Michael Radke

Institute for Hygiene and Environment, Hamburg, Germany · Environmental Studies

Hyporheic zones (HZs) are dynamic and complex transition regions between rivers and aquifers which are thought to play an important role in the attenuation of environmental micropollutants. Non-steady state and small-scale hyporheic processes which affect micropollutants in the HZ are poorly characterized due to limitations in existing analytical m...

Many transformation products (TPs) from organic micropollutants are not included in routine environmental monitoring programs due to limited knowledge of their occurrence and fate. An efficient method to identify and prioritize critical compounds in terms of environmental relevance is needed. In this study, we applied a strategic screening approach...

Although diclofenac ranks among the most frequently detected pharmaceuticals in surface waters, its environmental transformation reactions remain imperfectly understood. Biodegradation-induced changes in 15N/14N ratios (εN= -7.1‰ ± 0.4‰) have indicated that compound-specific isotope analysis (CSIA) may detect diclofenac degradation. This singular o...

Considerable knowledge gaps exist with respect to the fate and environmental relevance of transformation products (TPs) of polar organic micropollutants in surface water. To narrow this gap we investigated the fate of 20 parent compounds (PCs) and 11 characteristic TPs in four wastewater-impacted rivers. Samples were obtained from time-integrated a...

Occurrence of the antibiotic sulfamethoxazole (SMX) in the aquatic environment is of concern due to its potential to induce antibiotic resistance in pathogenic bacteria. While degradation of SMX can occur by numerous processes, the environmental fate of its transformation products (TPs) remains poorly understood. In the present work, biodegradation...

Chemical benchmarking was used to investigate the temporal variation of the persistence of chemical contaminants in a Swedish lake. The chemicals studied included 12 pharmaceuticals, an artificial sweetener and an X-ray contrast agent. Measurements were conducted in late spring, late autumn, and winter. The transformation half-life in the lake coul...

The hyporheic zone - the transition region beneath and alongside the stream bed - is a central compartment for attenuation of organic micropollutants in rivers. It provides abundant sorption sites and excellent conditions for biotransformation. We used a bench-scale flume to study the fate of 19 parent pharmaceuticals (PPs) and the formation of 11...

It is challenging to measure the persistence of chemicals under field conditions. In this work, two approaches for measuring persistence in the field were compared: the chemical mass balance approach, and a novel chemical benchmarking approach. Ten pharmaceuticals, an X-ray contrast agent, and an artificial sweetener were studied in a Swedish lake....

Of the tens of thousands of chemicals in use, only a small fraction has been analyzed in environmental samples. To effectively identify environmental contaminants, methods to prioritize chemicals for analytical method development are required. We used a high throughput model of chemical emissions, fate, and bioaccumulation to identify chemicals lik...

Multimedia fate and transport models are used to evaluate the long range transport potential (LRTP) of organic pollutants, often by calculating their characteristic travel distance (CTD). We calculated the CTD of several polycyclic aromatic hydrocarbons (PAHs) and metals using two models: the OECD POV& LRTP Screening Tool (The Tool), and ELPOS. The...

Previous studies revealed large differences in the transformation of pharmaceuticals in rivers with similar characteristics. The present work aimed at answering the question whether these differences are related to the transformation capacity of the specific river sediments. More generally, we also aimed at evaluating the overall diagnostic power o...

While the occurrence of pharmaceuticals in the aquatic environment has been extensively investigated, their environmental fate is less thoroughly explored. Scarce information on their transformation pathways and transformation products (TPs) limits conventional target analytical approaches. In this study, samples from water/sediment tests were anal...

Quantitative information regarding the capacity of rivers to self-purify pharmaceutical residues is limited. To bridge this knowledge gap, we present a methodology for quantifying the governing processes affecting the fate of pharmaceuticals in streaming waters and, especially, to evaluate their relative significance for tracer observations. A trac...

Detection of pharmaceutical residues in streaming waters is common in urbanized areas. Although the occurrence and source of these micropollutants is known, their behavior in these aquatic ecosystems is still only partly understood. Specifically, quantitative information of biogeochemical processes in stream-specific environments where predominant...

Ombrotrophic peat bogs are natural archives of atmospheric pollution, their depth profiles can be used to study the deposition chronology of harmful contaminants. Prerequisites for deriving historical deposition rates from the peat archive are that contaminants are persistent and immobile in the peat and that the applied dating technique is accurat...

Pharmaceutical residues are commonly detected organic micropollutants in the aquatic environment. Their actual fate in rivers is still incompletely understood as their elimination is highly substance specific and studies often report contradictory results. To elucidate the ceiling of attenuation rates of pharmaceuticals in rivers we carried out a s...

As ombrotrophic peat bogs receive only atmospheric input of contaminants, they have been identified as suitable natural archives for investigating historical depositions of airborne pollutants. To elucidate their suitability for determining the historical atmospheric contamination with perfluoroalkyl substances (PFAS), two peat cores were sampled a...

We used XAD-resin based passive air samplers (PAS) to measure atmospheric levels of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) at five ombrotrophic bogs in Eastern Canada. The aims of our study were to investigate the influence of local roads on contaminant levels in the bogs, to derive the regional pattern of atmo...

Sulfonamide antibiotics are a commonly used group of compounds in animal husbandry. They are excreted with manure, which is collected in a storage lagoon in certain types of confined animal feeding operations. Flood irrigation of forage fields with this liquid manure creates the potential risk of groundwater contamination in areas with shallow grou...

The fate of pharmaceutically active substances in rivers is still only incompletely understood, especially as the knowledge transfer from laboratory experiments to the real world is complicated by factors like turbidity, hydrodynamics, or heterogeneity. Therefore, we performed a tracer test with pharmaceutically active substances to study their fat...

Many rivers and streams worldwide are impacted by pharmaceuticals originating from sewage. The hyporheic zone underlying streams is often regarded as reactive bioreactor with the potential for eliminating such sewage-born micropollutants. The present study aims at checking the elimination potential and analyzing the coupling of hydrodynamics, bioge...

The occurrence of two pharmaceuticals, ibuprofen and diclofenac, in a vulnerable karst groundwater system was investigated. The hydrogeology of the karst system was identified by collecting (3)H samples in groundwater over 27years and by performing tracer tests. The isotopes and tracer data were interpreted by mathematical modeling to estimate the...

Contamination of drinking water supplies is a serious problem and a potential threat to public health. Organic micropollutants such as pharmaceuticals and personal care products are identified as an environmental risk and concern has been raised about their environmental presence and fate. These compounds are present in effluents of wastewater trea...

Purpose Up to 90% of antibiotics that are fed to livestock are excreted unaltered or as metabolites and thus are present in manure. By application of manure as fertilizer, veterinary antibiotics can reach soil and groundwater. The aim of this study is to determine the effect of three commonly used (and simultaneously applied) sulfonamide antibiotic...

While substantial knowledge on the occurrence of pharmaceuticals in the environment is available, their behavior and fate in surface waters is still poorly understood. Therefore, the aims of this study were to analyze the short-term dynamics of selected pharmaceuticals along a 13.6 km long river stretch downstream of a wastewater treatment plant (W...

Sulfonamide antibiotics are widely used in human and veterinary medicine. After their application, they are excreted in unchanged as well as in metabolized form. Due to incomplete elimination in wastewater treatment plants, they can be emitted into surface water. The environmental fate of both parent compounds and metabolites is currently unknown....

Pharmaceutical residues are commonly detected micropollutants in the aquatic environment. To derive mass balances of these substances in river stretches and to quantify their elimination, besides highly sophisticated analytical methods precise discharge measurements are inevitable. Two additional key parameters are the travel time of water along a...

The transition zone between surface waters like streams and rivers and the adjacent aquifers is a zone of paramount ecological importance. Due to the complexity of exchange processes, their temporal variability, and the spatial heterogeneity of the ecotone, the understanding and ability to modell the hydrodynamic, hydrochemical, and (micro-)biologi...

Pharmaceutical residues are commonly detected micropollutants in the aquatic environment. Biodegradation in sediments is a potentially significant removal process for these compounds in rivers which is constrained by the transfer of water and solutes into the sediment. The aim of this study was to determine the combined effect of flow velocity and...

Constraints on hypolimnetic methane production in productive lakes are of interest owing to the importance of methane emissions from lakes for the atmospheric methane burden. We studied carbon fluxes and terminal electron accepting processes in the hypolimnion of eutrophic Meerfelder Maar, Germany. Carbon fluxes from epilimnion and sediments were e...

Concentrations of steroids and inorganic ions were measured in waste water of an aerated sand trap as well as in aerosol particles emitted from this tank at the waste water treatment plant (WWTP) of Bayreuth, Germany, in January and February 2003. The investigations comprised seven sterols, two estrogens, and several inorganic ions. Since an approp...

Aerosol particles that are emitted from aeration tanks of wastewater treatment plants (WWTPs) can be enriched with environmentally relevant wastewater constituents. In this study, aerosol particles were sampled simultaneously at the pre-aeration tank of a municipal WWTP and at two urban locations approximately 1 km away from the WWTP to evaluate th...

To date, studies about historic PAH (polycyclic aromatic hydrocarbons) deposition at a regional scale have rarely been published. To address this research gap, we sampled 17 ombrotrophic peatlands across eastern Canada. The peat cores from hollows were dated with 210Pb for the period of about 1850-2000 and analyzed fortheir PAH concentration, so PA...

The analysis of PAH in peat samples is complicated by the high content of organic matter in peat which affects both extraction efficiency and analytical quality. Therefore, we evaluated the efficiencies of three extraction methods (accelerated solvent extraction (ASE), fluidized bed extraction, ultrasonic extraction) and several clean-up techniques...

Studies that document historic and recent polycyclic aromatic hydrocarbons (PAH) deposition rates over large regions are rare. To address this knowledge gap, peat cores of 15 ombrotrophic bogs along a transect across Eastern Canada were dated with 210Pb for the period of about 1850–2000, extracted using accelerated solvent extraction (ASE) and anal...

Aeration tanks of wastewater treatment plants (WWTP) are a potential source of atmospheric aerosol particles. Several groups of organic compounds (sterols, polycyclic aromatic hydrocarbons, estrogens) were analyzed in aerosol particles sampled at a municipal WWTP, and the particle size distribution was measured directly with optical particle counte...

In the work reported here, a state-of-the-art analytical method for the quantitative analysis of cationic surfactants in environmental matrixes is described. High-performance liquid chromatography on-line coupled via an electrospray interface to a mass spectrometer (HPLC-ESP-MS) is used for the determination of ditallowdimethylammonium chloride (DT...