Methane emissions and microbial communities under differing flooding conditions and seasons in littoral wetlands of urban lake.

Wetlands are the largest natural sources of methane (CH4) emissions worldwide. Littoral wetlands of urban lakes represent an ecotone between aquatic and terrestrial ecosystems and are strongly influenced by water levels, environmental conditions, and anthropogenic activities. Despite these littoral zones being potential "hotspots" of CH4 emissions, the status of CH4 emissions therein and the role of physicochemical properties and microbial communities regulating these emissions remain unclear. This study compared the CH4 fluxes, physicochemical properties, and CH4-cycling microbial communities (methanogens and methanotrophs) of three zones (a non-flooded supralittoral zone, a semi-flooded eulittoral zone, and a flooded infralittoral zone) in the littoral wetlands of Lake Pipa, Jiangsu Province, China, for two seasons (summer and winter). The eulittoral zone was a CH4 source (median: 11.49 and 0.02 mg m-2 h-1 in summer and winter, respectively), whereas the supralittoral zone acted as a CH4 sink (median: -0.78 and -0.09 mg m-2 h-1 in summer and winter, respectively). The infralittoral zone shifted from CH4 sink to source between the summer (median: -10.65 mg m-2 h-1) and winter (median: 0.11 mg m-2 h-1). The analysis of the functional genes of methanogenesis (mcrA) and methanotrophy (pmoA) and path analysis showed that CH4 fluxes were strongly regulated by biotic factors (abundance of the mcrA gene and alpha diversity of CH4-cycling microbial communities) and abiotic factors (ammonia nitrogen, moisture, and soil organic carbon). In particular, biotic factors had a major influence on the variation in the CH4 flux, whereas abiotic factors had a minor influence. Our findings provide novel insights into the spatial and seasonal variations in CH4-cycling microbial communities and identify the key factors influencing CH4 fluxes in littoral wetlands. These results are important for managing nutrient inputs and regulating the hydrological regimes of urban lakes.

The metacognition of vigilance: Using self-scheduled breaks to improve sustained attention.

Attention fluctuates over time and is prone to fatigue. Thus, maintaining sustained attention is difficult. The goal of this article is to evaluate the metacognitive penetrability of attention by examining whether dynamic control over the pacing of an ongoing attention-demanding task helps individuals maintain attention. In Experiments 1 and 2, breaks were found to provide a small localized benefit in performance, but self-administered breaks were no more beneficial than ones imposed by the experimenter. Experiment 3 and 4 provided subjects full control over the onset of each trial. Subjects who self-paced stimuli now outperformed yoked controls who experienced the stimuli at a fixed rate and also those who experienced the exact same schedule as the self-pacing subjects. Experiment 5 replicated this set of findings and demonstrated that the benefit of self-pacing was diminished under dual-task conditions. Taken together, it appears that providing workers control over the pace of work allows them to coordinate the occurrence of cognitively demanding events with moments of heightened attention. However, the improvement in performance is subject to important boundary conditions on the parameters of control, does not diminish the vigilance decrement associated with fatigue, and is reduced under conditions in which attention is divided. (PsycInfo Database Record (c) 2024 APA, all rights reserved).