The Uptake of Sporopollenin Exine Capsules and Associated Bioavailability of Adsorbed Oestradiol in Selected Aquatic Invertebrates.

Lycopodium clavatum sporopollenin exine capsules (SpECs) are known to both adsorb and absorb chemicals. The aim of the present work was to determine whether oestradiol (E2) is 'bioavailable' to bioindicator species, either pre-adsorbed to, or in the presence of, SpECs. SpEC uptake was confirmed for Daphnia magna and Dreissena bugensis. E2 levels varied among treatments for Caenorhabditis elegans though there was no relationship to SpEC load. E2 was not detected in D. bugensis tissues. Expression changes of general stress and E2-specific genes were measured. For C. elegans, NHR-14 expression suggested that SpECs modulate E2 impacts, but not general health responses. For D. magna, SpECs alone and with E2 changed Vtg1 and general stress responses. For D. bugensis, SpECS were taken up but no E2 or change in gene expression was detected after exposure to E2 and/or SpECs. The present study is the first to investigate SpECs and bound chemical dynamics.

Mixtures of sediment chemical contaminants at freshwater sampling sites across Europe with different contaminant burdens.

Extended chemical analyses of fluvial sediments were undertaken to establish the key pollutant pressures and mixtures present across nine European Union inland waterways. A wide range of chemical components and physical parameters were investigated including substances from the EU Priority List and Watch List. The data set was examined for key indicator compounds, however it was found that a wide range of pollution pressures were present in the different sediments including organic hydrocarbons, metal(loid)s, nutrients, polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyl (PCB) compounds, perfluoroalkyl and polyfluoroalkyl substances and pesticides, some of which exceeded regulatory guidance at different sampling points. The presence of such a wide range of compounds underpins the complex chemical composition of sediments that have acted as sinks for many decades absorbing contaminants from urban, industrial and agricultural sources. This dataset has been used to describe average overall toxicity of the sediments sampled, a calculation which was based on key components identified by Principal Component Analysis (PCA) and for those that had existing freshwater sediment regulatory values. A total of 33 components were used including PCBs, PAHs, metal(iod)s and pesticides. This analysis reflected the contamination of each site, with most indicating some level of toxicity during the sampling period. Watch List chemicals triclosan (TCS) and diclofenac (DIC) were also investigated; levels were relatively low, typically 10-100's ng L-1, however they were present at all sampling sites. The dataset is available as a resource for future chemical, and toxicological, sediment analysis comparisons.

Passive dosing: Assessing the toxicity of individual PAHs and recreated mixtures to the microalgae Raphidocelis subcapitata.

Risk assessment of hydrophobic organic compounds (HOCs) is difficult because maintaining a well-defined exposure during aquatic toxicity testing is challenging due to the limited water solubility and various loss processes such as volatilization, biodegradation and sorption. Passive dosing techniques help to overcome these challenges by providing a well-controlled and solvent-free exposure. In this study, the algal growth inhibition test (DIN EN ISO 8692) was converted into a miniaturized passive dosing setting. For this purpose, biocompatible O-rings were used as substance reservoirs and loaded with polycyclic aromatic hydrocarbons (PAHs). The growth inhibition of the microalgae Raphidocelis subcapitata induced by single PAHs (log KOW 3.24-5.91) was investigated. In addition, recreated PAH mixtures were tested representing field compositions of the pore water North Sea sediments. Some of the single PAHs revealed strong growth inhibiting effects on the algal growth, while the recreated mixture compositions had slightly lower effect on the growth inhibition in the highest concentrations. Overall, the toxicity of the PAHs generally increased with the maximum chemical activities (amax) of the PAHs and the inhibition data could be fitted with one maximum chemical activity response curve. Therefore, the miniaturized passive dosing approach appears as a promising practical and economical method that can be used for toxicity testing of the different trophic levels to improve comprehensive risk assessment.