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Objectives: Long-term meditation practice affects the brain's ability to sustain attention. However, how this occurs is not well understood. Electroencephalography (EEG) studies have found that during dichotic oddball listening tasks, experienced meditators displayed altered attention-related neural markers including theta phase synchronisation (TPS) and event-related potentials (ERP; P200 and P300) to target tones while meditating compared to resting, and compared to non-meditators after intensive meditation interventions. Research is yet to establish whether the changes in the aforementioned neural markers are trait changes which may be observable in meditators irrespective of practice setting. Method: The present study expanded on previous research by comparing EEG measures from a dichotic oddball task in a sample of community-based mindfulness meditators (n=22) to healthy controls with no meditation experience (n=22). To minimise state effects, neither group practiced meditation during / immediately prior to the EEG session. Results: No group differences were observed in behavioural performance or either the global amplitude or distribution of theta phase synchronisation, P200 or P300. Bayes Factor analysis suggested evidence against group differences for the P200 and P300. Conclusions: The results suggest that increased P200, P300 and TPS do not reflect trait-related changes in a community sample of mindfulness meditators. The present study used a larger sample size than previous research and power analayses suggested the study was suficiently powered to detect differences. These results add nuance to our understanding of which processes are affected by meditation and the amount of meditation required to generate differences in specific neural processes.

Field experiments were performed to obtain first-step estimates of the effects of selected chemical dispersant agents (OFC D-609 and Corexit 9550) on the behavior and retention of spilled crude oil in a shallow freshwater streambed environment in southcentral Alaska. Comparisons between experiments with and without prespill additions of dispersants to the oil included measurements of oil in sediment and water samples. Sediment and water contamination by oil was quantified by flame ionization detector capillary gas chromatography (FID-GC) as well as visual observations in the simulated streambed channel following the spill events. Inclusion of dispersants in the oil produced the intended result of enhancing dispersion of oil into the aqueous phase. However, distributions of oil in aqueous and sediment samples were controlled by interactions between a variety of factors including rheological properties of the oil (for example, oil/water interfacial surface tension values), particle size distributions of sediment matrices, exposure of sediment surfaces to oil, and in situ water flow characteristics at specific streambed channel sites. The results imply that use of chemical dispersants to mitigate effects of oil spills in freshwater streambed environments must include an understanding of the interplay between variables related to both the type of oil released and the specific streambed environment.

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