%0 journal article %@ 0025-326X %A von der Au, M., Zimmermann, T., Kleeberg, U., von Tümpling, W., Pröfrock, D. %D 2022 %J Marine Pollution Bulletin %P 114208 %R doi:10.1016/j.marpolbul.2022.114208 %T Characteristic regional differences in trace element pattern of 2014 German North Sea surface Wadden sediments – A judge and assessment %U https://doi.org/10.1016/j.marpolbul.2022.114208 %X The European Marine Strategy Framework Directive (MSFD) requires good ecological status of the marine environment. This also includes the Wadden Sea located in the southeastern part of the North Sea and its chemical status of sediments. Based on results from campaigns conducted in the 1980s, 32 surface sediment samples were taken in 2014 to check whether the sampling strategy required for characterizing the trace element content in sediments is representative and to determine the degree of pollution and potential changes over the last decades. For this purpose the elemental mass fractions of 42 elements were assessed in the ≤20 μm grain size fraction of the surface sediments. %0 journal article %@ 0269-7491 %A Hildebrandt, L., El Gareb, F., Zimmermann, T., Klein, O., Kerstan, A., Emeis, K., Pröfrock, D. %D 2022 %J Environmental Pollution %P 119547 %R doi:10.1016/j.envpol.2022.119547 %T Spatial distribution of microplastics in the tropical Indian Ocean based on laser direct infrared imaging and microwave-assisted matrix digestion %U https://doi.org/10.1016/j.envpol.2022.119547 %X The mean microplastic concentration of the analyzed samples was 50 ± 30 particles/fibers m−3 (1 SD, n = 21). Number concentrations ranged from 8 to 132 particles/fibers m−3 (20–300 μm). The most abundant polymer clusters were acrylates/polyurethane/varnish (49%), polyethylene terephthalate (26%), polypropylene (8%), polyethylene (4%) and ethylene-vinyl acetate (4%). 96% of the microplastic particles had a diameter <100 μm. Though inter-study comparison is difficult, the investigated area exhibits a high contamination with particulate plastics compared to other open ocean regions. A distinct spatial trend was observed with an increasing share of the size class 20–50 μm from east to west. %0 journal article %@ 0090-4341 %A Klein, O., Zimmermann, T., Ebeling, A., Kruse, M., Kirchgeorg, T., Pröfrock, D. %D 2022 %J Archives of Environmental Contamination and Toxicology %N 4 %P 481-492 %R doi:10.1007/s00244-022-00929-4 %T Occurrence and Temporal Variation of Technology-Critical Elements in North Sea Sediments - A Determination of Preliminary Reference Values %U https://doi.org/10.1007/s00244-022-00929-4 4 %X As interest in the investigation of possible sources and environmental sinks of technology-critical elements (TCEs) continues to grow, the demand for reliable background level information of these elements in environmental matrices increases. In this study, a time series of ten years of sediment samples from two different regions of the German North Sea were analyzed for their mass fractions of Ga, Ge, Nb, In, REEs, and Ta (grain size fraction < 20 µm). Possible regional differences were investigated in order to determine preliminary reference values for these regions. Throughout the investigated time period, only minor variations in the mass fractions were observed and both regions did not show significant differences. Calculated local enrichment factors ranging from 0.6 to 2.3 for all TCEs indicate no or little pollution in the investigated areas. Consequently, reference values were calculated using two different approaches (Median + 2 median absolute deviation (M2MAD) and Tukey inner fence (TIF)). Both approaches resulted in consistent threshold values for the respective regions ranging from 158 µg kg−1 for In to 114 mg kg−1 for Ce. As none of the threshold values exceed the observed natural variation of TCEs in marine and freshwater sediments, they may be considered baseline values of the German Bight for future studies. %0 journal article %@ 1618-3258 %A Hildebrandt, L., Nack, F., Zimmermann, T., El Gareb, F., Pröfrock, D. %D 2022 %J Mitteilungen der Fachgruppe Umweltchemie und Oekotoxikologie %N 1 %P 7-10 %T Mikroplastik als Trojanisches Pferd für Spurenmetalle %U 1 %X giert auch als Trojanisches Pferd für gelöste Metallkationen. %0 journal article %@ 1751-908X %A Ebeling, A., Zimmermann, T., Klein, O., Irrgeher, J., Pröfrock, D. %D 2022 %J Geostandards and Geoanalytical Research %N 2 %P 351-378 %R doi:10.1111/ggr.12422 %T Analysis of Seventeen Certified Water Reference Materials for Trace and Technology-Critical Elements %U https://doi.org/10.1111/ggr.12422 2 %X Concentrations of elements in the aquatic environment are a key parameter for various scientific fields such as biogeochemistry, biology and environmental science. Within this context, the scientific community asks for new analytical protocols to be able to quantify more and more elements of the periodic table. Therefore, the requirements for aqueous reference materials have increased drastically. Even though a wide variety of CRMs of different water matrices are available, certified values of many elements (e.g., rare earth elements, technology-critical elements, such as Ga and In, and generally those elements which are not part of current monitoring regulations) do not yet exist. Therefore, the scientific community relies on published elemental concentrations of many CRMs provided by other researchers. Some elements of interest, such as the rare earth elements, are well studied and plenty of literature values exist. However, less studied elements, such as Ga and In, are rarely studied. In this study, an 'externally' calibrated quantification method based on an optimised online pre-concentration method, coupled with ICP-MS/MS, is used for the quantification of thirty-four elements. The method is applied to seventeen water CRMs covering freshwater, brackish water and seawater. The measured data is combined with a comprehensive literature review on non-certified values in selected water CRMs and new consensus values are suggested for various non-certified elements. %0 journal article %@ 0269-7491 %A Logemann, A., Reininghaus, M., Schmidt, M., Ebeling, A., Zimmermann, T., Wolschke, H., Friedrich, J., Brockmeyer, B., Pröfrock, D., Witt, G. %D 2022 %J Environmental Pollution %P 119040 %R doi:10.1016/j.envpol.2022.119040 %T Assessing the chemical anthropocene – Development of the legacy pollution fingerprint in the North Sea during the last century %U https://doi.org/10.1016/j.envpol.2022.119040 %X The North Sea and its coastal zones are heavily impacted by anthropogenic activities, which has resulted in significant chemical pollution ever since the beginning of the industrialization in Europe during the 19th century. In order to assess the chemical Anthropocene, natural archives, such as sediment cores, can serve as a valuable data source to reconstruct historical emission trends and to verify the effectiveness of changing environmental legislation. In this study, we investigated 90 contaminants covering inorganic and organic pollutant groups analyzed in a set of sediment cores taken in the North Seas' main sedimentation area (Skagerrak). We thereby develop a chemical pollution fingerprint that records the constant input of pollutants over time and illustrates their continued great relevance for the present. Additionally, samples were radiometrically dated and PAH and PCB levels in porewater were determined using equilibrium passive sampling. Furthermore, we elucidated the origin of lead (Pb) contamination utilizing non-traditional stable isotopic analysis. Our results reveal three main findings: 1. for all organic contaminant groups covered (PAHs, OCPs, PCBs, PBDEs and PFASs) as well as the elements lead (Pb) and titanium (Ti), determined concentrations decreased towards more recent deposited sediment. These decreasing trends could be linked to the time of introductions of restrictions and bans and therefor our results confirm, amongst possible other factors, the effectiveness of environmental legislation by revealing a successive change in contamination levels over the decades. 2. concentration trends for ΣPAH and ΣPCB measured in porewater correspond well with the ones found in sediment which suggests that this method can be a useful expansion to traditional bulk sediment analysis to determine the biologically available pollutant fraction. 3. Arsenic (As) concentrations were higher in younger sediment layers, potentially caused by emissions of corroded warfare material disposed in the study area after WW II. %0 journal article %@ %A Klein, O., Zimmermann, T., Hildebrandt, L., Pröfrock, D. %D 2022 %J Science of the Total Environment %P 158464 %R doi:10.1016/j.scitotenv.2022.158464 %T Technology-critical elements in Rhine sediments - A case study on occurrence and spatial distribution %U https://doi.org/10.1016/j.scitotenv.2022.158464 %X Obtained mass fractions in conjunction with corresponding geoaccumulation indices (Igeo) provide first indications of a possible enrichment along the Rhine for the TCEs of interest (Ga, Ge, Nb, In, Te, rare earth elements, and Ta). Especially the mass fractions of Zn, Ge, In, La, Sm, and Gd exhibit significant anthropogenic inputs. For stations characterized by high Ge and In mass fractions, element fingerprints imply possible atmospheric deposition stemming from e.g. combustion processes. Distinct anomalies of La and Sm most likely originate from discharges located at the city of Worms into the Upper Rhine. Statistical analysis of all analyzed 55 elemental mass fractions revealed similar behavior of TCEs compared to classical heavy metals. Diffuse as well as point sources of TCEs are likely. As a result, this study provides further insight into the role of TCEs as potential emerging contaminants in the environment. %0 journal article %@ 0267-9477 %A Klein, O., Zimmermann, T., Pröfrock, D. %D 2021 %J Journal of Analytical Atomic Spectrometry %N 7 %P 1524-1532 %R doi:10.1039/D1JA00088H %T Improved determination of technologically critical elements in sediment digests by ICP-MS/MS using N2O as a reaction gas %U https://doi.org/10.1039/D1JA00088H 7 %X The investigation of technologically critical elements (TCEs) as emerging pollutants is a constantly growing field of environmental research and societal concern. Nevertheless, existing data for most TCEs are still unsatisfactory for an accurate assessment of their potential (eco)toxicological effects on humans and the environment. The limited availability of data mainly results from the technically challenging analysis of selected TCEs. Low concentrations of TCEs in environmental matrices (μg kg−1 or lower) and the associated complex and time-consuming sample preparation pose the greatest challenges. This work aims at developing a new ICP-MS/MS-based multi-elemental approach targeting the analysis of all major TCEs (Sc, Ga, Ge, Nb, In, Te, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Lu, and Ta) in sediment, which represents one of the most important matrices for environmental research. N2O is applied as a reaction gas to overcome possible spectral interferences during ICP-MS/MS analysis. The use of N2O as a reaction gas for ICP-MS/MS analysis enabled higher oxide-product ion yields for many TCEs in comparison to the frequently used O2 cell gas. Hence, the selectivity and sensitivity of the method were improved. The presented multi-element method using N2O as a reaction gas achieved LODs between 0.00023 μg L−1 (Eu) and 0.13 μg L−1 (Te) for all analyzed TCEs. Likewise, for all analyzed elements, except for Te, recoveries between 80% and 112% were obtained for at least one of the analyzed reference materials (GBW 07313, GBW 07311, and BCR-2). %0 journal article %@ 0304-3894 %A Hildebrandt, L., Zimmermann, T., Primpke, S., Fischer, D., Gerdts, G., Pröfrock, D. %D 2021 %J Journal of Hazardous Materials %P 125482 %R doi:10.1016/j.jhazmat.2021.125482 %T Comparison and uncertainty evaluation of two centrifugal separators for microplastic sampling %U https://doi.org/10.1016/j.jhazmat.2021.125482 %X For the first time in microplastic research, an expanded uncertainty was calculated according to the “Guide to the expression of Uncertainty in Measurement” (JCGM 100:2008). Bottom-up uncertainty evaluation revealed the different sampling methods (~ 44%), sample replicates (~ 26%) and the different detection techniques (~ 16%) as the major sources of uncertainty. Depending on the number of particles detected in the samples, the relative expanded uncertainty (Urel (k =2)) ranged from 24% up to > 200% underpinning tremendous importance of sound uncertainty evaluation. Our results indicate that scientist should rethink many “observed patterns” in the literature due to being insignificant and herewith not real. %0 journal article %@ 2666-9110 %A Hildebrandt, L., Nack, F., Zimmermann, T., Pröfrock, D. %D 2021 %J Journal of Hazardous Materials Letters %P 100035 %R doi:10.1016/j.hazl.2021.100035 %T Microplastics as a Trojan horse for trace metals %U https://doi.org/10.1016/j.hazl.2021.100035 %X Due to an assumed lack of anionic binding sites (most plastics are non-polar), scientists long considered virgin particulate plastics inert towards metal ions. However, we proved significant metal sorption to microplastics at neutral pH and release in a solution mimicking gastrointestinal chemistry serving as a proof-of-principle for environmental and human bioavailability. Competitive ion-exchange incubation experiments comprised 55 metals and metalloids. Fast kinetics were observed with 45 %–75 % of As, Be, Bi, Cr, Fe, In, Pb, Th, Sn and the rare-earth element ions being sorbed after 1 h. The investigated metal and metalloid cations showed significant differences in the extent of sorption, based upon which a distinct categorization was possible. Microplastics are not only a potential danger for aquatic and human life, but - as demonstrated in this paper - also serve as a Trojan Horse for dissolved metal cations. The corresponding effects on aquatic and human health will gain higher importance in the near future due to the predicted increases of marine plastic litter and microplastic sorbents. %0 journal article %@ 2375-2548 %A Van Dam, B., Zeller, M., Lopes, C., Smyth, A., Böttcher, M., Osburn, C., Zimmerman, T., Pröfrock, D., Fourqurean, J., Thomas, H. %D 2021 %J Science Advances %N 51 %P eabj1372 %R doi:10.1126/sciadv.abj1372 %T Calcification-driven CO2 emissions exceed “Blue Carbon” sequestration in a carbonate seagrass meadow %U https://doi.org/10.1126/sciadv.abj1372 51 %X Long-term “Blue Carbon” burial in seagrass meadows is complicated by other carbon and alkalinity exchanges that shape net carbon sequestration. We measured a suite of such processes, including denitrification, sulfur, and inorganic carbon cycling, and assessed their impact on air-water CO2 exchange in a typical seagrass meadow underlain by carbonate sediments. Eddy covariance measurements reveal a consistent source of CO2 to the atmosphere at an average rate of 610 ± 990 μmol m−2 hour−1 during our study and 700 ± 660 μmol m−2 hour−1 (6.1 mol m−2 year−1) over an annual cycle. Net alkalinity consumption by ecosystem calcification explains >95% of the observed CO2 emissions, far exceeding organic carbon burial and anaerobic alkalinity generation. We argue that the net carbon sequestration potential of seagrass meadows may be overestimated if calcification-induced CO2 emissions are not accounted for, especially in regions where calcification rates exceed net primary production and burial. %0 other %@ %A Hildebrandt, L., El Gareb, F., Zimmermann, T., Klein, O., Emeis, K., Pröfrock, D., Kerstan, A. %D 2020 %J %T Fast, Automated Microplastics Analysis Using Laser Direct Chemical Imaging : Characterizing and quantifying microplastics in water samples from marine environments %U %X It is estimated that more than 75% of the 8.3 billion metric tons of plastic produced over the last 65 years have turned into waste (1). Up to 13 million metric tons of this waste ends up in the ocean every year (2) and recent calculations estimate that more than 5.25 trillion plastic particles float in the world’s oceans (3). Scientists have demonstrated the alarming environmental ubiquity and persistence of particulate plastic in aquatic ecosystems (4). Models predict that approximately 14% of the plastic debris in the ocean surface layer can be classified as so-called microplastics (often referred to as particles between 1 μm and 5 mm in size) (5). These ingestible and potentially harmful particles have been formed by UV-induced, mechanical, or biological degradation of larger debris items (6). To verify the estimates and to meet upcoming regulatory measures (e.g., California Senate Bill 1422) and directives (MSFD, 2008/56/EC), accurate, time-efficient, and robust analytical workflows and techniques are required. %0 journal article %@ 1932-6203 %A Hildebrandt, L., von der Au, M., Zimmermann, T., Reese, A., Ludwig, J., Pröfrock, D. %D 2020 %J PLoS One %N 7 %P e0236120 %R doi:10.1371/journal.pone.0236120 %T A metrologically traceable protocol for the quantification of trace metals in different types of microplastic %U https://doi.org/10.1371/journal.pone.0236120 7 %X The presence of microplastic (MP) particles in aquatic environments raised concern about possible enrichment of organic and inorganic pollutants due to their specific surface and chemical properties. In particular the role of metals within this context is still poorly understood. Therefore, the aim of this work was to develop a fully validated acid digestion protocol for metal analysis in different polymers, which is a prerequisite to study such interactions. The proposed digestion protocol was validated using six different certified reference materials in the microplastic size range consisting of polyethylene, polypropylene, acrylonitrile butadiene styrene and polyvinyl chloride. As ICP-MS/MS enabled time-efficient, sensitive and robust analysis of 56 metals in one measurement, the method was suitable to provide mass fractions for a multitude of other elements beside the certified ones (As, Cd, Cr, Hg, Pb, Sb, Sn and Zn). Three different microwaves, different acid mixtures as well as different temperatures in combination with different hold times were tested for optimization purposes. With the exception of Cr in acrylonitrile butadiene styrene, recovery rates obtained using the optimized protocol for all six certified reference materials fell within a range from 95.9% ± 2.7% to 112% ± 7%. Subsequent optimization further enhanced both precision and recoveries ranging from 103% ± 5% to 107 ± 4% (U; k = 2 (n = 3)) for all certified metals (incl. Cr) in acrylonitrile butadiene styrene. The results clearly show the analytical challenges that come along with metal analysis in chemically resistant plastics. Addressing specific analysis tools for different sorption scenarios and processes as well as the underlying kinetics was beyond this study’s scope. However, the future application of the two recommended thoroughly validated total acid digestion protocols as a first step in the direction of harmonization of metal analysis in/on MP will enhance the significance and comparability of the generated data. It will contribute to a better understanding of the role of MP as vector for trace metals in the environment. %0 journal article %@ 1759-9660 %A Zimmermann, T., von der Au, M., Reese, A., Klein, O., Hildebrandt, L., Pröfrock, D. %D 2020 %J Analytical Methods %N 30 %P 3778-3787 %R doi:10.1039/D0AY01049A %T Substituting HF by HBF4 – an optimized digestion method for multi-elemental sediment analysis via ICP-MS/MS %U https://doi.org/10.1039/D0AY01049A 30 %X Determination of elemental mass fractions in sediments plays a major role in evaluating the environmental status of aquatic ecosystems. Herewith, the optimization of a new total digestion protocol and the subsequent analysis of 48 elements in different sediment reference materials (NIST SRM 2702, GBW 07313, GBW 07311 and JMC-2) based on ICP-MS/MS detection is presented. The developed method applies microwave acid digestion and utilizes HBF4 as fluoride source for silicate decomposition. Similar to established protocols based on HF, HBF4 ensures the dissolution of the silicate matrix, as well as other refractory oxides. As HBF4 is not acutely toxic; no special precautions have to be made and digests can be directly measured via ICP-MS without specific sample inlet systems, evaporation steps or the addition of e.g. H3BO3, in order to mask excess HF. Different acid mixtures with and without HBF4 were evaluated in terms of digestion efficiency based on the trace metal recovery. The optimized protocol (5 mL HNO3, 2 mL HCL, 1 mL HBF4) allows a complete dissolution of the analyzed reference materials, as well as quantitative recoveries for a wide variety of certified analytes. Low recoveries for e.g. Sr, Ba and rare earth elements due to fluoride precipitation of HF-based digestions protocols, can be avoided by the usage of HBF4 instead. Based on the usage of high purity HBF4 all relevant trace, as well as matrix elements can be analyzed with sufficiently low LOQs (0.002 μg L−1 for U up to 6.7 μg L−1 for Al). In total, 34 elements were within a recovery range of 80%–120% for all three analyzed reference materials GBW 07313, GBW 07311 and JMC-2. 14 elements were outside a recovery range of 80%–120% for at least one of the analyzed reference materials. %0 journal article %@ 2296-665X %A Hildebrandt, L., Mitrano, D., Zimmermann, T., Pröfrock, D. %D 2020 %J Frontiers in Environmental Science %P 89 %R doi:10.3389/fenvs.2020.00089 %T A Nanoplastic Sampling and Enrichment Approach by Continuous Flow Centrifugation %U https://doi.org/10.3389/fenvs.2020.00089 %X Substantial efforts have been undertaken to isolate and characterize plastic contaminants in different sample matrices in the last years as the ubiquitous presence of particulate plastic in the environment has become evident. In comparison, plastic particles <1 µm (nanoplastic) in the environment remain mostly unexplored. Adequate techniques for the enrichment, as well as the detection of nanoplastic, are lacking but are urgently needed to assess the full scope of (potential) nanoplastic pollution. Use of Pd-doped nanoplastic particles constitutes a powerful tool to develop new analytical approaches, as they can be traced accurately and with ease in a variety of complex matrices by highly sensitive, time-efficient and robust ICP-MS(/MS) techniques. In this lab-scale study, for the first time, the capability of continuous flow centrifugation to retain nanoplastic particles (∼160 nm) from ultrapure water, as well as from filtered and unfiltered water from the German Elbe River was evaluated. Depending on the pump rate, the retention efficiency for the nanoplastic particles in ultrapure water ranged from 92% ± 8% (1 L h−1) to 53% ± 5% (5 L h−1) [uc (n = 3)] and from 75% ± 5% to 65% ± 6% (uc) (2.5 L h−1) in river water. Recirculating the water through the system two and three times at the highest tested flow rate led to retention efficiencies >90%. In a proof-of-principle setup, it was demonstrated that operating two continuous flow centrifuges sequentially at different rotational speeds bears the potential to enable size- and density-selective sampling of the colloidal fraction. A significant fraction of the spiked nanoplastic particles [76% ± 5% (uc)] could be separated from a model mixture of natural particles with a well-defined mean size of approximately 3 µm. While the certified reference plankton material used here was quantitatively retained in the first centrifuge rotor together with 23.0% ± 2.2% of the effective dose of the spiked nanoplastic, the remaining fraction of the nanoplastic could be recovered in the second rotor (53% ± 5%) and the effluent [24.4% ± 2.4% (uc)]. Based on the good retention efficiencies and the demonstrated separation potential, continuous flow centrifugation has proven to be a very promising technique for nanoplastic sampling and enrichment from natural water samples. %0 journal article %@ 0048-9697 %A Zimmermann, T., Mohammed, F., Reese, A., Wieser, M., Kleeberg, U., Pröfrock, D., Irrgeher, J. %D 2020 %J Science of the Total Environment %P 135219 %R doi:10.1016/j.scitotenv.2019.135219 %T Zinc isotopic variation of water and surface sediments from the German Elbe River %U https://doi.org/10.1016/j.scitotenv.2019.135219 %X Recent studies suggested the use of the isotopic composition of Zn as a possible tracer for anthropogenic Zn emissions. Nevertheless, studies mainly focused on sampling areas of a few km2 with well-characterized anthropogenic Zn emissions. In contrast, this study focused on analyzing a large sample set of water and sediment samples taken throughout the course of the Elbe River, a large, anthropogenically impacted river system located in Central Europe. The primary objective was to evaluate the use of the isotopic composition of Zn to trace anthropogenic Zn emission on a large regional scale. In total 18 water and 26 surface sediment samples were investigated, covering the complete course of over 700 km of the German Elbe between the German/Czech border and the German North Sea, including six tributaries. Stable isotope abundance ratios of Zn were assessed by multi-collector inductively coupled plasma mass spectrometry (MC ICP-MS) in water filtrates (<0.45 µm) and total digests of the sieved surface sediment fraction (<63 µm) after analyte/matrix separation using Bio-Rad AG MP-1 resin via a micro-column approach and application of a 64Zn/67Zn double spike. Measured isotopic compositions of δ66Zn/64ZnIRMM-3702 ranged from −0.10 ‰ to 0.32 ‰ for sediment samples, and from −0.51 ‰ to 0.45 ‰ for water samples. In comparison to historical data some tributaries still feature high mass fractions of anthropogenic Zn (e.g. Mulde, Triebisch) combined with δ66Zn/64ZnIRMM-3702 values higher than the lithogenic background. The dissolved δ66Zn/64ZnIRMM-3702 values showed a potential correlation with pH. Our results indicate that biogeochemical processes like absorption may play a key role in natural Zn isotopic fractionation making it difficult to distinguish between natural and anthropogenic processes. %0 journal article %@ 2296-8016 %A Silva Campos, M.R., Blawert, C., Mendis, C.L., Mohedano, M., Zimmermann, T., Proefrock, D., Zheludkevich, M.L., Kainer, K.U. %D 2020 %J Frontiers in Materials %P 84 %R doi:10.3389/fmats.2020.00084 %T Effect of Heat Treatment on the Corrosion Behavior of Mg-10Gd Alloy in 0.5% NaCl Solution %U https://doi.org/10.3389/fmats.2020.00084 %X In 0.5 wt.% NaCl aqueous solution, Mg-10Gd alloy shows promising corrosion resistance. The microstructure of this alloy was modified via heat treatments to understand the effect of accompanying microstructural changes on the corrosion resistance. It was found that corrosion performance depends both on the amount and the distribution of the cathodic intermetallic phases. The T4 heat treatment (24 h at 540°C) caused the Gd to distribute uniformly in the matrix, which had positive effect on corrosion resistance showing a delay in the time required for the first observation of localized corrosion. The T4 heat treated specimens, specimens aged at 200°C and 300°C, showed relatively uniform degradation and thus these heat treatments are not detrimental in terms of corrosion resistance. In contrast, heat treatment at 400°C seems to increase the formation of small cuboidal particles rich in Gd, most likely to be GdH2 particles, in the matrix, resulting in a detrimental effect on the corrosion behavior. %0 journal article %@ 0141-1136 %A Hildebrandt, L., Voigt, N., Zimmermann, T., Reese, A., Proefrock, D. %D 2019 %J Marine Environmental Research %P 104768 %R doi:10.1016/j.marenvres.2019.104768 %T Evaluation of continuous flow centrifugation as an alternative technique to sample microplastic from water bodies %U https://doi.org/10.1016/j.marenvres.2019.104768 %X The scientific and public interest regarding environmental pollution with microplastic has considerably increased within the last 15 years. Nevertheless, up to now there is no widely applied standard operation procedure for microplastic sampling, resulting in a lack of inter-study comparability. In addition, many studies on microplastic occurrences do not indicate a sound methodological validation of the applied methods and procedures. This study presents an alternative volume-reduced sampling technique to sample the entire load of suspended particulate matter including microplastic particles in natural waters, based on continuous flow centrifugation. For the lab-scale validation of the proposed instrumental setup, six different microplastic types (PE, PET, PS, PVDC, EPS and PP) were used. The particles covered a size range from 1 μm to 1 mm and a density range from 0.94 g mL−1 to 1.63 g mL−1. Recoveries ranged from 95.0% ± 2.3%–99.1% ± 0.3% for virgin powders and from 96.1% ± 0.6%–99.4% ± 0.2% (1 SD, n = 2–3) for microplastic suspended in river water for 40 days. Gravimetric and microscopic analysis of the effluent indicates efficient removal of microplastic from the suspensions. Static light scattering analysis of the microplastic suspensions prior to and after centrifugation confirmed that no change of the particle size distribution has occurred – neither through aggregation nor through size-discrimination during centrifugation. Moreover, the system was tested in the field and used twice to sample suspended particulate matter from the Elbe estuary directly on site. Based on these first lab-scale experiments, continuous flow centrifugation proves a promising technique bearing potential to alleviate drawbacks such as contamination, filter clogging and particle size-discrimination of commonly used volume-reduced microplastic sampling approaches. %0 journal article %@ 0584-8547 %A Zimmermann, T., Retzmann, A., Schober, M., Proefrock, D., Prohaska, T., Irrgeher, J. %D 2019 %J Spectrochimica Acta B %P 54-64 %R doi:10.1016/j.sab.2018.11.009 %T Matrix separation of Sr and Pb for isotopic ratio analysis of Ca-rich samples via an automated simultaneous separation procedure %U https://doi.org/10.1016/j.sab.2018.11.009 %X This paper presents a systematic investigation of the effects of Ca on the matrix separation of Sr and Pb and subsequent isotope-amount ratio measurements using a variety of synthetic solutions and reference materials with varying Ca content during the application of an automated analyte/matrix separation approach. The separation method based on the DGA resin was optimized by using increased column bed volumes, comparing two different column sizes (1-mL and 3-mL-bed volume). Certified reference materials (synthetic calcium carbonate – MACS-3, basalt – BCR-2, saggital otolith – FEBS-1, bone meal – NIST SRM 1486, bone ash – NIST SRM 1400, and skim milk powder – BCR-063R) with varying Ca content, Ca/Sr and Ca/Pb mass fraction ratios were separated using the optimized method and analyzed for the Sr and Pb isotopic composition by multi collector inductively coupled plasma mass spectrometry (MC ICP-MS). The developed separation method based on the 3-mL-bed volume column provides quantitative recoveries (84% to 105% for Sr, 77 % to 96% for Pb), while maintaining a quantitative separation of Sr and Pb. Procedural blank levels were <0.04 ng g−1 for Sr and <0.05 ng g−1 for Pb, respectively. The method allows for the automated extraction of Sr in Ca-rich matrices with Ca/Sr mass fraction ratios of up to 4051 corresponding to an absolute Ca load of 965 µg ± 86 µg (BCR-063R, milk powder). Furthermore, the method allows for the simultaneous extraction of Pb from these matrices showing Ca/Pb mass fraction ratios of up to 42095 corresponding to an absolute Ca load of 761 µg ± 122 µg on column (NIST SRM 1400, bone tissue), respectively. %0 journal article %@ 0048-9697 %A Reese, A., Zimmermann, T., Proefrock, D., Irrgeher, J. %D 2019 %J Science of the Total Environment %P 512-523 %R doi:10.1016/j.scitotenv.2019.02.401 %T Extreme spatial variation of Sr, Nd and Pb isotopic signatures and 48 element mass fractions in surface sediment of the Elbe River Estuary - Suitable tracers for processes in dynamic environments? %U https://doi.org/10.1016/j.scitotenv.2019.02.401 %X This study indicates the general potential of combined element fingerprinting and isotope tracer approaches to elucidate processes in complex river systems. Furthermore, it represents an initial characterization of the catchment area of the Elbe River as basis for future studies on river and harbor management. %0 journal article %@ 1618-2642 %A Retzmann, A., Zimmermann, T., Proefrock, D., Prohaska, T., Irrgeher, J. %D 2017 %J Analytical and Bioanalytical Chemistry %N 23 %P 5463-5480 %R doi:10.1007/s00216-017-0468-6 %T A fully automated simultaneous single-stage separation of Sr, Pb, and Nd using DGA Resin for the isotopic analysis of marine sediments %U https://doi.org/10.1007/s00216-017-0468-6 23 %X A novel, fast and reliable sample preparation procedure for the simultaneous separation of Sr, Pb, and Nd has been developed for subsequent isotope ratio analysis of sediment digests. The method applying a fully automated, low-pressure chromatographic system separates all three analytes in a single-stage extraction step using self-packed columns filled with DGA Resin. The fully automated set-up allows the unattended processing of three isotopic systems from one sediment digest every 2 h, offering high sample throughput of up to 12 samples per day and reducing substantially laboratory manpower as compared to conventional manual methods. The developed separation method was validated using the marine sediment GBW-07313 as matrix-matched certified reference material and combines quantitative recoveries (>90% for Sr, >93% for Pb, and >91% for Nd) with low procedural blank levels following the sample separation (0.07 μg L-1 Sr, 0.03 μg L-1 Pb, and 0.57 μg L-1 Nd). The average δ values for Sr, Pb, and Nd of the separated reference standards were within the certified ranges (δ (87Sr/86Sr)NIST SRM 987 of -0.05(28) ‰, δ(208Pb/206Pb)NIST SRM 981 of -0.21(14) ‰, and δ(143Nd/144Nd)JNdi-1 of 0.00(7) ‰). The DGA Resin proved to be reusable for the separation of >10 sediment digests with no significant carry-over or memory effects, as well as no significant on-column fractionation of Sr, Pb, and Nd isotope ratios. Additional spike experiments of NIST SRM 987 with Pb, NIST SRM 981 with Sr, and JNdi-1 with Ce revealed no significant impact on the measured isotopic ratios, caused by potential small analyte peak overlaps during the separation of Sr and Pb, as well as Ce and