Towards an ecosystem service-based method to quantify the filtration services of mussels under chemical exposure.

As filter-feeders, freshwater mussels provide the ecosystem service (ES) of biofiltration. Chemical pollution may impinge on the provisioning of mussels' filtration services. However, few attempts have been made to estimate the impacts of chemical mixtures on mussels' filtration capacities in the field, nor to assess the economic benefits of mussel-provided filtration services for humans. The aim of the study was to derive and to apply a methodology for quantifying the economic benefits of mussel filtration services in relation to chemical mixture exposure. To this end, we first applied the bootstrapping approach to quantify the filtration capacity of dreissenid mussels when exposed to metal mixtures in the Rhine and Meuse Rivers in the Netherlands. Subsequently, we applied the value transfer method to quantify the economic benefits of mussel filtration services to surface water-dependent drinking water companies. The average mixture filtration inhibition (filtration rate reduction due to exposure to metal mixtures) to dreissenids was estimated to be <1% in the Rhine and Meuse Rivers based on the measured metal concentrations from 1999 to 2017. On average, dreissenids on groynes were estimated to filter the highest percentage of river discharge in the Nederrijn-Lek River (9.1%) and the lowest in the Waal River (0.1%). We estimated that dreissenid filtration services would save 110-12,000 euros/million m3 for drinking water production when abstracting raw water at the end of respective rivers. Economic benefits increased over time due to metal emission reduction. This study presents a novel methodology for quantifying the economic benefits of mussel filtration services associated with chemical pollution, which is understandable to policymakers. The derived approach could potentially serve as a blueprint for developing methods in examining the economic value of other filter-feeders exposed to other chemicals and environmental stressors. We explicitly discuss the uncertainties for further development and application of the method.

The Impact of Climate Change on Metal Transport in a Lowland Catchment.

This study investigates the impact of future climate change on heavy metal (i.e., Cd and Zn) transport from soils to surface waters in a contaminated lowland catchment. The WALRUS hydrological model is employed in a semi-distributed manner to simulate current and future hydrological fluxes in the Dommel catchment in the Netherlands. The model is forced with climate change projections and the simulated fluxes are used as input to a metal transport model that simulates heavy metal concentrations and loads in quickflow and baseflow pathways. Metal transport is simulated under baseline climate ("2000-2010") and future climate ("2090-2099") conditions including scenarios for no climate change and climate change. The outcomes show an increase in Cd and Zn loads and the mean flux-weighted Cd and Zn concentrations in the discharged runoff, which is attributed to breakthrough of heavy metals from the soil system. Due to climate change, runoff enhances and leaching is accelerated, resulting in enhanced Cd and Zn loads. Mean flux-weighted concentrations in the discharged runoff increase during early summer and decrease during late summer and early autumn under the most extreme scenario of climate change. The results of this study provide improved understanding on the processes responsible for future changes in heavy metal contamination in lowland catchments.

Climate change impact on infection risks during bathing downstream of sewage emissions from CSOs or WWTPs.

Climate change is expected to influence infection risks while bathing downstream of sewage emissions from combined sewage overflows (CSOs) or waste water treatment plants (WWTPs) due to changes in pathogen influx, rising temperatures and changing flow rates of the receiving waters. In this study, climate change impacts on the surface water concentrations of Campylobacter, Cryptosporidium and norovirus originating from sewage were modelled. Quantitative microbial risk assessment (QMRA) was used to assess changes in risks of infection. In general, infection risks downstream of WWTPs are higher than downstream CSOs. Even though model outputs show an increase in CSO influxes, in combination with changes in pathogen survival, dilution within the sewage system and bathing behaviour, the effects on the infection risks are limited. However, a decrease in dilution capacity of surface waters could have significant impact on the infection risks of relatively stable pathogens like Cryptosporidium and norovirus. Overall, average risks are found to be higher downstream WWTPs compared to CSOs. Especially with regard to decreased flow rates, adaptation measures on treatment at WWTPs may be more beneficial for human health than decreasing CSO events.

A novel approach in calculating site-specific aftercare completion criteria for landfills in The Netherlands: Policy developments.

As part of a more circular economy, current attention on waste is shifting from landfilling towards the prevention, re-use and recycling of waste materials. Although the need for landfills is decreasing, there are many landfills around the world that are still operational or at the point of starting the aftercare period. With traditional aftercare management, these landfills require perpetual aftercare at considerable cost due to monitoring and regular maintenance of liners. In an attempt to lower these aftercare costs, and to prevent that future generations become responsible for finding a sustainable solution of present day waste, the Dutch government takes action to explore the possibilities of sustainable landfill management. A project was started to investigate whether the use of source-oriented treatment techniques (so-called active treatment) of landfills can result in a sustainable emission reduction to soil and groundwater. During the next decade, sustainable landfill management is tested at three selected pilot landfills in the Netherlands. To enable this pilot testing and to determine its success after the experimental treatment period, a new methodology and conceptual framework was developed. The aim of this paper is to describe the development of the new methodology, and in particular the policy decisions, needed to determine whether the pilot experiments will be successful. The pilot projects are considered successful when the concentrations in the leachate of the pilot landfills have sufficiently been reduced and for longer periods of time and comply with the derived site-specific Environmental Protection Criteria (EPC). In that case, aftercare can be reduced, and it can be determined whether sustainable landfill management is economically feasible for further implementation.

Effect of climate change on runoff of Campylobacter and Cryptosporidium from land to surface water.

Faeces originating from wildlife, domestic animals or manure-fertilized fields, is considered an important source of zoonotic pathogens to which people may be exposed by, for instance, bathing or drinking-water consumption. An increase in runoff, and associated wash-off of animal faeces from fields, is assumed to contribute to the increase of disease outbreaks during periods of high precipitation. Climate change is expected to increase winter precipitation and extreme precipitation events during summer, but has simultaneously also other effects such as temperature rise and changes in evapotranspiration. The question is to what extent the combination of these effects influence the input of zoonotic pathogens to the surface waters. To quantitatively analyse the impacts of climate change on pathogen runoff, pathogen concentrations reaching surface waters through runoff were calculated by combining an input model for catchment pathogen loads with the Wageningen Lowland Runoff Simulator (WALRUS). Runoff of Cryptosporidium and Campylobacter was evaluated under different climate change scenarios and by applying different scenarios for sources of faecal pollution in the catchments, namely dairy cows and geese and manure fertilization. Model evaluation of these scenarios shows that climate change has little overall impact on runoff of Campylobacter and Cryptosporidium from land to the surface waters. Even though individual processes like runoff fluxes, pathogen release and dilution are affected, either positively or negatively, the net effect on the pathogen concentration in surface waters and consequently also on infection risks through recreation seems limited.

Effect of Climate Change on the Concentration and Associated Risks of Vibrio Spp. in Dutch Recreational Waters.

Currently, the number of reported cases of recreational- water-related Vibrio illness in the Netherlands is low. However, a notable higher incidence of Vibrio infections has been observed in warm summers. In the future, such warm summers are expected to occur more often, resulting in enhanced water temperatures favoring Vibrio growth. Quantitative information on the increase in concentration of Vibrio spp. in recreational water under climate change scenarios is lacking. In this study, data on occurrence of Vibrio spp. at six different bathing sites in the Netherlands (2009-2012) were used to derive an empirical formula to predict the Vibrio concentration as a function of temperature, salinity, and pH. This formula was used to predict the effects of increased temperatures in climate change scenarios on Vibrio concentrations. For Vibrio parahaemolyticus, changes in illness risks associated with the changed concentrations were calculated as well. For an average temperature increase of 3.7 °C, these illness risks were calculated to be two to three times higher than in the current situation. Current illness risks were, varying per location, on average between 10(-4) and 10(-2) per person for an entire summer. In situations where water temperatures reached maximum values, illness risks are estimated to be up to 10(-2) and 10(-1) . If such extreme situations occur more often during future summers, increased numbers of ill bathers or bathing-water-related illness outbreaks may be expected.

Direct and indirect effects of climate change on the risk of infection by water-transmitted pathogens.

Climate change is likely to affect the infectious disease burden from exposure to pathogens in water used for drinking and recreation. Effective intervention measures require quantification of impacts of climate change on the distribution of pathogens in the environment and their potential effects on human health. Objectives of this systematic review were to summarize current knowledge available to estimate how climate change may directly and indirectly affect infection risks due to Campylobacter, Cryptosporidium, norovirus, and Vibrio. Secondary objectives were to prioritize natural processes and interactions that are susceptible to climate change and to identify knowledge gaps. Search strategies were determined based on a conceptual model and scenarios with the main emphasis on The Netherlands. The literature search resulted in a large quantity of publications on climate variables affecting pathogen input and behavior in aquatic environments. However, not all processes and pathogens are evenly covered by the literature, and in many cases, the direction of change is still unclear. To make useful predictions of climate change, it is necessary to combine both negative and positive effects. This review provides an overview of the most important effects of climate change on human health and shows the importance of QMRA to quantify the net effects.

Constructing land-use maps of the Netherlands in 2030.

The National Environmental Assessment Agency of the RIVM in the Netherlands is obliged to report on future trends in the environment and nature every 4 years. The last report, Nature Outlook 2, evaluated the effects of four alternative socio-economic and demographic scenarios on nature and the landscape. Spatially detailed land-use maps are needed to assess effects on nature and landscape. The objective of the study presented here was how to create spatially detailed land-use maps of the Netherlands in 2030 using the Environment Explorer, a Cellular Automata-based land-use model to construct land-use maps from four scenarios. One of these is discussed in great detail to show how the maps were constructed from the various scenario elements, story lines and additional data and assumptions on national, regional and local land-use developments. It was the first time in the history of our outlooks that consistent, spatially detailed land-use maps of the Netherlands for 2030 were constructed from national economic and demographic scenarios. Each map represents a direct reflection of model input and assumptions. The maps do not show the most probable developments in the Netherlands but describe the possible change in land use if Dutch society were to develop according to one of the four scenarios. The large (societal) uncertainties are reflected in the total set of future land-use maps. The application of a land-use model such as the Environment Explorer ensures that all relevant aspects of a scenario, i.e. economic and demographic developments, zoning policies and urban growth, are integrated systematically into one consistent framework.