Resource modelling for control: how hydrogeological modelling can support a water quality monitoring infrastructure

The knowledge of the physical/chemical processes implied with the exploitation of water bodies for human consumption is an essential tool for the optimisation of the monitoring infrastructure. Due to their increasing importance in the context of human consumption (at least in the EU), this work focuses on groundwater resources. In the framework of drinkable water networks, the physical and data-driven modelling of transport phenomena in groundwater can help optimising the sensor network and validating the acquired data. This work proposes the combined usage of physical and data-driven modelling as a support to the design and maximisation of results from a network of distributed sensors. In particular, the validation of physico-chemical measurements and the detection of eventual anomalies by a set of continuous measurements take benefit from the knowledge of the domain from which water is abstracted, and its expected characteristics. Change-detection techniques based on non-specific sensors (presented by quite a large literature during the last two decades) have to deal with the classical issues of maximising correct detections and minimising false alarms, the latter of the two being the most typical problem to be faced, in the view of designing truly applicable monitoring systems. In this context, the definition of “anomaly” in terms of distance from an expected value or feature characterising the quality of water implies the definition of a suitable metric and the knowledge of the physical and chemical peculiarities of the natural domain from which water is exploited, with its implications in terms of characteristics of the water resource

Predictive models applied to groundwater level forecasting: a preliminary experience on the alluvial aquifer of the Magra River (Italy)

Computer-based decision support systems are getting a growing interest for water managing authorities and water distribution companies. This work discusses a preliminary experience in the application of computational intelligence in a hydrological modeling framework, regarding the study area of the alluvial aquifer of the Magra River (Italy)

Geothermal resources within carbonate reservoirs in western Sicily (Italy): A review

Low-to-medium temperature fluid reservoirs hosted in carbonate rocks are some of the most promising and unknown geothermal systems. Western Sicily is considered a key exploration area. This paper illustrate a multidisciplinary and integrated review of the existing geological, geochemical and geophysical data, mainly acquired during oil and gas explorations since the 1950s, specifically re-analyzed for geothermal purposes, has led to understanding the western Sicily geothermal system as a whole, and to reconstructing the modalities and particular features of the deep fluid circulation within the regional reservoir. The data review suggests the presence of wide groundwater flow systems in the reservoir beneath impervious cap rocks. We identified the main recharge areas, reconstructed the temperature distribution at depth, recognized zones of convective geothermal flow, and depicted the main geothermal fluid flow paths within the reservoir. We believe that our reconstruction of geothermal fluid circulation is an example of the general behavior of low-to-medium enthalpy geothermal systems hosted in carbonate units on a regional scale. Due to the recent technological developments of binary plants, these systems have become more profitable, not only for geothermal direct uses but also for power production

Stable water isotope as foundamental tool in karst aquifer studies: some results from isotopic applications in the Apuan Alps carbonatic complexes (NW Tuscany)

The management and protection of water resources in karst environment require detailed knowledge of the aquifer system which can be obtained through a multidisciplinary approach, including not only hydrogeological/structural assessment, but also the use of tools not commonly used in hydrogeology, as the isotope ratios. In the present work some examples of isotopic applications on karst aquifers are discussed in relation to hydrogeological studies carried out in the Carrione Stream, Frigido River, and Versilia River catchments (Apuan Alps, Tuscany). In particular, during such studies the isotopic ratios 18O / 16O and 2H / 1H of the water molecule, mainly, and 13C / 12C of inorganic carbon in solution were used. The isotopic data, and their comparison with the hydrogeological and structural-geological ones, were useful: to obtain information about the hydrodynamic conditions in the aquifer; to define the recharge area of main springs; and to identify different circulation systems drained by closing springs which have similar chemistry. The obtained results confirm that in karst systems, where it is often difficult to carry out conventional hydrogeological surveys, the isotopic instruments have a fundamental role in the study of water circulation

GEOCHEMICAL INVESTIGATION OF AQUIFER POLLUTION FROM WASTE MANAGEMENT. THE CASE OF KOMOTINI LANDFILL (GREECE)

According to European legislation, environmental control and monitoring of landfills has become of crucial importance. This study includes a thorough geochemical approach aiming to evaluate the environmental impact of the landfill of Komotini, N. Greece. Samples of waters were taken from inside the working landfill as well as from the area of the neighbouring old landfill. The waters were analyzed chemically (major elements and heavy metals) and isotopically (D and 18O). Also, biogas flow was measured and the ratio CH4/CO2. Based on the geomorphological, hydrogeological and land use data of the area, we proceeded to analyses of waters both from the area of the landfill and from the wider region (drainage basin). The obtained results were used to construct digital maps (GIS) in order to determine the special dispersion of the polluted aquifers. The biogas flow in the old and new garbage burial sites was measured by accumulation chamber device for methane and carbon dioxide ratio determination. The obtained results show an important agent of pollution in the water samples downstream from the landfill and in a distance more than 2km, along the dispersion of the leachate. The land use of the area was taken into account to evaluate the importance and the criticality of the situation

Contamination Assessment and Temporal Evolution of Nitrates in the Shallow Aquifer of the Metauro River Plain (Adriatic Sea, Italy) after Remediation Actions

Over the last decades, groundwater resources at global level have suffered a significant deterioration due to nitrate pollution, mainly related to the input of agricultural fertilizers, manure, sewage, and untreated urban and industrial effluents. The most impacted waters are those forming surface and shallow reservoirs, which usually play a key role in supplying waters to civil, agricultural, and industrial activities. The terminal portion of the Metauro River plain, located in central Italy along the Adriatic Sea coastline, hosts a strategic phreatic aquifer that, along with the surface water of the Metauro River, supplies water to the local population (i.e., about 60,000 people). This shallow coastal aquifer experiences a long-lasting story of nitrate contamination since the 1970s when the increase in the use of agricultural fertilizers contributed to very high levels of pollution (NO3- > 100 mg/L). This fact prompted the local authorities to carry out remediation actions that involve a pumping system to inject the NO3--poor waters from the Metauro River course directly into the shallow aquifer. The present work was aimed at defining the contamination of nitrates in this important water resource. The main geochemical characteristics and the temporal evolution of NO3- concentrations (between 2009 and 2020), in the shallow coastal aquifer of the Metauro River plain, were analyzed by means of classical geochemical analyses and multivariate methods accounting for the compositional nature of the data, to assess the efficiency of the in-situ remediation over time

Fluid geochemistry of the Los Humeros geothermal field (LHGF - Puebla, Mexico): New constraints for the conceptual model

Geothermal power in Mexico is mainly produced in four geothermal fields operated by the Comision Federal de Electricidad (CFE): Cerro Prieto, Los Azufres, Los Humeros, and Las Tres Virgenes. The Los Humeros Geothermal Field (LHGF) is ranked third in terms of generated capacity, and in the last decade its installed capacity has doubled (up to 95.0 MW). Further increases in the geothermal power generation capacity in Mexico are planned, and thus the LHGF warrants further examination. The development and growth phases of any geothermal project must start from an awareness of the conceptual model of the natural system studied. The recharge mechanism, feeding zones, and fluid flow-path must be identified, along with the estimation of the temperature at the productive level and of phase separation (liquid - steam). To accomplish this, detailed fluid geochemical surveys were carried out in June 2017 and March 2018, in which 57 and 87 samples were collected, respectively, from cold and thermal springs, water wells and maar lakes located around and inside the LHGF. Samples from fumaroles inside the producing area were also collected for the first time, together with fluid from re-injection wells. The presence of a meteoric component, which plays an important role at the regional scale, is confirmed by the chemical and isotope data, and its contribution in terms of recharge may be higher than previously assumed. The Sierra Madre Oriental, on the west side of the LHGF, is characterized by widespread outcrops of limestone belonging to the same geological formation as those at the bottom of the LHGF. The isotope composition (delta D and delta O-18, respectively -77.3 parts per thousand and -10.50 parts per thousand for the hypothetical Infiltration Water IW) is similar to that observed in cold springs located in the Sierra Madre Oriental, and from this the evolution of isotopes in the liquid-rock-steam system during water-rock interaction and phase separation processes can be modelled. Thus, the experimental data obtained for natural gas emissions (fumarolic condensates) and for geothermal fluids can be reproduced. These findings suggest that geothermal fluids in the LHGF are likely to be derived from meteoric water infiltrating (IW) the limestone outcrops of the Sierra Madre Oriental. During their flow-path, the infiltrating waters exchange isotopes at a high temperature with the crustal rocks, which have a much higher O-18/O-16 ratio, resulting in a shift towards higher delta O-18 (-4.35 parts per thousand +/- 1) as the water O exchanges with rock O. The vapor phase can be separated from this deep water (DW) and it is discharged from the fumarolic effluents of Loma Blanca. Single Step Vapor Separation (SSVS) and Continuous Steam Separation processes (CSS) were modelled using stable isotopes of water. The results of geochemical modeling agree with available data for geothermal liquids discharged from several geothermal wells, suggesting that steam separation may be interpreted either as SSVS or CSS. Other processes can affect the chemistry and isotope composition of geothermal fluids (e.g. phase segregation, gas exchange, contributions from magmatic-volcanic deep fluids and re-injection fluids). The proposed conceptual model is consistent with both the geochemical data and the geological setting, and provides a useful point of reference for examining the fluid flow-path and geochemical processes active in the LHGF, at least at a general level.An involvement of magmatic-volcanic deep fluids in the feeding mechanism of the geothermal system cannot be excluded at priori, but the regional meteoric end-member is supported by the data and it seems the most important component

L'utilizzo degli isotopi stabili da reti pluviometriche per la definizione degli areali di ricarica delle acque sorgive: problemi e possibili soluzioni da casi di studio nell'Appennino settentrionale

The water stable isotopes are widely exploited in hydrogeology to define the recharge area of mountain springs. In almost all cases, pre-existing relationships linking the isotopic contents of meteoric water that were collected in several rain gauges located at different altitudes are used. Although such approach is straightforward, it assumes that the water aliquots collected in the raingauges fully recharge the groundwater. From the hydrogeological point of view, this assumption does not take into account the water balance equation, as it neglects evapotranspiration and runoff. This manuscript deals on the preliminary comparison of water stable isotopes in meteoric water (1 raingauge) and groundwater (2 springs) from the northern Apennines of Italy. Results highlight that the pre-existing isotopic relationships commonly used in northern Apennines largely overestimate the mean altitudes of recharge of springs. This fact may be only in part due to the evapotranspiration processes taking place during summer period so that isotopic gradients obtained from weighting procedure linking effective rainfall with isotopic contents in raingauges are still not recommended. To date, isotopic gradients obtained from ephemeral springs fed by reduced surficial deposits seem to be the most reliable tool

Nanocomposite sprayed films with photo-thermal properties for remote bacteria eradication

Currently there is a strong demand for novel protective materials with effcient antibacterial properties. Nanocomposite materials loaded with photo-thermally active nanoparticles can offer promising opportunities due to the local increase of temperature upon near-infrared (NIR) light exposure capable of eradicating bacteria. In this work, we fabricated antibacterial films obtained by spraying on glass slides aqueous solutions of polymers, containing highly photo-thermally active gold nanostars (GNS) or Prussian Blue (PB) nanoparticles. Under NIR light irradiation with low intensities (0.35W/cm2) these films demonstrated a pronounced photo-thermal effect: 06Tmax up to 26.4 ffC for the GNS-containing films and 06Tmax up to 45.8 ffC for the PB-containing films. In the latter case, such a local temperature increase demonstrated a remarkable effect on a Gram-negative strain (P. aeruginosa) killing (84% of dead bacteria), and a promising effect on a Gram-positive strain (S. aureus) eradication (69% of dead bacteria). The fabricated films are promising prototypes for further development of lightweight surfaces with effcient antibacterial action that can be remotely activated on demand