Publications by authors named "I M Hedgecock"

Mercury is a toxic pollutant that poses risks for the human population, mainly by eating contaminated fish. Mercury is released into the atmosphere from a variety of anthropogenic activities, with levels of emissions and under policy controls that largely vary across the world, leading thus to different relative contributions to the environmental matrices. Establishing the exact sources of this contaminant in the environment is crucial to optimising the policies aimed at mitigating the exposure risks for specific populations or ecosystems.

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Article Synopsis
  • Mercury and its methylated form (MeHg) are toxic and primarily enter humans through seafood, with Mediterranean populations showing higher levels than other Europeans.
  • The Mediterranean has high MeHg concentrations due to efficient methylation processes, especially in low oxygen environments, with varying levels between Western and Eastern Mediterranean waters, affecting the local food web.
  • There is a significant need for monitoring Hg exposure in the Mediterranean to ensure public health, alongside a call for further research into Hg cycling in the region and its environmental impacts.
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The probability density function (PDF) of the time intervals between subsequent extreme events in atmospheric Hg concentration data series from different latitudes has been investigated. The Hg dynamic possesses a long-term memory autocorrelation function. Above a fixed threshold in the data, the PDFs of the interoccurrence time of the Hg data are well described by a Tsallis q-Exponential function.

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Redox conditions and organic matter control marine methylmercury (MeHg) production. The Black Sea is the world's largest and deepest anoxic basin and is thus ideal to study Hg species along the extended redox gradient. Here we present new dissolved Hg and MeHg data from the 2013 GEOTRACES MEDBlack cruise (GN04_leg2) that we integrated into a numerical 1-D model, to track the fate and dynamics of Hg and MeHg.

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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 the small-scale statistics, we found that the statistical properties of intermittency are identical to those obtained from the multifractal prediction in the Lagrangian frame for the velocity trajectory. The results suggest a possible universality of turbulence scaling.

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