Quicksilver sinking.
Sediments sequestering
in the cold, dark deep.
Mercury pollution can cause huge environmental damage, accumulating in the food chain and causing harm to wildlife and humans. Reducing mercury pollution is vitally important and monitoring mercury levels in the environment is crucial for understanding how mercury travels through ecosystems. Yet measuring mercury levels isn’t always easy.
Recent research by Sanei et al. (2021) examined some of the most challenging areas to access on the planet – the deep-ocean trenches. The researchers collected sediment core samples from areas of the Kermadec and Atacama Trench Systems in the Pacific Ocean, over 6km below the surface in the hadal zone.
The researchers found that some areas were mercury hotspots, with levels 6–56 times higher than the previously inferred deep-ocean average. Whilst the hadal zone comprises only around 1% of the deep-ocean area, the findings suggest that it may account for 12–30% of the mercury estimate for the entire deep-ocean.
The findings raise serious questions about levels of mercury pollution in the oceans, highlighting the need for further research into deep-ocean mercury pollution. There is one bright spark in this worrying cold, dark news – mercury in trench sediments is effectively locked away, buried for millions of years as plate tectonics shifts it deep into the earth’s upper mantle.
Original research: http://dx.doi.org/10.1038/s41598-021-90459-1