367 research outputs found
Sull'opportunità della terapia corticostreroidea non sostitutiva nelle sindromi da shock della bovina da latte
No full textMonitoring and Modeling Nitrate Persistence in a Shallow Aquifer
No full textA modeling study on fertilizer by-products fate and transport was performed in an unconfined shallow aquifer equipped with a grid of 13 piezometers. The field site was located in a former agricultural field overlying a river paleochannel near Ferrara (Northern Italy), cultivated with cereals rotation until 2004 and then converted to park. Piezometers were installed in June 2007 and were monitored until June 2009 via pressure transducer data loggers to evaluate the temporal and spatial variation of groundwater heads, while an onsite meteorological station provided data for recharge rate calculations via unsaturated zone modeling. The groundwater composition in June 2007 exhibited elevated nitrate (NO 3- ) and chloride (Cl-) concentrations due to fertilizer leaching from the top soil. The spatial distribution of NO 3- and Cl- was heterogeneous and the concentration decreased during the monitoring period, with NO 3- attenuation (below 10 mg/l) after 650 days. A transient groundwater flow and contaminant transport model was calibrated versus observed heads and NO 3- and Cl- concentrations. Cl- was used as environmental tracer to quantify groundwater flow velocity and it was simulated as a conservative species. NO 3- was treated as a reactive species and denitrification was simulated with a first order degradation rate constant. Model calibration gave a low denitrification rate (2.5e-3 mg-NO 3- /l/d) likely because of prevailing oxic conditions and low concentration of dissolved organic carbon. Scenario modeling was implemented with steady state and variable flow time discretization to identify the mechanism of NO 3- attenuation. It was shown that transient piezometric conditions did not exert a strong control on NO 3- clean up time, while transient recharge rate did, because it is the main source of unpolluted water in the domain. © 2010 Springer Science+Business Media B.V
Scenario Modelling of Climate Change's Impact on Salinization of Coastal Water Resources in Reclaimed Lands
No full textAbstractA numerical model accounting for variable density flow and transport was built up to quantify the actual and future (2050) salinization trends of a coastal aquifer in the Po delta (Northern Italy). SEAWAT 4.0 was employed to model the interaction between the surface drainage system and the underlying aquifer. PEST was employed for inverse parameter calibration using hydraulic heads and groundwater salinities as constraints. The calibrated model was used to predict the behavior of the coastal aquifer 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 irrigation canals dewatering due to salinization of the Po River branches. For each scenario, two sub-scenarios were established to account for the projected local sea level rise. The first three scenarios have only minimal effects on the aquifer salinization, while the fourth forecasts a severe aquifer salinization due to enhanced upward fluxes of saline and hypersaline groundwater. The scenarios quantified the possible future salinization trends of groundwater and could be useful to identify adaptation strategies which allow to better manage water resources of this and similar areas. Results show that the Po delta will experience a significant salinization by 2050 and that the major cause is autonomous salinization via seepage of saline groundwater rather than enhanced salt-water intrusion due to sea level rise. The enhanced autonomous salinization will increase the salt export into the drainage canals that are also employed for irrigation, posing serious treats to the local flourishing agricultural economy
The role of permeability distribution on nitrate fate and transport, in different scale experiments under saturated conditions
No full textA range of laboratory and field experiments has been performed to quantify NO 3 - 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. NO 3 - 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. Copyright © 2011 IAHS Press
Abnormal trace element concentrations in a shallow aquifer belonging to saline reclaimed environments, Codigoro (Italy)
No full textGeogenic trace element (TE) contamination is an upcoming concern. The present study reports the temporal and spatial variation of major ions and TEs in a shallow unconfined aquifer belonging to a complex marsh saline environment reclaimed in modern age and intensively cultivated. The use of intensive depth profiles in five different locations gave insights into groundwater and sediment matrix interactions. Data indicate that the dominant factor involved in determining the spatial variability of TE is the sediment–water interaction, while the temporal variation of TE is due to the organic matter content and to the water table oscillation, which in turn drive the groundwater redox status and the mobilization of some inorganic microconstituents, such as Fe and Mn. Despite that the anthropogenic input of TEs in groundwater from fertilizer sources cannot be undoubtedly ruled out, given the elevated TE background concentrations, the combined use of high-resolution sediment profiles, seasonal groundwater sampling and end-member analyses is a promising procedure to distinguish between anthropogenic metal contamination and geogenic contribution in reclaimed deltaic environments. Finally, this study underlines the need of having a dense piezometer network and to perform several monitoring campaigns to ensure that the temporal and spatial variability could be correctly represented and background values of TE confidently determined
Assessment of the anthropogenic fluoride export in Addis Ababa urban environment (Ethiopia)
No full textProtection of natural waters against excess of fluoride is a priority in the Middle Ethiopian Rift where high concentrations of fluoride occur in groundwater, lakes and hot springs. In recent years, a growing attention has been paid to geogenic sources of fluoride, while anthropogenic sources have been completely disregarded. Ethiopian people are subject to high levels of fluoride intake via food or drinks, resulting in elevated concentrations of fluoride in urine and subsequently in the human slurry waste. In Addis Ababa, 3 millions of people live without a suitable sewage waste collection/treatment facility and the superficial water system of the city often receives untreated domestic and municipal effluents. In this study, the impact of fluoride-rich human slurry on surface waters quality in Addis Ababa was evaluated. Physical-chemical and bacteriological assessments of rivers and shallow groundwater samples were performed. Several samples displayed critical levels of fluoride and faecal coliforms bacteria in the north-western part of the city. When uncontaminated fresh water flowing from the highland travels through the city, it experiences a rapid deterioration because of the interaction with untreated sewage outlets. This was clearly inferred by the combined analysis of water stable isotopes, fluoride and faecal coliforms bacteria. The methodological results of this study could be used to distinguish anthropogenic from geogenic sources of fluoride in urban environments of developing countries, which are often affected by multiple sources of fluoride
Reclamation influence and background geochemistry of neutral saline soils in the Po River Delta Plain (Northern Italy)
No full textReclaimed neutral saline sulphate soils constitute a large part of the eastern part of Po Plain lowlands, where intensive agricultural activities take place. The knowledge of their geochemical features is essential to develop the best management practices capable to preserve this threatened environment. With this aim, three boreholes were drilled in an agricultural field and a typical reclaimed soil profile has been characterized for major and trace element, pH, electrical conductivity, redox conditions and water-soluble anions and ammonium. Statistical analysis (cluster analysis and principal component analysis) has been used to understand the relationship between elements and grain size. The soil profile is characterized by high salinity and high organic matter contents responsible for high chloride, sulphate, and ammonium concentrations. Heavy metal content is naturally high, since Po Plain sediments are the result of ultramafic rocks erosion; in addition, organic matter tends to concentrate heavy metals by adsorption, mainly in peaty horizons. As a consequence of chemical and zootechnical fertilization, high NO3 − contents have been found in the top soil, thus enhancing the risk of nitrate discharge in the water system, especially in relation to extreme climatic events
L'induzione programmata del parto nella scrofa mediante una doppia somministrazione di PGF2 alfa analogo
No full textAttività miocinetica uterina dei liquidi cistici e dei liquidi follicolari di bovine in lattazione.
No full textRevisiting the Priestley-Taylor method for the assessment of reference crop evapotranspiration in Italy
No full textAim of the study is to test the Priestley-Taylor (P-T) method for the assessment of reference crop evapotranspiration ETo in the Italian territory using as a base the ASCE standardized Penman-Monteith method (ASCE). Monthly averages of daily mean climatic data which cover the period 1950-2000 were used in this study. Analysis was performed on the spatial variability of the seasonal difference between ASCE and P-T method using the typical value 1.26 for the advection coefficient apt. The results showed that the surface coverage of the Italian territory, with acceptable ±10% difference using apt=1.26, was 24.9% in Spring, 41.4% in Summer, 34.3% in Autumn and 11.9% in Winter. The recalculation of apt using the ASCE method showed high spatial and temporal variability of the coefficient. Regression analysis showed that more than 90% of the spatial variability of the seasonal apt is explained by the spatial variability of vapour pressure deficit DE (positive correlation). The rate of apt variation per unit DE was found significantly different between seasons and it was negatively correlated to net solar radiation Rn and consequently temperature. The general trends of the apt coefficient led to the conclusion that colder-drier environments due to low net radiation and high vapour pressure deficit tend to increase its values
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