Chiara Marchina

Extremely dry and warm conditions in northern Italy during the year 2015: effects on the Po river water

The presented research highlights relationships between the climatic anomalies that occurred in northern Italy in 2015 and the water system of Po river. We investigated the effect of anomalous high temperature and paucity of meteoric precipitation on the Po river discharge and water geochemistry. The new geochemical data, carried out on river water sampled at Pontelagoscuro (close to the city of Ferrara) and in the delta, have been compared with an extended dataset collected since 2009. The comparison emphasizes that water samples of 2015 were characterized by a high electrical conductivity due to high concentrations of conservative ionic species (e.g. Na, Cl, SO4) and nutrients such as nitrate. Oxygen and hydrogen isotopes, particularly sensitive to the observed climatic changes, reveal in a δ18O-δD diagram evaporative trends (highlighted by displacement from the Meteoric Water Lines) with a magnitude that was not recorded in the last years. The monitoring is currently in progress to develop functions that relate geochemical parameters to the evolving meteo-hydrological conditions.

Geochemical and isotopic analyses on the Po delta water: insights to understand a complex riverine ecosystem

This contribution was preliminarily presented with an oral communication during the “Water Day 2015” conference organized in Rome the 20th of March 2015 by the Accademia Nazionale dei Lincei. It implements a recent paper that studied the Po river water from the Alpine springs toward the Adriatic Sea (Marchina et al. Environ Sci Pollut Res 22, 5184–5203, 2015), specifically focussing on its deltaic part. The new geochemical analyses are useful to evaluate the extent of salinization (due to mixing with sea-water) and to monitor the flux of nutrients that are conveyed by the river toward the coastal environment. The paper also contains oxygen/hydrogen water isotopes that represent a snapshot of the current climatic conditions to be compared with the literature data and with the future composition to set up a hydro-archive that should be updated to evaluate on-going climatic changes. Moreover, the paper reports preliminary nitrogen isotopes composition of Po river water that trace the impact of human activities, to be monitored in the future to understand possible on-going pollutions. We conclude that geochemical researches on Po river should consider with particular attention the delta because it is an extremely fragile ecosystem where biogeochemical variations are more relevant.

Natural and anthropogenic variations in the Po river waters (northern Italy): insights from a multi-isotope approach

ABSTRACT Po is the main Italian river and the δ18O and δ2H of its water reveal a similarity between the current meteoric fingerprint and that of the past represented by groundwater. As concerns the hydrochemisty, the Ca–HCO3 facies remained constant over the last 50 year, and only nitrate significantly increased from less than 1 mg/L to more than 10 mg/L in the 1980s, and then attenuated to a value of 9 mg/L. Coherently, δ13CDIC and δ34SSO4 are compatible with the weathering of the lithologies outcropping in the basin, while extremely variable δ15NNO3 indicates contribution from pollutants released by urban, agricultural and zootechnical activities. This suggests that although the origin of the main constituents of the Po river water is geogenic, anthropogenic contributions are locally significant. Noteworthy, the associated aquifers have the same nitrogen isotopic signature of the Po river, but are characterized by significantly higher NO– 3 concentration. This implies that aquifers’ pollution is not ascribed to inflow of current river water, and that the attenuation of the nitrogen load recorded in the river is not occurring in the aquifers, due to their longer water residence time and delayed recovery from anthropogenic contamination.

Water–Rock Interaction and Lake Hydrochemistry in the Main Ethiopian Rift

This study investigates the halogen budget of the Main Ethiopian Rift (MER) lithologies and water, and on the basis of new laboratory experiments gives insights on the water–rock interaction processes which ultimately mobilize fluoride in the environment. The halogen composition, and in particular, the chloride content of MER lakes is also taken into consideration to evaluate compositional variation occurred during the last 80 years that have to be mainly related evaporative effects. The evaporation trends are also investigated on the basis of new analyses of stable isotopes of oxygen and hydrogen that are compared with those available in the literature since the 1970s. In such complex scenario, although the average annual temperature increased ~1 °C in 30 years, we did not observe systematic trends valid for all the investigated lakes. The record defined for the last 30 years by δ18O–δD denote fluctuations of the climatic parameters with extreme evaporation preceding the year 2005, then declining to more “normal” conditions. The relation between the observed climatic parameters and the water isotopic composition suggests that the study lakes quickly respond to the environmental changes, possibly within one (or two) year(s). We therefore suggest to continue the data acquisition of climatic and hydrochemical parameters in order to implement the existing hydro-archive that could be useful to point out possible environmental changes.