Giuseppe Sappa

Geochemical modeling and multivariate statistical evaluation of trace elements in arsenic contaminated groundwater systems of Viterbo Area, (Central Italy).

Contamination of groundwater by naturally occurring arsenic has recently become a disturbing environmental problem in Viterbo area, Central Italy. Arsenic concentrations in most of the public supply networks exceed the maximum allowable limit of 10 μg/l (WHO) for drinking water. The primary purpose of this paper is to obtain a better understanding of the factors contributing to the high levels of As in water supply networks. This study focuses on (a) the determination of basic hydrochemical characteristics of groundwater, (b) the identification of the major sources and processes controlling the As contamination in public supply networks, (c) to find out possible relationships among the As and other trace elements through principal component analysis (PCA). Groundwater samples from public water supply wells and springs were collected and analysed for physico-chemical parameters and trace elements. Springs and well water samples are predominantly of the Na–HCO3, Na –Ca–HCO3 and Ca–HCO3 types and the highest arsenic concentrations were observed in Na–HCO3 type water. Eh-pH diagrams reveal that H2AsO4− and HAsO42−, As(V) arsenate, are the dominating As species highlighting slightly to moderately oxidizing conditions. Geochemical modeling indicates that arsenic-bearing phases were undersaturated in the groundwater, however most of the samples were saturated with respect to Fe (i.e. magnetite, hematite and goethite) and Al (diaspore and boehmite) oxide and hydroxide minerals. Concentrations of As, Li, B, Co, Sr, Mo, U and Se are highly correlated (r > 0.7) with each other, however in some groundwater samples As show also good correlations (r > 0.5) with Fe and Mn elements reflecting the relationships among the trace elements result from different geochemical processes. Evaluation of the principal component (PCA) analysis and geochemical modeling suggest that the occurrence of As and other trace element concentrations in groundwater are probably derived from (i) weathering and/or dissolution of volcanic source aquifer materials and (ii) adsorption/desorption processes on the Fe and Al oxide and hydroxide minerals.

Multi-temporal mapping of the Caforchio earth flow, southern Italy

We used aerial photos and field observations to produce multi-temporal maps of the Caforchio earth flow from 1954 to 2013. The maps show the distribution of back-tilted surfaces, flank ridges, normal, thrust, and strike-slip faults and, springs, creeks, and ponds. The maps provide a basis for interpreting how geometric and hydrologic constraints influence earth-flow evolution.

A reliable computerized litho-morphometric model for development of 3D maps of Topographic Aggravation Factor (TAF): the cases of East Mountain (Utah, USA) and Port au Prince (Haiti)

A reliability analysis was performed of a model capable of computing Topographic Aggravation Factors (TAF) for real topographic features using a digital elevation model. This model is a module in the SiSeRHMap hybrid model that, by a metamodeling process, computes frequency depending maps (multispectral) of acceleration response taking into account the topographic effect. The model is described by a structure comparable to a series–parallel circuit problem that solves for the response of each given x, y, z map point by scaling the 1D seismic response by the TAF in the frequency domain (each a component of the series circuit). The TAF is dependent on two coupled factors (the parallel components): (1) the 3D shape of the surface and (2) the stiffness of an “equivalent uniform relief”. Reliability analyses were performed on two different areas each characterized by complex topographic features. The first case modelled the East Mountain area (Utah, USA), where a detailed topographic effects study was conducted. A comparison between the TAFs developed in this study and the estimated Median Reference Method and Standard Spectral Ratio results calculated from the recorded ground motions indicated good agreement between the numerical and experimental results. The second case performed a comparison-parametric analysis of two nearby topographic features located in Port-au-Prince, Haiti. For this case, the complete SiSeRHMap model was applied by utilizing stratigraphic and topographic modules. The results clearly confirm the role of the 3D-topographic surface in the seismic site response and the reliability of SiSeRHMap in predicting it.

Climate Change Impacts on Groundwater Active Recharge in Coastal Plain of Dar es Salaam (Tanzania)

This paper presents some early results of the ACC Dar Project (Adapting to Climate Change in Coastal Dar es Salaam), a three-year project co-funded by the European Commission that aims to improve the effectiveness of municipal initiatives for supporting coastal peri-urban populations in their efforts to adapt to the impacts of Climate Change (CC). The present study is focused on changes in groundwater active recharge in Dar es Salaam’s coastal aquifer, which are attributable to two factors: the decrease in precipitation recorded over the last 10 years, and the change in land cover during the same period. To assess the impacts that these factors have had on active groundwater recharge, the hydrogeological inverse budget was applied, introducing new values for the potential infiltration factor. Temporal analysis of climatic and land cover data for the last 10 years reveal a decreasing trend in groundwater availability. Study results therefore indicate that aquifer recharge is directly related to the amount of precipitation that can infiltrate into the soil, which in turn depends on precipitation and land cover.

Environmental Impact of a Motorway Tunnel Project on an Important Karst Aquifer in Southern Latium Region: The Case of Mazzoccolo Spring (Formia, Italy)

Due to the heavy traffic problems in Formia downtown, a motorway project was designed to reduce traffic congestion in the fastly growing city. The proposed motorway passes over one regionally an important karst aquifer feeding Mazzoccolo spring, in the southeast part of Latium Region. This paper deals with the analysis of the most important environmental impacts on this vulnerable karst aquifer and, as a consequence, on groundwater coming out form the Mazzoccolo Spring, which feeds one of the most important drinking water supply network in South Latium Region. A multisystem approach has been applied for vulnerability analysis using SINTACS method. The climatic, topographic, geomorphological and hydrogeological data and field investigations of previous works has been employed. On the other hand, this approach was also evaluated by geochemical and isotope tracers techniques of groundwater samples for the identification of environmental impacts. According to the proposed project, the Motorway tunnel has a significant environmental impact, on the vulnerability of the karst aquifer and hence, on the water supply networks. Thus, based on these analyses the highway investment strategy adapted to Variant of the SS 7 (Appian Way) project should ensure the protection of groundwater resources designing a new variant route avoiding the construction of Mola Mountain tunnel.

Contaminant back-diffusion from low-permeability layers as affected by groundwater velocity: A laboratory investigation by box model and image analysis

Low-permeability lenses represent potential sources of long-term release when filled from contaminant solute through direct contact with dissolved plumes. The redistribution of contaminant from low to high permeability aquifer zones (Back-Diffusion) was studied. Redistribution causes a long plume tail, commonly regarded as one of the main obstacles to effective groundwater remediation. Laboratory tests were performed to reproduce the redistribution process and to investigate the effect of pumping water on the remediation time of these contaminated low-permeability lenses. The test section used is representative of clay/silt lenses (k≈1∗10-10m/s/k≈1∗10-7m/s) in a sand aquifer (k≈1∗10-3m/s). Hence, an image analysis procedure was used to estimate the diffusive flux of contaminant released by these low-permeability zones. The proposed technique was validated performing a mass balance of a lens saturated by a known quantity of tracer. For each test, performed using a different groundwater velocity, the diffusive fluxes of contaminant released by lenses were compared and the remediation times of the low-permeability zones calculated. For each lens, the obtained remediation timeframes were used to define an analytical relation vs groundwater velocity and the coefficients of these relations were matched to grain size of the low-permeability lenses. Results show that an increase of the velocity field is not useful to diminish the total depletion times as the process mainly diffusive. This is significant when the remediation approach relies on pumping technology.

Boron isotopes in groundwater: Evidence from contamination and interaction with terrigenous–evaporitic sequence, east-central Italy

Boron isotope composition was used to identify boron sources in groundwater in the eastern part of central Italy, on the west side of the lower alluvial plane of the Pescara river, a few kilometres from the coastline. This area was characterized by two possible boron sources: human activity and a geogenic source. We collected 10 water samples during two sampling surveys, in October 2015 and February 2016. We conducted chemical analyses to determine major ions, boron concentrations and boron isotope values. The results obtained highlight that the groundwater is characterized by high mineralization with electrical conductivity values that reach 8180 µS/cm. Sodium and chloride are the principal ions, reaching values that exceed 3000 mg/L. Boron values exceed the limit provide by Italian legislation for groundwater (1 mg/L) in many samples, reaching the maximum value of 9630 µg/L during February 2016. The isotope values allow the identification of different sources of boron such as landfill leachate, rock leaching and water–rock interaction with terrigenous–evaporitic sequence. This manuscript highlights that isotope analyses are a powerful tool for monitoring and environmental planning.

Assessment of groundwater quality in the buffer zone of Limpopo National Park, Gaza Province, Southern Mozambique

Many areas in the Southern African Development Community are data-poor and poorly accessible. Water quality assessment in these areas therefore has to rely on the limited available data, coupled with restricted field sampling. This paper documents the first evaluation of the main geochemical processes and impact of anthropogenic and natural sources of contamination on the groundwater quality of the aquifer system used for domestic and agricultural purposes in Limpopo National Park, Gaza Province, Southern Mozambique. Twenty-five groundwater and surface water samples were collected during two field campaigns, one in October 2016 (the end of the arid period) and the other in March 2017 (the end of the wet period). In the field, the researchers analysed chemical–physical parameters such as temperature, pH and EC. In the laboratory, the major ions (boron, Na+, Ca2+, K+, Mg2+) and anions (Cl−, SO42−, NO3−, HCO3−, CO32−) were determined, and almost all groundwater samples fall into the brackish water category. The B/Cl ratio and δ11B concentrations were then measured to better understand the origin of these brackish waters. The direct relationship between boron and chlorine and δ11B concentrations above 40‰ suggests the presence of fossil water in the aquifer. The groundwater in this area was found to be above the limits stated as desirable by the Department of Water and Sanitation (DWS) and the World Health Organisation for domestic and irrigation purposes. The suitability of the groundwater for drinking purposes was also evaluated, with the results indicating that it is not suitable. The values of the sodium absorption ratio, sodium percentage and electrical conductivity show that most of the groundwater samples are also not suitable for agricultural purposes. However, the surface waters have higher quality for both domestic and irrigation purposes. The water of Massingir Lake turns out to be the most suitable resource for a possible rural development plan for the area.

Physical inactivity in Italian Society

The Palo Laziale wood represents one of the few remaining examples of Mediterranean wetland and it was identified as a Site ofCommunity Importance (SCI) according to the European Commission Habitats Directive (92/43/EEC).This paper reports levels of trace elements in wetland waters and possible risk for plants. Eight water points were sampled from private wells and analysed to investigate the distribution and enrichment of heavy metals in groundwater. In particular, Mn, Fe, Ni, Cu, Zn, As and Pb were analysed during four sampling events (from October 2010 to July 2011).The results obtained show similar temporal variation of elements. Mn, Cu, Zn and As show major values during December, while Fe present major value during March. Pb concentration shows a peak during March, probably due a failure in water pipes.

Frequency-dependent topographic seismic amplification using by a gray box model that usesimplementing GIS morphometric data

Topographic seismic amplification can have a relevant effect in hilly and mountain areas and it assumes a relevant role in urban planning and seismic slope instability. On the other hand, recent studies on this topic strongly suggest the necessity to assess or predict topographic effect as a frequency depending variable and in an adequate way, in contrast with the simplistic models that use an inadequate uniform spectral scaling factor. Following this suggestion and taking into account the results of the aforesaid studies, a computerized model was developed based on common topographic attributes such as DTM, slope angle and curvature, taking into consideration the uniform rigidity of the relief. The model is defined as grey box model due to the fact that it is constructed on the awaited physical behaviour along the relief and initially trained on topographic amplified data of uniform regular relief, data product by 2D numerical analysis The validation of model was performed on two well-known areas. The results show a high prediction capacity of the model and how it can be driven for the optimization of performance in different real areas.