Assessment of Risk and Social Impact on Groundwater Pollution by Nitrates. Implementation in the Gallocanta Groundwater Body (NE Spain)

Groundwater is an essential resource for humans concerning freshwater supply; therefore, preserving and protecting its quality is necessary. Risk assessment, based on hazard, intrinsic vulnerability information and mapping, may be considered as a key aspect of sustainable groundwater management. An approach has been made by combining the Nitrogen Input Hazard Index and the hydrogeological parameters considered in a modified DRASTIC method. A three-level classification has been used to determine the degree of risk, and the thresholds have been established following measurable criteria related to the potential nitrate concentration in groundwater. The second part of the study focused on estimating the socioeconomic impact of groundwater pollution by relating the degree of risk and social vulnerability to groundwater pollution. The method has been tested in the Gallocanta Groundwater Body (Spain). As a result, a risk map and an impact map are provided. The risk map shows that 67% of the study area can be classified as moderate and high-risk areas, corresponding to high hazard sources located in moderate and high vulnerability zones, whereas the impact of groundwater pollution is classified as moderate in the whole groundwater body. The proposed analysis allows comparison between aquifers in different areas and the results required by water authorities to implement control and mitigation measures.

Unusual catchment runoff in a high alpine karst environment influenced by a complex geological setting (Northern Calcareous Alps, Tyrol, Austria)

Garber Schlag (Q-GS) is one of the major springs of the Karwendel Mountains, Tyrol, Austria. This spring has a unique runoff pattern that is mainly controlled by the tectonic setting. The main aquifer is a moderately karstified and jointed limestone of the Wetterstein Formation that is underlain by nonkarstified limestone of the Reifling Formation, which acts as an aquitard. The aquifer and aquitard of the catchment of spring Q-GS form a large anticline that is bound by a major fault (aquitard) to the north. Discharge of this spring shows strong seasonal variations with three recharge origins, based on δ18O and electrical conductivity values. A clear seasonal trend is observed, caused by the continuously changing portions of water derived from snowmelt, rainfall and groundwater. At the onset of the snowmelt period in May, the discharge is composed mainly of groundwater. During the maximum snowmelt period, the water is dominantly composed of water derived from snowmelt and subordinately from rainfall. During July and August, water derived from snowmelt continuously decreases and water derived from rainfall increases. During September and October, the water released at the spring is mainly derived from groundwater and subordinately from rainfall. The distinct discharge plateau from August to December and the following recession until March is likely related to the large regional groundwater body in the fissured and moderately karstified aquifer of the Wetterstein Formation and the tectonic structures (anticline, major fault). Only a small portion of the water released at spring Q-GS is derived from permafrost.

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.

eNaBLe, an On-Line Tool to Evaluate Natural Background Levels in Groundwater Bodies

Inorganic compounds in groundwater may derive from both natural processes and anthropogenic activities. The assessment of natural background levels (NBLs) is often useful to distinguish these sources. The approaches for the NBLs assessment can be classified as geochemical (e.g., the well-known pre-selection method) or statistical, the latter involving the application of statistical procedures to separate natural and anthropogenic populations. National Guidelines for the NBLs assessment in groundwater have been published in Italy (ISPRA 155/2017), based mainly on the pre-selection method. The Guidelines propose different assessment paths according to the sample size in spatial/temporal dimension and the type of the distribution of the pre-selected dataset, taking also into account the redox conditions of the groundwater body. The obtained NBLs are labelled with a different confidence level in function of number of total observations/monitoring sites, extension of groundwater body and aquifer type (confined or unconfined). To support the implementation of the Guidelines, the on-line tool evaluation of natural background levels (eNaBLe), written in PHP and using MySQL as DBMS (DataBase Management System), has been developed. The main goal of this paper is to describe the functioning of eNaBLe and test the tool on a case study in central Italy. We calculated the NBLs of As, F, Fe and Mn in the southern portion of the Mounts Vulsini groundwater body, within the volcanic province of Latium (Central Italy), also separating the reducing and oxidizing facies. Specific results aside, this study allowed to verify the functioning and possible improvements of the online tool and to identify some criticalities in the procedure NBLs assessment at the groundwater body scale

Spatial Distribution of Integrated Nitrate Reduction across the Unsaturated Zone and the Groundwater Body in Germany

Nitrate pollution in groundwater and its mitigation strategies is currently a topic of controversial debate in Germany, and the demand for harmonised approaches for the implementation of regulations is increasing. Important factors that need to be considered when planning mitigation measures are the nitrogen inputs into water bodies and the natural nitrate reduction capacity. The present study introduces a nationwide, harmonised and simplified approach for estimating nitrate reduction as an integral quantity across the unsaturated zone and the groundwater body. The nitrate reduction rates vary from 0% to 100%, and are on average 57%, with high values in the north of Germany and low values in the south. Hydrogeological characteristics are associated with the estimated nitrate reduction rates, whereby the influence of aquifer type and redox conditions are particularly relevant. The nitrate reduction rates are substantially higher in porous aquifers and under anaerobic conditions than in fractured, consolidated aquifers and under aerobic conditions. This contribution presents a harmonised conceptual approach to derive the nitrate reduction rate at a 1 km × 1 km resolution. This information can be used when planning and designing mitigation measures to meet the groundwater nitrate limits.

The Guarani Aquifer System – from regional reserves to local use

The Guarani Aquifer System is a massive groundwater body underlying large areas of Brazil, Paraguay, Uruguay and Argentina, with a thickness of 50–600 m (averaging about 250 m). It is one of the world's largest sandstone aquifers. The mainly weakly-cemented sandstones were formed by aeolian, fluvial and lacustrine continental deposition during the Triassic–Jurassic period and are overlain by extensive Cretaceous basalt lava-flows. The system is totally storage-dominated, with recharge amounting to only about 0.2% of the estimated 30 000 km3 of water stored. Using 14C and81Kr techniques, it was possible to confirm extremely slow flow rates, with groundwater older than 730 000 years BP in some parts of São Paulo State, Brazil. The vast regional freshwater storage contrasts sharply with localized active flow systems of recharge areas, which are strongly impacted by land-use change. The aquifer is the best known and most exploited in São Paulo State (80% of total extraction) and the experience of groundwater use for the supply of Ribeirão Preto and São José do Rio Preto (both with populations of over 0.5 million), together with one transboundary urban area, will be summarized.Thematic collection: This article is part of the Hydrogeology of Sandstone collection available at: https://www.lyellcollection.org/cc/hydrogeology-of-sandstone

Regulations and guidelines on water quality requirements for Managed Aquifer Recharge. International comparison

Managed Aquifer Recharge (MAR) is a promising set of techniques to cope with a variety of water management-related issues. In recent years MAR implementations have witnessed an expansion and greater social acceptance. Nonetheless, there are still some gaps in the scientific, economic and governance dimensions of MAR which need to be addressed. One of these gaps is the lack in many countries of clear regulations addressing MAR. In this paper eighteen regulations and twelve guidelines on water quality standards from around the world have been reviewed to favour the advancement of the legal framework concerning MAR. The review has demonstrated that the existing MAR regulatory frameworks are implemented at different levels (i.e. from regional to international) and consider different aspects such as planning, permitting and monitoring as well as the risk assessment. Most regulations take into account some of these aspects, but seldom all of them. The detailed study and comparison of the water quality standards enabled to define conclusions regarding the differences in maximum allowable concentrations (MACs). Furthermore, this comparison made visible the different approaches to encompass the variability of MAR systems, and also the natural conditions prevailing in the receiving groundwater body. Based on the review of the selected regulations, their advantages and shortcomings, a series of recommendations are proposed for the development of future legal framework entailing the MAR technique.

Vertical Electrical Sounding Analysis for Local Subsurface Water Bearing Identification Due to Isolated Hill. Case-study: Madurejo Village, Prambanan District, Yogyakarta Province, Indonesia

<p class="AbstractText"><span lang="EN-AU">In a subsurface aquifer, there is a ‘barrier like’ phenomenon that blocks the flow of water. It will create a subsurface water bearing/dam and potential source for water well drilling. The existence of clay-limestone in the isolated hill in Madurejo village, Prambanan district, Yogyakarta seems to act like a natural groundwater body which is interesting to be analyzed by means of vertical electrical sounding (VES). For this purpose, three VES points measured with 150 meters apart, creating a line from south to north. Maximum distance for AB is 200 meters. We found the shallow unconfined from surface to 4 m depth and confined aquifers from 6 m to 29 m. The geometry of the second aquifer in combination with the existence of isolated hill seems to have a water-bearing structure which is very potential for water resources.</span></p>

The VIOLA project: geochemical characterization and natural background levels in a coastal groundwater body of the Apulia Region (southern Italy)

&lt;p&gt;Coastal areas worldwide are often highly impacted due to the concurrence of aquifer exploitation for irrigation, human consumption exacerbated during touristic seasons and industrial activities. In order to meet the objectives of the GWD, European groundwater bodies&amp;#8217; status (chemical and quantitative) is evaluated every 6 years. Criteria for good status include chemicals exceeding standards and threshold values, saline intrusion and others. Apulian region features a very high ratio coastline/area (44 m/km&lt;sup&gt;2&lt;/sup&gt;, for Italy is 25 m/km&lt;sup&gt;2&lt;/sup&gt;) thus seawater intrusion is a very common phenomenon, due to both natural and anthropogenic drivers.&lt;/p&gt;&lt;p&gt;In this contribution, the first results of the VIOLA project (Natural Background Values for the Apulian groundwater bodies) are presented, supplying a preliminary geochemical characterization of the coastal Murgia groundwater body. This is part of a fractured and karstified calcareous-dolomitic aquifer with groundwater naturally flowing to the Adriatic sea. Exceedances were reported for nitrates, as well as for EC, Cl, SO&lt;sub&gt;4&lt;/sub&gt;, Fe, Mn. The main objective for this groundwater body is to assess the natural background levels for the aforementioned parameters, and discriminate between the natural and anthropogenic origin of saline intrusion. Four sampling campaigns have been planned, and we present here the result of the first two sampling rounds carried out in spring and fall 2019.&lt;/p&gt;&lt;p&gt;Groundwater sampling was performed at 47 wells with submergible pumps or with a water depth sampler. Field parameters (T, EC, pH, DO, ORP) were measured with a multiparametric probe in a flow through cell. Ammonia, cyanides and nitrites were measured in the field (UV-VIS). Laboratory analysis were performed for major anions, major cations, minor and trace elements, environmental isotopes, DOC and microbial parameters.&lt;/p&gt;&lt;p&gt;Natural background values (NBLs) for the critical parameters have been provisionally assessed using the preselection method. Sampled waters show neutral/weakly alkaline and mostly oxidizing conditions, with conductivity values between about 700 and 20.000 &amp;#181;S/cm. The high salinity detected in some water points (chlorides up to 10 g/L, sulphates up to 1 g/L) is clearly linked to mixing with seawater. On a Piper diagram, the samples show a clear transition from earth alkaline-bicarbonate water towards mean seawater composition. A clear trend from coastline to inland can be recognized, with the most extended contamination in the northern and southern sectors. Trace elements (B, Sr, Ba), show a similar pattern. From spring (beginning of the irrigation season) to fall (end of the irrigation season) only a slight increase in salinity/chloride concentration can be observed. Nitrates are widespread in the study area, as well as the agricultural pressures, with values even higher than 100 mg/L without a specific spatial pattern.&lt;/p&gt;&lt;p&gt;As for the NBLs derivation, classic indicators of anthropogenic contamination (e.g. nitrates, ammonia, NaCl) for the pre-selection of uninfluenced samples failed, due to the extensive distribution of saline groundwaters in the study area. Thus, new solutions, including environmental isotope analysis, for discriminating the anthropogenic and natural origin of the salinity are under evaluation.&lt;/p&gt;