Spatial methane pattern in a deep freshwater lake: Relation to water depth and topography.

Freshwater lakes are regarded as important methane (CH) sources, accounting for ~20% of natural emission. To improve the assessment of the global greenhouse effect, it is necessary to consider spatial variability within lakes. Here, CH concentrations in the water column and sediment layers, as well as the sediment CH production potentials and diffusive fluxes, were studied in the littoral, intermediate, and profundal zones of the medium-sized (425 ha), deep (maximum depth 69.

Methane emissions from contrasting urban freshwaters: Rates, drivers, and a whole-city footprint.

Global urbanization trends impose major alterations on surface waters. This includes impacts on ecosystem functioning that can involve feedbacks on climate through changes in rates of greenhouse gas emissions. The combination of high nutrient supply and shallow depth typical of urban freshwaters is particularly conducive to high rates of methane (CH ) production and emission, suggesting a potentially important role in the global CH cycle.

Methanogens and Iron-Reducing Bacteria: the Overlooked Members of Mercury-Methylating Microbial Communities in Boreal Lakes.

Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems.

The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems: A latitudinal study across Europe.

Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes.