This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined ... more This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined coastal aquifer located in a lowland setting in order to understand the drivers of the groundwater salinization. Physical aquifer parameterization highlights a vertical hydraulic gradient due to the presence of a heavy drainage system, which controls the hydrodynamics of this coastal area, forcing groundwater to flow from the bottom toward the top of the aquifer. As a consequence, relict seawater in stable density stratification, preserved within low permeability sediments in the deepest portion of the aquifer, has been drawn upward. The hydrogeochemical investigations allow identifying the role of seepage and water-sediment interactions in the aquifer salinization process and in the modification of groundwater chemistry. Mixing between freshwater and saltwater occurs; however, it is neither the only nor the dominant process driving groundwater hydrochemistry. In the aquifer several concurring and competing water-sediment interactions - as NaCl solution, ion-exchange, calcite and dolomite dissolution/precipitation, oxidation of organic matter, and sulfate bacterial reduction - are triggered by or overlap freshwater-saltwater mixing The hyper-salinity found in the deepest portion of the aquifer cannot be associated with present seawater intrusion, but suggests the presence of salt water of marine origin, which was trapped in the inter-basin during the Holocene transgression. The results of this study contribute to a better understanding of groundwater dynamics and salinization processes in this lowland coastal aquifer.
ABSTRACT The coastal aquifer salinization is an urgent problem caused by groundwater resources ov... more ABSTRACT The coastal aquifer salinization is an urgent problem caused by groundwater resources overexploitation and climate change. This phenomenon is enhanced in areas lying below the sea level, like the polders in the Netherlands or the Po River lowland in Italy. In these reclaimed lands the saltwater intrusion is usually controlled by a network of irrigation canals that supplies freshwater to the shallow aquifer, maintaining soil salinity at acceptable levels. The 2012 was dramatic in terms of agricultural water supply, since the Po River plain experienced a prolonged drought. Despite this, continuous monitoring of piezometric heads and total dissolved solids (TDS) near a canal (Canale della Gronda) demonstrated that freshening was occurring in the shallow portion (first 4 m) of the unconfined aquifer, while the bottom part was characterized by elevated relic salinity. The two-dimensional model SEAWAT was calibrated using piezometric heads and TDS depth profiles measured along a transect perpendicular to the canal. The calibrated model was then used to predict the behaviour of this cross section using a multiple scenario approach: increase in evapotranspiration induced by temperature increase; increase in the frequency of extreme high rainfall events; extreme drought conditions; and canal dewatering due to salinization of the water courses. Moreover, for each scenario, two sub-scenarios were run to account for projected sea level rise. The first three scenarios had only a minor influence on the aquifer salinization rate, while the fourth one predicted serious upward flux of the high salinity groundwater actually residing in the bottom of the unconfined aquifer. The scenarios quantified the possible future effects on groundwater salinization and could be useful to find adaptation strategies to manage the water resources of this and similar areas.
Temperature is often used to infer the effect of land use and climate conditions on aquifers. Rel... more Temperature is often used to infer the effect of land use and climate conditions on aquifers. Reliable data are needed to examine the temperature behaviour in the subsurface, thus the use of robust acquisition techniques is unavoidable. Three temperature measurement techniques were applied to assess the sources of bias that could occur during temperature logging in a shallow Quaternary coastal aquifer in Ferrara (Northern Italy). Open borehole temperature logging (OBL), multi-level sampling straddle packers isolated temperature measurements within a flow cell above ground (MLS-AG), and multi-level sampling straddle packers isolated temperature measurements via an in well level logger (MLS-IW) were compared for several coastal monitoring wells, to gain insights on the limitations of each technique. Results show that the source of bias between the three applied techniques are different: (i) OBL method tends to record the heat convection through the open borehole, and it is not representative of the aquifer temperature distribution; (ii) MLS-AG method is swayed by the air temperature and the heating of the submersible pump used to lift groundwater above ground; (iii) MLS-IW provides the most reliable vertical thermal profiling both in summer and winter, because groundwater temperature is directly measured at the selected monitoring depth. The implementation of a 1D flow model demonstrates that, if precise temperature profiles are needed to infer the influence that land use and climate changes have on groundwater, the MLS-IW method is a reliable method that could be applied to existing monitoring wells.
ABSTRACT A contamination by petroleum hydrocarbons was detected in a sandy aquifer below a petroc... more ABSTRACT A contamination by petroleum hydrocarbons was detected in a sandy aquifer below a petrochemical plant in Southern Italy. The site is located near the coastline and bordered by canals which, together with pumping wells, control submarine groundwater discharge toward the sea and seawater intrusion (SWI) inland. In this study, a three-dimensional flow and transport model was developed using SEAWAT-4.0 to simulate the density-dependent groundwater flow system. Equivalent freshwater heads from 246 piezometers were employed to calibrate the flow simulation, while salinity in 193 piezometers was used to calibrate the conservative transport. A second dissolved species, total petroleum hydrocarbons (TPH), was included in the numerical model to simulate the plumes originating from light non-aqueous-phase liquid. A detailed field investigation was performed in order to determine the fate of dissolved hydrocarbons. Fifteen depth profiles obtained from multilevel samplers (MLS) were used to improve the conceptual model, originally built using a standard monitoring technique with integrated depth sampling (IDS) of salinity and TPH concentrations. The calibrated simulation emphasises that density-dependent flow has a great influence on the migration pattern of the hydrocarbons plume. This study confirms that calibration of density-dependent models in sites affected by SWI can be successfully reached only with MLS data, while standard IDS data can lead to misleading results. Thus, it is recommended to include MLS in the characterization protocols of contaminated sites affected by SWI, in order to properly manage environmental pollution problems of coastal zones.
This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined ... more This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined coastal aquifer located in a lowland setting in order to understand the drivers of the groundwater salinization. Physical aquifer parameterization highlights a vertical hydraulic gradient due to the presence of a heavy drainage system, which controls the hydrodynamics of this coastal area, forcing groundwater to flow from the bottom toward the top of the aquifer. As a consequence, relict seawater in stable density stratification, preserved within low permeability sediments in the deepest portion of the aquifer, has been drawn upward. The hydrogeochemical investigations allow identifying the role of seepage and water–sediment interactions in the aquifer salinization process and in the modification of groundwater chemistry. Mixing between freshwater and saltwater occurs; however, it is neither the only nor the dominant process driving groundwater hydrochemistry. In the aquifer several concurring and competing water–sediment interactions – as NaCl solution, ion-exchange, calcite and dolomite dissolution/precipitation, oxidation of organic matter, and sulfate bacterial reduction – are triggered by or overlap freshwater–saltwater mixing The hyper-salinity found in the deepest portion of the aquifer cannot be associated with present seawater intrusion, but suggests the presence of salt water of marine origin, which was trapped in the inter-basin during the Holocene transgression. The results of this study contribute to a better understanding of groundwater dynamics and salinization processes in this lowland coastal aquifer.
ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-t... more ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-term performance from a water quantity perspective to sustainably mitigate hydrologic impacts of groundwater overexploitation. Gravity driven infiltration ditches in forested areas are one of many MAR scheme that could augment the available water resources. Research on the longevity of these structures is sparse, leading to concerns about their long-term capability to sustain elevated infiltration capacity. In the present study, an infiltration system consisting of a regular grid of eight ditches divided into 4 sequential plots within a short rotation forested area (AFI) was monitored from its inception to determine its hydrologic performance over time and its possible export to similar areas of the Brenta Megafan (Northern Italy). During the monitored period, the AFI was not significantly affected by clogging since the suspended solids carried by the Brenta River water diversion were extremely low. The main source of clogging was the fallen foliage during the autumn, easily managed via ordinary maintenance. The AFI displayed an almost constant performance to infiltrate the diverted water over the first three years of operation, with a total amount of infiltrated water of approximately 0.8 Mm3/ha/y. The best tracer to reconstruct the downward water movement through this highly permeable vadose zone was temperature, while the groundwater table fluctuation could not be confidently used to infer the effective infiltration, because of its large seasonal variability. The good results suggest that promoting this technique in other areas of the Brenta Megafan that suffer from groundwater resources depletion. This article is protected by copyright. All rights reserved.
Il lavoro qui presentato ha come obiettivo lo studio idrogeologico del primo acquifero confinato ... more Il lavoro qui presentato ha come obiettivo lo studio idrogeologico del primo acquifero confinato A1 in un’area comprendente alcune
porzioni delle province di Ferrara, Mantova e Bondeno.
La ricerca è stata possibile grazie al reperimento di dati provenienti dalle stratigrafie dei pozzi profondi esistenti e da studi
precedenti effettuati dalla Regione Emilia Romagna, dalla Provincia di Ferrara, dal Comune di Bondeno e dalla ditta esercente la
cava di Settepolesini presso Bondeno (FE). Dai dati e dalle misure raccolte si è cercato di ricavare e proporre un modello
idrogeologico concettuale del sottosuolo che è poi sfociato in un modello numerico del flusso idrico sotterraneo (MODFLOW 2000).
Inizialmente il grado di calibrazione di tale simulazione risultava scarso per cui sono state avanzate diverse ipotesi per cercare di
migliorare il modello concettuale di riferimento. Una di queste ipotesi consisteva nel supporre la presenza di uno spartiacque
piezometrico subparallelo al fiume Po dovuto alla coalescenza tra gli acquiferi A1 ed A2. Per testare tale ipotesi è stato quindi
definito un piano di campionamento e di analisi che ha previsto il prelievo di campioni d’acqua presenti in 6 piezometri ubicati
nell’area d’indagine. Sulla base dei dati idrogeochimici ottenuti è stato realizzato un modello numerico di trasporto non reattivo in
regime stazionario, tramite il software MT3D-MS, che ha permesso di confermare la risalita di acque salate verso l’acquifero A1.
The effect of elevated salinity (>50 g/l) on the mobility of trace elements (Br, Sc, Ti, Cr, Ni, ... more The effect of elevated salinity (>50 g/l) on the mobility of trace elements (Br, Sc, Ti, Cr, Ni, Co, As, Cd, Pb and Zn) was studied, within a shallow coastal aquifer. The use of intensive depth profiles with resolution of 0.5 m in two different locations, gave insight into groundwater and sediment matrix interaction. The collected sediments were analyzed for major and trace elements via XRF powder pellets, while major ions in groundwater were analyzed via IC and trace elements via ICP-MS. The total concentration of trace elements within the aquifer matrix was higher in the fine sediments, since usually these elements concentrate in the clay fraction, while the concentration in groundwater generally increased with the ionic strength of the solution. The increase of salinity in conjunction with a high content in carbonates stimulated a release of Pb and Zn, suggesting surface complexation on carbonate and dolomite minerals. The elevated organic carbon content of the sediments induced reducing conditions throughout the aquifer, which further promoted trace elements dissolution. The only exceptions were V and As that did not followed this trend, most probably released by peaty layers and fertilizers leaching.
Although the Po river is the most important fluvial system of Northern Italy, the
systematic geoc... more Although the Po river is the most important fluvial system of Northern Italy, the systematic geochemical and isotopic investigations of its water are rare and were never reported for the whole basin. The present contribution aims to fill this knowledge gap, reporting a comprehensive data set including oxygen and hydrogen stable isotopes as well as major and trace element concentration of dissolved species for 54 Po river water samples, mainly collected in different hydrological conditions (peak discharge in April, ...
This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined ... more This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined coastal aquifer located in a lowland setting in order to understand the drivers of the groundwater salinization. Physical aquifer parameterization highlights a vertical hydraulic gradient due to the presence of a heavy drainage system, which controls the hydrodynamics of this coastal area, forcing groundwater to flow from the bottom toward the top of the aquifer. As a consequence, relict seawater in stable density stratification, preserved within low permeability sediments in the deepest portion of the aquifer, has been drawn upward. The hydrogeochemical investigations allow identifying the role of seepage and water-sediment interactions in the aquifer salinization process and in the modification of groundwater chemistry. Mixing between freshwater and saltwater occurs; however, it is neither the only nor the dominant process driving groundwater hydrochemistry. In the aquifer several concurring and competing water-sediment interactions - as NaCl solution, ion-exchange, calcite and dolomite dissolution/precipitation, oxidation of organic matter, and sulfate bacterial reduction - are triggered by or overlap freshwater-saltwater mixing The hyper-salinity found in the deepest portion of the aquifer cannot be associated with present seawater intrusion, but suggests the presence of salt water of marine origin, which was trapped in the inter-basin during the Holocene transgression. The results of this study contribute to a better understanding of groundwater dynamics and salinization processes in this lowland coastal aquifer.
ABSTRACT The coastal aquifer salinization is an urgent problem caused by groundwater resources ov... more ABSTRACT The coastal aquifer salinization is an urgent problem caused by groundwater resources overexploitation and climate change. This phenomenon is enhanced in areas lying below the sea level, like the polders in the Netherlands or the Po River lowland in Italy. In these reclaimed lands the saltwater intrusion is usually controlled by a network of irrigation canals that supplies freshwater to the shallow aquifer, maintaining soil salinity at acceptable levels. The 2012 was dramatic in terms of agricultural water supply, since the Po River plain experienced a prolonged drought. Despite this, continuous monitoring of piezometric heads and total dissolved solids (TDS) near a canal (Canale della Gronda) demonstrated that freshening was occurring in the shallow portion (first 4 m) of the unconfined aquifer, while the bottom part was characterized by elevated relic salinity. The two-dimensional model SEAWAT was calibrated using piezometric heads and TDS depth profiles measured along a transect perpendicular to the canal. The calibrated model was then used to predict the behaviour of this cross section using a multiple scenario approach: increase in evapotranspiration induced by temperature increase; increase in the frequency of extreme high rainfall events; extreme drought conditions; and canal dewatering due to salinization of the water courses. Moreover, for each scenario, two sub-scenarios were run to account for projected sea level rise. The first three scenarios had only a minor influence on the aquifer salinization rate, while the fourth one predicted serious upward flux of the high salinity groundwater actually residing in the bottom of the unconfined aquifer. The scenarios quantified the possible future effects on groundwater salinization and could be useful to find adaptation strategies to manage the water resources of this and similar areas.
Temperature is often used to infer the effect of land use and climate conditions on aquifers. Rel... more Temperature is often used to infer the effect of land use and climate conditions on aquifers. Reliable data are needed to examine the temperature behaviour in the subsurface, thus the use of robust acquisition techniques is unavoidable. Three temperature measurement techniques were applied to assess the sources of bias that could occur during temperature logging in a shallow Quaternary coastal aquifer in Ferrara (Northern Italy). Open borehole temperature logging (OBL), multi-level sampling straddle packers isolated temperature measurements within a flow cell above ground (MLS-AG), and multi-level sampling straddle packers isolated temperature measurements via an in well level logger (MLS-IW) were compared for several coastal monitoring wells, to gain insights on the limitations of each technique. Results show that the source of bias between the three applied techniques are different: (i) OBL method tends to record the heat convection through the open borehole, and it is not representative of the aquifer temperature distribution; (ii) MLS-AG method is swayed by the air temperature and the heating of the submersible pump used to lift groundwater above ground; (iii) MLS-IW provides the most reliable vertical thermal profiling both in summer and winter, because groundwater temperature is directly measured at the selected monitoring depth. The implementation of a 1D flow model demonstrates that, if precise temperature profiles are needed to infer the influence that land use and climate changes have on groundwater, the MLS-IW method is a reliable method that could be applied to existing monitoring wells.
ABSTRACT A contamination by petroleum hydrocarbons was detected in a sandy aquifer below a petroc... more ABSTRACT A contamination by petroleum hydrocarbons was detected in a sandy aquifer below a petrochemical plant in Southern Italy. The site is located near the coastline and bordered by canals which, together with pumping wells, control submarine groundwater discharge toward the sea and seawater intrusion (SWI) inland. In this study, a three-dimensional flow and transport model was developed using SEAWAT-4.0 to simulate the density-dependent groundwater flow system. Equivalent freshwater heads from 246 piezometers were employed to calibrate the flow simulation, while salinity in 193 piezometers was used to calibrate the conservative transport. A second dissolved species, total petroleum hydrocarbons (TPH), was included in the numerical model to simulate the plumes originating from light non-aqueous-phase liquid. A detailed field investigation was performed in order to determine the fate of dissolved hydrocarbons. Fifteen depth profiles obtained from multilevel samplers (MLS) were used to improve the conceptual model, originally built using a standard monitoring technique with integrated depth sampling (IDS) of salinity and TPH concentrations. The calibrated simulation emphasises that density-dependent flow has a great influence on the migration pattern of the hydrocarbons plume. This study confirms that calibration of density-dependent models in sites affected by SWI can be successfully reached only with MLS data, while standard IDS data can lead to misleading results. Thus, it is recommended to include MLS in the characterization protocols of contaminated sites affected by SWI, in order to properly manage environmental pollution problems of coastal zones.
This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined ... more This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined coastal aquifer located in a lowland setting in order to understand the drivers of the groundwater salinization. Physical aquifer parameterization highlights a vertical hydraulic gradient due to the presence of a heavy drainage system, which controls the hydrodynamics of this coastal area, forcing groundwater to flow from the bottom toward the top of the aquifer. As a consequence, relict seawater in stable density stratification, preserved within low permeability sediments in the deepest portion of the aquifer, has been drawn upward. The hydrogeochemical investigations allow identifying the role of seepage and water–sediment interactions in the aquifer salinization process and in the modification of groundwater chemistry. Mixing between freshwater and saltwater occurs; however, it is neither the only nor the dominant process driving groundwater hydrochemistry. In the aquifer several concurring and competing water–sediment interactions – as NaCl solution, ion-exchange, calcite and dolomite dissolution/precipitation, oxidation of organic matter, and sulfate bacterial reduction – are triggered by or overlap freshwater–saltwater mixing The hyper-salinity found in the deepest portion of the aquifer cannot be associated with present seawater intrusion, but suggests the presence of salt water of marine origin, which was trapped in the inter-basin during the Holocene transgression. The results of this study contribute to a better understanding of groundwater dynamics and salinization processes in this lowland coastal aquifer.
ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-t... more ABSTRACT Managed aquifer recharge (MAR) design and operation must incorporate the expected long-term performance from a water quantity perspective to sustainably mitigate hydrologic impacts of groundwater overexploitation. Gravity driven infiltration ditches in forested areas are one of many MAR scheme that could augment the available water resources. Research on the longevity of these structures is sparse, leading to concerns about their long-term capability to sustain elevated infiltration capacity. In the present study, an infiltration system consisting of a regular grid of eight ditches divided into 4 sequential plots within a short rotation forested area (AFI) was monitored from its inception to determine its hydrologic performance over time and its possible export to similar areas of the Brenta Megafan (Northern Italy). During the monitored period, the AFI was not significantly affected by clogging since the suspended solids carried by the Brenta River water diversion were extremely low. The main source of clogging was the fallen foliage during the autumn, easily managed via ordinary maintenance. The AFI displayed an almost constant performance to infiltrate the diverted water over the first three years of operation, with a total amount of infiltrated water of approximately 0.8 Mm3/ha/y. The best tracer to reconstruct the downward water movement through this highly permeable vadose zone was temperature, while the groundwater table fluctuation could not be confidently used to infer the effective infiltration, because of its large seasonal variability. The good results suggest that promoting this technique in other areas of the Brenta Megafan that suffer from groundwater resources depletion. This article is protected by copyright. All rights reserved.
Il lavoro qui presentato ha come obiettivo lo studio idrogeologico del primo acquifero confinato ... more Il lavoro qui presentato ha come obiettivo lo studio idrogeologico del primo acquifero confinato A1 in un’area comprendente alcune
porzioni delle province di Ferrara, Mantova e Bondeno.
La ricerca è stata possibile grazie al reperimento di dati provenienti dalle stratigrafie dei pozzi profondi esistenti e da studi
precedenti effettuati dalla Regione Emilia Romagna, dalla Provincia di Ferrara, dal Comune di Bondeno e dalla ditta esercente la
cava di Settepolesini presso Bondeno (FE). Dai dati e dalle misure raccolte si è cercato di ricavare e proporre un modello
idrogeologico concettuale del sottosuolo che è poi sfociato in un modello numerico del flusso idrico sotterraneo (MODFLOW 2000).
Inizialmente il grado di calibrazione di tale simulazione risultava scarso per cui sono state avanzate diverse ipotesi per cercare di
migliorare il modello concettuale di riferimento. Una di queste ipotesi consisteva nel supporre la presenza di uno spartiacque
piezometrico subparallelo al fiume Po dovuto alla coalescenza tra gli acquiferi A1 ed A2. Per testare tale ipotesi è stato quindi
definito un piano di campionamento e di analisi che ha previsto il prelievo di campioni d’acqua presenti in 6 piezometri ubicati
nell’area d’indagine. Sulla base dei dati idrogeochimici ottenuti è stato realizzato un modello numerico di trasporto non reattivo in
regime stazionario, tramite il software MT3D-MS, che ha permesso di confermare la risalita di acque salate verso l’acquifero A1.
The effect of elevated salinity (>50 g/l) on the mobility of trace elements (Br, Sc, Ti, Cr, Ni, ... more The effect of elevated salinity (>50 g/l) on the mobility of trace elements (Br, Sc, Ti, Cr, Ni, Co, As, Cd, Pb and Zn) was studied, within a shallow coastal aquifer. The use of intensive depth profiles with resolution of 0.5 m in two different locations, gave insight into groundwater and sediment matrix interaction. The collected sediments were analyzed for major and trace elements via XRF powder pellets, while major ions in groundwater were analyzed via IC and trace elements via ICP-MS. The total concentration of trace elements within the aquifer matrix was higher in the fine sediments, since usually these elements concentrate in the clay fraction, while the concentration in groundwater generally increased with the ionic strength of the solution. The increase of salinity in conjunction with a high content in carbonates stimulated a release of Pb and Zn, suggesting surface complexation on carbonate and dolomite minerals. The elevated organic carbon content of the sediments induced reducing conditions throughout the aquifer, which further promoted trace elements dissolution. The only exceptions were V and As that did not followed this trend, most probably released by peaty layers and fertilizers leaching.
Although the Po river is the most important fluvial system of Northern Italy, the
systematic geoc... more Although the Po river is the most important fluvial system of Northern Italy, the systematic geochemical and isotopic investigations of its water are rare and were never reported for the whole basin. The present contribution aims to fill this knowledge gap, reporting a comprehensive data set including oxygen and hydrogen stable isotopes as well as major and trace element concentration of dissolved species for 54 Po river water samples, mainly collected in different hydrological conditions (peak discharge in April, ...
Chemical, geological and hydrogeological investigations were conducted in a polluted site in sout... more Chemical, geological and hydrogeological investigations were conducted in a polluted site in southern Italy, with the aim of improving and validating a conceptual model of groundwater flow and contaminant transport. The collected data allowed building of a numerical model, which takes into account groundwater flow interaction with salt water intrusion by a density-dependent model. Simulation results agree with field data, showing that the salt wedge intrusion has reached the pumping wells, the dissolved contaminants are completely intercepted by a P&T system and that around 25% of exploited flow comes from losses from a surface seawater canal. Finally the three dimensional flow model was validated by new data collected in 2009, and it is now used to forecast and to manage the pumping rates of more than 70 wells.
A range of laboratory and field experiments has been performed to quantify NO3– clean up times in... more A range of laboratory and field experiments has been performed to quantify NO3– clean up times in sandy loamy sediments representative of the Po Plain lowlands (northern Italy), an intensively cultivated area affected by serious nitrate pollution for decades. Column and tank experiments were performed to elucidate the relevant transport and redox processes affecting nitrogen dissolved species, in order to study the same processes in controlled 1-D and 3-D environments. In addition, a grid of piezometers were installed and monitored in a former agricultural field, to quantify the presence and degradation of nitrogen dissolved species in the shallow unconfined aquifer. NO3- was found to be persistent in column, tank and field experiments, due to limited availability of organic substrates needed for denitrification processes. The comparison between laboratory transport experiments and the field site monitoring highlighted the role of permeability distribution in defining clean up times, with silt and clay lenses that hamper groundwater flux and provide a continuous source of nitrogen via diffusion. This study confirms that laboratory experiments can give a good representation of the redox processes undergone by nitrogen species in saturated conditions, but despite of this, laboratory experiments should not only account for 1-D flow and transport processes, but also for 3-D flow field.
LOS indices (abbr. of Losses) can be used for the assessment of the intrinsic vulnerability of ag... more LOS indices (abbr. of Losses) can be used for the assessment of the intrinsic vulnerability of agricultural land to water and nitrogen losses through percolation and runoff. The indices were applied on the lowland region of Ferrara Province (FP) in Italy and the upland region of Sarigkiol Basin (SB) in Greece. The most vulnerable zones in FP were the coastal areas consisting of high permeability sandy dunes and the areas close to riverbanks and palaeochannels, and in SB were the areas characterized by high slopes and high permeability soils at high altitude and areas belonging to the upper part of the alluvial plain close to the boundaries between agricultural land and mountainous regions. The application of LOS indices highlighted the specific features of both lowland and upland regions that contribute to water and nitrogen losses and showed their ability for use as tools in designing environmental management plans.
In order to identify the dominant processes affecting nitrate leaching in the Po River Delta area... more In order to identify the dominant processes affecting nitrate leaching in the Po River Delta area, field tests were
performed to determine the fate and transport of nitrogen species. Nitrogen (urea) was applied at a rate of 300
kg-N/ha/y, in both a sandy and a silty loamy sites cultivated with maize; the sandy soil was amended with
chicken manure (700 kg/ha), while the silty loamy soil never received chicken manure amendment. Each field
site was equipped with soil moisture probes, suction cups and piezometers to quantify the presence of nitrogen
and carbon dissolved species in the subsurface. Nitrate leaching was observed in the silty loamy soil, while in the
sandy soil the elevated dissolved organic matter, resulting from chicken manure decomposition, prevented the
nitrate migration towards the aquifer. Results highlight the reliability of increasing the labile organic matter in
the more permeable and intrinsically vulnerable sandy soil to prevent nitrate leaking.
A set of indices (LOS), based on a deterministic approach and regression
analysis were used to a... more A set of indices (LOS), based on a deterministic approach and regression
analysis were used to assess intrinsic and specific vulnerability to nitrates in
Ferrara Province, in northern Italy. To calibrate the LOS indices, using multiple
regression analysis, the simulation results of GLEAMS model for combinations of
different soil properties, topography and climatic conditions of a reference fieldcrop
were used as “observed values”. Results of model were introduced in a GIS
environment to obtain the vulnerability maps. Maps of water and nitrogen losses
under the root zone (LOSW-P and LOSN-PN respectively) were used to obtain the
map of relative concentration of percolated water (RCPW). Data on individual
crops were used to calculate specific crop evapotranspiration rates (ETc) from potential
evapotranspiration (PE). ETc values replaced PE values in the indices, to
obtain both specific vulnerability map for water and nitrogen losses under the root
zone (LOSW-P mod; LOSN-PN mod) and for relative nitrogen concentration of
percolated water (RCPW mod). The RCPW mod map shows that concentration of
nitrogen losses under the root zone is under water drinking limit of 50 mg/L
(WFD; 2006/118/EC) all over the territory with highest concentrations along small
areas of the coastal zone, where sandy textured soil are present (coastal dunes) and
lowest concentrations where ETc is higher.
The study was conducted in Ferrara Province (Italy), a lowland area
covering 2636 km2, located i... more The study was conducted in Ferrara Province (Italy), a lowland area
covering 2636 km2, located in the southern part of the Po River Delta. It is an intensively
cultivated area, with more than 50% of land cultivated with winter cereals
(32.11%) and maize (22.63%). The main nitrogen fertilizer used in this area is
synthetic urea which is suspected to cause nitrate leaching towards shallow
groundwater. A network of 56 piezometers, homogeneously distributed throughout
the whole area, was installed in order to monitor both water table fluctuations
and nitrogen species distributions in the shallow aquifer, over time. Data collected
at the end of November 2010 were used to obtain maps of water table, urea
(CO(NH2)2), ammonium (NH4
+), nitrate (NO3
-) and nitrite (NO2
-) distributions.
Maps show an accumulation of NH4
+ overlapping a stagnant zone, where drained
peaty soils are present. The peaty soils are characterized by a pH ranging between
moderately acid and slightly acid, and by high values of organic matter content.
Along the drainage line induced by peaty soils dewatering, the flow velocity is
very low or almost motionless, determining anaerobic conditions. Instead, the
largest accumulation NO3
- is observed in the Eastern part of the province, where
the groundwater head gradient is higher and soils are characterized by values of
pH that range between 8.1 and 8.3, providing the best conditions for nitrification
processes.
A large tank (4x8x1.4 m), equipped with 26 standard piezometers and
six temperature loggers with... more A large tank (4x8x1.4 m), equipped with 26 standard piezometers and
six temperature loggers with four channels each installed at different depth, is
used to carry out thermal monitoring test and investigate environmental impact of
heat borehole exchange. Loamy sediments (35 m3), used to fill the tank, were excavated
from an unconfined alluvial aquifer near Ferrara (Northern Italy). To evaluate
spatial heterogeneity, the tank’s filling material was characterized via slug
tests and grain size distribution analysis. Constant heat input rate test was conducted
by originating a heat plume using a groundwater heat exchanger (GHE).
Temperature was monitored in continuous via data loggers. The effect of heat borehole
exchange was small compared with the temperature applied. Results show
a heat flux dominated by temperature gradient and thermal conduction. The effect
of hydraulic conductivity heterogeneity on heat plume development is discussed.
Tank model presented in this research looks to be suitable for heat transport modeling.
Recommendations for future development of the research and future
groundwater and heat transport modeling are also reported.
Nitrate leaching from agricultural lands is a worldwide concern, and in Europe, a large part of f... more Nitrate leaching from agricultural lands is a worldwide concern, and in Europe, a large part of farmed
areas is affected by nitrate pollution since decades. A comprehensive case study is given by the Pianura
Padana lowland (Northern Italy), an intensively exploited area, which partly has been already declared
vulnerable to nitrate from agricultural sources (WFD; 2000/60 CE). Although groundwater nitrate
contamination is a well-known phenomenon, the key factors governing N transport and transformations,
through the vadose zone to the water table, are far from being fully clarified. In order to untangle the
complexity of the processes affecting nitrate leaching and define good fertilization practices, dedicated
also to groundwater protection, it is crucial to pick a representative case study and apply a clear rationale
and a stepwise approach on it. That is, first to perform a well-designed and continuous monitoring of
physical and chemical parameters dedicated to properly estimate cumulative infiltration, which is an
important parameter, especially in lowlands were the run-off is minimal. Besides, tracer tests have to
be used to quantify the field velocity and the dispersion coefficient to determine the conservative mass
transfer. As second step, parallel tests on other relevant soil parameters have to be conducted at different
scales in a laboratory controlled environment (e.g. batch test leaking, 1D columns elution and 3D tank
experiments) in order to gain the necessary flow and transport parameters for the quantification of the
reactive mass transfer. Finally, a numerical assessment via forward and inverse modelling, based on the
achieved parameters, can be performed to quantify indirectly other biological functions that are involved
in the complex fate of nitrogen species and nitrate. The presented results follow the proposed stepwise
approach and end up with some practical operative guidelines transferred into agricultural practice for the
reduction of nitrate pollution.
The integrated use of hydrogeologic, geochemical and isotopic approaches has been adopted in a co... more The integrated use of hydrogeologic, geochemical and isotopic approaches has been adopted in a coastal aquifer (Comacchio, Fe, Italy) for fingerprinting NH4+, NO3- and SO42- sources and processes that affect these compounds in groundwater. The study area, recently reclaimed, is characterized by a flat topography mainly below the sea level. A drainage system maintains the lowland dry, causing a vertical head gradient. The floodplain is interested by intensive agriculture, saltwater intrusion, land subsidence and soil salinization. Water isotopes highlight the mixing between freshwater and saltwater, confirming that the hyper salinity detected in the phreatic aquifer’s deep part (ADP) derives from evaporated palaeo-seawater. According to the dominant reducing environment and to the groundwater concentration profiles, the most abundant form of N is NH4+. The highest NH4+ concentrations, which increase with depth, have been detected in the ADP. NO3- is present at low concentrations in t...
The aim of this study is to examine the distribution of major anions and inorganic N species in t... more The aim of this study is to examine the distribution of major anions and inorganic N species in the unconfined aquifer of recently reclaimed wetlands of the Po River coastal floodplain (Northern Italy). The area is intensively cultivated; water is derived by gravity from the Po River and distributed by an extended hydrological network. Most of the territory lays below the sea level, with an altitude ranging from 5 to - 11 m above sea level (a.s.l.). In these special terrains, the drainage action created a new unconfined aquifer where the depth of the water table (and the related capillary fringe) is extremely superficial. Soluble salts, accumulated in the sediments before reclamation, are the source of groundwater salinity. For this study, an agricultural field of ca. 6 ha next to Codigoro town (45°50’33’’N and 12°05’40’’E) was chosen as experimental site for the ongoing LIFE project: ZeoLIFE - Water pollution reduction and water saving using a natural zeolitite cycle (LIFE+10 ENV/I...
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porzioni delle province di Ferrara, Mantova e Bondeno.
La ricerca è stata possibile grazie al reperimento di dati provenienti dalle stratigrafie dei pozzi profondi esistenti e da studi
precedenti effettuati dalla Regione Emilia Romagna, dalla Provincia di Ferrara, dal Comune di Bondeno e dalla ditta esercente la
cava di Settepolesini presso Bondeno (FE). Dai dati e dalle misure raccolte si è cercato di ricavare e proporre un modello
idrogeologico concettuale del sottosuolo che è poi sfociato in un modello numerico del flusso idrico sotterraneo (MODFLOW 2000).
Inizialmente il grado di calibrazione di tale simulazione risultava scarso per cui sono state avanzate diverse ipotesi per cercare di
migliorare il modello concettuale di riferimento. Una di queste ipotesi consisteva nel supporre la presenza di uno spartiacque
piezometrico subparallelo al fiume Po dovuto alla coalescenza tra gli acquiferi A1 ed A2. Per testare tale ipotesi è stato quindi
definito un piano di campionamento e di analisi che ha previsto il prelievo di campioni d’acqua presenti in 6 piezometri ubicati
nell’area d’indagine. Sulla base dei dati idrogeochimici ottenuti è stato realizzato un modello numerico di trasporto non reattivo in
regime stazionario, tramite il software MT3D-MS, che ha permesso di confermare la risalita di acque salate verso l’acquifero A1.
The total concentration of trace elements within the aquifer matrix was higher in the fine sediments, since usually these elements concentrate in the clay fraction, while the concentration in groundwater generally increased with the ionic strength of the solution. The increase of salinity in conjunction with a high content in carbonates stimulated a release of Pb and Zn, suggesting surface complexation on carbonate and dolomite minerals. The elevated organic carbon content of the sediments induced reducing conditions throughout the aquifer, which further promoted trace elements dissolution. The only exceptions were V and As that did not followed this trend, most probably released by peaty layers and fertilizers leaching.
systematic geochemical and isotopic investigations of its water are rare and were never
reported for the whole basin. The present contribution aims to fill this knowledge gap,
reporting a comprehensive data set including oxygen and hydrogen stable isotopes as well
as major and trace element concentration of dissolved species for 54 Po river water
samples, mainly collected in different hydrological conditions (peak discharge in April, ...
porzioni delle province di Ferrara, Mantova e Bondeno.
La ricerca è stata possibile grazie al reperimento di dati provenienti dalle stratigrafie dei pozzi profondi esistenti e da studi
precedenti effettuati dalla Regione Emilia Romagna, dalla Provincia di Ferrara, dal Comune di Bondeno e dalla ditta esercente la
cava di Settepolesini presso Bondeno (FE). Dai dati e dalle misure raccolte si è cercato di ricavare e proporre un modello
idrogeologico concettuale del sottosuolo che è poi sfociato in un modello numerico del flusso idrico sotterraneo (MODFLOW 2000).
Inizialmente il grado di calibrazione di tale simulazione risultava scarso per cui sono state avanzate diverse ipotesi per cercare di
migliorare il modello concettuale di riferimento. Una di queste ipotesi consisteva nel supporre la presenza di uno spartiacque
piezometrico subparallelo al fiume Po dovuto alla coalescenza tra gli acquiferi A1 ed A2. Per testare tale ipotesi è stato quindi
definito un piano di campionamento e di analisi che ha previsto il prelievo di campioni d’acqua presenti in 6 piezometri ubicati
nell’area d’indagine. Sulla base dei dati idrogeochimici ottenuti è stato realizzato un modello numerico di trasporto non reattivo in
regime stazionario, tramite il software MT3D-MS, che ha permesso di confermare la risalita di acque salate verso l’acquifero A1.
The total concentration of trace elements within the aquifer matrix was higher in the fine sediments, since usually these elements concentrate in the clay fraction, while the concentration in groundwater generally increased with the ionic strength of the solution. The increase of salinity in conjunction with a high content in carbonates stimulated a release of Pb and Zn, suggesting surface complexation on carbonate and dolomite minerals. The elevated organic carbon content of the sediments induced reducing conditions throughout the aquifer, which further promoted trace elements dissolution. The only exceptions were V and As that did not followed this trend, most probably released by peaty layers and fertilizers leaching.
systematic geochemical and isotopic investigations of its water are rare and were never
reported for the whole basin. The present contribution aims to fill this knowledge gap,
reporting a comprehensive data set including oxygen and hydrogen stable isotopes as well
as major and trace element concentration of dissolved species for 54 Po river water
samples, mainly collected in different hydrological conditions (peak discharge in April, ...
performed to determine the fate and transport of nitrogen species. Nitrogen (urea) was applied at a rate of 300
kg-N/ha/y, in both a sandy and a silty loamy sites cultivated with maize; the sandy soil was amended with
chicken manure (700 kg/ha), while the silty loamy soil never received chicken manure amendment. Each field
site was equipped with soil moisture probes, suction cups and piezometers to quantify the presence of nitrogen
and carbon dissolved species in the subsurface. Nitrate leaching was observed in the silty loamy soil, while in the
sandy soil the elevated dissolved organic matter, resulting from chicken manure decomposition, prevented the
nitrate migration towards the aquifer. Results highlight the reliability of increasing the labile organic matter in
the more permeable and intrinsically vulnerable sandy soil to prevent nitrate leaking.
analysis were used to assess intrinsic and specific vulnerability to nitrates in
Ferrara Province, in northern Italy. To calibrate the LOS indices, using multiple
regression analysis, the simulation results of GLEAMS model for combinations of
different soil properties, topography and climatic conditions of a reference fieldcrop
were used as “observed values”. Results of model were introduced in a GIS
environment to obtain the vulnerability maps. Maps of water and nitrogen losses
under the root zone (LOSW-P and LOSN-PN respectively) were used to obtain the
map of relative concentration of percolated water (RCPW). Data on individual
crops were used to calculate specific crop evapotranspiration rates (ETc) from potential
evapotranspiration (PE). ETc values replaced PE values in the indices, to
obtain both specific vulnerability map for water and nitrogen losses under the root
zone (LOSW-P mod; LOSN-PN mod) and for relative nitrogen concentration of
percolated water (RCPW mod). The RCPW mod map shows that concentration of
nitrogen losses under the root zone is under water drinking limit of 50 mg/L
(WFD; 2006/118/EC) all over the territory with highest concentrations along small
areas of the coastal zone, where sandy textured soil are present (coastal dunes) and
lowest concentrations where ETc is higher.
covering 2636 km2, located in the southern part of the Po River Delta. It is an intensively
cultivated area, with more than 50% of land cultivated with winter cereals
(32.11%) and maize (22.63%). The main nitrogen fertilizer used in this area is
synthetic urea which is suspected to cause nitrate leaching towards shallow
groundwater. A network of 56 piezometers, homogeneously distributed throughout
the whole area, was installed in order to monitor both water table fluctuations
and nitrogen species distributions in the shallow aquifer, over time. Data collected
at the end of November 2010 were used to obtain maps of water table, urea
(CO(NH2)2), ammonium (NH4
+), nitrate (NO3
-) and nitrite (NO2
-) distributions.
Maps show an accumulation of NH4
+ overlapping a stagnant zone, where drained
peaty soils are present. The peaty soils are characterized by a pH ranging between
moderately acid and slightly acid, and by high values of organic matter content.
Along the drainage line induced by peaty soils dewatering, the flow velocity is
very low or almost motionless, determining anaerobic conditions. Instead, the
largest accumulation NO3
- is observed in the Eastern part of the province, where
the groundwater head gradient is higher and soils are characterized by values of
pH that range between 8.1 and 8.3, providing the best conditions for nitrification
processes.
six temperature loggers with four channels each installed at different depth, is
used to carry out thermal monitoring test and investigate environmental impact of
heat borehole exchange. Loamy sediments (35 m3), used to fill the tank, were excavated
from an unconfined alluvial aquifer near Ferrara (Northern Italy). To evaluate
spatial heterogeneity, the tank’s filling material was characterized via slug
tests and grain size distribution analysis. Constant heat input rate test was conducted
by originating a heat plume using a groundwater heat exchanger (GHE).
Temperature was monitored in continuous via data loggers. The effect of heat borehole
exchange was small compared with the temperature applied. Results show
a heat flux dominated by temperature gradient and thermal conduction. The effect
of hydraulic conductivity heterogeneity on heat plume development is discussed.
Tank model presented in this research looks to be suitable for heat transport modeling.
Recommendations for future development of the research and future
groundwater and heat transport modeling are also reported.
areas is affected by nitrate pollution since decades. A comprehensive case study is given by the Pianura
Padana lowland (Northern Italy), an intensively exploited area, which partly has been already declared
vulnerable to nitrate from agricultural sources (WFD; 2000/60 CE). Although groundwater nitrate
contamination is a well-known phenomenon, the key factors governing N transport and transformations,
through the vadose zone to the water table, are far from being fully clarified. In order to untangle the
complexity of the processes affecting nitrate leaching and define good fertilization practices, dedicated
also to groundwater protection, it is crucial to pick a representative case study and apply a clear rationale
and a stepwise approach on it. That is, first to perform a well-designed and continuous monitoring of
physical and chemical parameters dedicated to properly estimate cumulative infiltration, which is an
important parameter, especially in lowlands were the run-off is minimal. Besides, tracer tests have to
be used to quantify the field velocity and the dispersion coefficient to determine the conservative mass
transfer. As second step, parallel tests on other relevant soil parameters have to be conducted at different
scales in a laboratory controlled environment (e.g. batch test leaking, 1D columns elution and 3D tank
experiments) in order to gain the necessary flow and transport parameters for the quantification of the
reactive mass transfer. Finally, a numerical assessment via forward and inverse modelling, based on the
achieved parameters, can be performed to quantify indirectly other biological functions that are involved
in the complex fate of nitrogen species and nitrate. The presented results follow the proposed stepwise
approach and end up with some practical operative guidelines transferred into agricultural practice for the
reduction of nitrate pollution.