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.

Effect of ammonia on the gene expression levels of the freshwater cyclopoid Eucyclops serrulatus.

Ammonia pollution is a critical issue in Europe, since more than half of the European freshwater bodies actually fail to meet EU quality standards for this chemical. In this study, the response of stress-related genes to a sublethal ammonia concentration has been investigated in the adults of the freshwater cyclopoid Eucyclops serrulatus. Two short-term exposures (12h and 24h) at 12mg/L NH4+ have been tested. Results indicate that 12mg/L NH4+ causes a significant increase in the expression of some proteins, namely CAT, HSP90 and HSP40, suggesting an activation of the protecting antioxidant system after both 12h and 24h.