Description: Micro-Fourier transform infrared (micro-FTIR) spectroscopy and Raman spectroscopy enable the reliable identification and quantification of microplastics (MPs) in the lower micron range. Since concentrations of MPs in the environment are usually low, the large sample volumes required for these techniques lead to an excess of coenriched organic or inorganic materials. While inorganic materials can be separated from MPs using density separation, the organic fraction impedes the ability to conduct reliable analyses. Hence, the purification of MPs from organic materials is crucial prior to conducting an identification via spectroscopic techniques. Strong acidic or alkaline treatments bear the danger of degrading sensitive synthetic polymers. We suggest an alternative method, which uses a series of technical grade enzymes for purifying MPs in environmental samples. A basic enzymatic purification protocol (BEPP) proved to be efficient while reducing 98.3 ± 0.1 % of the sample matrix in surface water samples. After showing a high recovery rate ( 84.5 ± 3.3% ), the BEPP was successfully applied to environmental samples from the North Sea where numbers of MPs range from 0.05 to 4.42 items m -3_ Experiences with different environmental sample matrices were considered in an improved and universally applicable version of the BEPP, which is suitable for focal plane array detector (FPA)-based micro-FTIR analyses of water, wastewater, sediment, biota, and food samples.

Description: The increase in atmospheric carbon dioxide (CO2) results in acidification of the oceans, expected to lead to the fastest drop in ocean pH in the last 300 million years, if anthropogenic emissions are continued at present rate. Due to higher solubility of gases in cold waters and increased exposure to the atmosphere by decreasing ice cover, the Arctic Ocean will be among the areas most strongly affected by ocean acidification. Yet, the response of the plankton community of high latitudes to ocean acidification has not been studied so far. This work is part of the Arctic campaign of the European Project on Ocean Acidification (EPOCA) in 2010, employing 9 in situ mesocosms of about 45 000 l each to simulate ocean acidification in Kongsfjorden, Svalbard (78°56.2' N 11°53.6' E). In the present study, we investigated effects of elevated CO2 on the composition and richness of particle attached (PA; 〉3 μm) and free living (FL; 〈3 μm 〉0.2 μm) bacterial communities by Automated Ribosomal Intergenic Spacer Analysis (ARISA) in 6 of the mesocosms and the surrounding fjord, ranging from 185 to 1050 initial μatm pCO2. ARISA was able to resolve about 20–30 bacterial band-classes per sample and allowed for a detailed investigation of the explicit richness. Both, the PA and the FL bacterioplankton community exhibited a strong temporal development, which was driven mainly by temperature and phytoplankton development. In response to the breakdown of a picophytoplankton bloom (phase 3 of the experiment), number of ARISA-band classes in the PA-community were reduced at low and medium CO2 (∼180–600 μatm) by about 25%, while it was more or less stable at high CO2 (∼ 650–800 μatm). We hypothesise that enhanced viral lysis and enhanced availability of organic substrates at high CO2 resulted in a more diverse PA-bacterial community in the post-bloom phase. Despite lower cell numbers and extracellular enzyme activities in the post-bloom phase, bacterial protein production was enhanced in high CO2-treatments, suggesting a positive effect of community richness on this function and on carbon cycling by bacteria.

Description: The ubiquitous presence of microlitter (ML), precisely microplastics (MP) and microfibres (MF) in the global environment is of growing concern for science, and society in general. Reliable methods are urgently needed for the identification and quantification of these emerging environmental pollutants. Recently a rapid Fourier transform infrared (FTIR) imaging pipeline was developed for automated identification and quantification of MP. However, although the usefulness for the quantification of MP could already be shown in several studies, microfibres could not be targeted so far by the developed analysis pipeline. In this study we present a novel approach for the simultaneous identification and quantification of MP and MF. By concentrating the sample on membrane filters and applying a BaF2 window on top of the filter, all objects – including MF – are fixed in the focal plane of the FTIR microscope. Furthermore, the analysis pipeline was augmented with algorithms which take into consideration the filamentous structure of MF. The novel analysis pipeline now allows to separate MP and MF via a preselection of fibres from the dataset by object size and shape. MP and MF are subsequently further investigated for specific polymer types and lengths/sizes. After parameter optimization the newly developed analysis approach was applied to archived samples from previous studies on treated waste water. The results were compared with respect to the original detected polymer types and numbers, but also considered MF detection.

Description: Specific associations of bacteria with phytoplankton have recently been reported in the literature. In our study, we analyzed bacterial communities of microalgal cultures related to algal growth phases. Seven freshly isolated key diatom and dinoflagellate species from Helgoland Roads, North Sea, were investigated. The community composition of associated bacteria as well as the cell numbers, the photosynthetic efficiency of the algae, and the depletion of inorganic nutrients in the medium were recorded over a period of 8 weeks in batch cultures. Diversity and succession of bacterial communities was analyzed by ribosomal intergenic spacer analysis. Phylogenetic analysis of bacterial populations was performed by denaturing gradient gel electrophoresis of 16S rRNA genes followed by DNA sequence analysis. Members of Alphaproteobacteria and Gammaproteobacteria and the Flavobacteria–Sphingobacteria group within the Bacteroidetes phylum predominated in the cultures. Differences in free-living and attached bacterial populations were observed between the phylogenetic groups. Shifts in the bacterial communities could not be correlated to changes of nutrient levels or algal growth phases. Regarding our results, it should not be generalized that the compositions of the bacterial communities are strictly species specific for microalgae. The importance of factors like the composition of exudates is apparent.

Description: Das Statuspapier fasst die Inhalte der Verbundprojekt-übergreifenden Diskussionen und Abstimmungen innerhalb des Querschnittsthemas (QST) „Analytik und Referenzmaterialien“ des Forschungsschwerpunkts zusammen. Die vorliegende Fassung wurde aus dem Diskussionspapier (Link Dokument Stand Oktober 2018) entwickelt. Dieser kontinuierliche Entwicklungs- oder Erarbeitungsprozess wurde durch eine Reihe von Veranstaltungen organisatorisch untermauert: • 1. Workshop (21. März 2018, Karlsruhe) • 2. Workshop (4. Juli 2018, Augsburg) • Statuskonferenz (9.-10. April 2019, Berlin) • 3. Workshop (27. November 2019, Berlin). Folgende Verbundprojekte haben sich aktiv bei den Veranstaltungen eingebracht: EmiStop, ENSURE, MicBin, MicroCatch_Balt, MikroPlaTaS, PLASTRAT, PLAWES, RAU, REPLAWA, RUSEKU, SubµTrack und TextileMission, sowie Vorläuferprojekte (MiWa, BASEMAN). Die einzelnen Textbeiträge im vorliegenden Statuspapier wurden durch ein Kommentierungsverfahren innerhalb des QST „Analytik und Referenzmaterialien“ abgestimmt. Motivation dieses Statuspapiers ist es, die im Forschungsschwerpunkt „Plastik in der Umwelt“ verwendeten physikochemischen Untersuchungsverfahren zur Analytik von Mikroplastik (MP) zusammenzuführen. Dadurch sollen möglichst validierte Methoden und vergleichbare Ergebnisse in den verschiedenen Projekten für die jeweils spezifische Fragestellung erreicht werden – insbesondere für zukünftige Projekte. Am Ende soll ein möglichst einheitlicher Methodenpool für die relevanten Fragestellungen in Wissenschaft, Wirtschaft und Verwaltung zur Verfügung stehen. Die vorliegenden Verfahrensempfehlungen beruhen auf dem aktuellen Wissensstand zur Analytik von MP und richtet sich an Akteure in der Wissenschaft als auch Anwender in der Praxis. BMBF Forschungsschwerpunkt „Plastik in der Umwelt“ November 2020 Statuspapier Mikroplastikanalytik 7 Es werden keine Verfahrensempfehlungen zu Untersuchungen von Wirkungen von MP auf Umweltmedien, Pflanzen oder Tiere gegeben (Siehe QST „Ökotoxikologie“). Es stellt nicht einzelne Ergebnisse oder Daten dar, die im Rahmen des Forschungsschwerpunktes entstanden sind.

Description: Temperate coastal marine environments are replete with complex biotic and abiotic interactions that are amplified during spring and summer phytoplankton blooms. During these events, heterotrophic bacterioplankton respond to successional releases of dissolved organic matter as algal cells are lysed. Annual seasonal shifts in the community composition of free-living bacterioplankton follow broadly predictable patterns, but whether similar communities respond each year to bloom disturbance events remains unknown owing to a lack of data sets, employing high-frequency sampling over multiple years. We capture the fine-scale microdiversity of these events with weekly sampling using a high-resolution method to discriminate 16S ribosomal RNA gene amplicons that are 〉99% identical. Furthermore, we used 2 complete years of data to facilitate identification of recurrent sub-networks of co-varying microbes. We demonstrate that despite inter-annual variation in phytoplankton blooms and despite the dynamism of a coastal–oceanic transition zone, patterns of microdiversity are recurrent during both bloom and non-bloom conditions. Sub-networks of co-occurring microbes identified reveal that correlation structures between community members appear quite stable in a seasonally driven response to oligotrophic and eutrophic conditions.