the cation exchange. The excess deuterium method revealed that mineral dissolution contributed 81%–98% to the salinity of shallow groundwater and 84%–98% to the salinity of deep groundwater. Anthropogenic activities are secondary contributions to the hydrochemical evolution with fertilizer application, human waste and sewage discharges causing an increase in NO3-N content and coal mining activities affecting the ion content of Na+, Cl-, SO42-, and HCO3- in the groundwater.

Shedding Light on Microbial Communities in Deep Aquifers

Researchers use a packer system to study the microbial communities living in waters sampled from deep, uncontaminated peridotite aquifers.