The GOS4M Knowledge Hub (GOS4M-KH) is an operational integrated multi-model and multi-domain computational platform where scientist, decision-makers and citizens can discover, analyse and understand information for characterizing the linkages between impacts and effect of mercury contamination on Earth system and human health at different geographical and temporal scales. The GOS4M-KH was designed to evaluate the potential effectiveness of measures that nations may undertake to reduce the impact of mercury contamination on human health and ecosystems. The GOS4M-KH provides information on mercury fate, from sources to receptors, and in the future estimate of costs associated with policies. This platform includes analyses of complex chemo-physical atmospheric model outputs, bio-geochemical models to simulate processes in the ocean and ecological models to estimate mercury uptake by the trophic net. The first level macro-indicator is the Hg bioaccumulation in biological endpoints, which can be Hg in fish at upper trophic level, the second level is the Hg concentration in ambient air and precipitation samples. Long- term trends of macro-indicators can be analysed to assess the effectiveness of measures on medium-long term time period and eventually estimate associated socio-economic costs.
Mercury in the environment derives from both anthropogenic and natural sources. While natural sources cannot be controlled, the major anthropogenic source sectors are known, and potentially can be controlled. Mercury may be emitted to the atmosphere or released to land and water bodies. The most recent Global Mercury Assessment 2018 published by UN Environment reports the most recent emission estimate. A tool to visualize Global Mercury Emissions by Country and by Source Sector can be explored here .
Mercury concentrations in ambient air are monitored around the Globe, mostly within regional and global networks. The GOS4M is creating a partnership to provide access to these measurements. Two options are available for data access:
CTMs can simulate the fate of Hg in the atmosphere from an emission source to the final receptors, and therefore allow for a source-receptor (S-R) assessment. However, simulations of the Hg atmospheric cycle by CTMs have a temporal limit (few years), due to the fact Hg exchange at the interface of atmosphere with other compartments (soil and oceans), and is poorly characterized. Therefore, a CTM is simply not designed to simulate long-term Hg perturbation scenarios, beyond the temporal validity of the Hg exchange approximations.
The activity that prepared the design and development of deposition scenarios was the following:
Select emission database and model (New scenarios will be published when available)
It is possible to reduce Hg Anthropogenic emission from 12 source regions and 3 different industrial sectors. By clicking on a region, you can also customize the reduction by 3 industrial sectors. (De Simone et al. 2020)
The inputs are passed in near-real time to the statistical engine that calculates the change (%) on Hg deposition due to the selected emission reductions. If a reduction is not statistically significant (95% confidence interval) the deposition change is shown in blue. If reduction is significant for a given receptor the value is displayed in green.
Bar charts visually compare the current deposition scenario (Business as Usual) with the new customized scenario (New Scenario) for both Land and Ocean receptors.
Hg deposition changes are used as input for a six-box biogeochemical model adapted from Selin, 2014 . The model is run in near-real time to calculate the perturbation of the biogeochemical cycle Hg over a period of 30 years. Deposition and the concentrations of Hg over and within the ocean layers due to natural and legacy sources is also calculated.
Plots show the New Scenario compared to the Business As Usual and Deep-Green Scenario, this last considering a drastically 100% reduction of emission in all source regions.
The concentration of total Hg in biota is calculated, as variation (%) respect to the current value, from Hg burden within global ocean compartments as simulated by BioGeoChemical Model adapting the approach proposed by Schaefer et al., 2020