Microplastic-Contaminant Interactions: From Experimental Data to Environmental Implications

Microplastic particles are ubiquitously detected in all environmental compartments. Despite intensive public and scientific discussions, their potential to transport contaminants in rivers and oceans is still under assessment. To consider such particle facilitated transport, this thesis aims to quantify the underlying sorption mechanisms and to develop a comprehensive mechanistic model with parameter values derived from experimental data. The developed models consider material characteristics, physico-chemical properties of chemical compounds as well as different types of sorption isotherms. The sorption kinetics was modeled as a combination of external mass transfer governed by diffusion through an aqueous boundary layer and intraparticle diffusion within the plastic particles. Which of these processes controls the kinetics depends on the sorption strength, particle size, diffusion coefficients, and time. Based on the determined sorption isotherm, a semi-analytical model was developed for linear sorption and a numerical approach was applied to simulate coupled mass transfer for the case of non-linear sorption. Both model types were successfully validated for several plastic types, allowing to accurately describe the measured kinetics. To broaden the scope and environmental relevance of this thesis, further experiments were performed. It was revealed that changing pH conditions and the presence of additional natural sorbents significantly influenced both equilibrium partitioning and desorption kinetics. Due to the combination of experimental and mechanistic modelling tools, it was possible to elucidate coupled mass transfer processes for different experimental and field settings. Eventually, it was ascertained that time scales observed under experimental conditions may not be transferred to field conditions without an appropriate mechanistic model accounting for coupled mass transfer and the specific boundary conditions. Appropriate hydrodynamic relationships coupled to a thorough mass transfer analysis can serve to assess the vector function of pollutant-loaded particles and to evaluate whether microplastics rather act as a passive sampler or show potential to facilitate long-range contaminant transport. Moreover, as the theoretical mass transfer considerations also apply to other suspended particles, well-defined microplastic particles are ideally suited to perform in-depth mass transfer studies and to act as surrogates for particles occurring in the environment, including microplastics in urban runoff and contaminated sediment

Pharmaceutical pollution of the world's rivers

Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world's rivers, representing the environmental influence of 471.4 million people across 137 geographic regions. Samples were obtained from 1,052 locations in 104 countries (representing all continents and 36 countries not previously studied for API contamination) and analyzed for 61 APIs. Highest cumulative API concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. The most frequently detected APIs were carbamazepine, metformin, and caffeine (a compound also arising from lifestyle use), which were detected at over half of the sites monitored. Concentrations of at least one API at 25.7% of the sampling sites were greater than concentrations considered safe for aquatic organisms, or which are of concern in terms of selection for antimicrobial resistance. Therefore, pharmaceutical pollution poses a global threat to environmental and human health, as well as to delivery of the United Nations Sustainable Development Goals

A combined experimental and modeling study to evaluate pH-dependent sorption of polar and non-polar compounds to polyethylene and polystyrene microplastics

Abstract Background The contamination of aquatic ecosystems with both anthropogenic pollutants and particles in particular (microscopic) plastic debris items is of emerging concern. Since plastic particles can accumulate contaminants and potentially facilitate their transport, it is important to properly investigate sorption mechanisms. This is especially required for a large variety of chemicals that can be charged under environmental conditions and for which interactions with particles may hence go beyond mere partitioning. Results In this study, sorption experiments with two types of microplastic particles (polyethylene and polystyrene) and 19 different contaminants (pesticides, pharmaceuticals, and personal care products) were performed at three different pH values. We could show that sorption to plastic particles is stronger for hydrophobic compounds and that neutral species usually contribute more to the overall sorption. Bulk partitioning coefficients were in the same order of magnitude for polyethylene and polystyrene. Furthermore, our results confirm that partition coefficients for polar compounds can only be accurately determined if the solid-to-liquid ratio in batch experiments is more than 6–7 orders of magnitude higher than any plastic concentration detected in the environment. Consequently, only a minor fraction of pollutants in water bodies is associated with microplastics. Conclusions Although neutral species primarily dominate the overall sorption, hydrophobic entities of ionic species cannot be neglected for some compounds. Notwithstanding, our results show that since microplastic concentrations as currently observed in the environment are very low, they are only a relevant sorbent for strongly hydrophobic but not for polar compounds

Using police data to measure criminogenic exposure in residential and school contexts: experiences from a data linkage project in Germany

Police data and survey research provide different bases to inform research on crime and delinquency. We argue that linking police data on local crime incidences to criminological surveys allows for new insights on the role of residential and school contexts for juvenile delinquency and violence. We describe the challenges and solutions of combining these data sources in a collaboration between the state police of North Rhine-Westphalia – Germany’s most populous state – and social scientists from a major German university. In this academic-practitioner partnership, data from a four-wave longitudinal study of more than 3800 students were linked to spatially aggregated data from the police crime statistics for the years 2013–2016. We discuss how the simulation of nearby addresses can serve as a tool for anonymized data linkage, how knowledge of the local data collection practices is crucial to evaluate the geocoding accuracy of address-level crime data, and how sensitivity and implication analyses can help to reduce uncertainties at the analysis stage. We also give recommendations for future research and data collection practices

Shift in Mass Transfer of Wastewater Contaminants from Microplastics in the Presence of Dissolved Substances

In aqueous environments, hydrophobic organic contaminants are often associated with particles. Besides natural particles, microplastics have raised public concern. The release of pollutants from such particles depends on mass transfer, either in an aqueous boundary layer or by intraparticle diffusion. Which of these mechanisms controls the mass-transfer kinetics depends on partition coefficients, particle size, boundary conditions, and time. We have developed a semianalytical model accounting for both processes and performed batch experiments on the desorption kinetics of typical wastewater pollutants (phenanthrene, tonalide, and benzophenone) at different dissolved-organic-matter concentrations, which change the overall partitioning between microplastics and water. Initially, mass transfer is externally dominated, while finally, intraparticle diffusion controls release kinetics. Under boundary conditions typical for batch experiments (finite bath), desorption accelerates with increasing partition coefficients for intraparticle diffusion, while it becomes independent of partition coefficients if film diffusion prevails. On the contrary, under field conditions (infinite bath), the pollutant release controlled by intraparticle diffusion is not affected by partitioning of the compound while external mass transfer slows down with increasing sorption. Our results clearly demonstrate that sorption/desorption time scales observed in batch experiments may not be transferred to field conditions without an appropriate model accounting for both the mass-transfer mechanisms and the specific boundary conditions at hand

За кадры. 1987. № 53 (2703)

Мы верим в вас! / С. ГонтаренкоДело случая? / С. НенашевПриглашаем к дискуссии / М. КолесникПоговорим о философии / А. СавенкоПоздравляем!Институт - селу / О. ЗорникНа Совете институтаВопрос, волнующий всех / Д. ЧащинОт разработки к внедрению / Т. СажинНа главной выставке страны / П. И. ШеринПервый год / К. Н. БелякТруд и праздник познания / Р. ГорскаяУсловия созданы / А. Василье