Microbial, chemical, and isotopic monitoring integrated approach to assess potential leachate contamination of groundwater in a karstic aquifer (Apulia, Italy).

Landfill sites are subjected to long-term risks of accidental spill of leachate through the soil and consequential contamination of the groundwater. Wide areas surrounding the landfill can seriously be threatened with possible consequences to human health and the environment. Given the potential impact of different coexisting anthropic pollution sources (i.e., agriculture and cattle farming) on the same site, the perturbation of the groundwater quality may be due to multiple factors. Therefore, it is a challenging issue to correctly establish the pollution source of an aquifer where the landfill is not isolated from other anthropic land uses, especially in the case of a karstic coastal aquifer. The present study is aimed at setting in place an integrated environmental monitoring system that included microbiological, chemical, and isotope methods to evaluate potential groundwater pollution in a landfill district in the south of Italy located in Murgia karstic aquifer. Conventional (microbial plate count and physical-chemical analyses) and advanced methods (PCR-ARISA, isotope analysis of δ18O, δ2H, 3H, δ 13C, δ 15N-NO3-, and δ 18O-NO3-) were included in the study. Through data integration, it was possible to reconstruct a scenario in which agriculture and other human activities along with seawater intrusion in the karst aquifer were the main drivers of groundwater pollution at the monitored site. The microbiological, chemical, and isotope results confirmed the absence of leachate effects on groundwater quality, showing the decisive role of fertilizers as potential nitrate sources. The next goal will be to extend long-term integrated monitoring to other landfill districts, with different geological and hydrogeological characteristics and including different sources of pollution, to support the ecological restoration of landfills.

Coastal hydrogeological system of Mar Piccolo (Taranto, Italy).

The Mar Piccolo basin is an internal sea basin located along the Ionian coast (Southern Italy), and it is surrounded primarily by fractured carbonate karstic environment. Because of the karstic features, the main continental water inflow is from groundwater discharge. The Mar Piccolo basin represents a peculiar and sensitive environment and a social emergency because of sea water and sediment pollution. This pollution appears to be caused by the overlapping effects of dangerous anthropogenic activities, including heavy industries and commercial and navy dockyards. The paper aims to define the contribution of subaerial and submarine coastal springs to the hydrological dynamic equilibrium of this internal sea basin. A general approach was defined, including a hydrogeological basin border assessment to detect inflowing springs, detailed geological and hydrogeological conceptualisation, in situ submarine and subaerial spring measurements, and flow numerical modelling. Multiple sources of data were obtained to define a relevant geodatabase, and it contained information on approximately 2000 wells, located in the study area (1600 km(2)). The conceptualisation of the hydrogeological basin, which is 978 km(2) wide, was supported by a 3D geological model that interpolated 716 stratigraphic logs. The variability in hydraulic conductivity was determined using hundreds of pumping tests. Five surveys were performed to acquire hydro-geochemical data and spring flow-yield measurements; the isotope groundwater age was assessed and used for model validation. The mean annual volume exchanged by the hydrogeological basin was assessed equal to 106.93 10(6) m(3). The numerical modelling permitted an assessment of the mean monthly yield of each spring outflow (surveyed or not), travel time, and main path flow.