Analysis of the geological control on the spatial distribution of potentially toxic concentrations of As and F- in groundwater on a Pan-European scale.

The distribution of the high concentrations of arsenic (As) and fluoride (F-) in groundwater on a Pan-European scale could be explained by the geological European context (lithology and structural faults). To test this hypothesis, seventeen countries and eighteen geological survey organizations (GSOs) have participated in the dataset. The methodology has used the HydroGeoToxicity (HGT) and the Baseline Concentration (BLC) index. The results prove that most of the waters considered in this study are in good conditions for drinking water consumption, in terms of As and/or F- content. A low proportion of the analysed samples present HGT≥ 1 levels (4% and 7% for As and F-, respectively). The spatial distribution of the highest As and/or F- concentrations (via BLC values) has been analysed using GIS tools. The highest values are identified associated with fissured hard rock outcrops (crystalline rocks) or Cenozoic sedimentary zones, where basement fractures seems to have an obvious control on the distribution of maximum concentrations of these elements in groundwaters.

Water governance diversity across Europe: Does legacy generate sticking points in implementing multi-level governance?

The Water Framework Directive (WFD) aims to protect and improve water quality across Europe through an integrative and multi-level water governance approach. The goal is to ensure that water quality in Europe meets good ecological status by 2027. Whilst the WFD has been hailed as a cornerstone for governance innovation in water management, most EU member states (MS) still struggle to achieve good ecological status of their waters. The realignment to a multi-level governance structure under the WFD is discretionary, and has generated diversity in WFD multi-level governance implementation approaches and final governance arrangements across MS. This diversity may contribute to low goal achievement and weak compliance. This paper investigates how visual impressions of legislative structure across nine MS can illustrate and contribute to understanding the differences in multi-level implementation of WFD and associated water protection directives. We explore, in-depth, the drivers of visual differences in Portugal, Germany (Lower Saxony) and France. We hypothesise that many of the challenges of WFD implementation, and resulting governance arrangements can be explained in terms of the legacy effects of previous water governance choices. With this conceptual framework of investigating the history and legacy, we found the three in depth studies have had different starting points, paths, and end points in their water governance, with sticking points influencing the decision-making processes and compliance required by the WFD. Sticking points include the complexity of existing water governance structures, lobbying by different sectors, and the mandatory WFD timeline for implementation. Portugal had to resolve its focus on water infrastructure and engineering to enable a re-focus on water quality. France and Portugal experienced 'top down' governance at different points in time, slowing the shift to a multi-level governance system. Lower Saxony, representing just one of 16 federal state systems in Germany, highlighted the complex historic governance structures which cannot easily be restructured, generating a layering effect where new governance systems are fitted to old governance systems. We conclude that there is a need to implement a hybrid approach to water governance and WFD implementation including decentralisation (discretionary) to ensure collaboration and engagement of stakeholders at the local level. This hybrid governance system should run in parallel with a centralised (mandatory) governance and regulatory system to enable national environmental standards to be set and enforced. Such systems may provide the best of both worlds (bottom-up involvement of stakeholders meeting top-down goal achievements) and is worthy of further research.

Water isotopes and chemical tools for understanding pesticide transfer in a watershed of the volcanic island of Martinique (French West Indies).

Monitoring of water quality over several years has revealed a persistent pesticide contamination of surface and groundwater in several Caribbean Islands, with pesticide concentrations locally over the drinking-water limit set in Europe, i.e. 0.1 µg L-1 per substance. For Martinique, mainly one pesticide, chlordecone (CLD), remains of major concern despite its withdrawal from the market in 1993. Since the first sampling campaign in 1999-2000, time and space variations of CLD concentrations in surface water and groundwater are still not well understood and difficult to correlate with climate, geological or hydrogeological contexts. We carried out a study in the Chalvet catchment (northeast Martinique) in order to understand more precisely how water movements may explain pesticide transfer. Various tools such as δ2H - δ18O and chemical parameters were used. Deuterium excess d was proven relevant for determining how CLD is transported in groundwater; it highlighted the role of the groundwater/surface water interaction in spatial and temporal variability of surface water quality. The resulting conceptual hydrogeological model also helps understanding why CLD still has high concentrations in surface water. The approach proposed here can be used in other Caribbean islands that are poorly equipped for explaining pesticide occurrences in surface waters.

Sorption and mineralization of S-metolachlor and its ionic metabolites in soils and vadose zone solids: consequences on groundwater quality in an alluvial aquifer (Ain Plain, France).

This study characterizes the transfer of S-metolachlor (SMOC) and its metabolites, metolachlor ethane sulfonic acid (MESA) and metolachlor oxanilic acid (MOXA) to the alluvial aquifer. Sorption and mineralization of SMOC and its two ionic metabolites were characterized for cultivated soils and solids from the vadose (unsaturated) zone in the Ain Plain (France). Under sterile soil conditions, the absence of mineralization confirms the importance of biotic processes in SMOC degradation. There is some adsorption and mineralization of the parent molecule and its metabolites in the unsaturated zone, though less than in soils. For soils, the MESA adsorption constant is statistically higher than that of MOXA and the sorption constants of the two metabolites are significantly lower than that of SMOC. After 246 days, for soils, maximums of 26% of the SMOC, 30% of the MESA and 38% of the MOXA were mineralized. This partly explains the presence of these metabolites in the groundwater at concentrations generally higher than those of the parent molecule for MESA, although there is no statistical difference in the mineralization of the 3 molecules. The laboratory results make it possible to explain the field observations made during 27 months of groundwater quality monitoring (monthly sampling frequency). The evolution of both metabolite concentrations in the groundwater is directly related to recharge dynamics; there is a positive correlation between concentrations and the groundwater level. The observed lag of several months between the signals of the parent molecule and those of the metabolites is probably due to greater sorption of the parent molecule than of its metabolites and/or to degradation kinetics.

Investigations of natural attenuation in groundwater near a landfill and implications for landfill post-closure.

The controlled landfill technology is now adopting passive attenuation techniques as an increasing number of landfill sites reach the post-closure phase. During the post-closure phase, landfill operators need to convince environmental authorities that landfills no longer pose a threat to health or the environment. The demonstration of acceptable risk should rely in particular on data collected during environmental monitoring in addition to modelling of possible future evolutions of environmental concentrations. One difficulty that is typically encountered in France is related to the fact that groundwater monitoring systems around landfills are often insufficiently detailed to provide conclusive evidence of natural attenuation mechanisms. This paper presents data on groundwater quality in the vicinity of an old landfill located in a complex aquifer system. While isotopic data show a signature of the landfill leachate in the groundwater in the vicinity of the landfill, chemical analyses do not suggest a strong influence, which could be indicative of natural attenuation mechanisms in the groundwater. However, the complexity of the groundwater system in this area is such that it cannot be excluded that a pollutant flux is being overlooked. Implications of demonstrating natural attenuation during the landfill post-closure phase, with respect to groundwater monitoring, are discussed.

Improving the knowledge of pesticide and nitrate transfer processes using age-dating tools (CFC, SF6, 3H) in a volcanic island (Martinique, French West Indies).

Numerous successful examples of CFC and SF(6) groundwater dating applications were recently published. However the proposed CFC/SF(6) method needs various hydrodynamic parameters that are not always available. In order to predict groundwater-quality trends in areas where the hydrogeological context is poorly known, a dating method using tritium, CFC and SF(6) was successfully implemented in Martinique. Hydrogeological understanding is limited in this volcanic island where groundwater contamination by pesticides and nitrate has been recently proven in various areas. A negative correlation was observed between nitrate concentrations and groundwater ages while pesticide contamination showed a more complex schema. Consequently the presence of old groundwater clearly explained the absence or low pesticide and nitrate concentrations in some areas. However a possible degradation of the water quality is to be feared in the future. In view of the relatively long transfer times and the complexity of the remobilization processes of solutes, the expected effects of any modifications in the use of fertilizers, or of changes in pesticide-use legislation, would take a long time to become apparent.

Isotope methods for management of shared aquifers in northern Africa.

Access to fresh water is one of the major issues of northern and sub-Saharan Africa. The majority of the fresh water used for drinking and irrigation is obtained from large ground water basins where there is minor contemporary recharge and the aquifers cross national borders. These aquifers include the Nubian Aquifer System shared by Chad, Egypt, Libya, and Sudan; the Iullemeden Aquifer System, extending over Niger, Nigeria, Mali, Benin, and Algeria; and the Northwest Sahara Aquifer System shared by Algeria, Libya, and Tunisia. These resources are subject to increased exploitation and may be severely stressed if not managed properly as witnessed already by declining water levels. In order to make appropriate decisions for the sustainable management of these shared water resources, planners and managers in different countries need an improved knowledge base of hydrological information. Three technical cooperation projects related to aquifer systems will be implemented by the International Atomic Energy Agency, in collaboration with the United Nations Educational, Scientific and Cultural Organization and United Nations Development Programme/Global Environmental Facility. These projects focus on isotope hydrology studies to better quantify ground water recharge and dynamics. The multiple isotope approach combining commonly used isotopes 18O and 2H together with more recently developed techniques (chlorofluorocarbons, 36Cl, noble gases) will be applied to improve the conceptual model to study stratification and ground water flows. Moreover, the isotopes will be an important indicator of changes in the aquifer due to water abstraction, and therefore they will assist in the effort to establish a sustainable ground water management.