Combining statistical methods for detecting potential outliers in groundwater quality time series

Quality control of large-scale monitoring networks requires the use of automatic procedures to detect potential outliers in an unambiguous and reproducible manner. This paper describes a methodology that combines existing statistical methods to accommodate for the specific characteristics of measurement data obtained from groundwater quality monitoring networks: the measurement series show a large variety of dynamics and often comprise few

Adapting classical water quality diagrams for ecohydrological and policy applications

Ecological values of water have gained increasing attention over the past decades in both (eco)hydrological research and water resources management. Water quality is an important ecological steering variable, and graphical water quality diagrams may aid in rapid interpretation of the hydrochemical status of a site. Traditionally used water quality diagrams for showing multiple variables (e.g. Stiff, Maucha) were developed primarily for hydrogeological purposes, with limited information on ecologically relevant nutrient parameters. This paper presents adapted classical water quality diagrams that retain the traditional information on ions for hydrogeological characterization, and additionally provide information on nutrients for ecological water quality characterization. A scaling factor is used for the minor ions to visually get them across more equally compared to the macro-ion ions in the water quality diagram. Scaling of minor ions is presented based on average concentrations, as well as on water quality policy norms. Four different water quality diagrams are presented, all with the same ions included, but with different appearances to suit different preferences of individual users. Regional, national and continental scale data are used to illustrate how the different diagrams show spatial and temporal water quality characteristics. The adapted diagrams are innovative with respect to adding comprehensive visual information on the four ecohydrologically relevant nutrient species levels (NO3, NH4, PO4, K), advanced insight in redox status from the combination of four redox sensitive parameters (Fe, NO3, SO4, NH4) and the option to scale minor ions relative to average measured concentrations or to water quality policy norms. Using policy norms for scaling has the advantage of providing an ‘alarm function’ of exceedance of norms when concentrations surpass the ring used in the diagram. We discuss possible standardisation of scaling factors to enable comparability between sites

Coupling ANIMO and MT3DMS for 3D regional-scale modeling of nutrient transport in soil and groundwater

We developed an on-line coupling between the 1D/quasi-2D nutrient transport model ANIMO and the 3D groundwater transport model code MT3DMS. ANIMO is a detailed, process-oriented simulation model code for the simulation of nitrate leaching to groundwater, N- and P-loads on surface waters and emissions of greenhouse gasses. It is the leading nutrient fate and transport code in the Netherlands where it is used primarily for the evaluation of fertilization related legislation. In addition, the code is applied frequently in international research projects. MT3DMS is probably the most commonly used groundwater solute transport package worldwide. The on-line model coupling ANIMO-MT3DMS combines the state-of-the-art descriptions of the biogeochemical cycles in ANIMO with the advantages of using a 3D approach for the transport through the saturated domain. These advantages include accounting for regional lateral transport, considering groundwater-surface water interactions more explicitly, and the possibility of using MODFLOW to obtain the flow fields. An additional merit of the on-line coupling concept is that it preserves feedbacks between the saturated and unsaturated zone

Metro Mapping:development of an innovative methodology to co-design care paths to support shared decision making in oncology

Treatment decision-making can be complex, notably when there are multiple treatments available, with different (probabilities of) benefits and harms, for example, survival and side effects.1 It is precisely in these complex situations that the preferences of the patient are of utmost importance, as the trade-offs of benefits and harms are subjective and concern patients' lives.2 In such trade-offs, shared decision making (SDM) has gained momentum as a strategy to include both the best available evidence and the patient's preferences.3</p

Accumulation and transport of atmospherically deposited PFOA and PFOS in undisturbed soils downwind from a fluoropolymers factory

PFOA and PFOS are widely found PFAS components in Dutch topsoils. PFOA was emitted to the atmosphere during 1970-2012 from a fluoropolymers factory, and was deposited mainly within a radius of 50 km. For the first time, detailed concentration-depth profiles of PFOA and PFOS were measured in undisturbed soils downwind of the factory. Three locations were selected with about 3 meters of sand soil and free infiltration of rain. An adjacent peat soil was selected for comparison. In the sand soils, concentration-depth profiles of PFOA showed a distinct bell-shaped pattern with the highest contents at 0.2-0.5 m below surface, and lower contents both at the surface and at further depth (up to 3.5 m below surface). This observation indicates that the highest atmospheric deposition has passed, and that PFOA gradually migrates towards groundwater. Concentrations of PFOS are highest near the surface and reach the detection limit at 1 m below surface, suggesting that its downward migration occurs much slower. HYDRUS was used to model PFAS transport in the vadose zone assuming steady-state infiltration. The PFOA depth profiles in the sand soils can be described assuming plausible historic, atmospheric emission of PFOA from the factory and Koc values within the literature range. However, the retention observed must be attributed to linear partitioning between water and both soil organic matter and the air-water interface. Somewhat stronger retention holds for PFOS, but PFOS cannot originate from the factory in the extent found. An alternative explanation is historic, rather parallel emissions from nearby sources such as waste incinerators. Based on measurements and modelling, this study illustrates that PFOA, and to a lesser extent PFOS, should not be treated as immobile contaminants in topsoil as is currently the case in Dutch soil policy, but rather as mobile contaminants of which the legacy amounts in soil will pollute groundwater for many decades