Modelling emissions of microplastics in Europe from wastewater sources, including land applied biosolids
Public information regarding microplastics in the environment is frequently available and comes from a variety of sources, often in the form of retrospective sources such as measured aquatic data. Science-based risk assessment must utilize both retrospective and prospective exposure information to effectively estimate potential risk to ecological receptors. While monitoring data provide information at only a few locations for several points in time, prospective models can estimate the potential for ecological exposures across many landscapes and over long periods of time, and both have a role in risk assessment. Wastewater treatment plants are often cited as a source of microplastics entering the environment. Microplastics are highly removed (generally >90%) during the waste water treatment process, via skimming of floating particles or sorption to solids and settling into sludge. Understanding the eventual fate of this sludge, and the potential for contained microplastics to re-enter surface water, is one step of many in determining the fate of microplastics in the aquatic environment. Sludge management in Europe varies geographically, with up to 90% of sludge used on agriculture in Portugal, and 0% in other countries (Eurostat, 2017) with other disposal including incineration, landfill or composting. We present a model which addresses both direct aquatic emissions into surface water via waste water effluent, as well as indirectly from land applied biosolids coupled with spatially-defined surface runoff potential. Generalized runoff potential is estimated using fate and transport models used for plant protection products found in the EFSA FOCUS scenarios. To our knowledge, this coupling of direct aquatic emission and sludge-biosolids-runoff is a novel approach for examining environmental emissions of microplastics which enter municipal wastewater treatment plants. This spatially-explicit model is based on publicly available datasets, combined with a hydrologic framework containing geographically variable emissions linked to a river network simulating environmental transport via surface water.
Christopher Holmes, Joshua Amos, Amy Ritter, Marty Williams, and Scott Dyer (Waterborne Environmental). Modelling emissions of microplastics in Europe from wastewater sources, including land applied biosolids. Poster SETAC Europe 2019. Helsinki, Finland.
PresentationsHome and Personal Care Products2019
Using eco-epidemiology to assess the potential risks of UV filters to corals
A recent study in Archives of Environmental Contamination and Toxicology (Downs et al 2016) indicating potential ecotoxicity issues for coral exposed to UV filters, such as benzophenone-3, has gained a global-level of visibility. This single study has provided laboratory evidence that calls into question the sufficiency of environmental risk assessments associated with benzophenone-3 via sunscreen use, particularly for swimmers and sunbathers. For sub-tropical and tropical climates, the potential occurrence for exposure of BP-3 may be year-around. Spatial coincidence of BP-3 exposure and marine ecosystems highly dependent on corals amplifies the potential issues highlighted in the Downs et al study. However, coral reefs have been shown to be adversely affected by numerous other chemical, biological and physical stressors, ranging from local to global scales. Hence, the protection of corals requires a multi-faceted approach that considers not only potential chemicals stressors, but physical stress – including temperature and changes in habitat quality. We advocate the use of eco-epidemiology to evaluate the relationships between environmental stressors and ecological status within a realistic ecological context. This approach supports the recognition that ecosystem status is driven by a multitude of physical, chemical and other environmental factors. Since the foundation of the evaluation relies on measured ecological status, recommendations from such an assessment have great potential for decision-making (including regulations) that will yield fruitful management actions. Our initial analysis utilizes data obtained from experts at the University of Hawaii (e.g., Coral Reef Assessment and Monitoring Program (CRAMP) http://cramp.wcc.hawaii.edu/default.htm). Measured UV filter and surrogate exposure data were collected for the island of Oahu from Mitchelmore et al (2018). To date, published works by the CRAMP experts indicate that both natural and anthropogenic factors may influence coral cover and species richness. Importantly, no single factor has been found to serve as a proxy for coral cover. Hence, it is clear that coral cover and species richness is dependent upon many factors. Based on CRAMP data alone, there appears to be a lack of data supporting the hypothesis that UV filters provide an adverse influence on corals. Our study places into context UV filters amongst several physical and chemical factors that potentially affect coral community health.
Scott Dyer (Waterborne Environmental), Christopher Holmes (Waterborne Environmental), Iain Davies (Personal Care Products Council), and Carys Mitchelmore (UMCES Chesapeake Biological Laboratory). Using eco-epidemiology to assess the potential risks of UV filters to corals.
Platform Presentation SETAC Europe 2019. Helsinki, Finland.
A prospective approach for assessing chemical mixtures in river catchments with diverse land uses
Field-based ecological risk assessments incorporate risks from chemical mixtures and a myriad of stressors because ecosystems are continuously exposed to a wide-array of contaminants and nonchemical stressors. Considering the large numbers potential combinations of mixtures and stressors, this problem could seem insurmountable. We demonstrate that such combinations can be simplified by 3 land-use related chemical emission scenarios: agriculture, domestic, and urban. We applied a tiered methodology to assess the implications of each of the scenarios via a quantitative model. The results showed land use–dependent mixture exposures, clearly discriminating downstream effects of land uses, with unique chemical “signatures” regarding composition, concentration, and temporal patterns. Associated risks were characterized in relation to the land-use scenarios. Comparisons to measured environmental concentrations and predicted impacts showed relatively good similarity. The results suggest that the land uses imply exceedances of regulatory protective environmental quality standards, varying over time in relation to rain events and associated flow and dilution variation. Higher-tier analyses using ecotoxicological effect criteria confirmed that species assemblages may be affected by exposures exceeding no-effect levels and that mixture exposure could be associated with predicted species loss under certain situations. The model outcomes inform various types of prioritization to support risk management, including a ranking across land uses as a whole, a ranking on characteristics of exposure times and frequencies, and various rankings of the relative role of individual chemicals. Though all results are based on in silico assessments, our land use–based approach yields useful insights for simplifying and assessing potential ecological risks of chemical mixtures and can therefore be useful for catchment-management decisions.
Scott Dyer (Waterborne Environmental), Leo Posthuma (RIVM), Colin D. Brown (University of York), Dick de Zwart (RIVM), Jerome Diamond (Tetra Tech), Christopher Holmes (Waterborne Environmental), Stuart Marshall (Bedford, UK), and G. Allen Burton Jr (University of Michigan). A prospective approach for assessing chemical mixtures in river catchments with diverse land uses.
Poster SETAC Europe 2019. Helsinki, Finland.