Person: Meinecke, Stefan
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Veröffentlichung Fate, bioaccumulation and toxic effects of triclosan on a freshwater community - a mesocosm study(2021) Berghahn, Rüdiger; Contardo-Jara, Valeska; Feibicke, Michael; Meinecke, Stefan; Mohr, Silvia; Schmidt, RalfThe antibacterial agent triclosan (TCS) is added to many daily-used consumer products and can therefore reach the aquatic environment via treated wastewater and potentially harm aquatic ecosystems. A 120 days pond mesocosm study was conducted in order to investigate the fate of TCS in water and sediment, its bioaccumulative potential in different biota as well as the effects of TCS and its main transformation product methyl-triclosan (M-TCS) on plankton, periphyton, macrophytes, and benthos communities. TCS was dosed once each in six pond mesocosms (nominal concentrations: 0.12, 0.6, 3.5, 21, 130 and 778 (micro)g/L TCS, respectively) while two ponds served as controls. A concentration-dependent increase in the DT50 values from 5.0 to 15.0 and 7.5 to 16.3 days was observed for TCS in water and the whole pond system (water, sediment, biota), respectively. Consequently, the substance should be categorized as non-persistent. For TCS, the bioaccumulation factors (non steady-state conditions, BAFnssc) in Lymnaea stagnalis, Myriophyllum spicatum and periphyton were below the critical limit of 2000, above which a substance is classified as bioaccumulative. In contrast, a BAFnssc value of >10,000 was found for M-TCS in L. stagnalis, denoting that M-TCS definitely falls under this classification. Although strong effects on freshwater communities could only be observed in the highest TCS treatments, some periphyton species, such as Oedogonium spp., reacted very sensitive to TCS with an EC50 (time weighted average, 28 d) of 0.3 (micro)g/L TCS. Considering the high bioaccumulative potential of M-TCS in combination with the observed effects of TCS at low doses suggests that the use of TCS, and therefore its release into the environment, should cease. © 2021 The AuthorsVeröffentlichung Error models for the kinetic evaluation of chemical degradation data(2019) Ranke, Johannes; Meinecke, StefanIn the kinetic evaluation of chemical degradation data, degradation models are fitted to the data by varying degradation model parameters to obtain the best possible fit. Today, constant variance of the deviations of the observed data from the model is frequently assumed (error model "constant variance"). Allowing for a different variance for each observed variable ("variance by variable") has been shown to be a useful refinement. On the other hand, experience gained in analytical chemistry shows that the absolute magnitude of the analytical error often increases with the magnitude of the observed value, which can be explained by an error component which is proportional to the true value. Therefore, kinetic evaluations of chemical degradation data using a two-component error model with a constant component (absolute error) and a component increasing with the observed values (relative error) are newly proposed here as a third possibility. In order to check which of the three error models is most adequate, they have been used in the evaluation of datasets obtained from pesticide evaluation dossiers published by the European Food Safety Authority (EFSA). For quantitative comparisons of the fits, the Akaike information criterion (AIC) was used, as the commonly used error level defined by the FOrum for the Coordination of pesticide fate models and their USe(FOCUS) is based on the assumption of constant variance. A set of fitting routines was developed within the mkin software package that allow for robust fitting of all three error models. Comparisons using parent only degradation datasets, as well as datasets with the formation and decline of transformation products showed that in many cases, the two-component error model proposed here provides the most adequate description of the error structure. While it was confirmed that the variance by variable error model often provides an improved representation of the error structure in kinetic fits with metabolites, it could be shown that in many cases, the two-component error model leads to a further improvement. In addition, it can be applied to parent only fits, potentially improving the accuracy of the fit towards the end of the decline curve, where concentration levels are lower. Quelle: http://www.mdpi.comVeröffentlichung Comparison of software tools for kinetic evaluation of chemical degradation data(2018) Ranke, Johannes; Meinecke, Stefan; Wöltjen, JaninaBackground For evaluating the fate of xenobiotics in the environment, a variety of degradation or environmental metabolism experiments are routinely conducted. The data generated in such experiments are evaluated by optimizing the parameters of kinetic models in a way that the model simulation fits the data. No comparison of the main software tools currently in use has been published to date. This article shows a comparison of numerical results as well as an overall, somewhat subjective comparison based on a scoring system using a set of criteria. The scoring was separately performed for two types of uses. Uses of type I are routine evaluations involving standard kinetic models and up to three metabolites in a single compartment. Evaluations involving non-standard model components, more than three metabolites or more than a single compartment belong to use type II. For use type I, usability is most important, while the flexibility of the model definition is most important for use type II. Results Test datasets were assembled that can be used to compare the numerical results for different software tools. These datasets can also be used to ensure that no unintended or erroneous behaviour is introduced in newer versions. In the comparison of numerical results, good agreement between the parameter estimates was observed for datasets with up to three metabolites. For the now unmaintained reference software DegKinManager/ModelMaker, and for OpenModel which is still under development, user options were identified that should be taken care of in order to obtain results that are as reliable as possible. Based on the scoring system mentioned above, the software tools gmkin, KinGUII and CAKE received the best scores for use type I. Out of the 15 software packages compared with respect to use type II, again gmkin and KinGUII were the first two, followed by the script based tool mkin, which is the technical basis for gmkin, and by OpenModel. Conclusions Based on the evaluation using the system of criteria mentioned above and the comparison of numerical results for the suite of test datasets, the software tools gmkin, KinGUII and CAKE are recommended for use type I, and gmkin and KinGUII for use type II. For users that prefer to work with scripts instead of graphical user interfaces, mkin is recommended. For future software evaluations, it is recommended to include a measure for the total time that a typical user needs for a kinetic evaluation into the scoring scheme. It is the hope of the authors that the publication of test data, source code and overall rankings foster the evolution of useful and reliable software in the field. © The Author(s) 2018Veröffentlichung Passive sampler phases for pesticides: evaluation of AttractSPE_TM SDB-RPS and HLB versus Empore_TM SDB-RPS(2021) Becker, Benjamin; Kochleus, Christian; Spira, Denise; Meinecke, StefanIn this study, three different passive sampling receiving phases were evaluated, with a main focus on the comparability of established styrene-divinylbenzene reversed phase sulfonated (SDB-RPS) sampling phase from Empore_TM (E-RPS) and novel AttractSPE_TM (A-RPS). Furthermore, AttractSPE_TM hydrophilic-lipophilic balance (HLB) disks were tested. To support sampling phase selection for ongoing monitoring needs, it is important to have information on the characteristics of alternative phases. Three sets of passive samplers (days 1-7, days 8-14, and days 1-14) were exposed to a continuously exchanged mixture of creek and rainwater in a stream channel system under controlled conditions. The system was spiked with nine pesticides in two peak scenarios, with log KOW values ranging from approx. - 1 to 5. Three analytes were continuously spiked at a low concentration. All three sampling phases turned out to be suitable for the chosen analytes, and, in general, uptake rates were similar for all three materials, particularly for SDB-RPS phases. Exceptions concerned bentazon, where E-RPS sampled less than 20% compared with the other phases, and nicosulfuron, where HLB sampled noticeably more than both SDB-RPS phases. All three phases will work for environmental monitoring. They are very similar, but differences indicate one cannot just use literature calibration data and transfer these from one SDB phase to another, though for most compounds, it may work fine. © The Author(s) 2021Veröffentlichung Effects of a realistic pesticide spraying sequence for apple crop on stream communities in mesocosms: negligible or notable?(2023) Duquesne, Sabine; Feibicke, Michael; Frische, Tobias; Gergs, René; Meinecke, Stefan; Sahm, René; Mohr, SilviaBackground Several large-scale studies revealed impacts and risks for aquatic communities of small rural lakes and streams due to pesticides in agricultural landscapes. It appears that pesticide risk assessment based on single products does not offer sufficient protection for non-target organisms, which are exposed repeatedly to pesticide mixtures in the environment. Therefore, a comprehensive stream mesocosm study was conducted in order to investigate the potential effects of a realistic spraying sequence for conventional orchard farmed apples on a stream community using pesticides at their regulatory acceptable concentrations (RACs). Eight 74-m-long stream mesocosms were established with water, sand, sediment, macrophytes, plankton and benthic macroinvertebrates. In total, nine fungicidal, four herbicidal and four insecticidal pesticides were applied in four of the eight stream mesocosms on 19 spraying event days in the period from April to July while the remaining four stream mesocosms served as controls. The community composition, the abundance of benthos, periphyton and macrophytes, the emergence of insects, physico-chemical water parameters, and drift measurements of aquatic invertebrates were measured. Results The pesticide spraying sequence induced significant effects on invertebrates, periphyton, and macrophytes as well as on the water ion composition especially in the second half of the experiment. It was not possible to relate the observed effects on the community to specific pesticides applied at certain time points and their associated toxic pressure using the toxic unit approach. The most striking result was the statistically significant increase in variation of population response parameters of some taxa in the treated mesocosms compared to the controls. This inter-individual variation can be seen as a general disturbance measure for the ecosystem. Conclusions The pesticide spraying sequence simulated by using RAC values had notable effects on the aquatic stream community in the conducted mesocosm study. The results indicate that the current risk assessment for pesticides may not ensure a sufficient level of protection to the field communities facing multiple pesticide entries due to spraying sequences and other combined stress. Hence, there is still room for improvement regarding the prospective risk assessment of pesticides to further reduce negative effects on the environment. © The Author(s) 2023