Groundwater quality trend and trend reversal assessment in the European Water Framework Directive context: an example with nitrates in Italy.

Groundwater resources are of utmost importance in sustaining water related ecosystems, including humans. The long-lasting impacts from anthropogenic activities require early actions, owing to the natural time lag in groundwater formation and renewal. The European Union (EU) policy, within the implementation of the Water Framework Directive (WFD), requires Member States to identify and reverse any significant and sustained upward trend in the concentration of pollutants, defining specific protection measures to be included in the River Basin Management Plans (RBMP). In Italy, official guidelines for trend and trend reversal assessment have been published recently. Statistical methods, such as the Mann-Kendall test for trend analysis and the Sen's method for estimating concentration scenarios, should be applied at the fixed terms stated by the WFD implementation cycles to identify upward trends, while the Pettitt test is proposed for the identification of trend reversal. In this paper, we present an application of a slightly modified version of the Italian Guidelines to a groundwater body in Northern Italy featuring nitrate pollution and discuss its advantages and limitations. In addition to Pettitt test, for the trend reversal analysis, we apply the Mann-Kendall test in two sections and compare the results. We conclude that this method seems more reliable than Pettitt test to identify a reversal point in quality time series. The overall procedure can be easily applied to any groundwater body defined at risk across Europe, for the assessment of the upward trends of pollutants and their reversal, even with little chemical monitoring data. Although focused on the EU legislative framework, this procedure may be relevant for a wider context, allowing to individuate upward trend as early warning for contamination processes in an integrated water resources management context.

Disentangling natural and anthropogenic impacts on groundwater by hydrogeochemical, isotopic and microbiological data: Hints from a municipal solid waste landfill.

Within human-impacted areas, high levels of inorganic compounds in groundwater are broadly and preventively attributed to local anthropogenic pollution, thoroughly disregarding geogenic natural background levels. Particularly in landfills, a proper evaluation of the significant adverse environmental effects should be completed through a detailed groundwater characterization, and appropriate reference values established prior to landfill onset. However, the monitoring network may lack a full hydrogeological representativeness of the site and of the background conditions of groundwater. This study aimed at disentangling natural and anthropogenic impacts through a synoptic analysis of hydrogeochemical, isotopic and microbiological characteristics of groundwaters from a municipal solid waste landfill area in Central Italy. Samples were collected during four seasonal monitoring surveys from the mostly anoxic aquifer underlying the target area. Field parameters, inorganic and organic compounds, environmental isotopes, faecal contamination, and microbial community characteristics were determined, along with a detailed hydrogeological conceptual model. Key inorganic contaminants (As, Fe and Mn) exceeded the local threshold values in most of the sampling points, while organic contamination was generally very low. Stable isotopes suggested that groundwater originated mainly from local rainfall, except at one monitoring points where tritium levels might indicate moderate impact. Microbiological data and the microbial community characterization, assessed by flow cytometry and BIOLOG assays, provided further supportive information, also highlighting fundamental effects of groundwater quality alterations. Overall, an integrated multi-parametric approach proved suitable to distinguish geogenic and anthropogenic impacts, thus improving strategies and schemes for protection and management of groundwaters in landfills and waste related industrial areas.