Ian M. Hedgecock

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The lifetime of elemental mercury in the marine boundary layer(MBL) has been studied using AMCOTS (Atmospheric Mercury Chemistry Over The Sea), a box model of MBL photochemistry including aerosols and detailed mercury chemistry. Recently measured Hg(0)(g) oxidation reactions have been included, and the studies were performed as a function of latitude, time(More)
Mercury is a global pollutant that is ubiquitous in the environment. Enrichment of mercury in the biosphere as the result of human activities and subsequent production of methylmercury (MeHg) has resulted in elevated concentrations in fish, wildlife and marine mammals globally. Elemental mercury (Hg0) is the most common form of mercury in the atmosphere,(More)
Mercury (Hg) is a global pollutant since its predominant atmospheric form, elemental Hg, reacts relatively slowly with the more abundant atmospheric oxidants. Comprehensive knowledge on the details of the atmospheric Hg cycle is still lacking, and in particular, there is some uncertainty regarding the atmospherically relevant reduction-oxidation reactions(More)
Mass balance of contaminants can provide useful information on the processes that influence their concentrations in various environmental compartments. The most important sources, sinks and the equilibrium or non-equilibrium state of the contaminant in individual environmental compartments can also be identified. Using the latest mercury speciation data,(More)
Centuries of anthropogenic releases have resulted in a global legacy of mercury (Hg) contamination. Here we use a global model to quantify the impact of uncertainty in Hg atmospheric emissions and cycling on anthropogenic enrichment and discuss implications for future Hg levels. The plausibility of sensitivity simulations is evaluated against multiple(More)
This study is part of the Global Mercury Observation System (GMOS), a European FP7 project dedicated to the improvement and validation of mercury models to assist in establishing a global monitoring network and to support political decisions. One key question about the global mercury cycle is the efficiency of its removal out of the atmosphere into other(More)
Human activities have altered the biogeochemical cycle of mercury (Hg) since precolonial times, and anthropogenic activities will continue to perturb the natural cycle of Hg. Current estimates suggest the atmospheric burden is three to five times greater than precolonial times. Hg in the upper ocean is estimated to have doubled over the same period. The(More)
The emission, transport, deposition and eventual fate of mercury (Hg) in the Mediterranean area has been studied using a modified version of the Weather Research and Forecasting model coupled with Chemistry (WRF/Chem). This model version has been developed specifically with the aim to simulate the atmospheric processes determining atmospheric Hg emissions,(More)
The properties of mesoscale geophysical turbulence in an oceanic environment have been investigated through the Lagrangian statistics of sea surface temperature measured by a drifting buoy within the Agulhas return current, where strong temperature mixing produces locally sharp temperature gradients. By disentangling the large-scale forcing which affects(More)