Monitoring of the groundwater chemical status in the Azores archipelago (Portugal) in the context of the EU water framework directive

Abstract

A main challenge associated to EU Water Framework Directive corresponds to groundwater monitoring, both quantitative and chemical. The need for monitoring was also stressed by the Azores Water Plan. Monitoring of the chemical status of groundwater in Azores started in 2003 and has been progressively enlarged to all islands, totalizing 72 springs and 32 wells. A large number of parameters are analysed biannually, as major, minor and trace elements, pesticides and total hydrocarbons, as well as microbial indicators. Spring waters are mainly from HCO 3 -Na type; instead water from wells is predominantly from the Cl-Na type, been differences attributed to their respective hydrogeologic framework. Springs discharge mainly from perched-water bodies, been influenced mainly from CO 2 in soils, silicate weathering, and seawater spraying and aerosols. Wells are in basal bodies, therefore subject to seawater intrusion influence, and 9% of Cl analyses made in wells exceed the standard value. Heavy metals, metalloids, hydrocarbons and pesticides all comply with standard values. Agriculture pollution also influences groundwater quality, as revealed by both NO 3 and PO 4 content, been the guide value exceeded respectively in 8 and 9% of the analyses. Despite the discontinuous variation of coliforms over time microbial indicators present an impact on water quality.

A Grey Water Footprint Assessment of Groundwater Chemical Pollution: Case Study in Salento (Southern Italy)

“…Nevertheless, the need for monitoring is also stimulated by Regional Water Plans, as reported by some international studies in other EU areas [39].…”

Nitrates in Groundwater Discharges from the Azores Archipelago: Occurrence and Fluxes to Coastal Waters

“…Surface water and groundwater bodies monitoring is coordinated by the Directorate-Regional for the Environment (Azores Regional Government). The development of the monitoring network was made according to a phased approach, and the criteria for the selection of springs and wells, as well as an insight into the constraints and major achievements, are described in [41,45]. The development of the monitoring programme, as well as a full description of the field and analytical procedures, is presented in [41].…”

“…The development of the monitoring network was made according to a phased approach, and the criteria for the selection of springs and wells, as well as an insight into the constraints and major achievements, are described in [41,45]. The development of the monitoring programme, as well as a full description of the field and analytical procedures, is presented in [41]. The studied springs are mainly located between 201 and 400 m above sea level (asl) (51.2%), but are spread along a wider altitudinal range ( Figure 3A): 6.4% of the springs discharge below 100 m asl, while 7.7% are located at an altitude higher than 700 m asl.…”

“…From this plot, it is possible to show a group of samples that present a NO3-enrichment (springs 3,15,26,28,41,43,48,53) …”

“…Accordingly, the 2015-2021 Azores River Basin Management Plan showed that from the 30 coastal water bodies delimited, 89% have an Studies conducted in the Azores archipelago have shown that surface water and groundwater pollution due to agriculture may be a major concern to water authorities. In fact, through both the application of synthetic and organic fertilizers and the leaching of pasture lands, nutrient enrichment in waters occurred, sometimes associated to microbiology pollution, which led to the failure to comply with EU and national water quality regulations [38][39][40][41][42][43]. Due to the hydrogeological setting and nitrogen pollution loads, groundwater pollution risk was also considered a major concern in some areas along the archipelago [44].…”