English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Mercury (Hg) is a toxic pollutant. In its elemental form, gaseous mercury has a long residence time in the atmosphere, up to a year, allowing it to be transported long distances from emission sources. Mercury can be emitted from natural sources such as volcanoes, or from anthropogenic sources, such as coal-fired powerplants. In addition, all sources of Hg on the Earth’s surface can re-emit it from land and sea back to the atmosphere, from which it is then redeposited. Mercury in the atmosphere is present in such low concentrations that it is not considered harmful. Once Hg enters the aquatic environment, however, it can undergo a series of biochemical transformations that convert a portion of the Hg originally present to methylmercury, a highly toxic organic form of mercury that accumulates in fish and birds. Many factors contribute to creation of methylmercury in aquatic ecosystems, including Hg availability, sediment and nutrient load, bacterial influence, and chemical conditions. In the United States, consumption of fish with high levels of methylmercury is the most common pathway for human exposure to Hg, leading the U.S. Environmental Protection Agency (EPA) to issue fish consumption advisories in every State (fig. 1). The EPA estimates that 50 percent of the Hg entering the atmosphere in the United States is emitted from coal-burning utility powerplants (U.S. Environmental Protection Agency, 2011a). An EPA rule, known as MATS (for Mercury and Air Toxics Standards), to reduce emissions of Hg and other toxic pollutants from powerplants, was signed in December 2011 (U.S. Environmental Protection Agency, 2012). The rule, which is currently under review, specifies limits for Hg and other toxic elements, such as arsenic (As), chromium (Cr), and nickel (Ni). MATS also places limits on emission of harmful acid gases, such as hydrochloric acid (HCl) and hydrofluoric acid (HF). These standards are the result of a 2010 detailed nationwide program by the EPA to sample stack emissions and thousands of shipments of coal to coal-burning powerplants (U.S. Environmental Protection Agency, 2011b,c). The United States is the only nation to have collected such detailed information for Hg in both its coal and its utility emissions.

Mercury and halogens in coal--Their role in determining mercury emissions from coal combustion