RESUMO
Nitrogen losses from intensive agricultural production may end up as high nitrate (NO3-) concentrations in groundwater, with a long-term impact on groundwater quality. The main objective of this study was to evaluate the impact of fertilization practices used for grape cultivation on groundwater quality of Tidone Valley, northwest of Italy, following an integrated socio-hydrogeological approach that consists on (i) the involvement of 175 farmers in the description of agricultural and fertilization practices, using a survey of ad hoc questionnaires, (ii) the evaluation of NO3- occurrence in groundwater and (iii) the identification of NO3- sources through isotopic and hydrochemical analysis. In this area, as for certain particular Apennines shallow aquifers, groundwater is of reduced interest due to its limited storage capacity and there are insufficient wells currently monitored by the local Environmental Agency (ARPAE) to evaluate the impact of agricultural fertilization on existing local aquifers. Farmers' questionnaires results highlighted an extensive use of inorganic nitrogen fertilization and a tendency of farmers to follow their own experience for fertilization. Chemical analyses revealed high variability of major and trace elements concentrations isotope data. NO3- concentrations were significantly higher in deeper wells with respects to shallow wells. Isotopic results indicated that groundwater NO3- origin is inorganic, in agreement with the land use and the declared viticultural practices. Comparing groundwater NO3- occurrence from the studied area with values of entire Emilia-Romagna Region, only 7.7% of groundwater samples showed values above the EQS. (50 mg NO3-/L) between Nov 2017 and Sept 2018, while in the entire region 11.5% of groundwater samples showed values above the EQS in the same period. Considering that the vineyards surface in the studied area represents almost 75% of the entire regional vineyard surface, the obtained results suggest a low to moderate impact of viticulture on NO3-concentration of regional groundwater.
RESUMO
In Europe, 25% of groundwater has poor chemical status. One of the main stressors is agriculture, with nitrates and plant protection products (PPPs) causing failure in 18% and 6.5%, respectively, of groundwater bodies (by area). EU legislation for the placement of the PPPs on the market is one of the most stringent in the world. However, recent monitoring studies in hilly vineyards of Tidone Valley, north-west of Italy, show presence of PPPs used for grapevine cultivation in 15 out of 26 groundwater wells monitored, at values above the Environment Quality Standard (EQS) for groundwater (0.1 µg/L). However, no information about the contamination sources are available. Therefore, the objective of the present work is to evaluate the groundwater contamination sources by PPPs, in a small catchment with intensive viticulture, by collecting and integrating monitoring data, sub-surface water movement data and territorial characteristics. The results show that in wells used for PPP's mixture preparation and sprayer washing located at the top of hilly vineyards, with low slope and no water movement in the surrounding soil, the contamination is most likely from point sources. On the contrary, for wells located in a fenced area at the bottom of the hill, far away from vineyards and being used for drinking water production, the contamination is most likely from diffuse sources. Our results were used to raise awareness on groundwater contamination from PPPs among farmers in the study area; moreover a waterproof platform for sprayers washing, equipped with wastewater recovery and disposal system, able to avoid point-source contamination, was implemented in a local demonstration farm. Several demonstration activities were then organised with the farmers of the entire Valley in order to show its functionality and promote its diffuse use.
