While mercury is a naturally occurring element, concentrations found in the atmosphere, surface waters and soils have increased as a result of human activities. Once in the environment, bacteria can convert elemental mercury into methylmercury, which can bioaccumulate and biomagnify in organisms. Methylmercury can cause significant impacts to human health, most notably causing harm to the nervous, digestive and immune systems. During the last decade there have been efforts to minimize anthropogenic sources of mercury. In 2013, the Minamata Convention on Mercury was adopted: a global treaty to protect human health and the environment from anthropogenic emissions of mercury.

A survey of 56 upland lake catchments in Ireland was conducted during summer 2017 to assess decadal changes in mercury. Water (n=56), soil (n=28), and sediment (n=24) samples were collected and analyzed for concentrations of total mercury (THg), and other chemical characteristics, including organic matter. The upland lakes are situated along the Western Irish coast, and are primarily influenced by long range transport and atmospheric deposition of pollutants rather than local emissions. Average THg (± SD) were 6.0 ng/L ± 4.1, 236.4 ng/g ± 93.3, and 51.5 ng/g ± 50.2 for water, soil and sediment respectively. Total Hg concentrations in water had the strongest relationship with SUVA-320, and THg in soil and sediment had a significant relationship with organic matter. Total Hg concentrations were statistically higher during the 2017 survey in comparison to a previous survey conducted in 2008.