About this Research Topic
Mercury is a global pollutant that constitutes a significant threat to ecosystem viability and human health. Primary emissions are predominantly from anthropogenic sources. Once in the environment, mercury undergoes a series of complex transport and transformation processes. Central processes include long-range transport of mercury in the atmosphere, distribution and exchange of mercury between the atmosphere and Earth's terrestrial and aquatic surfaces, and bioaccumulation of mercury through food webs. Molecular-level chemical reactions, chemically and microbially mediated redox and methylation reactions, are critical drivers of regional and global cycling of mercury. The environmental processes of mercury at various scales are closely associated with the chemical forms of mercury present in different phases of the environment.
Technical developments and scientific discoveries during the last decade have significantly advanced our understanding of the biogeochemical cycling of mercury. Stable mercury isotope measurements have emerged as a powerful approach to both identify sources and study environmental processes of mercury. Combining isotope and flux measurements have advanced, and partly altered, our understanding of the processes governing the exchange of mercury between the atmosphere and terrestrial ecosystems. Advancements are synchrotron radiation X-ray spectroscopy and hyphenated chromatography-mass spectrometry techniques have significantly improved our understanding of the chemical speciation of mercury in the environment. Experimental and modeling studies have revealed new insights on molecular-level interactions of mercury with natural organic matter and mineral surfaces, and the importance of these interactions for the chemical speciation and transformation reactions of mercury. Novel environmental datasets on mercury have been generated from field studies (including the Atmosphere, Oceans, and Polar regions) and laboratory experiments and the implementation of these into new or improved global and regional models has helped constrain the magnitude of reservoirs and fluxes of mercury in the environment.
Despite significant advancements, our understanding of the complex biogeochemical processes governing mercury cycling remains incomplete, which causes uncertainties in the risk assessment of future environmental and human exposure to mercury. Large uncertainty exists in quantifying the response of mercury in biota, including humans, in different ecosystems following reductions in anthropogenic mercury emissions enforced under the UN Minamata Convention on mercury. The potential impact of climate and land-use change on future mercury cycling and exposure remains uncertain.
This Research Topic aims to cover novel studies of environmental chemistry processes of mercury at scales from molecular to global. We welcome original research papers, perspectives, and mini-reviews and we encourage submissions focusing on (but not limited to) the following themes:
· Cycling and chemical processes of mercury in the atmosphere
· Chemical reactions and processes in the control of mercury exchange between the atmosphere and the Oceans and terrestrial environments
· Chemical speciation of mercury in air, water, soil, and sediment - thermodynamic and kinetic aspects
· Advances in speciation analysis of mercury in environmental samples
· Mercury transformation reactions mediated via interactions with natural organic matter and mineral surfaces
· Tracking geochemical processes and transport of mercury through stable isotope studies
· Cellular uptake, bioaccumulation, and biomagnification of mercury through food webs
· Molecular modeling of mercury biogeochemical reactions
· Regional and global scale modeling of mercury biogeochemical cycling
Keywords: Mercury, Environmental Chemistry, Biogeochemical Cycling, Chemical Speciation
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